Considerations for Choosing CNC Machining to Manufacture Plastic Parts

Plastic parts are an important part of everyday life. From bottled beverages and cleaning products to bath products and laptops, manufactured plastic parts come into contact every day.

The malleability and adaptability of plastics are the reasons why plastics are prevalent, and plastics can be used to make all types of parts, from flexible parts that can withstand repetitive motion to rigid, impact-resistant parts that are durable even in extreme temperatures part.

Manufacturers can do it through injection molding, additive manufacturing, polyurethane casting and CNC machining. CNC machining is the most commonly used method due to its reliability, compatibility and ability to manufacture parts with complex geometries. However, there are some considerations to keep in mind during the design and production lifecycle. This article will explain what you should know before using CNC to make plastic parts.

CNC machining process and part design

CNC machining is a subtractive manufacturing process that uses rotating computer-controlled cutting tools such as drills, end mills, and turning tools to remove material from a solid block of material to form a part.

The digital design file instructs the CNC machine how to cut the block (also known as the "workpiece"), and multiple machines can use the same design file at the same time, greatly increasing the speed of the production process.

One of the main considerations in machining plastic parts is the shape of the desired part, which will help determine whether a 3-axis or multi-axis machining process makes the most sense. 3-axis CNC machining involves moving the cutting tool along the X, Y or Z axis as the tool or workpiece rotates.

On the other hand, multi-axis processes allow the tool and workpiece to move simultaneously, enabling manufacturers to produce parts with complex geometries faster and more accurately without repositioning or rotating the workpiece between operations.

The axial limitations of CNC machining mean that part design must ensure adequate tool contact. This can make certain designs, such as curved internal channels, extremely difficult or impossible, leading to extensive design modifications for manufacturability (DFM) to improve production cost-effectiveness.

Additional features that increase part complexity, such as undercuts or design elements on multiple part faces, may require the workpiece to be rotated one or more times, resulting in higher production costs and longer lead times.

However, since machining is a subtractive process, issues such as insufficient wall thickness, draft and sink marks (usually addressed during the design phase of cast or molded plastic parts) are less of a concern, making CNC machining a good choice . The choice for hard-to-form part designs. The precision of the machining process also enables manufacturers to make plastic parts with extremely tight tolerances.

A cost-effective option for manufacturing plastic parts

In addition to axial limitations, CNC machining can be used to rapidly manufacture parts of virtually any shape and material with exceptional precision and precision. It is also a trustworthy and reliable process.

Additional Manufacturing Considerations

Another key consideration is the size of the production run. Some manufacturing methods require a large up-front investment (such as the tooling required for injection molding), but the low to moderate setup costs required for CNC machining make it ideal for low-volume production of plastic parts.

These setup costs are related to the specific number of operations required to create the workpiece and optimize the production part. If the part geometry is complex enough to require rotating or resetting the workpiece or tool, the production cost and time per part also increases.

However, because CNC machining does not require the manufacture of expensive molds, manufacturers can start production faster than other processes. CNC machining is highly automated and can be put into production with minimal manpower during commute hours. In addition, multiple CNC machines can use the same design and produce the same parts at the same time – ultimately reducing cycle times and saving costs.