How to Streamline Part Design for CNC Machining

by Amber Barlow

Photo Credit: Pexels

Computer programs form the backbone of modern life, powering everything from Internet browsing to mass production. And with manufacturing continuing to expand globally, it's no surprise that the market size for computer numerical control (CNC) machines reached $81 billion last year — and the demand for them only continues to grow.

If you want to keep up with the market's activity, one method you can employ is to streamline the part design for various CNC applications. Below are some ways you can do so. Choosing the right material


When choosing a material for a specific purpose, its durability will determine the part's lifespan and the type of material that will impact your overall costs. For example, if the part isn’t going to be used for demanding projects, plastic is the most cost-effective option. However, if the project involves high temperatures or needs a material that's stronger and more rigid, there are an array of metals to choose from like steel and brass. You also need to take other factors into consideration, such as the fastening required and dimensional tolerance.

Consider design limitations


Although we've previously written about CNC's versatility, as with all things, it has design limitations. Part designs that fully take these considerations into account will work better for longer, saving money that might have been spent on repairs or replacements. One limitation is tool geometry. As they work into the material, tools, regardless of their size, will imprint their shape onto it, limiting their cutting length. However, features like a smooth, curved "nose" between cutting edges can ensure a smoother finish on the final product. Another limitation is tool access. Not all features can be machined from the high angle that most CNCs work from. However, this can be resolved by aligning all your features along one of the tool's axes. Plus, by lessening the need to rotate a piece to get at it from multiple angles, you'll be saving time, as well. Consider size limitations


By determining the overall dimensions of your parts, you can choose a machine that's appropriately sized to get the job done better and faster. This is an especially important consideration if the part is to be milled or lathed. If a part is to be milled, refer to its size to establish its machinable height. Allowing for at least a 30-inch difference will give the tool a good clearance angle. This will improve machinability and let the tool cut with minimal shear deformation and power consumption. Meanwhile, with lathing, the dimensions of the build space will determine the largest possible machine you can use. And thanks to CNC providing capabilities for live tooling, you can cut down on lead times significantly. Be meticulous to the last detail


CNC machining is constantly evolving and doesn't serve as a one-size-fits-all solution. This means the best practices to use vary depending on the desired end product. However, there are a few rules of thumb you can follow.


For instance, with CNC's accuracy, you can make holes with a diameter of at least 1 millimeter. This makes it good for manufacturing tiny objects like printed circuit boards (PCBs), which exist in nearly all electronic devices. After all, an integral — and often miscalculated — part of PCB layouts are the through holes drilled into them. That's why it's recommended you determine hole diameter before cutting using standard drill bit sizes. Meanwhile, thread mills can help you produce threads more accurately. The walls of your part should also be at least 0.8 millimeters thick for metal and 1.5 for plastic. If the walls are too thin, it can reduce accuracy during cutting by vibrating or warping over time from stress. This method formulated by Shanghainese researchers can help you predict and compensate for errors in wall thickness. By being meticulous down to the last detail, you can preserve the integrity of the part design while working efficiently enough to reduce the number of resources expended in production.

Written by Amber Barlow

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