TROUBLESHOOTING

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Injection Rate Too High
When TPV material is injected too fast, trapped air compresses and ignites. By reducing injection speeds, air will have more time to escape. Traditionally, injection speeds should be set to achieve a fill time of 0.5 to 1.5 seconds.

Screw RPM Too High
We recommend a high screw RPM (100 to 200) to ensure high shear during plasticizing. However, when screw RPM is too high, there may be an over-shearing of the TPV material. This can cause scorching of the material.

Back Pressure Too High
We recommend using only enough back pressure needed to provide good mixing of TPV material. The minimum back pressure recommended is 0.3 MPa (50 psi). Higher back pressure could over-shear TPV materials and might even mix in air which could ignite and cause a burn mark towards the last place to fill.

Clamp Pressure Too High
Excessive clamping force can shut off or crush vents. The machine should be capable of applying a clamping force of 4.0 to 6.9 kN/cm² (3 to 5 tons/in²) of the projected area.

Venting
Generous venting is necessary when using our TPVs because of their fast filling times. As molten TPV material enters a mold quickly and under high pressure, enclosed air must exit just as quickly. Burn marks located at the end of fill are usually a sign of improper venting and are caused when trapped air ignites (called dieseling).

Venting Recommendations for Our TPVs:

TPV Family	Rec. Max. Depth	Land Length	Width
General Purpose Grades	0.038 mm (0.0015")	3.8 to 5.0 mm (0.15 to 0.20")	5.0 to 12.0 mm (0.20 to 0.50")
Molding Grades	0.025 mm (0.0010")	3.8 to 5.0 mm (0.15 to 0.20")	5.0 to 12.0 mm (0.20 to 0.50")
High Flow Grades	0.025 mm (0.0010")	3.8 to 5.0 mm (0.15 to 0.20")	5.0 to 12.0 mm (0.20 to 0.50")

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