Plastic Machining vs. Plastic Molding

What are the Top 8 Things to Consider?

We routinely partner with customers who are debating whether to use machining or molding to fabricate their custom plastic parts. Molding and machining of plastics are both trusted production processes, but how do you know which is best for your components? Before prototyping your component, it is critical to analyze your options, such as material selection and the pace and volume of part production, and then decide which strategy works best for your requirements. It's a complex decision that can be answered by weighing eight distinct factors. Before we address the 8 things to consider, let’s define the difference between machining and molding of plastics.

What is Plastic Molding?

In the plastic molding process, solid polymer pellets - which are rigid when cool but viscous at higher temperatures - are heated to their melting point and injected into a cavity known as a mold – they are also known as tools. The pellets then cool in the mold's form and once completed, the mold is opened, and the part is ejected.

What is Plastic Machining?

Precision plastic machining is a complex process that involves using sophisticated equipment to cut away extra material from a larger block of a solid material until the final output is the correct form and size. Secondary machining operations on plastic components may be necessary to provide tighter tolerances than what a molded process can offer.

What are the Top 8 Things to Consider?

Now that you better understand the differences between the processes, here are the top 8 things to consider in the debate on machining versus molding.

• Volume
• Speed
• Time to First Part
• Price Per Part
• Repeatability
• Material Savings
• Surface Finish
• Shape Complexity

The infographic below is a great starting point when deciding which method to use. In the infographic, we go into greater detail about the specific considerations and provide some helpful tips in the decision-making process.

CDI Experts

Here at CDI, we think that having more knowledge is always better when it comes to choosing the optimum production procedure for your plastic parts. Interested in learning more about your machining versus molding options for plastics? We also offer machining and molding for rubber which are distinct processes from plastic production. Whether it’s plastics or rubber components, we are here to help. Our experts in custom design, material science, machining, molding, tooling, and parts production are able to assist you at any stage of the process, from prototype design through mold manufacturing to domestic and international parts production.