High quality molds are expensive because labor and numerous high- precision machining operations are time-consuming. Product development and manufacturing costs often can be significantly reduced if sufficient attention is paid to product and mold design.
The way in which the mold is constructed is determined by:
- shape of the part
- number of cavities
- position and system of gating
- material viscosity
- mold venting
A simple mold with a single parting line is shown in the figure above. More complex molds for parts with undercuts or side cores may use several parting lines or sliding cores. These cores may be operated manually, mechanically, hydraulically, pneumatically or electro-mechanically.
The figure below shows an example of a sliding cam. The cam pins that operate the cams are mounted under a maximum angle of 20° - 25° in the injection side. The angle is limited because of the enormous force that is exerted on these pins during mould opening and closing.
Cammed mold for part with undercut cams move in vertical direction when mold is opened.