Processing Information
Successful processing of flexible vinyl compounds by injection molding is dependent upon a wide range of variables such as mold design, screw geometry, machine size and shot size. 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.
Click on the panels below for helpful processing information.
Successful processing of flexible PVC compounds by injection molding is dependent upon a wide range of variables such as, mold design, screw geometry, machine size and shot size. Exact machine conditions for optimum processing have to be determined by the processor. The following will help the processor in attaining optimum conditions.
Mold Temperature
Inlet water temperature should be between 70 and 100 degrees Fahrenheit. The ejector side should be 10 to 20 degrees colder to help in part removal.
Stock Temperature
This will be controlled by a combination of heater band settings, screw rpm, and screw back pressure. Consult technical data sheet for recommended temperature.
Heater Band Settings
For starting purposes, set barrel temperatures 20 degrees less than recommended stock temperature. Set nozzle temperature 10 degrees less than recommended stock temperature.
Screw RPM
A rotation speed of 35 to 50 rpm's should be satisfactory for most applications.
Screw Back Pressure
This will vary from machine to machine, but generally 60 to 100 PSIG is recommended.
Injection Speed
Slow to moderate for start up, then increase to moderate
fast for production run.
Injection Pressure
20% to 40% of the maximum available will yield the best consistency.
Holding Pressure
Usually 50% of the injection pressure. Use just enough to maintain a full part.
Purging
Purge the barrel until all of the material is out. You may use a commercial grade purge compound or general purpose polystyrene or ABS.
Mold
Remove any residual plastic and clean the mold with a commercial metal polish or with a 2% solution of baking soda in water. Wipe clean, then add a coating of commercial oil or grease for storage.