Design Tech Academy: What is draft Angle in Plastic parts??

Overview:-

Basic principle for plastic part design is draft.
You should always consider this during the design process.
Insufficient draft can greatly impact the cost and appearance of your part.

Tooling direction:-

The core of a mold separates in a direction that is known as the "Tooling Direction".

Draft or taper is the angle of a surface with respect to tooling direction.

Main reason of draft is important because it allows to part to separate easily from mold parts (Core and cavity).

If no draft applied on sides of part then more force needed to separate parts from core and cavity, which can effect part surface quality and time may need to allow parts to cool than drafted part and more time will make it expensive.

Draft helps to part ejection from core and cavity.

Without draft may part can't be eject from the core and cavity which will make useless and worthless process.

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Draft angle:-

For draft, there is no such thumb rule because for maximum angle you can go with your requirement but for minimum values its directly depends on some factors, Like:-

Material type

Part depth or height

Surface texture

A goo draft value can be (minimum) 0.5 to 1 degree (Standard value) for all sides of the parts but in many cases i can be 0.25 Degree (Depends on special material and condition).

Texture:-

When part have texture on its surface then texture generate more friction on surface of core and cavity which required more draft value to release/Separate parts from mold parts.

Generally texture value comes in 3 to 5 Degree. So for texture surface we required 3 to 5 degree draft angle.

Note-> With high height and depth (more than 25 mm) minimum draft value changes means we have to increase draft angle value.