Modeling Injection Molding Witness Line
Modeling Injection Molding Witness Line
(OP)
I am trying to 3D model a witness line in an injection molded plastic part that is shaped like half of a sphere. Average thickness is 1/8" (Acrylic DS or Polycarbonate). We want to have a mold with interchangeable inserts, but are worried about the witness line affecting our part photometrically. What is an average dimension (cut or boss) that I can rotate around my circular part where the insert and base mold meet? Will the witness line be on the cavity side --> ) or the outer surface -->( or both? Not too familiar with injection molding, sorry.
Let me know if you need more information.
Let me know if you need more information.






RE: Modeling Injection Molding Witness Line
The geometry of the witness line will vary based on construction of the mold the texture of the mold and characteristics of the material. I doubt you can accurately model it. Your best bet is to look at the witness lines of ejectors or other mold features in similar parts and make a judgment based on real parts.
The best plan is to design in a feature to hide the witness line. For example if the insert is for a logo put a ring around it so the witness line is in the ring or on the edge of it.
RE: Modeling Injection Molding Witness Line