Sylvin Technologies > Processing > Extrusion > Extrusion Processing Guides

Successful processing of flexible vinyl compounds with extrusion technology is dependent upon a wide range of variables. For optimum processing, exact machine conditions will need to be determined by the processor. The following information will aid the processor in attaining the best possible results.

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Processing Guide

Since flexible vinyl comes in a wide range of hardness and density, the setting of the extruder temperatures will vary greatly. If you have prior experience with a similar flexible vinyl then those temperatures would be a great starting point. If not, refer to the compound's Technical Data Sheet for the recommended stock or melt temperature for vinyl extrusion which will normally be shown as a range.

Take the midpoint of the range and set all barrel, head and die temperatures ten degrees less than the midpoint temperature.
Once material is flowing through the extruder, it may be necessary to adjust each temperature zone depending on the aesthetics and output of the material. The most critical zones will be the rear barrel temperature of the feed zone and the temperature of the die.
- The feed zone temperature controls the compound sticking to the barrel wall, otherwise known as the bite. Too much bite will lead to overheating of the compound and too little bite will lead to poor output.
- The die temperature will also influence output and will have an effect on the dimensions of the extrudate. A cold die will restrict flow where as a too-hot die will affect dimensions.
When optimum temperatures are reached, it is known as the temperature profile; temperature profiles vary greatly and include:
Straight Profile – a temperature profile with all the same temperatures.
Ascending Profile - temperatures that rise from the rear to the die.
Inverted Profile - temperatures that decrease from the rear to the die.
Hump Profile - a temperature profile with the hottest temperatures in the middle.

All of these temperature profiles may work but finding the right combination for output and aesthetics may take time.

Another controllable setting is the screw RPM. This should be set as high as possible as long as you are producing a consistent quality product.

Equipment Guide

A typical extrusion line for processing flexible Vinyl will contain the following equipment.

Extruder	Length to diameter ratio should be 24 to 1. Sizes include 1.5 to 4.5 inch machines.
Barrel	Lined with a wear and chemical resistant layer of Xaloy 101.
Screw	Compression ratio of 2.5 to 1 or 3.0 to 1. Flights should be flame hardened and then a layer of Colmonoy 56 added. Finish with chrome plating.
Breaker Plate	Hardened and polished. Entrance and exit should be chamfered.
Screens	Stainless Steel Mesh sizes ranges from 20 to 200 Starting point would be 20,40,40 Put 20 mesh against breaker plate.
Die	Stainless Steel or Chrome plated Steel. Streamlined for long production runs.
Cooling	Extrudate is generally cooled in a water trough.

Troubleshooting Guide

Problem	Cause	Solution
Lumpy Surface	Too Cold	Increase all temperatures Increase screen packs
Orange peel surface	Overheating	Raise die temperature Decrease speed
Bubbles on surface	Moisture	Dry material, 220F for 1 hour
Pimples on surface	Resin Gels	Increase screens Decrease speed
Excessive Shrinkage	Too much stress	Cool shower Decrease speed Design die with lower draw down
Low production	Worn Screw	Replace Screw
Surging	Equipment/Settings	Take off puller irregular Motor speed varies, inconsistent RPM's Uneven feed, particle size of material Bridging in hopper If Ammeter is varying by 5% or more increase temperatures of the feed and compression zone

For a complete listing of Sylvin's extrusion compounds, click here.

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