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“Almost every business which works with textiles uses a mix of traditional industry crafts and techniques which are more modern,” says Aeronaut’s John Clark. “Many have taken small steps into automation and lean manufacturing and are looking for a giant leap forwards to something bigger. But maybe there is no giant leap? Perhaps it’s just a series of short, careful steps.”
Over the last few months, Aeronaut has been doing testing for a leading home furnishings company. “It’s always interesting working with people who are at the top of their game and by any standard, these people are right at the top and their sharp focus on every aspect of their manufacturing process is enlightening.”
“The tests were looking at the cost benefits and time savings to laser cut and edge seal fabric instead of stack cutting and overlocking every piece. Cutting single or low ply may save hours on laying up fabric but you have to cut many more tables. Edge sealing saves hours of overlocking and of course with a laser, the patterns can be nested with a zero gap and even pushed into the selvedge which reduces waste.”
“This evaluation process is a world apart from another of our customers, one who makes space suits for NASA. I’ve never seen anyone paid to sew more slowly than the women who make gloves for astronauts. Slow, but very, very precise because reducing waste is not a significant part of the final production goal.”
“Most manufacturers sit somewhere between these two states of extreme efficiency and extreme quality, but most would like to move more towards one or the other.”
“The big buzzword these days is additive manufacturing. Mostly, this is taken to mean 3D printing. Most textile based business are firmly in the old subtractive manufacturing era and we can often do a lot better optimising our processes and control.”
WASTE MANAGEMENT IN SUBTRACTIVE MANUFACTURING
“The most expensive fabric you have in any business is the stuff you throw away,” says Clark. “It’s almost impossible to avoid waste when cutting textiles and in most cases, 15% waste is considered good and typically, more than 20% is wasted. However with optimised nesting it’s possible to do a lot better. One Aeronaut customer claims to save $500,000 a year on a fabric spend of $2.5 million through waste reduction. That’s a very big saving and one which would pay for an automated cutting system in a few months.”
Looking closely at the whole concept of waste management can have a big payback, he says. “That doesn’t mean how do you dispose of production waste but how you avoid throwing away high value material and how to recycle as much of the rest as possible.”
MAKING THE BEST USE OF EXPENSIVE FABRIC
Probably the biggest factor in this type of fabric saving is efficient nesting… fitting patterns onto lengths of fabric to minimise waste. There are a few keys to efficient nesting of patterns. Wider fabric will almost always provide better nests but if more than one width is available in a fabric style, then doing a ‘what-if’ nest on each width can result in dramatic savings at the cost of slightly greater fabric inventory.
“If the manufacturing process can be stretched over days rather than hours, orders can be better consolidated so that more jobs are nested and cut on the same fabric. Cutting one-off jobs is far more wasteful than well nested queues of several orders.”
“Longer cutting tables may be less efficient in terms of time, ergonomics and workspace but will almost always save fabric compared with short cutting tables.”
“Nesting across frames can be more efficient. Here, you ignore the table length and nest for maximum efficiency. Cutting is done only within frames, which is a bit fiddlier than having a square cut-off at the end of each frame of patterns, but saves fabric. How does the cost of a few metres of expensive fabric compare with hourly costs of running a cutter or the space taken up by a longer cutting table?”
MAKING THE BEST USE OF CHEAP, RECYCLABLE MATERIAL
Vacuum hold down on cutting tables is notably more efficient than any clamping system, Clark says. Clamping systems don’t allow efficient nesting so waste fabric is much higher. Cutters using clamp systems are slower. A typical clamp cutter claims 150 – 200 skins a shift while a vacuum table cutting system can produce 250-320+ skins.
“With a good vacuum hold down, nesting gaps can be reduced, leading to significant savings over time.”
“With very porous fabrics, a sacrificial plastic overlay may be required to allow the vacuum to hold the fabric. However, this plastic overlay is very cheap compared with most blind fabrics and unlike blind fabrics, the plastic overlay can be 100% recycled.”
For many porous synthetic fabrics, laser cutting may be the best option. Since lasers don’t touch fabric while cutting, nesting gaps can be zero and you get edge sealing as a bonus.
REDUCING MISTAKES AND REJECTS
“Mistakes and rejects can make a big dent in efficiency. Automatic data entry, where order information is used to automatically create cut patterns without operator input can almost eliminate human errors on the cutting side.”
“Scanning traditional barcodes is not particularly useful in terms of automating data entry though barcodes can be used to make sure the right cut files are imported. On the other hand, QR codes have great potential since they can contain enough information to generate an entire order of patterns. Codes generated by order management software can be rescanned by the cutter itself to create jobs.”
“That being said, the best method of optimising nests is to do off-line nesting either the day before or overnight. Nesting software can be set to work for a set number of minutes or to attempt to achieve a percentage efficiency. Queues of nests can be created and run one by one so the right lengths of the right fabric are available at the cutter during every shift.”
“Fabric is rarely perfect and rejects are common due to fabric faults. One of the issues looked at with the leading home furnishings company was the idea of importing fabric fault data into nesting software and doing just in time nests to avoid faults. This is something which works with single ply but not with multi-ply cutting.”
“Good fabric inspection and machine vision systems can pick up fabric faults so they can be automatically nested around. Rejected skins can be used to cut smaller blinds… easily positioned within the reject shape using machine vision systems on the cutting table.”
THE PAYBACK
“The cost of autonesting software isn’t very important. One program has a calculator built in where you can enter the cost per square metre of fabric and monthly usage and it will output the cost saving per month. For most businesses, one or two nests and calculations will demonstrate that autonesting pays for itself in just a few weeks in fabric savings.”
“Properly run, most automated cutting systems have a ridiculously short payback figure to the point where the purchase price is almost immaterial.”
“If you are not using optimised autonesting, it’s likely that fabric savings alone with good autonesting could pay for a cutting system. One Aeronaut customer, a huge US blind maker, claims to get US$ 570 per hour from their cutter. That gives a payback for the machine in a few months.”
