Plastic: How to Avoid Bad Cut Edges When Using CNC Routers

Through this article, you will get to learn about machine fundamentals. Bad cut edges have more effect on the final product than just visual distraction. They will also lead to inaccuracy making it hard to fit different joints together. You have to cut any piece in a specific size so that it can fit with others. This is the reason that you have to ensure that you strive to achieve fine cut edges. You will not meet customers’ demands if your parts fail to pass the quality test caused by bad cutting.

Various machine fundamental features can have an impact on cut edge quality, spindle, and general construction and drive systems. If you fail to focus on these while in the production process, you will have a hard time achieving good quality cut edges during the time of processing acrylic and other similar materials. To deal with any issue concerning cut edge quality, you need to spend some time cleaning up the cuts after the production process.
Machine Fundamentals

Let us see how the CNC router configuration can affect the quality of the cut edges of plastics.

  • Machine Construction

The vibration of the machine greatly affects the cut quality of plastic materials. Slight vibration can lead to marking on the cutting head affecting the quality of quality cut edge. Things like spindle or controller, drive systems and how your machine generates motions can cause vibrations of the machine. Although it is very hard to deal with these, a machine constructed and designed well can dampen and eliminate them in a way that you cannot notice them.

The most effective way to do away with vibrations is to ensure that your heavy-duty, welded frame is mounted on the highest quality router mounts. This will ensure proper restraining of your machine thus minimizing vibrations. Ensure that you use the correct specified mounts and you will reduce vibrations by 98%. This will also increase the life span of your router and reduce the levels of noise in the working environment.

  • Drive System

The drive system used in your CNC router has a major impact on cut quality. Vibrations by roughness or misalignment of the drives will be transmitted to the cutter showing up ripples or notches on the surface you were cutting. The common drive systems you will find in CNC routers include helical or straight rack and ball screws or pinions.

Although they provide smooth motions, ball screws effect when used in larger machines. A long ball screw can lead to vibrations affecting the router quality cut. You need to adequately support the screw or ensure that it has sufficient diameter that can be costly. However, you can use a pinion or straight rack. They are compatible with long lengths and not expensive. The set back of this is that when one pinion tooth is engaged, it will lead to motions that can cause wear over time. The wear will affect the drive system leading to default in cut quality and accuracy.

Using a more advanced pinion and helical rack, you will easily solve all these problems. A helical drive engages several teeth at once hence the machine will run smoothly reducing wear and any ability to achieve higher feed rates and accelerations. Incorporating quality server motors to the pinions and helical rack, you will produce perfect cut quality.

  • Routing Spindle

Any bearings or spindle imbalance while running at a speed above 24,000 rpm can cause marks on your workpiece. If you want a high-quality cut, you have to consider investing in a quality spindle. Always follow what your manufacturer recommends. They will advise you on what is compatible with the router and help you with suitable alternatives.

Consider spindles that can run at a speed of 40,000 rpm. This is twice the normal spindle speed. Although they are very expensive, they work best in coming up with fine cut quality at a faster speed. Their processing speed is three times faster than the normal spindles. However, due to the high operating speeds, you have to ensure proper cooling system in your machine. Ensure a good restraining system to hold your CNC router in position securely and precisely while working. Before choosing high-speed spindles, consult your manufacturers to know whether your machine can operate well with speedy spindles.

  • Chip Removal

To achieve the best cut quality using your CNC router, you have to ensure the effective removal of debris and dust pre and post-work. If you do not remove the chip efficiently and quickly, the chips will be trapped in the machine clogging the cutting flutes or melt. You cannot get quality cut with this. Your piece will have frosted or milky edge which will be rough to touch.

To remove chip effectively, you need to ensure a well-designed pressure foot. When using this correctly, a cyclonic vortex will be generated to suck waste quickly from the plastic cut edge. The best thing to do when you cannot identify the best cutting method is to contact your manufacturer.

You can also consult vendor technicians to advise you on the ways you can achieve the best quality plastic cut edge. The technicians are trained well in anything concerning the CNC router and things to do with cutting information. They can take you through the whole process of getting a fine edge cut. When you follow advice from the technicians, you will get a smooth finish product without ripples.


It is a dream of any CNC router operator to achieve the best quality cut edge in whichever material they are dealing with. There are several steps to consider when you want to avoid bad cut edges on your plastic material. The first thing you have to ensure is following what your machine’s manufacturer recommends. Some of the things that can harm your plastic cut edge include machine construction, routing spindle drive system and chip removal. Following the manufacturer’s protocol, you will avoid bad cut edges while using the CNC router machine.

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