Click for the BBB Business Review of this Die Castings in Langley BC


Ask Simalex

Die Casting v/s Plastic Injection Molding

Jan 25, 2019

Depending on whom you ask you may hear that Metal Die Casting and Plastic Injection Moulding are much the same or to some, worlds apart. That’s because the processes follow very similar flows creating parts for assemblies yet their real world applications can be quite distinct. On the other hand, there are still key differences in the way parts are formed and yet a die cast part and a plastic molded part, in some cases, can be used interchangeably. Confused yet?

In both cases material is injected into a die to then cool and be removed. With Die Casting the metal is pushed into the die under enormous pressure in a liquefied form whereas the plastic is injected in a soft state. Both processes have similar design guidelines to account for this cooling of the material (ie thick walls are better than thin and uniformity in thickness helps).

Die Casting and Injection Molding share many other challenging realities. These are just a few examples:

Sharp corners are undesirable

Draft angles are a necessary evil


Ejector pin marks on parts

On the flip side, neither process requires considerable post processing. That being said, Die Casting allows for significant opportunities to correct the surface finish in post processing whereas most forms of plastic do not.

For all of their similarities, each process has significant advantages over the other in certain areas:

Advantages of Plastic Injection Moulding:

Higher production output

More materials to chose from


Fillers can be used in plastic molds to increase strength

Efficient process with very accurate finishes

Advantages of Aluminum Die Casting

Look and feel for consumers indicates higher quality/durability

Mitigates need for secondary operations

Lends itself to complex parts

Stronger than plastics

Better tolerances

Thermal and conductive properties

In some cases the choice between Die Cast and Plastic Injected process should be an obvious choice but sometimes it’s not as clear and the reality is that the right choice is not always made. If you have any doubts let us know – if we think plastic injection is the way to go we’ll be happy to give you a referral but if Die Casting makes the most sense we would like to be a small part of your success.


Get the
latest News

Receive Fred's Die Casting Tips
and News direct to your inbox.

Recent Posts