Is there a draft in this injection molded pen cap?
Hello, I'm new to injection mold. I found this pen cap is a perfect circular shape. The curve at the parting line is perfectly smooth. If there is even a 0.5 degree draft, the curve at the parting line is already not as smooth as this. Anyone knows if there is a draft in here or sometimes drafting is not necessary? Or some grinding smooths it in a post treatment process? As I can barely see the parting line.
- 3 年前最愛解答
Most of the injection molded parts I have designed have had draft. You can get away without draft for very short pull distances with certain materials. One part I did had about 1/8" with no draft for a press fit with a tiny little check valve. The part you are looking at would be very hard to measure accurately to determine if there is draft. Take a half inch or 12 mm and multiply by the sin of 1/2 degree and see what you get. With high enough clamping pressure, sharp enough corners, and a really excellent mold maker, you can minimize parting line mismatch. Some do post grinding. All depends on circumstances.
- 3 年前
For deep parts, draft should be added for molds.
For very shallow parts, close to a board, no draft is ok.
We do custom plastic injection molding as well as molds in China.