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8 Tips for Selecting the Right CNC Cutter

Using the right cutter for the job makes all the difference between getting a jagged, rough, frosty cut or a nice, smooth, clean cut. Even though it’s a small piece of the machine, the cutter is doing the majority of the hard work. When it comes to cut quality, it’s one of the most important parts.

The best cutters are specific cutters. While a cutter may work well with one type of material, it might not always be the best choice for others. In fact, some cutters are designed specifically for certain types of materials. Typically, these cutters last longer and perform more effectively than general-purpose cutters.

The main issue with using a cutter not specifically designed for use with a material is in the quality of the edge cut. There are many applications where that edge will be seen, such as in a retail environment display stand. In these instances, it’s important to achieve a smooth, clean, and shiny edge versus one that is frosty, untidy, and rough.

In fact, when working with acrylic, if the wrong tool is used, the cut may result in a rough finish with ripple marks. The modifications in specifically designed cutters can make a substantial difference in their cut quality.

Cheapest isn’t always best. The saying, “You get what you pay for,” is true when it comes to cutters. A less-expensive tool may work adequately for a little while but usually won’t last long. Focus on selecting the right tool for the job instead of focusing on the cost of the tool. Cutters designed for specific materials last longer than general cutters.

Consider tool fit. Whether the tool is changed manually or through a semi-automatic or fully automatic tool changer, it’s important to keep the collets and locknuts clean and free of dust and chips. Otherwise, the tool won’t be straight during the cutting process, decreasing the quality of the cut edges.

Match the tool size for the job. In general, use the largest tool possible for the design being cut. Bigger tools are stronger and more rigid, which means they won’t bend or deflect when cutting. Smaller tools are needed for cutting fine details on parts and for cutting sharp, tight internal corners.

For the best cut quality, use a larger-sized tool to do most of the cutting, then use a finishing tool to take a very fine amount of material off the part at the end of the process. While this two-stage procedure increases the cutting time, it creates better results than a single cut and has the effect of polishing the part during the cutting process.

Upcut versus downcut spirals. The general recommendation for cutting plastics is to use single flute, upcut spiral cutters. Upcut spirals eject dust and chips upwards out of the cut, which reduces heat buildup, extends the life of the tool, and produces cleaner cuts. However, when cutting thin, flexible plastics, the recommended cutter is a single flute, downcut spiral, one that pushes the material down onto the bed and prevents movement and poor quality of the cut edge.

Keeping things cool. When cutting softer materials, there can be issues with heat buildup and a tendency for the material to stick to the cutter. The solution is to use a cold air gun to direct a jet of cold air at the cutter, keeping it cool. Not only will this result in better quality cutting results, but it also helps prolong the life of the cutter tool.

Speed and sharpness. The speed used to cut through the material and the RPM at which the bit is run are critical to achieving a good finish. CNC router suppliers can provide advice as to the appropriate settings for cutting specific materials.

Additionally, cutting tools must be sharp to produce a clean cut. As a tool is used, it wears down and its performance gradually deteriorates. When you’re looking for the best possible finish, always use a new router bit.

Ask the experts. Choosing the correct cutter for the job can be a confusing and time-consuming process because it can involve testing a multitude of tools on a variety of materials. A more effective method for selecting the right cutter is to partner with an experienced CNC router supplier.

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Susan Mattine

Susan Mattine

Susan Mattine is the communications and PR associate for the AXYZ Automation Group, a global manufacturer of tailored cutting solutions. She can be reached at smattine@axyz.com.

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