The suitabililty of Rayon fibers in Staple spinning processes
The suitabililty of Rayon fibers in
Staple spinning processes
When chosing a 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.
materials worldwide, factory owners are made to face harsh realities:
procurement department has to make a tough choice.Any mistake in 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 important.
Considering a purchase of fiber, the following criteria is essential :
- cost of raw material as the major factor in production cost, with a share of near 50 % of overall Spinning cost
- Fiber properties ( wet-, conditioned -, dry Tenacity, Elongation, shrinkage, Pilling resistance, etc.) are excellent indicators of fiber quality
- Staple length – obviously – is of extreme importance in order 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)
fiber add on and its source (Origin and type of fatty Ester application as well as percentage)
- Price and supply Terms of fiber lot purchase Credit terms, etc.)
(Type of packing is of extreme importance !, normally laminated PP sheet fully covered will be the Norm)
- Date of Manufacture (of utmost importance, life of Add – ons is limited !)
- Storage of fibers (extremely important) 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 in order to secure a purchase order.
In normal temperate climates, fibers manufactured by a renowned supplier will be accompanied by 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.
This leads to the logic 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 being used. One particular candidate is Cotton
lint. One must imagine the lint being the base material,
passing through the full caustic soda process, filtered and extruded. The fiber length of lint, passed through the process is in fractions mm.
As against Viscose derived from Nordic wood, with fiber lengths of 1-2 mm, parallels are very far apart. So are prices.
When a prospective buyer goes for a cheaper Viscose fiber, he must realize that he may have to prepare for essential modifications on his plant. In very few cases, personnel is able to adapt to changing fiber properties.
When things go bad, a culprit is found.
Technical Personnel which handles issues on the manufacturing floor, normally 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 Expert
knowledge in all Spinning processes.
This has to be acquired over years, and will not be taught in Colleges.
It will invariably involve first hand knowledge of Blowroom
machinery, Carding -, Drawing, and subsequent Roving – and Spinning Machinery, i.a. Ringspinning -, OE-Spinning -, Airjet (MVS), as well as subsequent – Machinery, and its processes.
When the Spinning process shows high ends down, slubs,
imperfections, are shown, then mostly the fault is not on
the machine, but rather in the preparation. Standard
Efficiency can never be achieved thus, the Mill is losing money.
Here, many blunders can happen. Rewinding of defective yarns to hide the faults, hoping that the end-user will overlook the mistakes. (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 dtex Microfiber, yarn cross sections would contain hundreds of individual fibers which must be controlled, guided, 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.