CNC Machining Vs. Injection Molding Parts

Compare the pros and cons of CNC machining and injection molding for powder coating parts, examining factors like precision, accuracy, durability, and cost-effectiveness.

Why The Manufacturing Process Matters

The majority of plastic replacement parts used in powder coating equipment is either machined on a CNC, or injection molded.

Although both forms of manufacturing can produce parts for powder coating equipment, there are differences quality, wear, and tolerances that should be considered before choosing the process that will produce the part.

Benefits of Injection Molding

The main benefits of molding:

1. It is cheaper to produce parts in larger quantities by molding.
2. Complex parts are quite often only feasible to produce by either molding or printing.
3. The range of resins necessary to print parts are currently limited.

Drawbacks of Injection Molding 

Unfortunately, there are several drawbacks to molding:

1. Injection molded parts are only 60-80% as strong and durable as machined parts when using the same polymer. 
2. Molded parts inherently have surface quality issues, such as flow lines, jetting, and flash at the parting line.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Common molding defects that can impact part quality and appearance                                                                                                                                                                                                                                                                                                                                                                                                                        
   
3. While a high-quality mold can initially hold a close tolerance, the mold itself will produce less defined parts with each batch of parts produced.
4. The type of resins that can be mold are limited when compared to CNC machining.

Benefits of CNC Machining 

The main benefits of CNC machining:.

1. Machined parts offer superior precision and accuracy.
2. Unlike molded parts, machine parts offer consistency in production, and do not become of poorer quality the longer that they are produced.
3. Machined parts can be manufactured by using any plastic resin, assuring the best resin is chosen for the manufacturing process.

Drawbacks of CNC Machining 

Two drawbacks to machining are:

1. It is usually more expensive to produce parts in larger quantities.
2. some desired part shapes are more effectively produced through molding.

So, Which Process is Right for You?

While molding is often chosen for making replacement parts for powder coating because it's cheaper than CNC machining, it’s not always the best choice. Molding can sometimes lead to surface defects like flash, jetting, and flow lines, which compromise the part’s appearance and durability. 

In many cases, CNC machining provides higher precision, better material options, and more consistent results, especially when the required material is only available in a machinable form and cannot be molded.

By understanding the differences between CNC machining and molding, you can choose the best option for getting parts that are just right for your project—whether you’re looking for better quality, stronger materials, or more precision.