3D printing processes such as FDM, SLA and SLS are today considered the most economic way to make plastic prototypes. Sometimes, however, certain non-printable materials are needed, and sometimes CNC machining is the only option. Our company has rich experience making plastic concept models and precise functional components. Understanding the properties of different plastics, with lots of testing and experimentation with pre-heating, tool paths and other factors, we are able to minimize deformation on plastics such as PP, PA (nylon), PE, POM (Delrin), etc. 3ERP provides a range of solutions for the machining of plastic parts.
One of the main advantages of plastic machining — especially for prototypes and short-run production — is its ability to create parts without molds or support structures. The most expensive part of injection molding is creating the metal tooling; with CNC machining, however, that stage is not required.
Because machined plastic parts are made directly from a plastic sheet or rod using a digital file, it is easy for engineers to make small modifications to the digital design between iterations. And since they do not have to make new tooling, there is little cost involved in upgrading and updating the part.
The range of machine tools allows for total control over a part’s final appearance, offering fine trimming and cutting capabilities not available to injection molding or 3D printing equipment. Machined parts are also free from 3D printer layer lines and seams from injection molding parting lines, which can be unsightly to view.
CNC milled plastic parts are very popular in the automotive industry, especially for automobile lighting.When making an outer lens cover, for example, a 3D printed SLA prototype only provides about 60% transparency when compared with a CNC machined PMMA prototype. Marks left by the printer can be a major problem, while SLA printing materials are not as effective as PMMA block.
Light guides are also suited to machining, since they require optical details such as prisms, teeth and other tiny shapes.
CNC machining is widely used for small and medium-size high-strength components like pulleys, clamps and levers, which can be made from engineering plastics.
The process is particularly valuable for parts in custom machinery, where mass production using injection molding would be economically inefficient.
CNC machining is commonly used within the electronics industry to create plastic parts for goods such as semiconductors, IoT equipment and consumer electronics. Many electronic devices are contained within machined plastic enclosures, while CNC machining is also highly useful for the rapid prototyping of various electronic components.
CNC machining is frequently used to make plastic parts for the medical industry. These include medicine dispenser components, handles for surgical tools and components for electronic medical devices.
Consumer products, including household goods, appliances and even sporting goods and toys, are frequently made with CNC machined plastic components.
In addition to the prototyping of parts, CNC machining can be used to fabricate items such as custom models, enclosures, jigs and fixtures.
1. When plastic parts need to be large and solid. These parts can take hours to 3D print, while it takes just a few minutes to mill them from a sheet or rod with a CNC machine.
2. When special material is needed. If you design a component in a material like PVC, POM, PEI or PEEK, there is virtually no way to 3D print them, since reliable and affordable printing formulations of these plastics are not yet available. Instead, we can get blocks and bars of the materials, which can be used for CNC machining.
3. When concept models or functional prototypes need a high-quality surface finish. The 3D printing process leaves layer marks on the surface of part that can be difficult to remove. But since we can achieve surfaces of Ra 0.2 from milling, we save a lot of time on finishing.
4. When parts have tiny details that can only be made from CNC machining. Some small details are not suited to printing. For example, lots of optical patterns are designed with a small radius, and with CNC milling we can achieve radii as small as R 0.05 mm.
Although machined plastics are not as amenable to surface finishing procedures as machined metals, there are still several options for altering and improving the surface appearance of a plastic part.
All machinable plastics can be finished with a selection of finishes such as basic smoothing or bead blasting, while certain plastics can be treated with high-gloss polishing, brushing, painting, chroming or metallizing, allowing for a diverse range of finishes across different plastic machined parts. 3ERP can guide you to the right surface finish if you are unsure.