Textile
EXTRUSION OF FINE FILAMENT YARNS
The extrusion of fine filament yams presents some unique problems that may be readily solved through the use of Vortex Tubes.

Some polymer filaments as fine as 25 microns in diameter can undergo a crystallization almost immediately after exiting the extrusion head that, if not properly controlled, will render the filament useless. An accelerated cooling of the filaments, used in the apparel industry or for medical sutures, may be required to help control the crystallization.

Because dozens of filaments exit the head at once, cooling must be delivered in a very delicate and precise manner so as to keep the hair-like fibers from contacting and tangling with each other. Water bath cooling is generally unacceptable and the use of nitrogen too has its drawbacks.

SOLUTION: One local extruder who had encountered these problems worked with our design engineering team to develop a diffuser that utilizes our smallest 106 Vortex Tube. The diffuser encircles the exit area and creates a cold air path that helps control crystallization without disturbing the course of the tiny fibers.

For extrusions that utilize a water bath for cooling, remember that a Transvector is ideal for stripping the water from the extrusion by blowing the water back into the bath as the extrusion travels through the throat of the transvector.

Spinnerets are used to manufacture the individual filaments that are spun into yarn. A Spinneret can be a small metal plate, thimble or cap with a controlled number of fine holes through which a hot plastic solution (such as polyethylene, polypropylene or elastomeric material etc) is forced in the spinning of man-made filaments into yarn. The yam can contain from 32 to 298 individual filaments.

As the plastic solution is “spun”, the yam is drawn down by the gun, through a cooling chamber to prevent the individual filaments from sticking together. The gun pulls the yarn at a strictly maintained speed to control the molecular structure and strength of the yam. Once the yarn reaches the "gun" a turbulent airflow is forced through the bundle to increase its surface volume by as much as 40 times.

Immediately after the surface volume of the yarn has been increased, the yarn is laid down in an interlaced non-woven web. The width of the web is determined by the number of spinnerets. Each spinneret can cover approximately 8 to 10 inches in width. (example: A 20 foot wide web would have 20 spinnerets and 20 guns). In order to control the thickness (loft) of the web, multiple banks of spinnerets and guns are used. Some equipment may have as many as 60 spinnerets and guns representing a cost of $180,000.00 for just the guns.

SOLUTION: The consultant sold his customer on the 901XSS Stainless Steel Transvector to provide the proper yam speed. The customer received an additional benefit by being able to remove the cooling chamber because the 901XSS was able to provide enough cooling to the yam to prevent the filaments from sticking together.

The customer used a 903XSS Stainless Steel Transvector supplied with 90 PSIG compressed air to create the turbulent airflow necessary to increase the surface volume of the yam. Total cost for each 901XSS and 903X55 combination was $529.00 - a savings of $2471.00 per spinneret. On a 60 spinneret - gun machine that's a $148,260.00 savings for the customer.

Producer of silk screened yarn goods uses a 921-12 (12”) Curtain Transvector to cool the ink to speed up a 4 color silk screen process.

Carpet manufacturer uses a 208-25-H Vortex Tube to cool carpet backing after hot melt fusing of yarn to the carpet backing material.