Simply put, plastics machining is the subtractive method of removing material from a sheet or piece of plastic to create a specific shape using CNC (computer numerical control) machines, “revealing” a final remaining “part” that is the desired shape and structure. Michelangelo is reported to have looked at a piece of marble he was going to carve and have said “The sculpture is already complete within the marble block, before I start my work. It is already there, I just have to chisel away the superfluous material.” In essence, this is what plastics machining is all about. Where material is removed depends on the final shape of the part that we are trying to make. For Michelangelo, he saw the form of David within the marble. For us, we see many components, that our customers want made within a specific set of numerical measurements, and we must create the separate parts with great efficiency, and proper planning (utilizing our many years of expertise) to yield the most cost-effective results, and produce the smallest amount of waste. And for some CNC machining shops like ours, it’s an art form as well.
Plastics machining is also a very broad term, as there are many methods that can be employed to machine plastics. This article will cover the most common methods of processing plastic materials in use today in manufacturing.
The first of these techniques is that of milling. Milled plastics have been used for years in a variety of industries and applications, and are an extremely cost-effective way to create intricate shapes and surface finishes on plastic sheet material. Milling refers to the process of using a milling machine, consisting of a rotating cutter blade that is able to cut away material by traveling along a predetermined track, which is controlled by the computer. Milling machines have been in widespread use since the 1950’s, and are still very popular in numerous industries.
The main reason for this popularity is that the milling process has a tremendous amount of versatility when it comes to options. Milling machines can be used with either programmed or manual fixtures as well as either conventional mills or CNC milling machines. Our CNC milling machines can control depth milling capable to a tolerance of .002, and we are also able to provide a .015 smallest internal radius. An example of milling is illustrated below.
Drilling is perhaps the most common method of plastic machining. Some other CNC shops use fluid coolants for their process as high speed drilling can cause materials to heat and expand making drilling very difficult. We do not. We prefer a dry process, and have special proprietary drilling techniques that we have mastered, operating our high speed 120 K multi-spindle drilling machines to accurately produce parts to very tight tolerances in many materials. The process yields better results that we believe maintain the insulation and thermal integrity of the original materials better in the final results.
Routing is a third method of removing material, usually employed to create channels in plastic sheet material, with varying levels of depth for specific parts’ needs. The process of routing is not dissimilar to milling. It can be done either manually with a handheld router, or CNC machined with a router on a CNC machine. The processes are similar, however the outcome is different based on the shape of each part. Below is an image that depicts the process that we use to create such parts using our high-speed multi-spindle routing machines. We use a state of the art optical measuring system to assure consistent parts quality and very tight tolerances.
A frequently requested, but less common method than those listed above, of plastics machining is tapping. Our tapping process cuts a thread on the inside surface of a hole, creating a female surface which functions like a nut, so that screws can be used with a final part. This is sometimes a very specialized process depending on where the holes are positioned in the part, and the depth of the drilling. Our tapping provides excellent tolerances as are required, as most of the parts require screws to fit snugly for proper tightening. Tapped holes may also need to be drilled again after the tapping process, making it an extra step for our machining technicians to remove any excess material that may still be in the holes.
In a nutshell, plastics machining allows our clients to create parts in their specific shapes and desired dimensions. The removal of material is accomplished by one of the 4 processes mentioned above, plus optional finishing techniques we’ll cover in future articles as well, creating an extremely accurate and cost-effective part that is perfect for their needs. In many cases, our CNC machining provides an opportunity for the client to expand upon their product line or utilize a process that they had not been able to implement previously due to time constraints or inability to produce parts at costs that would be affordable.
We strive to be communicative partner for our customers, and allow them the opportunity to see all of the steps that contribute to their parts being made for them. We hope that this article on plastics machining has been educational, and we look forward to continuing our efforts to provide the customers of JMJ Profile with informative information, as well as continued excellence in service.
If you have any questions regarding these processes or other machining services, please don’t hesitate to contact us directly. We are standing by, and ready to discuss your next important project!