Material selection is a key consideration in injection molding. For example, for consumer parts, if aesthetics are important, materials that can be easily dyed, colored or surfaced may be chosen. For aerospace parts, temperature resistance may be a priority.
How complex will production be?
Again, the complexity of production may involve several factors: is the part itself complex, and is the injection mold complex? Will your part be overmolded? Will more than one type of material be used? In considering these questions, consider the following qualities discussed above.
Viscosity：For complex parts, a lower viscosity may be preferred so that the material can flow through the mold and fill the entire cavity more easily.
Melting temperature. A lower melt temperature may also be useful for more complex parts to ensure that the material remains liquid for a longer period of time as it flows into the mold cavity.
Melt profile：If multiple materials are to be mixed in production, melt profile is a critical issue and should take into account both the production and end-use characteristics of the material. If amorphous and semi-crystalline resins are mixed together, they will not melt uniformly and therefore are less likely to fill the mold properly.
Material interactions： For overmolded parts, make sure that your material does not have any undesirable chemical reactions with the material of the surrounding molding resin.
What is the intended use of the part?
Will your part be used in a high-impact application? Be sure to consider the hardness and flexibility of the material to ensure proper strength without the risk of cracking or fracture. The harsh environments used in aerospace (as mentioned above), underwater and even in the aviation industry can also have a significant impact on materials - temperature adaptation, UV resistance, chemical action and resistance, etc. Of course, more traditional uses (such as children's toys) can also be considered "harsh environments". Therefore, the materials selected for these applications should have greater resistance to breakage.