Sometimes, we found there is no draft angle with customers’ CAD drawing. We told them that we need to add draft angle, and they asked what is draft angle. Here is the answer.

Draft angle is a must in plastic molded part design. Since there will be a shrink when plastic from molten state to solid state, the plastic part will tightly grip the core of mold. To avoid scratch on surface of plastic part and easily take out the part from mold, draft angle is a must in plastic injection molding process.

The number of degree of draft required is associated with plastic part’s geometry, shrink rate, thickness, surface texture requirements, etc. But in general, the more the better.

Here are some rough guidelines to follow:
We advise using at least 0.5 degrees on all “vertical” faces.

Typically 1 to 3 deg draft is recommended.

2 degrees works very well in most situations.

3 degrees is minimum for a shutoff (metal sliding on metal).

1 to 3 degrees is required usually for light texture.

4 to 5 or more degrees is required for heavy texture.

Any more questions, please contact us. We will be glad to answer.