kg cement bagging process youtube

china cement bag machine, cement bag machine manufacturers, suppliers, price

A complete one stop sourcing platform for packaging & printing suppliers, manufacturers and factories, we are big enough to be able to offer an expanded product line of labels and packaging design capabilities yet small enough to be able to provide the personal service that is still so very important in business today. Not only do we offer high quality labels and packaging, we offer valuable solutions. Technology is forever changing, and so are our suppliers and Cement Bag Machine who always keep their standards high and has fostered innovation in everything they do. From their strategies and end products to how that are preserving and protecting the environment. We provide global buyers with a complete resource for their packaging needs such as cheap China Cement Bag Machine. You can also find other packaging and printing solutions such as valve bag packing machine, cement packing machine, valve bag filling machine with competitive price. Let us help you to utilize our value-added products offerings to meet the demanding needs of your local market and customers.

cement packing machine | buildings materials | concetti

The bagging of dry mortars and cement-based building products can be considered one of the most smashing Concetti achievements: over the last few years, our Company has in fact given to numerous Clients the possibility to change from pre-made valve bags to PE bags obtained from a tubular reel, preventing their batches to suffer any leakage and ensuring a cleaner and healthier environment for the operators, while still ensuring a nicely pillow-shaped bag and a very stable pallet.It is a successful packaging revolution that the Concetti company didnt miss a chance to promote and lead.

Thanks to our special auger feeding system, produced with a higher thickness and anti-abrasive coating to guarantee a longer durability and effectiveness, these products, often a blend of cement, little stones, gravel and sand, are fed to our one or two net weighers (NET/CC) and from there into the bag-holder of our Continua FFS machine.

In this type of machine, along with the usual vibration devices and option for corner sealing to improve the products distribution inside the bag, we find the Concetti patented handle-maker device, capable of creating one or two handles on the bag short sides to allow a better transportation and manipulation of the bag.

The full bags, ranging from 10 to 40 kg, are conveyed and treated along the way thanks to some specific Concetti vibrating and pressing devices to the palletising unit;For this family of product, the ideal choice is a fed-from-above palletisercomplete with bag flatting units and bag orientating device.

For the Clients who need to stick with flat or gusseted open-mouth paper bags, the Concetti solution for concrete premixes and dry mortars isnt less brilliant: our IMFbagging machine class can work bags ranging from 5 to 20 kg, featuring several different closing systems and remarkable capacities, even if the use de-aeration probes is required.

The final result of this innovative packaging process has turned out to be so brilliant that some world-leading industrial Groups like Ameren, Hanson, Remix and Draco have decided to add a combination of several Concetti automatic bagging lines to their production process, enjoying the advantages of a top-level technology and the possibility to work in a cleaner and tidier environment.

bagging equipment | bag filling machines - choice bagging equipment

Many of our customers are acquiring bagging equipment for the first time, and appreciate the in-depth experience we can offer. If you are evaluating the best type of bagging solution for your product packing requirements, the information below is an excellent place to start.

Valve bag fillers are well suited for both manual and automated applications ranging from building products and minerals to seed and food products. Because the filling spout inserts into the opening of the bag, the product flow is totally enclosed during the filling process controlling potential spillage and dust emissions.

There are four ways to feed product into a valve bag filler: pressurized air, auger, impeller, and gravity. They are frequently used to bag products such as cement, concrete, minerals, fertilizer, resins, chemicals, flour, starch, feed, salt, sugar, and wood products.

Valve bags are pre-formed bags with a fill spout, or valve, in one corner to allow for fast and easy filling. The valve is made with an inner flap which functions as a self-closing check valve (no secondary sealing step required) after filling. More valve bags are used worldwide than any other bag style. These bags can be manufactured with a variety of styles of valve sleeves to meet the needs of the specific application including poly sleeves, tuck-in sleeves, heat seal and sonic-seal sleeves. Valve bags can be equipped with PE-free film or PE-liners where enhanced moisture protection is needed.

Open mouth bag fillers are very simple, fast-filling and easy-filling of both food grade and non-food grade materials. They are well suited for both manual and automated applications. Open mouth bag filling systems are ideal for hard to handle materials or products that are dry, free flowing and minimally dusty ranging from landscaping materials, feed, seed, fertilizer, and food products.

There are two classes of open mouth bag fillers: gross weigh (fill and weigh simultaneously) and net weigh (pre-weigh and fill as a secondary step). Within those 2 classes of fillers, each can be fed by one of the following types of feed systems: gravity, vibratory pan fed, belt fed and auger fed.

Open mouth bags are pre-formed bags that arrive from the factory closed on one end and open on the other end. The closed end is typically the end of the bag that the end user will recognize as the top of the bag. The factory-made seal or closure of the top of the bag makes it more visually appealing.

Open mouth bag bags can be manufactured in a variety of different styles and constructions. There are pinch bottom (paper) bags, sewn open mouth (both paper and plastic) and heat sealed (film) bags. Depending on the construction of the bag, open mouth bags are closed by a process of sewing, heat sealing or gluing.

Sewn open mouth bags are the preferred choice for agricultural, feed and seed applications. They are economical, tough, and can easily be opened with a pull tab chord at the top. Open mouth bags can be manufactured with PE-free film or PE-liners where enhanced moisture protection is needed.

Bulk bag fillers are a very efficient, fast filling and economical method of packaging both agricultural and industrial materials. They can be designed to operate as either manual or automated systems. Primarily designed for agricultural and industrial usage, bulk bags are commonly used to package materials like fertilizer, food grains, seeds, flour, sugar, salt, animal feed, industrial minerals and industrial chemicals.

There are two classes of bulk bag fillers: suspended hanging style fillers and bottom supported platform style fillers. Either style can be designed with a gross weigh (fill and weigh simultaneously) or net weigh (pre-weigh and fill as a secondary step) type of weighing scale. Most bulk bag fillers are fed by either a gravity flow gate (ex. slide-gate or butterfly valve), rotary valve or an auger feeder.

Bbuil bag and bulk bag filler machineulk Bags Offer Several Advantages Over Other Types of Packaging. They improve plant safety by reducing the amount of physical handling required to load and unload the packaged material since they are designed to be moved by mechanical means (fork truck, pallet jack, or hoist).

Bulk bags or FIBCs (Flexible Intermediate Bulk Containers) are large woven polypropylene bags capable of storing and transporting the heavy loads of dry flowable bulk materials weighing up to 4,000 lb. (1,818 KG). Bulk bags are designed to take a high amount of abuse that would quickly destroy other types of packaging. There are several bag designs available: spout top, duffel top or open top and flat bottom, discharge spout or port-hole bottom. Bag Style selection will depend on the requirements of the application.

The operating cost per container is typically reduced when bulk bags are used. Filling, lifting, opening, dumping, and disposal of forty, 50-lb paper bags is in most cases more costly and time consuming than positioning and opening one single 2000-lb. bulk bag. Bulk bags can also be handled, transported and stored without pallets because integrated lifting loops are built into the upper corners of each bag further adding to cost savings and reducing the disposal costs of used packaging materials.

Additionally, bag capacity increases, the empty bag weight as a percentage of bulk material weight transported decreases. This means more material can be shipped with less packaging for the same cost. Bulk bags can also be positioned and stacked more efficiently to heights exceeding that of smaller bags, maximizing shipping container usage and storage facility space.

Often customers come to us with a specific bag filling machine in mind, but after a few minutes of conversation with us about what they want to accomplish in their production line, a different bagging machine is recommended, often a less costly solution. This post will describe the three basic types of industrial and agricultural []

Its not surprising that pressure is an important factor in bagging dry bulk powders; for a cement bagging machine or concrete bagging machine it is especially critical to speedand weight accuracy. This article explains how one customer significantly improved productivity and accuracy by following the fundamentals. Our Model 730 Pressure Flow Air Packer is one []

the importance of pressure for cement bagging machine performance - choice bagging equipment

Its not surprising that pressure is an important factor in bagging dry bulk powders; for a cement bagging machine or concrete bagging machine it is especially critical to speedand weight accuracy. This article explains how one customer significantly improved productivity and accuracy by following the fundamentals.

Our Model 730 Pressure Flow Air Packer is one of the most popular concrete and cement bagging machines on the market today. We recently installed a pair of Model 730 Pressure Flow Air Packers to bag concrete and mortar mixes at a dry mix plant in Montreal, Canada. Shortly after installation, the customer called to say that the weight accuracy was not within weight tolerance and also that the concrete bagging rate was much slower than expected. Additionally, the machine is designed to empty out completely at the end of a production run but for some reason he reported that when these machines would empty down to its last 2-3 bags of material, it would completely stop flowing out of the machines. This was a problem because the customer made very small batches of product and had very frequent product grade changeovers that required opening and completely cleaning the interior of the machine between batches. This meant that nearly ever batch, the customer would have to open the chamber and dump 100-150 pounds of material creating waste and extra cleanup time. Our customer asked that I come to the plant to evaluate the machines and determine whether they had some kind of mechanical or electrical problem. The presumption was that there must be some sort of internal problems with the filling machines.

Upon arrival to the plant, it was quickly apparent that there was a problem. Although in that moment, bag weight accuracy was within specification, the bags were taking unusually long to fill. All of the mechanics of the machine and the controls were operating as designed, but product was taking too much time to load into the bag. Looking at the pressure gauge on the side of the pressure gauge on the side of the chamber, I noticed that it registered no pressure. So I began a diagnostic analysis of the chamber and its pressurizing system which consisted of the pressurizing chamber, the air pad and the blower control valve that regulating the inlet of high volume, low pressure air into the machine.

I looked for obstructions in the flow of air to the air pad the fluidized the material and also the disseminator that provided the pressurizing air to drive the air with force down and out of the machine. Neither had any obstructions but neither were flowing the amount of air needed to fill a bag properly.

Then I asked to see the low pressure blowers that were supplied with the machines. Our blowers are specially designed to provide high volume, low pressure air to provide the pressurizing and fluidizing air required for the machines to operate properly. At this point, I learned that the blowers had not been installed. Instead the old set of blowers from the previous set of baggers that ours had replaced were left in place and used to feed air to our machines. I asked to see them.

The first thing I noticed is that they were exceptionally old and smaller than the blowers that we had provided. Additionally, the relief valves that prevented the old blowers from over-pressuring when not filling bags had been modified by someone at the plant to vent off half of the air that the blowers could generate before that air was even transferred over to our machines.

I asked what it would take to shut the line down to exchange the old blowers out for the new ones. This was not possible as the customer was in the middle of a campaign and this was there busy season. I told the customer that without knowing the exact condition of the old blowers there would be no way to assure that we could generate the volume of air and pressure required to achieve the results he was looking for.

He asked me to see what I could do. I went back to look at the blowers. I noticed that the reason the relief valves had been modified was that they were worn out and someone had done their best to rig them to keep them going. Replacing them was the first order of business. I asked to see the pumps we had provided. I Compared the relief valves on our pumps to the relief valves on the old pumps. Fortunately, with some simple plumbing changes, our pressure relief valves able to be retrofitted to the old blowers. Once I replaced the reliefs, we were able hold steady pressure at 5 PSI although the volume was still much slower than optimal.

I then switched my attention to the Model 730s. They were designed to divide the flow of incoming air from the low pressure blowers and direct the bulk of the air to the upper half of the pressurizing chamber to utilize as pressurizing air and the remainder down to the bottom of the machine to provide fluidizing air to lift and convey the material into the bag. Realizing that the old pumps were not capable of generating the volume of air required to both pressurize and fluidize simultaneously, I shut off completely the pressurizing air and directed the entire air flow to the air pad to fluidize the material. Although this solution had its own drawbacks, the machines were now capable of filling bags at a respectable pace and bag weight accuracy was improved.

We began to run and check weigh all of the bags coming down the line to the bag palletizing system. We would see that the bag weights would begin good but then the weights would begin to drift after a period of time. At this point, I asked what the minimum level of product was required to be maintained above the machine for it to be allowed to run. I was told that there was no minimum standard. I then asked what type of level controls were in the bin to indicate to the operator how much material was in the bin at a given time. I was told there were level sensors in the bin but they were not visible to the machine operator and were only used to signal the blending system when there was room in the bin for the next batch of product.

I told the client that especially without the blower capable of generating pressurizing air to generate artificial head pressure in the filling machine, that maintaining product head pressure of product above the machine would be imperative to maintaining good filling speed and weight accuracy. Varying head pressure is very important as changing head pressure changes how the product flows and how the product flows (and at what rate and consistency) directly affects bag weight accuracy. I then trained the system operators to manually monitor the level of product in the supply bin and to stop filling bags when the level of product in the bin got low. This did not cause a production problem as the Model 730s were capable of bagging much faster than the blending process was able to make new product.

With these changes in place and the customer now aware of how to compensate for the lack of air pressure and head pressure, the results improved dramatically. Bag fill times averaged 5 seconds per bag per spout on 30 KG (66 Lb) bags and weight tolerance averaged +/- .25-.5% depending on the grade of material packaged.

Paying attention to how to properly install and setup a cement bagging machine (or any other application) is critical. Installing a bagging machine is not simply a matter of sliding it under a supply bin and connecting it to utilities. It must be supplied with a good and consistent flow of material and especially if this is not possible, then assuring that the machine has good access to an adequate air supply is even more critical. And if these fundamentals are not fully understood, then it is advisable toseek the help and advice of someone who can help get the fundamentals right. Failing to pay attention to the details or work with someone who will can be costly and cause results to suffer.

Often customers come to us with a specific bag filling machine in mind, but after a few minutes of conversation with us about what they want to accomplish in their production line, a different bagging machine is recommended, often a less costly solution. This post will describe the three basic types of industrial and agricultural []

Its not surprising that pressure is an important factor in bagging dry bulk powders; for a cement bagging machine or concrete bagging machine it is especially critical to speedand weight accuracy. This article explains how one customer significantly improved productivity and accuracy by following the fundamentals. Our Model 730 Pressure Flow Air Packer is one []

cement bagging machines, cement packing machines

The automated system illustratedbelow is an example of a complete line built with our cement/grout bagging and packaging equipment. This line is equipped with an impeller valve packer, a robotic bagpalletizer and a stretch hooder. No matter the scope of your project, Premier Tech manufactures cement bagging and packaging equipment for small- and large-scale productions.

Valve bag sealers, valve bag applicators and robotic bag handling systems from STONEPAK are available for complete automation. If you use several bag fillers, bag placers, bag sealers and a robot applicator, STONEPAKs integrated packer is a great choice: it consists of a single HMI that controls and monitors the entire bagging system. Premier Tech also offers conventional palletizing systems and a rotary arm stretch wrapping machine. Cement bagging and packaging equipment from Premier Tech are accurate, fast and reliable.

step-by-step earthbag building : 9 steps (with pictures) - instructables

This Instructable explains each main step of construction for building vertical earthbag walls. Videos on my Earthbag Natural Building YouTube channel demonstrate the process. For those who dont know, earthbag building uses polypropylene rice bags or feed bags filled with soil or insulation that are stacked like masonry and tamped flat. Barbed wire between courses keeps bags from slipping and adds tensile strength. The final plastered walls look just like adobe structures. Thousands of people are now building with bags to create their dream homes, home offices, shops, resorts, rootcellars, storm cellars and survival shelters. Non-profit organizations are building schools, orphanages, emergency shelters and other structures. I got involved with earthbag building when the Indian Ocean tsunami hit Southeast Asia in December, 2004. As the director of Builders Without Borders at that time, I searched all available affordable, sustainable building methods and decided building with bags was the most practical. Theyre flood resistant (used for flood control), earthquake resistant (passed an ICBO shake table test), bullet and blast resistant (used for military bunkers), and now engineer and code approved plans are available. Just search for earthbag house plans on the Internet. Our websites at EarthbagBuilding.com and Earthbag Building Blog explain just about everything you need to know for free. And if youre looking for house plans, my Earthbag House Plans site features over 110 sustainable plans that can be purchased through Dream Green Homes. My new Earthbag Building Guide and Earthbag Building DVD are now available. The following instructions assume you have cleared and leveled the site, removed topsoil, positioned fill soil around the building site to minimize work, dug a trench to stable subsoil, put about 12 of gravel in the trench, and added corner guides and stringlines.

Step 1. Tools and materials (listed left to right): woven polypropylene bags (about 18 x 30), bucket chute (4-gallon bucket with bottom cut off), 4 or 5 heavy duty 2-gallon cement buckets, stringline, metal chisel and scrap steel for cutting barbed wire (or bolt cutters), hammer, sheetmetal slider (about 13 x 16), 15 gauge galvanized wire, knife, wire cutters, tape measure, 4-point barbed wire, corner guide, grub hoe or grape hoe, level, tampers, bundle 500 bags, shovel.

Step 2. Fill the bags: Use the same number of buckets for each bag. Fill bags approximately 90% full, leaving just enough to sew the bags closed. This technique ensures each bag is filled to capacity to save bags, and each bag is the same size, which helps keep walls level.First Foundation Bag

Step 3. Sew or stitch the bags closed: fold the bag end over; use 15 gauge wire about 9 long with one end cut at a sharp angle; make one stitch on one side and bend the end over; make a stitch in the center and pull the corner over; make a stitch in the other corner and pull the corner over; poke the remaining wire into the earthbag. This technique facilitates handling, prevents spills and enables bags to be filled to capacity.Stitching Bags Closed

Step 4. Lower courses: place gravel-filled bags (double-bagged for strength) working from the corners and openings to the center. Align bags to stringline; tamp the bags solid and level after the course is complete. Always put tops of bags (the ends youve sewn closed) butted against other bags to prevent spillage. Maintain a running bond as in masonry.Second Foundation Bag

Step 6. Use a sheetmetal slider to place additional courses so bags do not snag on the barbed wire: fill the bags on the slider; sew the end closed; tilt the bag into position and push it against the previous bag. After the bag is aligned, hold the end of the bag and jerk the slider out. Continue with gravel-filled bags until you are safely above the height where moisture can cause damage.First Bag Second Course

Step 7. Repeat the process using earth-filled bags for upper courses, but with a few minor changes: turn bags inside out to avoid protruding corners; use lightly moistened soil; lightly tamp the contents after each bucket of soil is added; pre-tamp each bag after it is aligned in position. This last step lengthens each bag to ensure good overlap.First Earth Filled BagTamping First Earth Filled Bag

Step 8. Make custom-sized bags to fill odd-sized spaces: measure the opening; fill the bag to the approximate level; cut off excess bag material; fold each side of the end toward the center and tuck under the bag; place the bag in the wall.

Step 9. Tamping: Tamp earthbags solid and level after each course is complete. Tamp the high points first. Once the wall is approximately level, evenly tamp the entire wall several times as you continually move the tamper so as not to create low spots.Tamping First Course of Earth Filled Bags Repeat the process for the remainder of the walls, adding doors and windows as you go. Check often to keep walls plumb and level. If you like this Instructable, please check out my other one that covers almost every detail for building a roundhouse: How to Build an Earthbag Roundhouse Owen Geiger is the former director of Builders Without Borders, a Mother Earth News Green Home Adviser, The Last Straw Journal Correspondent and the director of the Geiger Research Institute of Sustainable Building . Photos and videos by Got Chankamol

What about building with sand bags in west Africa, on sandy ground, and to resist rising sea levels and rainy season. What would be mixed with sand? Foundations? How to do a raised floor? Is there some info on this pls?

First of all, thank you so much for all of this information! My husband and I are in the process of researching building one of your homes. Are home would be built in Northern Wisconsin, so we really like the solar pit design. Since, this plan is free on your site (thank you by the way!) I wasn't sure who/ how to contact the right person if I had a question. I know since we get heavy snow fall here that we'll have to work with someone in our area to make sure it is code friendly. I just wanted to ask you coding permitting do you think it would be possible to add a large skylight to each of the bedrooms and one small one in the bathrooms? Thanks again!

The electrical wires go in the recesses between earthbags. Electrical boxes are attached to wood anchors embedded between earthbags. This and all other details are covered in my earthbag ebook with photos of each step:http://www.naturalbuildingblog.com/owens-book-dvd/

Thank you! This will be a weekend project.My plan involves:Hobbit House with deck on roof. Guest rooms will be added later on.Earth bag fence around perimeter with pvc pipe along the top (keeps coyotes out).Water tankCellarA work shopA garageSolar panels, fenced off so my crazy dog can't get near them.All on a couple acres. Also, big enough for my crazy dog to run around.

Please check this project in Almafraq, Jordanhttps://www.facebook.com/groups/1099689303401001/Its earth bags house under construction first of its type in the country.We are planning also other eco- and permaculture systems like aquaponics, rocket stove mass heater ..We lack of local experts though things are going forward.I have a question regarding the bags plastic after construction: should it be removed before butting the clay on the walls and how?

Do not damage the bags. They add lots of strength. Watch my free videos on YouTube to see each step of construction including the basic process of plastering the bags. The plaster 'anchors' or bonds itself in the recesses between bags. The 2nd coat covers the bags entirely. Plaster mesh will help bonding but is not required if money is limited.Email me if you have other questions. natural houses @ [gmail.com]Sorry, I can't open facebook.

Hello, I am in northern Wisconsin and would like to build an earthbag small home. The soil on my land is all sand. I would like to use the sand to fill the bags and build in the side of a hill. Would this work for my cold winter climate? What do you suggest for insulation?

Sand bags shift and become unstable without some type of binder. This is explained in my earthbag ebook and also our websites. Clay is the lowest cost binder. Mixing clay with sand adds extra time and labor. Personally, I would buy good quality soil such as road base that can be put into the bags immediately as is.

Sand bags shift and become unstable without some type of binder. This is explained in my earthbag ebook and also our websites. Clay is the lowest cost binder. Mixing clay with sand adds extra time and labor. Personally, I would buy good quality soil such as road base that can be put into the bags immediately as is.

hello, would scoria filled bags for the foundation be structurally sound for high seismic areas? i have access to scoria. I'd be building a rubble trench with the small rock and gravel on the land (limestone and dolomite) I have a caliche clay sand soil that tamps into pretty solid bag. Would the lightweight scoria be compromised under the earth filled bags? Thank you...

Hello! I'm fairly new to the idea of the earthbag homes but after spending 2 years trying to unsuccessfully find a 4 bedroom home and having an increasing need to lessen our cabon footprint, we stumbled on the earthbag home via another person sharing the interest on facebook. We began to research but there is so much information out here that we really don't know where to start. We have 4 children and 2 adults, we were hoping to build a 4 bedroom, 2 bathroom, 2 level home (basement and 1st floor...possibly a survival shelter on the same level as the basement or lower. I've looked at plans online but again I'm a true newbie so I'm pretty lost. Is there a general direction you would point someone like me to begin looking? Can you give me an estimate on what type of money we would be spending for a structure so large? Are there companies that would build this for you? (i'm not really handy @ major DIY...bows and ribbons yes...building...no) Really any help in the right direction would be greatly appreciated. Thanks much!! :)

My long comment got deleted. Here's the short version. Check out my earthbag Instructable first: https://www.instructables.com/id/Step-by-Step-Earthbag-Building/Then get my ebook and DVD if you're still serious:http://www.naturalbuildingblog.com/owens-book-dvd/All of my plans are here: https://earthbagplans.wordpress.com/Earthbag is a DIY building method unless you have cheap labor.In Ohio and other cold climates I would use strawbale and post and beam like this: http://www.naturalbuildingblog.com/?s=post+and+beam+hardware

how to calculate number of bricks, cement and sand for brickwork? (calculator)

Note The above volume is in a wet condition that means we need 0.2305 cement mortar in mixed condition (after adding water). In order to find the dry volume, we need to multiply 33 % as bulkage of sand.

Please note that the information in Civilology is designed to provide general information on the topics presented. The information provided should not be used as a substitute for professional services.

concrete calculator - ultimate concrete estimation tool - inch calculator

So far, weve covered how to calculate yards, but if your project is small, you can use pre-mixed bags of concrete. Pre-mixed bags are sold by companies like Quikrete or Sakrete, and come in 40-pound, 60-pound, or 80-pound sizes.

Using bags can be easier than ready-mix when you have many small pours or a small project where a truck is not practical or cost-effective. But, keep in mind that mixing bags on-site can become difficult if youre pouring a large slab or many footings.

Ready-mix concrete typically starts around $115 per yard but could cost upwards of $150 or more, depending on the mix and your location. Consider that there will likely be additional fees for ready-mix for smaller projects, such as delivery or short-load fees.[3]

A standard brush finish will likely be on the low end of the price range, while a decorative finish with coloring will be on the high end of the range. Consider getting a professional concrete installation estimate from contractors in your area for a more accurate cost estimate.

Much of the work to pour concrete is done before the truck even arrives at the project. Youll need to measure and lay out the site and install forms to create the edges of a slab or contain a footing.

Use rebar or fiber/steel mesh to reinforce the concrete and to prevent cracking in the future. Use our rebar material and reinforcing mesh calculators to estimate the amount of reinforcement needed for your project.

introduction to vacuum bagging | explore composites!

This article is about how to make vacuum bags for use with composites. Well start with what vacuum is and then discuss how to harness the heavy ol atmosphere to clamp your stuff. Specific details about how to do it come next, followed by some common problems and how to avoid them.

Vacuum bags are a common and effective way to put pressure on composite materials. The pressure is huge compared to clamps or weights and uniform. It works because the earths atmosphere is actually kind of heavy and pushes down on everything at around 14 pounds per square inch! Were used to it (and built for it) of course so we dont notice.

A vacuum pump and bag allow us to remove the air from an enclosed volume. Without the inside air pushing back we get the full weight of the atmosphere bearing down on whatever is in the bag from all sides! You have to see it to get a feel for how much pressure you can bring down just with a sheet of plastic. For a 1 square foot area you have 12 x 12 = 144 in^2 and multiply that by 14 psi and you have 2016 lbs of atmosphere pushing down on that one square foot! Try doing that with lead weights or a bunch of clamps!

With the great power of vacuum bagging come plenty of challenges. The bag has to be relatively leak-free and the plastic cant press unevenly on the work-piece or it can do serious damage. Its pretty easy to use the bag to pop itself because plastic film isnt that strong. Lots of other things can happen Over decades of development, people have come up with lots of great products and techniques to make the process easy and effective. Im going to share what I know here an hopefully spare you some of the mistakes I have made.

Ill start with a story of my first vacuum bagging experience probably in 2004 or so. Having done plenty of hand layup and glassing of wood with epoxy and fiberglass cloth, I was attempting my first part on a mold with foam core. It was a cylinder section about two feet long and the core wasnt going to bend over it and stay without some pressure. This was before I knew about kerfed core or thermoforming. I read an article about vacuum bagging and had some materials Id ordered. It was going to be awesome!

First off, I put tacky tape (aka sealant tape, bag mastic and dum dum) around the outside of my mold a few inches beyond the edge of the part and then I laminated one skin of glass and placed the foam on the part all gooped up with resin. Then I put some peel ply on top and some breather fabric. The foam wasnt bending into place so I just laid them over the top and figured Id work it all into place as the bag came down. I placed a big sheet of vacuum bag film over all of it and started to stick it down to the tacky tape around the mold. This is when I started having problems

Some resin had run out and gotten on the tacky tape so the bag wouldnt stick in a few places. The bag also got all bunchy and there seemed to be more bag edge than tape except in one corner where there wasnt enough! I finally got it all kind-of-stuck and put a piece of plastic tube that was connected to the vacuum pump inside the bag through a hole that I wadded up with more tacky tape. I turned on the pump and waited.

Slowly the bag shrunk down and crinkled into place and I worked the foam down over the surface of the cylindrical mold. I was only 1/8 core and it went pretty easily. The bag kept popping up off the tacky tape in the spots where resin got under and I held it down with Duct tape and lots more tacky tape. One area there wasnt enough bag to go into the corner and it stretched and pulled tight and the tacky tape started coming undone. I couldnt stretch the bag or pull more from somewhere else so I let it do its thing. I also had to keep pulling the bag out of the end of the vacuum tube where it wanted badly to get sucked in. By now the resin was starting to gel and I was not at all sure that things would be ok. I cleaned up, crossed my fingers and came back a few hours later.

Turns out I had made ALL the mistakes, and I the part I demolded was an expensive heap of trash. The core had popped up, and the bleeder fabric was hopelessly stuck to the peel ply which was bunched up with resin chunks and wanted very much to remain attached to the foam. My corner where the bag wouldnt come down fully was all puddled with resin and the glass had pulled completely away from the mold. Everything was full of air and the hose to the vacuum pump had filled up with resin fortunately it didnt reach the pump!

It wouldnt be for another year or so that I would get my first real schooling in vacuum bagging. I got a job working for Goetz Custom Boats building carbon fiber racing sailboats and just about every piece of those boats was vacuum bagged! I was rapidly educated in vacuum bagging basics and Im still building on that education to this day.

Youre also going to need a hose to connect the bag to the pump. For many things polyethylene hose is great. Its cheap and stiff and wont collapse under vacuum. This is the standard for vacuum infusion and can be bough at hardware stores or composite material suppliers. If youre going to connect it right to your pump, either be very careful or use a catch pot as described below.

Generally you should use quick connect fittings only where they dont run a huge risk of getting gooped up with resin. From the pump to a catch pot or a manifold is great. I use the ISO-B style fittings (see picture) for small stuff. Brass is the best mix of economy and not rusting stainless is nice but expensive. For room temperature use, you have many options: heavy duty air hose, hydraulic hose, etc. but for cooking it is best to buy purpose-designed cook hoses they arent crazy expensive and hose-failure is a silly way to lose an expensive part.

I strongly recommend that you use a catch pot, especially with infusion or big wet layups. This can be a pressure pot with the hose coming from the bag dumping into the pot and the hose to the pump sucking air from the pot but not resin! If you put a bucket inside the catch-pot (and mold release in there too as backup) you can keep any resin from gooping up your nice pot.

If you dont want to spring for a fancy pot you can make catch pots from PVC pipe for about $20 US each. I made some of these for small infusions and wet-layup and they lasted for years. Brass barbed hose fittings will glue nicely into PVC pipe caps with pipe cement. When in doubt add some bag sealant tape! Best to tap the holes, but if not itll probably be ok if you drill holes slightly undersized and make the threads engage. Vacuum will tend to pull things tighter rather than blow it up which is handy!

The sketch shows my basic design which is far from perfect but worked for me. The pipe is 4 PVC with a cap glued on and some barbed hose fittings of the right size for the polyethylene hose that works best for disposable infusion and wet-layup hose. No sense using expensive quick-connects on a catch pot inlet though you can add multiple inlets and it does make sense to use whatever type of fitting you use for vacuum hoses to connect the pot to the pump. The base is a piece of PVC (or metal, or something vacuum-tight) that is held on with tacky tape (yellow). If you overflow your job and get resin in the pot, you can bust open the base and clean it out after the resin cures or you can just leave it if its a small amount. Either way mission accomplished no resin in the pump.

The basic materials you will need are bag film and sealant tape (AKA bag mastic, tacky tape, etc.) Both of these come on a roll, and my advice is to be really fussy about keeping them on their rolls and well protected before use. A tiny hole in vacuum bagging film can totally ruin your day, and is extremely hard to find without the right approach and equipment.

Bag film comes in a wide variety of materials, thicknesses, widths, and stretchynesses. If you are curing at high heat, you will have to make sure it is rated for the temperature. My advice is to start with a standard nylon bagging film unless you have a very compelling reason to do otherwise. There are several types of high elongation bag films (Stretchlon by Airtech is an example) that are described as making vacuum bagging easier. This material can be useful in certain situations, but it brings up a whole bunch of other potential problems, and forgives or appears to forgive several errors in technique that you are better off learning how to deal with the right way. The fact that it stretches makes it easy to conform to a complex part, but the very act of stretching can slide material around under the bag and will decrease the available pressure that the bag can exert on the part. Do not use the stretchy bag for infusion all kinds of issues there! Go simple and get the pleating details square in your head and then try out the fancy stuff.

In order to distribute vacuum under your bag you will need some type of breather fabric. This is usually a soft non-woven sheet of fuzzy stuff. It comes in a variety of thicknesses. Id suggest you stick to the thin stuff (4oz, 150g, or so) because it is easier to use and wont suck up a ton of resin. You will need something to keep this breather (also called bleeder because it sucks up excess resin really it has two jobs!) from sticking to your part. Generally this is either a coated peel ply (usually green or blue) that has a release agent on it and peels off your part easily or a perforated release film.

Peel ply is made of nylon, polyester and other coated fabrics but mostly nylon. It goes right against the part to provide a clean surface to use for secondary bonding or finishing. Coated peel plies are great and release very easily. For infusion, a coated peel ply can be used to help remove resin coated surface-flow media. For wet-layup or pre-preg if you are using an un-coated nylon peel ply it is best (ok, necessary!) to use release film. This will throttle the amount of resin that the breather/bleeder can suck up and will make it way to separate the breather cloth exposing your peel-ply covered part.

Release film does two things it controls the flow of resin into the bleeder while allowing air to escape. It also allows you to remove the resin-clogged breather easily after the part is cured. There are many different types of perforated (and un-perforated for you autoclave users) release films with different size perforations with different spacing. The most common is P3 which is good for wet layup and infusion if youre infusion is one that benefits from release film.

One time when I was young(er) and foolish(er) I didnt use release film on a large part and spent several days with pliers pulling peel ply and resin-soaked breather off my part. That sucked! Avoid that.

Sealant tape is what youll use to stick the bag down to the mold, or to the part on which you are adding vacuum bagged laminate. It is like Silly Putty in tape form but stickier and comes on rolls with paper backing between the layers. If you buy a bunch of rolls or a case of sealant tape, be very careful to keep it cool and to keep the rolls stacked up neatly and aligned with the cardboard tubes. I once had some rolls of sealant tape in a box in my car during the summer on the way to a job. They shared a cardboard box with some other materials I planned on using. In a surprisingly short time several rolls became one gooey mass all over all the other things. It was a mess and a waste of expensive tape and I didnt get my job done that day a learning experience!

There are several different types of sealant tape with different heat ratings. For low temperature prepregs, infusion and all room temperature work, the basic kind will be fine. If you are doing high temperature things, spend the time to find a suitable sealant. The issue with high temperature will have to do with viscosity too hot and the cheap stuff flows too much to keep doing its job.

This same basic material is often sold for sealing metal roofing and siding in building construction and may be available at building supply stores.You want it at least 1/2 wide dont get the thin stuff even though its cheaper you will become frustrated!

Youve got to have a way to connect your bag to your vacuum pump. Depending on what type of process you are using there are lots of good options. Your ideal bag-connections will look different for wet layup and pre-preg compared to the vacuum and resin feed connections you need for infusion.

The simplest is just a hose wrapped in something and stuck through a pleat in your bag see the image below. This is great for bagged wet-layup because if it gets resin on it its no big deal. For infusion, a variation of this using spiral wrap covered in peel ply or MTI hose (on the vacuum side) or similar. The key here is making sure the bag cant get sucked into the end of the hose so something like breather cloth or infusion mesh should be taped around the end of the hose. The other thing to aim for is keeping the hose and material off our actual part unless you have made provision for that. A hose and a big wad of stuff will print a dent into your part and probably cause a localized not-optimal resin bleed best to place it off to the side on a tab of breather or mesh just like you would a plate fitting.

When putting hoses through pleats it is really important to use the pleat as a shock absorber by making it several times the hose diameter high. Small pleats with hoses in them can too easily pop up from the mold flange and cause small (or large) leaks. Bad news! Putting hoses though pleats is less problematic than punching holes in the bag (for infusion, say) but it does require good technique.

Next up is the plate type vacuum connector also called a frog or puck that comes in two parts that clamp the bag around a hole. These are usually made of aluminum and have a gasket see the image. They arent cheap and once you add a quick-connect to the threaded adapter for plugging in a hose you are talking $50(US) worth of stuff that you could destroy with resin. These are best for pre-preg or very controlled wet-layup. Theyre very secure and vacuum tight and quick to attach provided you remembered to put the bottom half under the bag!

Other methods include vacuum ports built into tools or re-usable bags. These are usually custom designed to the situation and will have valves or quick connects or places to plug in and clamp a disposable hose. Large parts will often have a vacuum manifold to supply vacuum built into the tool and also a second vacuum system to hold the part in the mold if multiple cures or cook cycles are needed. It can get complicated!

The lamination itself and the application of process materials often called the bagging stack or consumables stack is a topic for another day. This stack usually consists of a peel ply, some release film and a flow or bleeder layer depending on what type of process youre using. Assume that at this point we have all the process material placed and tailored over the laminate and the last thing to do is put on the bag and pull vacuum.

Unless you are working with prepreg or infusion, where no resin is actively starting to cure during the bagging step, it is best to get all the stack materials and the bagging gear set up before you start the actual lamination. Get your pump set up with a catchpot and hoses run to where you will need them. Measure and make your bag. Either apply sealant tape to the bag or the workpiece (mold, perimeter of the repair, etc.) and leave the paper backer on the sealant tape! Lay everything out and think through the process before you mix resin.

The first problem is figuring out how big the bag needs to be. My advice after thousands of bags of my own, and seeing many other people battle this process is to make your bag bigger than you think it should be! Heres an example of measuring a mold and coming up with the size of the bag:

This part has a big lump in the middle of a rectangle its a mold for a composite sink. If we made a bag the exact dimensions of the perimeter, there would be no room for the sink basin, and the bag would never reach the perimeter where we need to seal it. Here I am using a cloth tape to measure the distance from one edge, up and over the basin and back down to the other edge. In one direction this is about 36, and its is about 32 in the other direction. Now think about the diagonal direction if we made a bag exactly 36x32 it would just work in each of the directions we measured, but on the diagonal, there wouldnt be enough to get around the bowl.

The bag film I am using is on a 50 roll. So the long way, I would be adding 14 to the 36 to just use the roll width. I am inclined to use roll width bag film where-ever possible why cut when you could not cut? Here Im going to add 14 or so to the other direction and zip off about 4 of bag from the roll. Looking at it now it looks way to big but well just go with it. Just keep thinking: too big is just right.

There are two ways to use sealant tape on a bag like this. One option would be to put it down on the mold, and then place pleats into the perimeter by adding extra sealant tape as you stick the bag down. The better option for something small is to put the sealant tape directly around the perimeter of the bag before even placing it over the mold. This is totally the best way to go with anything with lots of pleats really anything that is not either flat or huge. For really big things, handling the bag is too risky and it is best to unroll it right out onto the part and do your pleating in place. But if you have a clean table that will reasonably accommodate most of the bag, go ahead and put the tacky tape on the bag first. Leave the paper backer on, and then go around the edge and trim off the excess bag on the outside of the sealant tape. This seems fussy and it is but it will save you the trouble of having a flap of bag stick to the wrong side of the sealant tape when you are placing the bag down. It is easier to un-stick sealant tape from the middle of a piece of bag than from the edge!

First, place your vacuum fittings or hose! Now is the time! I have forgotten this more times than I care to admit and its no fun to pull up the tape and try to work your vacuum fittings into place. It makes you feel like a knucklehead.

Second, vacuum fittings need to go clear of wet resin, and clear of any resin that will squeeze out of the part when the bag compresses it. If you are using pre-preg or infusion, then you will probably have a specific set of vacuum-related plans. For vacuum bagging wet-laid laminate, you can use a plastic hose with bleeder, fiberglass, or (my favorite) infusion flow mesh wrapped around the end. This is cheap and low risk. Just run the hose to a barbed fitting on a catch pot. If you want to use a quick-connect mounted to a purpose-made vacuum through-bag connector you will need to be aware of the possibility of resin flowing into the $50 worth of hardware at the end of your hose. I have personally ruined dozens of these and while Im sure your record will be better be mindful of the risk!

Third, if you are putting a bag down over a part with wet resin, it is important to not get resin on the sealant tape or on the perimeter area where you plan to stick the sealant tape. Many experienced laminators stick masking/painters tape on the perimeter area where the bag sealant will go to protect it from resin. Wipe up any drips of resin outside your peel ply with a solvent BEFORE you pull up this masking tape. It takes a lot of wiping and you have to let the solvent evaporate before you stick the sealant tape down. Sealant tape will not stick if it has resin on it and you will waste much more time fixing this problem than you would have spent avoiding it in the first place!

Imagine an inch-worm working its way along. Stretched out it is like an inch long. All scrunched up it is still an inch long but it only needs half an inch of ground from head to tail. A pleat in a vacuum bag uses the inch-worm trick to make a lot of inches of bag stick down to a smaller number of inches of mold perimeter. Well use inch-worm pleats of varying lengths to put more bag in the middle than we have room for on the edge.

Now imagine you are vacuum bagging a swimming pool with a deep end and a shallow end. You are using a huge rectangular bag. You will be putting the sealant tape around the edge and will need pleats to allow for enough bag to run down into the pool and fully cover the surface without stretching or pulling tight anywhere.

Looking at the pool from the end, where the cross-section is uniform, you would have two huge pleats right near each edge, like ears on a giant rabbit. The shallow end pleats would be the same height as the deep end ones, so there will be excess material at the shallow end. From the sides, you will need more bag to get down into the deep end, so you can make a huge pleat near the edge of the deep end, and a smaller one near the edge of the shallow end. You can then make a few smaller ones along the long sides of the pool where the bottom slopes up just for some extra bag to play with. To have enough bag in the middle, you will have to have extra at the edges pleats let us handle the extra gracefully.

I like to place the bag over the part and pull the perimeter clear of the edge just drape it over and roughly align it. This is easy on a table but the same goes for working on a vertical or overhead surface even if you need a few extra hands and some masking tape. I almost always stick the corners down first. Even if you have to walk around a mold a few times, make sure you have things in the right orientation and gently stick down the four corners.

Next, I look at where the bag will have to go up or down any features in the part. Think of the bag as having a grid on it like graph paper. For your first go at a new part it is totally reasonable to actually draw a grid on the bag with marker while you have it flat on a table no really try it! Your goal is to keep the lines of this grid running roughly at right angles to each-other. You will make inch-worm-like pleats in the bags edge to give the middle enough volume to completely cover all the area of the part. Unless you have a very good reason, try to make the pleats as symmetrical as possible from one side of the bag to the other.

For symmetrical things, my next move is to stick down the middle of each edge. You can pull the edge up away from the mold until it starts to get tight and then visually find the center and just remove the paper from the sealant tape in a little area and stick it down. I am careful to fold back the edges of the paper backing on the sealant tape so it will be easy to grab when the time comes to stick down more. Think about the pool example and see where you have any areas that will use up a lot of bag like the wall of the pool. In theory, for a vertical surface, the pleat needs to be help as tall as the vertical part the bag goes up and down the pleat but best to give it a little more. Place these big pleats first. Gently tear the paper backer on the sealant tape, and fold the two sides together, gently pressing the sealant tapes together until you have a pleat that is the right height. Do the same on the opposite side of the bag. You can also just join the bottoms of the pleats leaving the paper on the tape inside the rabbit ear part. Now continue placing symmetrical pleats in all four edges of the bag. Take a moment to press the bag into all the features and make sure there are no tight spots. Because you have only gently stuck down the biggest pleats, you can pull them up and slide them along the edge to relieve any diagonal stretchy spots or areas where you dont have enough slack. Your imaginary (or real!) graph-paper lines on the bag should not show any serious skews or systematic asymmetry.

Keep testing as you work your way around and finally have the bag gently stuck down all around the perimeter. With the bag sealed and all the slack placed roughly where it should be, it is time to connect the vacuum hose to the bag and turn on the pump.

As the pump begins to pull the air out of the bag, work your way around the perimeter pressing down the sealant in the pleats and making sure there are no holes where air could get between the sealant and the mold. As the bag begins to tighten, work excess bag into inside corners and try to pull up small vertical folds that center on inside radii. This way, as the bag pulls down further, these vertical folds can slide open, leaving enough extra bag to follow the increasing radius of the inside corners. Feel free to stop or slow the vacuum to have enough time to get the bag just right. Try to avoid pulling a lot of vacuum and then releasing it entirely as this can introduce extra air to the laminate and mess things up. There should be no spots where the bag feels tight or like it is stretching!

Youll hear small leaks now, and you can find them and squish them down. If you are bagging wet-laid laminate, it should start to bleed through the perforated film as your vacuum gets good. Keep working the edges until there are no leaks and the bag is squeezed tight to the sealant tape all around the edge. A small strip of air visible as a radius in the bag just inside the sealant tape is an indication of a nearby leak.

Once youre all sucked down to the vacuum level you want, and you cant hear any leaks, you are ready to go on to the next operation. If you are bagging wet laminate, this may be enough just leave it and come back when the resin is cured. For prepreg or infusion, the bag is going to have to be really good. You may want to do whats called a drop test. In a drop test, you disconnect the vacuum pump (with a valve so the vacuum stays under the bag) and let the bag sit for a given duration 10 minutes maybe with a vacuum gauge on one of the through-bag fittings. By measuring how much the vacuum level drops in a given time, you are able to quantify the air-tight-ness of your bag. Often in a production environment, a process will require a vacuum standard for a given job. For example, a bag cant drop more than 2in/Hg in 10 minutes. If it drops more, you have got to find the leak(s) and try again.

Finding leaks is hard. Unless you have a mold with a history of holding good vacuum, you cant always be sure that the leak is coming through the bag itself. The most common source of vacuum leaks is the tacky tape seal. Kinks in the tacky tape leave thin spots and it is hard on a large bag to make sure everything has been chased down. The next most common place for leaks is in the vacuum plumbing. Hose fittings leak, vacuum through-bag fittings leak, and infusion feed and vacuum lines leak. Look closely at these if you are having problems.

Sometimes theres just a hole somewhere in the bag. You can try putting your ear close to the bag and moving back and forth but this has its limits! There is a tool called and ultrasonic leak detector, which is used for finding small leaks in all kinds of situations. The most common ones look like a box with a little tube connected to earphones. The detector picks up high frequency noise made by the air rushing into the leak and makes it audible. Youve got to be patient, and these are a last pass when you cant find a leak in the usual spots. Good ones are not cheap, but in a commercial composites processing environment, they are very useful on occasion. If youre making really fancy (expensive!) stuff or autoclaving, it is probably worth going around your sealant tape with an ultrasonic leak detector just to be sure.

If you are really fancy you can use a thermal camera to find leaks. Ive never done this but it is done in industrial situations for finding leaks in pipes. The leak shows up as a colder spot. Im going to try to find out how this works and get some pictures because it is promising for factory situations where silence is impossible and finding leaks quickly is valuable. Let me know if you have information on this!

You can bag to a mold, but sometimes you have to bag secondary operations onto a semi-finished part. This might be tapes to tie to separate pieces together or additional reinforcements to a specific location. As long as your part is vacuum tight (or close) you can bag right to it! Here are two examples:

In the first, a few layers of biaxial carbon are laminated to tie the halves of a yacht rudder together around the leading edge. In the second, the bag is compacting several layers of secondary bonding/tapes/tabbing to join the insides of a few pieces that have been molded separately. For both situations the parts are able to hold vacuum well enough, even though the bag mastic goes over flash tape and even masking tape in a few places. You may find that sticking high quality masking tape down and then putting your bag mastic to the masking tape will keep mastic from sticking to not-so-shiny or peel ply surfaces. Of course its is always a good idea to leave peel ply on as long as possible but here we havent done that!

An envelope bag is a bag that fully contains the part (and tooling) that is being vacuum bagged. Imagine putting your job in a huge Zip-loc bag and pulling all the air out! This can be very useful for small parts, or for jobs where the tooling is not air-tight.

Envelope bagging requires padding the back of your mold or the non-laminated areas of a secondary bonding operation so they dont tear the bag. Breather fabric or masking tape (or a mix) can cover up any nasty things that might become a problem. It is often easier to slide a small molded part into an envelope bag rather than to try to seal a bag on a perimeter flange that is too small. This works great with small molds that have no backing structure. It is also necessary for parts where the tooling is made from MDF for plywood which cannot be reliably sealed.

I will include as envelope bagging the bagging of things down to a vacuum tight table. This a really common and useful way to deal with lots of problems. If you have a one-off MDF or tooling board mold (like the rudder molds above on the right) that doesnt have enough flange for a bag and wouldnt hold vacuum if it did go ahead and bag it right down to a flat table. You get a good vacuum and the table will hold the mold perfectly flat. Youll have to be careful to release coat the table or put plastic sheet under the mold (do both!) so things dont get stuck permanently. A thin sheet of painters plastic under a mold will save a lot of trouble in this situation. Just remember to place the bag sealant perimeter outside the edge of the sheet plastic! Its just like envelope bagging the part, except one of the pieces of bag is really stiff and flat!

And how do you get a big flat table that holds perfect vacuum well there are a bunch of ways! One of the best is a metal plate ideally thick enough to be stiff and ground flat. MIC-6 aluminum is the best but its expensive. You can also make a table by hand out of plywood and then fiberglass and fair it. Make sure to seal the back or it will want to warp. The best one Ive ever had was 2mm aluminum sheet bonded on 50mm aluminum honeycomb. It was vacuum bagged up on a giant granite surface plate and was almost perfectly flat and easy to handle. I had it made by a business called Atlantic Industrial Models which happened to be close to where I was working. It was cheaper than an equivalent piece of MIC-6 and way stiffer. If youre doing lots of cooking and carbon work, it may be good to make high temperature carbon tables with or without core to have a matched CTE. Aluminum honeycomb is probably the best core for this, but at lower temperatures, balsa works well too.

I cant not mention tube bag because it is just that good. It is just what it sounds like vacuum bag in the form of a lay-flat tube. It comes in diameter from 100mm / 4 to 1.2m/4 and in a variety of bag materials. It is perfect for sliding items into for envelope bagging. You can also use it to bag tubes by sealing it around the tube. For mandrel molding it is perfect!

The great thing about tube-bag is that you can bag long things without long seams. Seams are always a weak-point in a bag and tube bag is just more likely to remain sealed than something with lots of seam. You only need to apply sealant tape to the insides of the ends of the tube and attach it over or around the long skinny thing youre bagging.

For things with internal bags, tube it perfect because it avoids sealant tape inside often-confined areas. There are also high-elongation tube bags that are much more forgiving for internal-bagged parts especially in an autoclave where any bridging will pop and ruin the fun.

The second most common problem is getting it skewed or bunched up so that as the vacuum pulls the bag down it stretches and pulls up the sealant tape or bridges an area and threatens to pop. This is where systematic alignment of pleats and careful arrangement of the bag before the vacuum is fully on are really helpful.

From here, holes are probably the next biggest problem, and they come in a wide and frustrating variety. Itll happen. If you are careful with your bag film and fit it carefully, you will probably not have a ton of trouble with holes in the bag but youll have them from time to time.

Be careful cutting bag off a big roll! Many times I have seen a slip with scissors leave a hole in the roll of bag that keeps on giving many layers deep. If you do it, at least mark the spot and leave a note to warn the next user of the roll of film!

Vacuum plumbing can also be a source of frustration. Gauges that dont work or complicated valve manifolds that are prone to mis-use are worth attention. Avoid having too many jobs on the same pump, especially if those jobs have different requirements.

The worst defect I see in wet laid parts is air or voids in outside radii of parts. It easy to have this happen if you do not follow up slip joints in the laminate and bag stack with enough extra bag to allow for full vacuum pressure on what will be inside corners for the back (bag side) of the part. Make sure your really push the bag into these corners and allow for small pleats in the corners to release extra bag if needed. If you are careful, a rounded stick with some peel ply or breather over the end can be used to really hammer in these radii I have actually seen people hammer the push stick gently and it works. Gotta be gentle though.

Also, sucking resin into the vacuum fittings. There is a trick for protecting fittings and also making the bag attachments more flexible that I learned while working in an excellent but quite fussy shop building a boat. See picture to the right. It involves placing your vacuum fitting inside a secondary piece of 4 tube bag that has strips of infusion flow media inside. Its kind of like a remote vacuum port. The infusion mesh is held together with a few dots of bag sealant tape (circled in red) which keep it from sliding out. The vacuum port is on one end and the other end sits under the perimeter bag seal with its own extra tacky-tape seal.

You probably wont do this much, but if you dont have room for a vacuum fitting and youre worried about a hose printing into the part, this is a great solution. Also excellent for pre-preg cooking or debulking where you want to keep the fitting with the bag but dont have room to place it on a un-laminated part of the mold.

With infusion, you dont just have features to pull air out of the bag, you have to get the resin in too. For small infusions it is a good idea to place both your vacuum plumbing and your resin feed tubes in perimeter pleats in the bag. For larger parts, you have to make holes in the bag to fit resin inlet tubes. There are lots of specific products that help make this work, but the most common are spiral wrap, resin channels (EnkaFusion, etc.) and plastic tube fittings. This all makes the bagging operation more complicated and leaks are more catastrophic than with bagged wet layup.

Also, if you are using a surface flow mesh, the cut edges of this can be sharp. Be careful pushing your bag over these and if you have leaks, this is a good place to check once your sure the perimeter is good.

The environment inside an oven is often windy with all the fans moving air around. Youll have thermocouples to deal with and vacuum hoses running all over. It is a good idea to tape down flaps of bag so the wind doesnt get em and flop them around. Its also good to make sure hoses and thermocouple wires are not sitting directly on the bag put a little breather under them to be safe.

One thing to keep in mind is that tacky tape gets much softer when it heats up. This is no problem, unless your bag has bridging or some feature that puts pressure on the tape. As the tacky tape heats up and softens, the bag will be able to slide. Too much of this and the tape will get thinned out and pulled apart and you wont have vacuum anymore more!

For reasons I wont go into here, prepreg often needs to be debulked during layup. Every few layers (or every single layer you fussy guy!) you will want to vacuum bag the whole thing to compress the prepreg plies together and pull air out. Debulk bags dont need to be perfect but they should be good and should have some type of flow media covering the laminate. I am a big fan of infusion mesh for a flow media and will choose to leave the thin backer on the prepreg and perforate it with a spiky wheel but enough on that here!Check out Laminating with Pre-pregs.

One feature (probably not aerospace approved!) that is awesome is the duct tape zipper on an envelope bag or from a bag to a table. If you take an edge of a bag that you want to be able to open and close several times (for quick and easy debulking) and put a line of duct tape on each face of the bag, you can then grab it and the duct tape keeps the bag from stretching! You just stick the tacky tape to the duct tape, and give it a tug and the tacky tape comes off the duct tape. It requires a little more pushing to stick it down, but it saves a ton of time. The zipper works great for envelope-type debulk bags. Just zipper one side and youll be in and out of those bags in seconds instead of minutes!

This site contains information that reflects the opinions of individual authors mostly me, Chris. I make no promises about its usefulness! Some of this stuff can be dangerous and the warning dont try this at home applies. You are responsible for your own judgement and outcomes. Be safe!

retrofit of weighing controllers improves performance of bagging processes | bulkinside

The retrofit made it possible to visualize the entire packaging station in the central plant management system and to integrate all packaging processes into the ERP system. The integrated web server can also be used for remote access.

The modernization of the weighing controllers is part of an extensive retrofit of different packaging groups at the refractory sand plant run by EKW GmbH in the German town of Eisenberg. We have replaced our entire control technology, transferring and adapting the programming of the old automation systems and adding the latest safety technology. Of course, the weighing controllers have also seen a generational shift, explains Meik Wendel, PLC programmer at EKW GmbH. The company has been using B+L weighing controllers since the 1980s. They have consistently proven themselves to be precise and reliable and we also appreciate the great and fast support from B+L, concludes Axel Deubert, manager of the electronics and maintenance workshop at EKW. This is a crucial point, since the individual types of refractory sand can vary greatly in terms of dosing and packaging due to differences in composition, humidity and granulation.

Luting sand (Klebsand in German) is an essential component of many products manufactured at EKW, such as sand mixes for refractory applications, self-flowing and cement-free refractory concrete as well as system solutions for the functional lining of different melting and heat treatment furnaces including their peripherals. EKW is a technological leader in the field of refractory materials, not only in steel and iron casting but also in various industries.

The different types of refractory sand are produced in the central mixing system according to customer specifications or the intended application. From there, they are either loaded as loose bulk materials or delivered to the various packaging groups via conveyor belts and silos. In these packaging groups, we use several centrifugal belt packers that pack the refractory sand into bags with a filling weight of 25kg, explains Meik Wendel. Each packaging group is operated by an employee who attaches the valve bags to the packaging spout and selects the appropriate set of pre-defined parameters for the type of refractory sand at the start of the bagging process.

Previous B+L controllers already had a high level of user-friendliness, recalls Axel Deubert. The employee had to do no more than select the type of refractory sand to set the necessary dosing parameters. This ease of use is something we didnt want to miss after the retrofit. It was mainly the increasing difficulty of obtaining spare parts that led to the modernization of the packaging stations. On the other hand, this also created an opportunity to leverage a next-generation weighing controller to implement a range of options and functions throughout the entire process control system that had not been possible before. The aim was to make the entire bagging process more transparent, to integrate it into the ERP system, and to ensure its sustainability with a view to future integration and documentation requirements.

With the MID-approved miniPond 3F from B+L Industrial Measurements, EKW has opted for a verifiable weighing controller that provides precise and repeatable filling and dosing processes. At the push of a button, the operator can choose from a range of pre-settings that are saved on the device. That way, the weighing controller can quickly be switched to other products and filling weights.

Because of the different product characteristics and the application environment of the centrifugal belt packers at EKW, there are various features of the miniPond controllers that are particularly decisive: Their digital filter technology, the proven evaluation algorithms, and the smart free-fall compensation achieve the best possible filling results despite any vibrations at the scales or refractory sands with varying density and consistency.

At the same time, each miniPond in the packaging groups automatically monitors and evaluates a number of process parameters contributing to the optimization of the plant, such as filling weight, tolerances and process errors. In addition, information such as count, total and diagnostic data can be logged on the controller. Even with all of these options, the weighing controller is easy to operate via its interactive menu interface. This made for a straightforward commissioning process, which we were able to do in-house, recalls Meik Wendel. The connection to the scales and to the new higher-level automation system via fieldbus went smoothly, and after a quick operator training by B+L, all employees were immediately familiar with the new system.

The miniPonds offer a range of integration options and can be flexibly integrated into almost any machine and control environment. For the first time, this gave us at EKW the opportunity to link the weighing controllers to our ERP system and to replace the previous pallet-specific recording of the product quantity with bag-specific recording, explains Axel Deubert. The entire filling process is now controlled and documented up to and including the closing of the valve bag without any media disruption.

A further advantage is that after the retrofit, EKW can now access all miniPonds remotely. This is made possible by the integrated web servers of the weighing controllers. We use this new functionality to connect the miniPonds of all packaging groups to the central visualization in our electronics and maintenance workshop, says Meik Wendel. We can immediately see how the system is running, which controller is doing what, and which error messages come up during operation. If necessary, we can log into the error history to retrace any settings, changes or operating errors, explains Wendel.

In addition, EKW can also give B+L temporary remote access directly to the packaging groups via a browser, e.g. to set parameters, perform functional tests or diagnose failures. If and when errors do happen, they can be fixed quickly, which ensures the availability of the plant, says Axel Deubert. This access option also makes data backups and the firmware update easier to do. If needed, the miniPonds could also be integrated into condition monitoring applications at the higher control level, using the fieldbus interfaces.

Intelligent weighing technology for industrial requirements 50 years of maximized quality made in GermanyB+L Industrial Measurements develops and manufactures verifiable weighing controllers for industrial and process weighing technology. With our sophisticated solutions, we are a leader in the field ...

silage in bags | quality silage

The process of packing forage in a bag, particularly corn silage, can result in significant additional mechanical treatment to the forage. This additional mechanical action of the packing mechanism has been shown to benefit silage by reducing particle size, lowering the number of whole cobs and lessening the number of whole kernels in the final silage. Take this into consideration when settling the theoretical length of cut (TLC) at the chopper.

Site preparation is critical for bagged silage. Be sure to select a clean, hard surface for the bag and locate bags away from heavily trafficked areas, trees and livestock. Ensure the site is free of sharp rocks and sticks to reduce potential damage to the bag. Concrete, asphalt or packed gravel makes for a base with good drainage properties and minimizes hygienic issues during feedout. The bag should be positioned so the face is not in the direction of the prevailing wind.

In general, a pressure of 400 to 450 psi should be used and then adjusted as appropriate, based on the stretch indicators when initially setting the cable drum brake. Stretch indicators must not be exceeded. If insufficient pressure is applied, then an uneven fill of the bag occurs. This can be compounded with forage harvested at a high DM level or at too-long of a chop length.

Efficient filling of the silage bag is achieved by ensuring appropriate drum-break pressure and tension against the cables. Physical conditions of bagging directly impact the brake pressures required to effectively fill the bag:

The easiest and most effective point of inoculant application is always on the forage harvester. If this is not possible, then inoculant can be applied at the bagger. It is advisable to raise the liquid application rate of the inoculant dilute and apply a greater liquid volume of inoculant so that the desired microbial application rate is achieved if it is being applied at the bagger due to the reduced amount of turbulence of the forage.

All fermentations produce gas (carbon dioxide) with the efficiency of the fermentation directly impacting the amount of gas that is produced. If the forage has been ensiled with residual nitrate in the plant then toxic gas can be produced as the pH of the forage falls. Listen to our podcast on silage gas here.

Be sure to use bag vents to release the gases produced during fermentation to avoid the bag becoming pressurized and ripping or blowing open. Vents can be placed in the bags once completed to allow the produced gas to be released from the bag and the bag to be resealed airtight.

Storing forage in bags can result in significant losses in DM if bags are not routinely monitored for holes and tears. It may be necessary to limit the access of birds and wildlife to the storage area with fences, bird netting and other pest control measures.

Feed silage at a rate that prevents heating. Loose plastic should be cut off tight to the face. The bag should not be resealed as this encourages a greenhouse environment and fosters daily losses. Recommended feedout rates are 6 to 12 inches (15.24 cm.) of silage per day. Reach the higher end of the range during warmer temperatures or with lower density ranges.

When removing silage for feeding, the silage face should remain tight and smooth. Avoid methods that result in dislodging the face. Creating gouges, cracks and potholes result in air penetration deep into the silage mass and lead to added spoilage.

The typical life of silage stored in bags is around 12 months due to plastic integrity issues. If bags are to be stored for longer, the farm should consider the use of shade cloths to protect plastic from ultraviolet (UV) light degradation.

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