Injection Mould Cavity Surface Roughness Measurement Using Silicon Replicas
Indirect silicone replica metrology resolves deep mould cavity roughness parameters non-destructively within five percent variance of direct steel scans.
Strain Deformation
Meaning
A physical change represents the proportional deformation of a material when subjected to an applied mechanical stress. In polymer engineering, strain deformation describes how much a plastic part stretches or compresses relative to its original dimensions under load. This metric is essential for assessing the structural integrity of moulded components under service conditions.
Polymer Behavior
Polymers respond to stress in a viscoelastic manner, meaning their deformation depends on both the load and the duration of application. Under short-term loads, the material exhibits elastic behavior, recovering its shape once the force is removed. Long-term loads, however, can lead to viscous flow and permanent deformation, a phenomenon known as creep.
Sourcing the right resin requires understanding these time-dependent responses to prevent long-term distortion.
Processing Variable
The molding process itself determines the molded-in stress that influences how a part reacts to external forces. High injection speeds and low melt temperatures lock orientation into the polymer chains, making the part anisotropic. This anisotropy means the part will undergo greater deformation when stressed parallel to the flow direction.
Moulders optimize melt temperature and packing pressure to distribute these internal stresses more uniformly.
Component Failure
Excessive deformation can lead to mechanical failure, especially in load-bearing components. For snap-fit joints, too much deformation can cause permanent set, preventing the joint from holding. Proper part design and material selection ensure that expected stresses remain well below the yield point of the polymer.