Suitability of Rayon fibers in Staple spinning processes

Rayon fibers and processing

When choosing substandard fiber with lower properties, one must exercise high caution.

The suitability of Rayon Staple fiber is discussed, in
particular the fiber parameters, and end-user application.


Heinz Rainer

Due to rising cost factors of raw materials worldwide, factory owners are made to face harsh realities:
When purchasing Modal fibers with excellent fiber parameters, the
Procurement department has to make a tough choice. Any mistake in the selection could mean the demise of a company, and many factories have found that out in the course of time.

It comes as no surprise, many factories in the Spinning sector will fall into this trap, for lack of specific fiber processing expertise responsible personnel could bring them to their demise.

One must consider several factors :

With falling Rayon yarn prices worldwide, this single cost factor is ever more of importance.

When procuring fiber stock, the following criteria are essential :

Cost of raw material as the Nr.1 factor in production cost, with a share of near 50 % of the overall Spinning cost

  • Fiber Origin
  • Fiber properties ( wet-, conditioned -, dry Tenacity, Elongation, shrinkage, Pilling resistance, etc.) are excellent indicators of fiber quality
  • Staple length is of extreme importance to achieve final desired tenacity and Elongation parameters (i.g. : Where to employ a 32 mm – or 38 mm or even 60 mm staple (Cotton type)
  • Active fiber add-on and its source (Origin and kind of fatty Ester application as well as a percentage)
  • Price and supply Terms of fiber lot purchase Credit terms, etc.)
  • Packing
  • (Type of material is of extreme importance !, laminated PP sheet fully covered will be the Norm)
  • Date of Manufacture (of utmost importance, the life of Add-ons is limited !)
  • Storage of fibers
  • Mode of shipment (sea-transport can cause problems, extreme temperatures always do)

In many years of managing Spinning Mills, I came across various fiber Manufacturers worldwide. These manufacturers outbid each other to secure a purchase order.

In normal temperate climates, fibers manufactured by a renowned supplier will deliver raw materials with sound warranties, and nothing or little can go wrong in the spinning process.

Prime badges (Modal) carry a hefty price tag, and with margins in cents, one would have to consider such choice carefully.

Many Spinning mills in Europe went out of business; fiber manufacturers are still operating.

It leads to the logical assumption that margins in Viscose
processing plants are higher than those of their brethren in
the downstream Spinning Plants.

With more competition coming on stream, lower grade raw materials are much in use today. One particular candidate is Cotton lint. One must imagine lint being the base material, passing through the full caustic soda process, filtered and extruded. The fiber length resulting is in fractions of mm.

As against Viscose derived from Nordic wood, with fiber lengths of 1-2 mm, parallels are very far apart. So is the price.

When a prospective buyer goes for a cheaper Viscose fiber, he must realize that he may have to prepare for much-needed modifications on his plant. In very few cases, personnel can adapt to changing fiber properties.

When things go from good to bad, finger pointing is the norm.

Technical Personnel which handles issues on the manufacturing floor are of limited capacity when confronted with such scenarios.

They quickly point their fingers to the raw material, without considering that a change of raw material can bring financial advantages to the Employer.

Changes required are often time-consuming and need an Expert
of the Spinning process.
Such Expertise will take years to acquire, and it is not a listed subject in Colleges.It will invariably involve first-hand knowledge of Blowroom
machinery, Carding -, Drawing, and subsequent Roving – and Spinning Machinery, i.a. Ring spinning, OE-Spinning -, Airjet, as well as subsequent – Machinery, and its processes.

When the Spinning process shows high ends down, slubs,
imperfections, are visible, then mostly the fault is not on the machine, but in the preparation.
Standard Efficiency will be hard pressed to achieve. Thus, the Mill is losing money.

Here, many mistakes can happen. Rewinding of faulty yarns, hoping that the end-user will overlook the resulting yarn faults. (A simple run on a UT will tell the story).

In Staple fiber spinning, the individual count varies based on the Main Count of the Spun yarn.
In case of a 1.1 denier Microfiber, yarn cross sections would contain hundreds of individual fibers which must have guidance and control, and this under the constraints of factors of speed, quality, and damage free processing.

Fibers tend to lap in all processes, impairing production efficiency, quality.

Heinz Rainer – 26 Feb 2009

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