Select ejection mechanism(s) to minimize mechanical damage to surface.
Consider using pneumatic air poppets as a means to create initial molded TPE surface release from tool steel – excellent method for very thin wall components. Use pneumatic poppets (air) release approach where feasible.
Determine the most cosmetically important requirements from end user to prioritize surface needs which will guide tool details.
Use stripper plate to spread stress across molded TPE surface.
Where feasible, have stripper plate push against the exposed thermoplastic surfaces which are slightly less prone to surface damage.
Avoid using “sharp” (small diameter) ejector pins in component ejection system.
Slow ejector speed to minimize the “punch through effect” into the newly molded TPE surface.
Use texture on mold surface to promote ejection/release.
If clarity is required, use SPI/SPE #2 finish and use air poppets and a stripper sleeve for ease of ejection.
Basic Feel of a soft over-molded surface is affected by three primary factors.
RTP Company TPE product selection (modulus vs. hardness)
TPE component wall thickness coupled with modulus
Structural geometry of plastic substrate under the TPE
The Benefits of Using Custom TPE Surface Textures
Can provide a softer feel when using a harder RTP Company TPE grade
Can decrease total cycle time (vs. using thicker TPE across section)
Help reduce scuff and mar
Can assist in shedding fluid from TPE surface
Can help “hide” gate marks and cosmetic surface defects
Can actually increase total surface area that consumer uses with finished product
Select appropriate RTP Company TPE to maximize bond strength to selected RTP Company thermoplastic compound