With more jeans today being made for fashion wear than work wear, the technology for decorating them is an increasingly important means of adding value. Here Niki Tait looks at some of the new equipment available to help with the making up of jeans and their embellishment.

Stone washing, enzyme washing, sand blasting and seam grinding are long-established techniques, but many these special effects can also be reproduced using speciality laser machines such as the E-Laser by East Systems Technology of Hong Kong.

Lasers such as those developed by Proel can be used for fabric engraving and burning, which can lead to many special effects particularly on denim fabrics. Euroflex is Proel's price conscious model, the Galvalaser is for high speed cutting and engraving, and the high speed (2m/sec) Evo matrix covers a large area of 1500mm x 1500mm.

Of particular interest in terms of leg embroidery is the Barudan BEVY-Z1204C which claims the world's largest embroidery area for long tubular goods. Using specially designed long cylinder frames, for the first time it is possible to embroider the cross seam of finished jeans.

As a well known thread supplier to the jeans industry, BST's Mystigo novelty thread looks like the traditional indigo thread but reveals other colours (red, yellow and red-orange) through local abrasion.

The Korean company Salli offers several ultrasonic hot-fix setters for pearl, rhinestones (glass), rhine studs (metal) and nail head (metal) patterning, commonly found on fashion jeans. The Multiple 21, for example, is a twin head machine incorporating both ultrasonics and electrical hot-fix setting. Machine speed is adjustable from between 20 to 120 pieces per minute.

The Korean Dairo Machine company produces an apparently equivalent machine, the DK-2400/2400N.

Tranfer prints are being increasingly developed to decorate dark fabrics. TheMagicTouch MagiCut digital image transfer process, for example, enables full colour imaging onto any colour and indeed almost any fabric or garment, including all grades of denim. Major advances in gold and silver glitter decoration now give high durability.

Impression Technology Europe's DTG range enables ink jet printing direct onto garments. The machine lays down a white base on which CMYK inks are printed to give a vibrant effect that is said to be as durable as any water based screen print even on dark fabrics.

Important in the operation of the DTG machines is the specially developed software. Print Pro works with Adobe Photoshop files and is able to work out the placement and density required for the white ink.

Since the Shima Seiki SIP-100F and SIP-160F high-resolution eight colour printing systems were originally developed for 'WholeGarment' knitwear applications, they feature printing heads that are height-adjustable, enabling them to print directly onto finished goods including jeans. Using its SDS-ONE system pattern-matching software, designs can be wrapped around the garment from front to back.

Production improvements
Demands on fashion jean manufacturers to make smaller batches with an increasing array of decorative features require innovative ways to simplify production and reduce manual handling.

The ability of the Eton UPS (Unit Production System) to sort and separate items based on multiple criteria provides one solution. As the Eton system carries a single unit through the production process on a special hanger it eliminates much of the challenge of managing small orders, since processing a small batch of ten units versus a larger batch of a thousand makes little difference to the manufacturer.

The system can automatically sort products according to the needs of the manufacturer, from thread colour or pre embroidery design to fly types, pocket designs, product size or other special handling requirements.

Sewing machinery
With the production of jeans such a competitive market, all the key sewing machinery manufacturers have developed specialist jeans making machinery - details of which can be well accessed using the internet.

Pfaff's website offers a choice of 31 jeans-making operations and recommends machines to use for each. For hemming, for example, five machines are recommended.

The Yamato MG20002P two-needle, four-thread, needle feed 4000 rpm double chain stitch machine with pulley can be used for attaching the waistband. For inside legs, the two-needle five-thread safety stitch machine with top feed, the AZF8600G, is recommended, as is the VF2560-PA four needle six thread flat bed interlock stitch machine for pockets.

The Yamato DT 30 two or three needle feed-off-the-arm double chain stitch machine for lap seaming uses a differential feed mechanism and upper driven feed roller to help prevent twisting on the crotch seam.

Within Rimoldi's range, the Vega 11 F29-49-3MD-69/92 three-needle machines attach zip fasteners to the left fly facing and simultaneously serge the inside edge of the facing.

The Kansai SX series is a three-needle feed-off-the-arm double chain stitch machine with upper puller for lap or side seaming on heavy weight fabrics such as jeans. It features an upper puller and differential feed mechanism which help feed the fabric uniformly at the cross seam sections.

Brother's DA-9280 two or three-needle narrow cylinder bed feed-off-the-arm double chain stitch machine has a tractor-type presser foot designed to go over folded material and ride over thick sections, and can cope with 16 layers or more of 14oz denim sewing at a maximum speed of 4,000 rpm. Separate easily adjustable loopers and a movable needle guard help prevent skipped stitches.

Low-tension sewing enables attractive 'balloon stitches,' produces pliant seams and prevents puckering. A movable needle guard helps prevent skipped stitches and an optional puller device feeds thick sections of material.

For closing seams Pegasus recommends its 6000 rpm EX3216H-A05/785-5x10/Y two-needle, five-thread safety stitch machine which gives an extra wide 15mm seam which is strong, durable and protects the fabric from fraying.

Its EXT3244M-A04/435K-5x3x4/TK122/PL020/Y three-needle, variable top feed safety stitch machine is also recommended for seaming extra heavy weight fabrics.

Sunstar has five new machines associated with jeans production, including the SC8200J direct drive, feed-off-the-arm, three-needle, six-thread double chain stitch machine with puller device; the SC8100J four-needle, eight-thread, double chain stitch machine with needle feeding and puller for automatically attaching the waist band; and the SJS/A-PS/A direct drive, automatic jeans pocket setter.

Within the Maica Sri jeans range the automatic pocket edger unit, model 2006, hems all types of material and stacks the pockets neatly for the next process. Around 2,400 pockets are produced each hour. The 2006 E performs the same operations whilst automatically sewing a label to the pocket hem.

The Maica model 1001 features a new way to crease pockets through a patented design which uses high pressure and temperature without causing damage to the pockets. Twin creasing units aid productivity whilst pressure and temperature can be varied to suit different materials.

New Tech produces several automats for jeans. The 2800/1 front J stitch automat, for example, has a capacity of 2,800 pieces per eight hours. Features include a Mitsubishi single needle lock stitch head (PLK 1010), sewing speeds of 300-2,800 rpm and a sewing area of 220mm x 100mm.

Juki says its MEB-3200 computer controlled, eyelet buttonholing machine is the world's first machine incorporating a computer controlled thread tension mechanism that electronically controls the needle and looper thread tensions.

The MEB 3200JS has been specially developed for jeans. Needle and looper thread tensions can be digitally set on the operating panel and the machine responds immediately to material changes, significantly reducing the set-up time. Thread tensions can be set for buttonhole sections, and the beginning and end of sewing. The machine runs at a maximum sewing speed of 2,200 spm.

Specialising in jeans and casual trouser production, Italian company Vi-be-Mac has almost 40 dedicated machines and is developing a range of multi-functional automats. Its 'back-side' module for manufacturing the rear part of jeans, uses four machines: the 007V or 006VLS hems the watch and back pocket with or without label insertion; The 1010V3 decorates the back pocket with a fancy stitch which is then creased using the 001V and attached and bartacked using the 2516V2.

Needles
Groz-Beckert's titanium nitride coated needle Gebedur SAN 6 has been developed for sewing jeans, where high sewing speeds and heavy materials can lead to skipped stitches and needle breakage.

A conical blade and newly designed lateral looper chamfer scarf cross section give the SAN 6 a higher bending resistance, and the guiding of the thread in the eye and scarf area improves pick-up of the thread by the looper. A reduced cross section at the eye area also helps reduce the force needed for the needle to penetrate the fabric. The titanium nitride coating protects the needle from wear and tear.

Schmetz has a leaflet on denim garment manufacturing that discusses how to choose the right needle for different operations and how to avoid any sewing problems, including the application of embroidery and appliqué.

The Schmetz Serv 7 is particularly useful for sewing denim since it creates a larger loop to reduce skip stitching. The reinforced blade helps minimise needle deflection and breakage and gives a tidy seam appearance.

Niki Tait, C.Text FTI, FCFI heads Apparel Solutions, which provides independent assistance to the apparel industry in the areas of manufacturing methods, industrial engineering, information technology and quick response.