Different raw material properties

Deformation properties as a function of temperature and time When the temperature of the material is closer to its melting point, the temperature and time will directly affect the deformation performance of the raw material. Most plastics exhibit changes in mechanical properties when exposed to stress at room temperature or for short periods of time. On the other hand, unless a metal approaches its recrystallization temperature (>300°C), its mechanical properties do not change substantially.

If the use temperature and deformation rate change greatly, the properties of engineering thermoplastics can also change from hard and brittle to elastic. For example, when the door of an air bag is opened, its deformation performance is completely different from that of the slow assembly parts during practical application (such as explosive opening) (see Figure 2). Similarly, snap fittings must also choose different assembly methods as the temperature changes. Here, the effect of temperature is much larger than that of loading rate.

Factors Affecting Material Properties

The properties of plastics are not just those of the pure raw material. Under different operating environments, the basic properties of plastic components will change with different factors (such as UV radiation, Figure 3). Even the best design can fail if the raw material is processed in an inappropriate range. Likewise, artifacts cannot be processed to address design weaknesses. Therefore, only an optimized process that takes into account all factors can guarantee the quality of plastic parts

Unlike metals, plastics do not have much tolerance for errors in design, and when designing plastic parts, designs that match their characteristics are required. Therefore, a complete and detailed analysis of all requirements and constraints of the product must be performed prior to design.