As one of the leading suppliers of industrial polyester yarn in the United States, we are often asked about quality standards. These considerations are traditionally at the top of the list for industries that are held to strict safety standards (like in the automobile industry), but are also of great importance to companies that place quality at the forefront of their product production, such as sewing yarn, hose, and rope producers. 

Market Quality Requirements to Consider

Every market is different in terms of quality and technical requirements.  There are, however, basic and general requirements shared by all markets. 

General Requirements Shared by All Markets:

How does the yarn behave throughout all of the customers’ various manufacturing steps? This is heavily impacted by level of broken filaments, slubs/knots and type of spin finish (and/or over-finish) that is applied. 

Broken Filaments
AA Grade (or 1st quality yarn) cannot exceed an unacceptable level of broken filaments or processability will be compromised. For the general industrial market, a level of ~30 – 40 broken filaments per 12kg package is considered to be within spec.  This does vary by market as the seatbelt and airbag industries require an extremely low amount, somewhere in the range of one or two per pallet (which is 48 packages x 12kg each).  This is difficult to achieve.  The use of in line, high speed monitoring equipment is essential.  These electronic eyes are able to detect broken filaments at very high extrusion speeds.  The packages are then culled if they exceed the acceptable level.

These are normally not allowed for a product to be deemed 1st An isolated defect may pass unknown through a manufacturing process but a higher number of these larger defects will prompt a downgrade of that particular lot.

Spring Finish
Not all finishes are created equal. Spin finishes are designed to minimize static build up and protect the filaments against abrasion by enhancing lubricity, allowing the yarn to be processed at high speeds across multiple contact points.  Some spin finishes perform better than others, in tandem with customers’ chemistries in their given processes or end products (i.e. the chemical composition of PVC if going into a thermoplastic hose).

Specialty Over-Finishes
Some applications require an additional, specialty finish, in addition to the normal spin finish as described above. These finishes can be designed to improve adhesion to RFL/Rubber compounds, prohibit, reduce or increase the wicking of moisture, improve yarn to yarn abrasion (silicone finish, commonly referred to as “Marine Finish”), reduce conductivity, provide anti-microbial properties or other performance advantages.  The efficacy of the finish to meet these criteria is the performance requirement.  Over-Finishes can also change the way the yarn processes so that factor must also be analyzed.

There are many different variations of yarn in regards to denier, shrinkage, elongation at break, elongation at various loads, breaking strength, spin finish/over-finish percentage on the yarn and tenacity. Whether you use HMLS, LS, HT, Ultra HT or some other variant, consistency of the properties is critical.  Large variations indicate extrusion processes that are out of control and could lead to failures further down in the supply chain.  A tight range on all properties is desirable. 

Package Formation
Winding a yarn extruded at 3,000 – 5,000 meters/minute can be challenging. Precision winders are necessary to form a package that is usable in our customers’ processes.  A poorly wound package can slough and cause problems during the unwinding process, which is usually at high speeds as well.  A properly wound package will be tight and unwind well without catching and breaking out on its surroundings.

Next Steps

Understanding what quality considerations should be evaluated when making a purchasing decision shouldn’t be overlooked. The information in this article is designed to offer key insights into these considerations, but they don’t represent a fully exhaustive list. Should you be interested in discussing quality considerations further, reach out to us today to begin a conversation.