A mould’s quality is the basis for qualified plastic products. And mould design is the foundation for a high quality mould manufacturing. Here are 5 things we need to pay attention on when do precision mould design.

1. Check part drawing and confirm the mould opening direction and parting line position. Each plastic product needs to determine its mold opening direction and parting line at the beginning of mould design to minimize sliders or lifters to do the best avoid the impact of cosmetic surface caused by parting lines. After determining the mold opening direction, try the best to make the product ribs, clips, protrusions and other related structure can be consistent with the mold opening direction. In this case, it can help to avoid core pulling, reduce joint lines, and the expanding of molding time. At the meantime, an appropriate parting line can be selected to avoid possible undercut in the mold opening direction, this can improve the part’s appearance and mould’s performance.

2. When checking the parts drawing, we make DFM to customers and give suggestion of draft angle in the part. Adjust draft angle properly will help to avoid potential problems like drag mark, deformation and crack. When make mould design with structure of deep cavity insert, the draft angle of outer surface should be bigger than draft angle of inner surface to avoid sticking on cavity (keeping the parts on core side), and assure the uniform product wall thickness, assure the material strength and opening time.  

3. Plastic parts wall thickness is one of the critical factors for plastic tooling. Normally, when the wall thickness is more than 4mm, it will cause problem of big shrinkage, deformation and welding line in parts and need very long cooling time in injection moulding process. In this case, we need to think about changing the plastic part structure. Sometimes, we can add ribs to enhance the part’s strength and reduce the possibility of deformation.

4. Mould cooling system is a very fatal element we need to consider when do mould design. Cooling will have big impact of moulding cycle time and parts’ deformation risk. A good design of cooling channel can help to shorten moulding cycle time, postpone mould life and reduce risk of moulded part’s deformation.

5. The gate position is also very important. It affect the part’s cosmetic surface, deformation risk, injection pressure, moulding cycle time, and if customer want runner can be cut directly after moulding to save workforce cost, how chose the gate is a must consideration.