Where is the best position to put the gate?
Locate the gate in:
1. the thickest wall section so that hold pressure will be effective during processing, this will ensure quality parts will be made.
2. an area where the part is not subject to high loads in the field. The area around the gate is already highly stressed – this is normal for injection molded parts.
3. an area where the flow length is a minimum. This will keep the machine clamp tonnage to a minimum.
4. an area where the filling pattern is even and will not lead to weld lines and weak areas.
5. an area where venting can be easily designed into the mold design. Venting should always be put at the last place to fill in a mould cavity.
6. An area where the appearance of the part is not compromised.
With an ideal part, all of these guidelines can be successfully applied but often they can conflict.
For example: the gate location for a plastic fork is located at the end of the handle which conflicts with point 3-an area where there is minimum flow length. The reason why it can’t be placed at some point along the handle to minimise the flow length is because it would likely break while using it to eat your noodles because of the built in molded stress already in the part.