Machines for Covered Elastic, Textured and Chenille Yarns

Covered elastic yarn: single, double and air covering

Bare elastane is not used for weaving. A Ghent University study in *AUTEX Research Journal* notes that it is always combined with, or covered by, another yarn, so the fabric takes the look and feel of the outer yarn. The study names four routes: single covering, double covering, core spinning and air covering.

Single and double covering. The elastane is pre-tensioned and passed through a hollow spindle that carries the cover yarn, which is twisted around it. For double covering, the yarn then passes through a second hollow spindle twisting in the opposite direction. The Swicofil yarn manual describes the second layer as compensating the twist direction of the first. The Ghent paper explains why double covering is more common: on single-covered yarn the cover tends to untwist and expose the elastane. It also notes that the bobbin mass on the hollow spindle limits speed, and that speed falls as twist rises.

Two parts therefore come with every covering-machine quotation: the spindle and the bobbin it carries. Wanheng's WH hollow covering-spindle family lists several individually labelled variants, but the reviewed entry has no dimensioned drawing. Hesheng's aluminium covering bobbins likewise publish no dimensional, rated-speed or balance schedule. Both have to be matched to the spindle and drive interfaces, so put them on the wear and spare parts list with drawings. Other components are listed under parts and accessories.

Air covering. Here a filament yarn is blown together with stretched elastane through an air jet. A Rieter article says the yarns are interlaced rather than twisted, and that up to eight plies can be combined with elastane, against one or two in conventional covering. Rieter also states that conventional covering gives the best evenness and covering quality. The Ghent paper describes air-covered yarn as less uniform, with the elastane partly visible and less protected, and fabrics that are less regular as a result. The trade-off between speed and coverage is a product decision, not a machine feature.

Settings that define the yarn. In every route a draft (draw ratio) is applied to the elastane before it is combined. In covering, the turns of cover yarn per metre matter as well; see twist, TPM and direction. Lanbo's LB-192 is listed for spandex single and double covering. Its technical tab publishes spindle, twist, draft and package data, but it does not map every choice to a complete machine version. Ask Lanbo, or any covering supplier, to confirm which draft and twist ranges apply together on the version offered.

False-twist texturing: POY to DTY

A review of false-twist texturing from RWTH Aachen's Institut für Textiltechnik describes the process this way. Partially oriented yarn (POY) is drawn, twisted hard, heated above its glass transition temperature, cooled to fix the deformed shape, untwisted and wound. The result is draw-textured yarn (DTY). The review makes several points that matter when reading a machine schedule:

• Draw is set only by the speed ratio of the two feed units.
• Primary heater. Polyester and polyamide are typically heated above 190 °C, measured at the heater exit. Higher temperature raises crimp and filament breakage and worsens dye uptake.
• Cooling brings the yarn back below its glass transition temperature before the twist unit. For polyester, that means below 90 °C.
• Twist unit. Friction discs on usually three shafts are now the predominant method, and the number of discs varies with the twist required. The D/Y ratio, disc surface speed divided by yarn speed, has to be chosen for the specific yarn. For polyester, crimp contraction rose up to a D/Y of 2.0 and fell beyond it.
• Set heater. Without it the yarn is highly elastic (HE), which suits some downstream processes such as knitting. A second heater produces less crimped SET yarn, which is favoured for weaving.
• Speed limit. "Tension surging" limits speed. Depending on machine and process, it usually appears at about 1,000 m/min.

Uneven twist gives uneven crimp and uneven dyeing, so dye uniformity belongs in any acceptance test. The review also notes that machines usually have two sides that can run different yarns. Yongle's YQ800DS is listed as a four-level winding draw-texturing machine for POY to polyester DTY, with friction false twist and optional interlacing. Its published starting specification includes a 384-position base arrangement, heater lengths and winding geometry. Quote the feed and target yarns in dtex and filament count, using our count conversions. Ask Yongle, or any texturing supplier, which positions and heater settings apply to that yarn. Heater-based machines also need an electrical supply plan.

Chenille yarn machines

Chenille is short lengths of effect (pile) yarn held between a twisted pair of core yarns. A 1975 US patent for a chenille machine describes the classic arrangement:

1. A rotating flyer wraps effect yarn around forming tapes that carry core yarns.
2. A blade cuts the wrappings at a nip, producing two strands.
3. Ring twisters then twist each strand.

The patent's background names uniform yarn at high speed, and hard-to-cut fibres such as polypropylene and nylon, as long-standing difficulties. A study in *Fibres and Textiles in Eastern Europe* made acrylic chenille at three twist levels and three pile lengths (0.7–1.0 mm). It found that twist, pile length and weave all significantly affected the abrasion resistance of upholstery fabric.

Lanxiang's LX600 is a sectional chenille machine. Its independently driven rollers let the yarn recipe be adjusted, while the spindle drives and the package-building motion have separate jobs. Agree the section count, winding arrangement and trial conditions, not just a maximum speed.

How to specify and trial

State the input yarns and the target yarn: count, filament number, elastane draft, twist and direction, pile length. State the finished package too, using package and tube specifications. Then compare configurations rather than model names, and run a trial on your own material. Measure what the sources link to the settings:

• covering evenness and elastane exposure for covered yarn
• crimp, broken filaments and dye uniformity for DTY
• pile retention after abrasion for chenille, as in the cited Martindale tests

Write the agreed results into the factory acceptance test. Related downstream steps include two-for-one twisting, choosing a loom for stretch weft, and the wider spinning machinery listings.

Sources

1. S. De Meulemeester, L. Van Langenhove and P. Kiekens, "Study of the weavability of elastane based stretch yarns on air-jet looms", *AUTEX Research Journal* 9(2), 2009, De Gruyter Brill. (accessed 2026-11-04) View source
2. "Covering Yarn: Faster Elastic Yarn Production with Air Covering", Rieter, 7 September 2020. (accessed 2026-11-04) View source
3. "Covering", Swicofil AG textile applications / yarn processing. (accessed 2026-11-04) View source
4. M. Ortega, A. Saynisch, B. Yurtseven and T. Gries, "A Review on False-Twist Texturing", *Fibers* 12(4), 36, 2024, MDPI. (accessed 2026-11-04) View source
5. R. C. Whitaker, "Chenille yarn-producing machine", US Patent 3,861,128, issued 21 January 1975, via Google Patents. (accessed 2026-11-04) View source
6. Ş. Ülkü, H. G. Örtlek and S. Ömeroğlu, "The effect of chenille yarn properties on the abrasion resistance of upholstery fabrics", *Fibres and Textiles in Eastern Europe* 11(3), 2003, pp. 38–41; Bursa Uludağ University repository record. (accessed 2026-11-04) View source