The rigid and hardwearing nature of denim and the garments it is associated with means there is a wealth of apparel manufacturing technology built around the peculiarities of this fabric. Here, Niki Tait looks at some of the technology newly available for making up denim products.

Denim tends to be difficult to spread quickly and precisely. The fabric's rigidity also means that sewing machines demand consistently good cut quality. The Assyst Bullmer Economic 13 is a spreader that uses a roll bar without cones for easier loading. Capable of spreading rolls up to 500kg, the Economic 13 can move at up to 120m/minute.

Cutting denim demands knife stability for good quality and a high level of engineering in the cutting head so that the fabric can be cut all day without wear. The Assyst Bullmer Procut 7500 is designed for cutting heavy fabrics such as denim.

Gerber manufactures a number of high-speed cutting systems with over 100 off-the-shelf configurations available. The S-91 high-ply cutter, for example, is for high-volume, high-quality cutting and utilises Gerber's vacuum hold-down system to cut lays of up to 76 mm (3 inches) of compressed fabric. The S-91 Dual Beam GerberCutter option has two heads for maximum productivity.

Vector Denim is Lectra's cutting solution for the mass production of denim fabric. Its cutting head and advanced steering software control material constraints but give a high level of productivity. Vector Denim can cut up to 5cm of compressed material (60 plies of 14oz denim) seven days a week, three shifts per day, giving a claimed 1000 jeans per hour.

Fusing
Freudenberg Gygli specialises in all types of formal and casual shirt interlinings, including those for denim shirts where there may be a desire for a washed look and seam crimping with a collar and cuffs having some volume and a soft handle. After production, the completed shirt is usually washed to achieve the typical denim look. Denim shirts are traditionally fused with nonwoven interlinings such as Gygli 9540.

Assyst Bullmer's Procut 7500

In jeans, quality is improved with properly fused belt loops. This helps prevent thread fraying during cutting and stone washing, and sewing productivity is increased when attaching the loop to the band because of the added stability of the fused loop.

The new Astex BL1000 Belt Loop Processor by Adams International Technologies is designed to fuse denim loops with anti fraying films and webs. Over 33 feet of top and bottom heated length assure an even melt of the resin at maximum speeds and minimal temperatures.

Decoration
With lasers billed as the latest in garment finishing technology, E-laser, developed by East Systems Technology Ltd, engraves, cuts and/or marks ready-made garments or piece panels. The engraving/marking process is simple, with graphics designed in programmes such as CorelDraw, Photo Shop or Auto Cad. Images with different effects including photos, pictures, patterns, or even abrasion and fabric breaks can be printed without changing the texture or strength of the fabric. Using an RF-Sealed metal tube laser head, the marking field size measures 400 x 1200mm.

CadCam Technology's GraphixScan Laser engraving machine is a new product which can produce images, text, logos and textures on finished items or raw materials including leather, wood, plastic, manmade and natural fabrics.

Laser marking software gives total control of speed and power, which also allows the GraphixScan to etch and cut to precise depths at very fast speeds. The largest machine in the range can engrave 1500mm x 1500mm and maintain a 0.5mm spot size across the entire bed. Engraving speeds are up to 24 metres a second.

Using Madeira's special FS 30 metallised thread from its FS Supertwist colour card enables denim to be embroidered or decoratively stitched as cut pieces before the garment is made up. The six gold and silver shades are produced with a special chemical treatment that makes the thread resistant to the chlorine and bleaching agents used to treat the finished jeans.

Sewing
The Vi-Be-mac 1010 V3 is a new series of modular, programmable automatic machines for applying labels and Velcro, embroidering rear pockets or performing any other type of ornamental stitch. The units have a wider stitching field (250 x 130mm), which allows applications such as small pocket and flap stitching.

Brother BAS 7610

The BAS 7610 is Brother's new high speed electronic pocket setter for denim and other heavy material. The maximum sewing speed has been increased to 4,250 rpm and, as no deceleration is necessary when sewing around corners, this results in a substantial reduction in cycle time. The pocket clamp assembly can be replaced in about one minute, and there is an expanded sewing area of 250 x 250mm.

The new Brother 4,000 rpm DA 9270 DA 9280 twin/three needle narrow cylinder bed feed-off-the-arm double chainstitchers are ideal for materials from shirtings to denim. A tractor type presser foot can be used to ride over thick sections, even 16 layers or more of 14oz denim. Separate adjustment type loopers can be easily modified, and a movable needle guard effectively prevents skipped stitches.

Specially developed to attach waistbands to jeans and casual pants, Juki's 5,000 rpm MH 1410 cylinder bed, needle feed, double chainstitch machine includes an automatic lubricating system. The machine uses a right and left split type needle thread take up guide. Even when the right and left needles sew materials of different thicknesses, separate stroke can be set for the right and left thread take up guide to ensure consistent seam quality.

Juki Union Special has a new jeans leg hemmer, the DLN6390 high speed, cylinder bed, 1 needle, needle feed lockstitch machine with large hook. The needle bar stroke is as high as 35mm, offering increased penetration of the needle into the material and helping prevent sewing problems such as stitch gathering, stitch skipping and needle breakage.

The machine employs a highly reliable horizontal thread trimming mechanism which cuts thick thread and each time it operates the air blower keeps the knife clean by blowing off thread chips from the blade, ensuring the dependable operation.

Kansai Special has enlarged its jeans product line to include everything necessary in the chainstitch sector. For belt loops up to 20mm in width there is the new BLX 2202CW 1/4; for the waistband the needle-feed FBX 1104P; for the double lap seams the flat bed DLR 1503PTF or feed-off-the-arm SX 6803PD; for the bottom hem the RX 9701J CD/UTC (one needle double chain stitch, condensed stitch, automatic thread trimmer); for the joint seam the LX 5802TMF with tandem needles and floating foot; whilst for the pocket facing, the WX 8842 or WX 8842 1.

The Schips HS C12J has been developed for automatic feeding of leather labels from a magazine, positioning it under the sewing clamp and attaching the top and bottom of the label to a pair of jeans using a programmable lockstitch bar tack machine. Maximum label size is 100 x 60mm.

Finishing
Denim jeans mostly require the smooth, non creased finish that a blower tensioned unit provides. The most critical element with these units is to control the fabric's extreme pliability when introduced to steam and hot air during the finishing cycle. If not, there is a likelihood of stretching the jeans' waist and leg while puckering and distorting other areas of the garment.

As there are many weights and blends of denim, the finishing unit must supply exacting applications of steam, hot air and tension to prevent unwanted stretching and puckering.

Brother DA-9280

Using a multi-channel microprocessor to control each step of the finishing cycle Hoffman New Yorker's model T 814 and T 815 tensioning finishers are designed to give jeans a smooth and soft finish in one operation. The variable speed blower and anti-stretching air system are independently programmed. The T 815 has front pocket/pleat pressing attachments.

The introduction of stretch fibres such as spandex and Lycra into denim fabrics has presented new finishing challenges since these denim elastane blends are prone to shrinkage at high temperatures. Demands on the finishing section are further increased by calls for 100 per cent measurement checks on the garments.

The Veit Group has introduced two new products to meet the requirements of the denim market. The Veit 8740 with HFCD (Hands Free Clamping Device), and the more advanced Veit 8750 which has the capability to measure three critical dimensions (waistband, inner and outer seam) and record them for further analysis, identifying the garments that are not within tolerance specifications.

The 'Hands Free' system allows the operator to load and secure the waistband area into position. The garment is lightly inflated to ensure the legs hang correctly and clamps automatically close on the cuffs. At the end of the cycle, the clamping assembly returns to the original position. This attachment also allows one operator to run up to three machines at a time.

The VEIT 8750 Pants Finisher it is designed for size specification compliance, precisely controlling the tension on the waistband and the legs to stay within designated tolerance measurements. The waistband, inner and outer seam can be measured for every pair of jeans during the finishing cycle and recorded for further analysis.

The Macpi 321 is a high productivity topper with innovative devices for finishing trousers without pleats and any kind of fabric. Model 321 is available in two versions (.00 and .10), both of which share the sequential cycle single foot pedal, shaped plates for tops, flap blocking, top tension adjustment according to size, and super heater steam adjustment.

Model 321.10 has a set of accessories such as flap and front pockets pressing using heated and steaming shapes, and a top and leg sizing device with warning light for out of size (small and/or short).

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.