Basic points of mold designing (P1)

When you want to make smaple for injection process, you must care many point : quanlity, cycle of product, material, injection machine, liquidity, mold designing condition,... In this lesson, i will write about basic point of mold designing.

1. Thickness of sample.
 If thickness of sample is too thick:
    + it will be the cause of defect: sink mark, short short,...
    + It will take time to cold up and the mold cycle will be longer. 
    + To spend much on production is up.
 So we try to design thinner thickness .
Example for design thickness:

 Design of thickness change

Design of thickness distribution (http://www.m-ep.co.jp)

In these picture you will know how to design thickness for samples. Thickness of sample about 0.5~4 mm and we always want thinner thickness if can.
2. Try not to make the sharp corne 

make radius

                                                    In this picture:   r =( 0.2~0.6)t

Sharp conner will block the resin flow when molding , which will become a cause of flow marks.The stress will concentrate on the sharp corner part.
 Result when we make radius for sample:
   +  The stress will down
   + The resin flow will better.
   + Warping of product:  defect rate of product will down.
   + The molten plastics will insert to mold better.

Corner radius and stress concentration factor