3. Design for Wall Thicknesses
Managing wall thickness is important for controlling stress marks. But there is also a minimum wall thickness to consider.
There is high injection pressure near the gate
In this area, the original design called for a wall thickness of only .6mm. In practical terms this can create at least three problems.
Firstly, it takes a lot of injection pressure to fill this narrow area. That much pressure creates internal stress that can damage the part or cause the plastic resin to degrade.
Secondly, this pressure is exerted right at the split line, increasing the likelihood of flash. That flash will take extra time and effort to remove and will leave a corresponding mark on the finished piece.
Thirdly, this stress also adversely affects the mold tool, significantly degrading potential tool life. This can be an expensive problem and needs to be avoided. Therefore our advice was to increase wall thickness to at least 1mm. This reduced the stress in this area to a much more manageable degree.