A lot of progress has been made in the concept of welded seams since it was first introduced more than three decades ago. The technical replacement of traditional stitching has grown from being a useful waterproof sealing machine for products like tents, sleeping bags, designed for outdoor usages and also in medical disposables to being used on garments. As the acceptability of the concept increases, so does the technology to support the concept. Among the various technology providers, Sonobond Ultrasonics, manufacturers of ultrasonic welders, has a range of sewing equipment – SeamMaster® – designed specifically for textiles and nonwovens. In the range, the company offers two welding machines – SeamMaster High Profile Ultrasonic Sewing Machine and SeamMaster 10 Ultrasonic Cutter/Sealer, a table mounted version.
SeamMaster High Profile Ultrasonic Sewing Machine
The Sonobond SeamMaster can seal, sew and trim synthetic fabrics without the use of any consumables such as thread or glue. SeamMaster is available as modular units which can be integrated into production lines just like basic sewing machines while providing a speed of 60 feet per minute, nearly 4 times faster than a sewing machine and 10 times faster than adhesive methods. Seams welded on the machine fulfil the OSHA requirements for barrier seams, which state that any seam in a garment to be used by a medical professional must be capable of barricading liquid from entering the garment.
The machine offers a higher clearance between the horn and the wheel than what is available in a conventional stitching machine, creating an ideal space for hand-guided applications with tight tolerance or when welding a curve in the article. Operations such as side-seaming that require two stitches at least, can be coupled if they are welded together, saving the operators’ time and increasing productivity.
Welding requires minimal training to operate, especially for operators with experience of working on sewing machines, and is less hazardous than operating a sewing machine, in which the needle used can injure the operator even when it’s not running.
The machine has a workstation which is 48 inches-wide and 21 inches-long, a comfortable workspace for constructing a garment. It covers a pattern width of up to 1 inch, which will cover standard seam allowances. The machine can be tuned automatically and works at a frequency of 20 kHz. It can work with bulky materials, which is a plus when welding denim or any fabric with a high GSM.
Working of SeamMaster Sewing Series
Ultrasonic welding is accomplished by channelling high frequency vibrations to the fabric by passing it between an ultrasonic unit’s horn and anvil, and creating a rapid heat build-up. This heat causes the material’s synthetic fibres to melt and fuse, creating bonded seams that will not fray or unravel.
SoftSeam™, a trademark of Sonobond which produces seams that are soft and smooth against the skin, offers an advantage over stitched seams with bulky or abrasive threads. The process eliminates the need of threads, which additionally rules out the problems caused due to needle and thread breakage, thread colour changeover and thread unravelling problems. Seams such as shoulder attachment, side seam in both woven and knit top wear, side seam in legwear, all seams in activewear and lingerie, back yoke attachment in shirts can be welded rather than sewed, as these are the areas of garments in which the user requires comfort and stretchability. Holes caused by stitching are eliminated when garments are welded, and there is no damage caused to the fabric while welding.
Materials that can be welded by ultrasonic machines have to be either 100 per cent synthetics such as polypropylene, polyester, nylon, acrylic, vinyl, PVC, and thermoplastic urethanes that are constructed as wovens, nonwovens, knits, films, and laminates or blends with up to 40 per cent natural fibres.
Another model by Sonobond, which is a table mounted version of SeamMaster line, is SeamMaster 10 Ultrasonic Cutter/Sealer (SM 10), which has a 16 inches by 20 inches working area and a variety of patterns up to 10mm-wide, made from the pattern wheel which is easily interchangeable – designed for table mounting. The SM 10 works on the same principle as all other machines in the SeamMaster line possess the same features as SeamMaster High Profile Ultrasonic Sewing Machine, explained above.
In a Q&A with Team StitchWorld,
Janet Devine, President of Sonobond Ultrasonics, divulged into finer details of the market reactions and acceptability of welding machines in apparel industry…
How is the welding machine more efficient than a sewing machine in terms of energy consumption?
The company reports that it does not use less energy as the system has electric motors and also needs electrical power to generate the ultrasonic vibration. It runs faster than conventional sewing machines and is easier to use as no rethreading or changing thread colour is required, thus giving a high production rate.
Has any apparel company started using the welding machine?
Most of the customers are not apparel makers in the conventional sense but specialize in disposable garments for medical use and in special items like ballistic vests. Some lingerie makers use the system for bras and trim bands.
What would be the training period required to train an operator to work on this machine?
An operator can be trained in less than a day, especially if they are conventional sewing machine operators used to handling fabrics.
How different is the maintenance that this machine requires from conventional sewing machine?
The machine requires occasional cleaning if lint builds up. If the machine settings are correct, very low maintenance is required.
In terms of finances, where does the welding machine stand with reference to its equipment lifecycle, right from purchase to day-to-day upkeep and maintenance?
The machine is more expensive than a conventional sewing machine but no needles or threads are needed and the maintenance is also low. A pattern roller and horn replacement may be needed every few months, depending on how it is used. We have machines in operation even after 15 or more years of production use.