Mold Mechanics Requirements
The requirements of mold mechanics are an essential part of the design and construction of molds and allied products and components. This is because the molded part needs to be of a consistent quality and should not be affected by any external or internal forces to cause it to erode or become distorted. The mechanical properties of the molds need to be able to withstand the environmental and operational conditions in which they are used.
Mold mechanics requirements are primarily focused on three key areas which are; strength, stiffness and fatigue life. Strength is the ability of a material to resist forces which may cause it to deform or be damaged. Stiffness is a measure of the material’s ability to resist or ‘flex’ forces. Fatigue life is the ability of a material to withstand repeated cycles of loading and unloading cycles.
Strength is normally evaluated by using standard tests such as tensile, strain and compression tests. The results of these tests give an indication of the material’s ability to withstand specific forces. Tensile and strain tests measure the capability of the material to withstand forces in the direction of the force being applied. Compression tests measure the ability of the material to withstand forces concentrated along the compression axis.
Stiffness is usually evaluated by testing the material’s resistance to flexure and bending. Flexure testing measures the ability of the material to resist forces when it is bent or deflected from its original shape. Bending tests are performed on a sample of the material to determine how it will perform when under strain when flexed. The results of these tests can be used to determine the maximum desirable size of a mold and the degree of accuracy with which it should be manufactured.
Fatigue life is normally evaluated by subjecting a sample of the material to repeated cycles of load and unload. Tests such as the endurance and cyclic fatigue test help to determine the material’s ability to withstand repeated cycles of loading and unloading without suffering structural failure.
Mold mechanics requirements are important to ensure that the desired performance characteristics are met and the molded part is consistently of a high quality. It is important that the requirements that are specified in the design meet the correct specification and any subsequent changes should be made with due regard for the safety of the component and its end use. The manufacturing process should ensure that the mechanical properties are met and that the properties are consistent with the design requirements.
