Glossary
Wall thickness — definition
The thickness of metal in the walls of the part — the single parameter with the greatest effect on both quality and price.
The rule is not that the section should be thin. The rule is that it should be even.
Where the section is locally thick, the metal solidifies last. That is where shrinkage voids form, and that is where the part is weakest — often precisely where the designer thought extra strength was being added.
Thick sections also cost twice: more metal per part, and a longer cycle because solidification takes longer.
The remedy is almost always to core out the heavy sections and replace them with ribs. A ribbed structure is stiffer than a solid one of the same weight, and it casts better.