9 Tips For CNC Machining Design

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Are you fascinated by the precision and intricacy of CNC machining but find yourself lost in the maze of design complexities? Fear not, for you’ve stumbled upon the right guide!

Welcome to our comprehensive exploration of CNC machining design tips, where we’ll unravel the mysteries behind creating flawless designs that seamlessly translate into immaculate machined parts.

As a seasoned CNC machining expert and enthusiast, I’m here to demystify the process, providing you with invaluable insights and practical advice to elevate your design game.

So, fasten your seatbelts and prepare to embark on a journey where creativity meets precision engineering!

9 Tips to Optimize Part Design for CNC Machining

Material Selection


Opting for the appropriate material can significantly influence both the machinability and performance of your final product. Some materials stand out for their ease of machining, such as aluminum, brass, and certain grades of plastic like ABS and Delrin. These materials exhibit favorable machinability characteristics, including low cutting resistance and excellent chip evacuation, making them ideal choices for intricate CNC machining projects.

However, it’s crucial to consider not only machinability but also material properties such as strength, corrosion resistance, and thermal conductivity to ensure the optimal performance of your machined parts.

Simplify Geometry

Embrace the mantra of “less is more” by simplifying your part geometry. Complex shapes may bewitch the eye but can bewilder the CNC machine, leading to unnecessary complications and production bottlenecks.

Minimize Undercuts and Overhangs

Keep your designs grounded by minimizing undercuts and overhangs. These pesky features can throw a wrench in the CNC milling and CNC turning process, causing headaches for both machinists and designers alike.

Avoid Sharp Internal Corners

Sharp corners may be the epitome of sleek design, but in the world of CNC machining, they’re akin to navigating a maze blindfolded. Smooth out those edges to ensure seamless machining and prevent tool breakage.

Optimize Fillets and Radii

Optimize Fillets and Radii

Embrace the art of curvature by optimizing fillets and radii in your designs. Not only do they add aesthetic appeal, but they also alleviate stress concentrations and improve machinability, resulting in smoother operations and finer finishes.

Remember, simplicity is sophistication, and a dash of design finesse goes a long way toward manufacturing mastery.

Avoid Tight Tolerances

Avoid Tight Tolerances

While precision is paramount, unnecessary constraints can lead to inefficiencies and inflated costs. Instead, opt for tolerances that strike a balance between accuracy and feasibility.

Typically, if you do not specify tolerances in your design, the machine will only use its standard tolerances. However, if you do specify strict tolerances, you should maintain consistency throughout the design. This helps reduce machining time.

By allowing for a reasonable margin of error, you not only expedite production but also mitigate the risk of costly rework. Remember, in the pursuit of perfection, sometimes a little wiggle room can make all the difference.

Avoid Partial Holes

Partial holes pose a risk of tip wander, compromising accuracy and structural integrity. When necessary, ensure the drill axis remains within the material to contain the majority of the hole within the CNC machined part, minimizing deviations and ensuring precise machining. Avoiding partial holes altogether reduces the risk of misalignment and enhances the quality of your CNC-machined components.

Typically, 0.1 mm increments are used for holes up to 10 mm in diameter, and 0.5 mm increments are used for larger holes.

Similarly, if there are multiple holes in the part, you try to minimize the number of different bit sizes. Obviously, in some cases, you absolutely need thread holes of different sizes, but if they are relatively close together, see if you can choose one size. This will reduce the time spent changing tools.

Avoid Excessively Thin Walls

Wall Thickness

Beware of overly thin walls in your CNC machining designs—they’re a potential headache waiting to happen! Stick to standard minimum thickness guidelines, such as 0.794 mm for metals and 1.5 mm for plastics, to ensure structural integrity and manufacturability.

If thinner walls are a must, consider alternative processes like sheet metal fabrication for cost-effective solutions.

By avoiding excessively thin walls, you’ll sidestep potential machining challenges and ensure your parts are sturdy and reliable. Remember, a little extra thickness goes a long way in CNC machining!

Avoid Deep, Narrow Slot

Don’t let your CNC machining designs fall into the trap of narrow passages that spell trouble for cutters. Deep, narrow slots might seem like a space-saving solution, but they’re a machining nightmare, prone to tool breakage and surface imperfections. Opt instead for wider, more accessible slots that keep the cutter happy and your production smooth.

The final cutting depth of the end mill should be no more than 15 times the diameter for plastic, no more than 10 times the diameter for aluminum, and no more than 5 times the diameter for steel.


In conclusion, mastering the art of CNC machining design is a journey filled with challenges and rewards. By adhering to the nine essential tips outlined in this guide, you can unlock the full potential of CNC machining, transforming your designs into precision-engineered masterpieces. From material selection to toolpath optimization, each step plays a vital role in ensuring the success of your CNC projects.

Ready to bring your designs to life? Look no further than EJCNC for top-notch CNC machining services. Our team of experts stands ready to assist you at every stage of the process, from design consultation to final production. With state-of-the-art technology and a commitment to quality, we guarantee unmatched precision and efficiency in every project.

Designing for manufacturability accelerates the CNC machining process, reduces operating costs, elevates energy efficiency, and helps product teams create clean, functional parts. Contact us today and get started with a Design for Manufacturability (DFM) expert. We will guide you through the process, ensuring seamless integration of design and manufacturing principles. Your journey to CNC machining excellence begins here!


What are the points to be considered while designing CNC tooling?

When designing CNC tooling, several crucial points merit consideration to ensure optimal performance and efficiency.

1. select appropriate tooling materials and coatings suited to the specific machining operation and workpiece material.

2. carefully choose cutting tool geometries, such as cutting-edge angles and chip breaker designs, to maximize cutting performance and chip evacuation. 

3. consider tool holders stability and rigidity to minimize tool deflection and vibration during machining.

4. integrate features for coolant delivery and chip evacuation to maintain machining quality and prolong tool life.

What software is used to design CNC parts?

A variety of software options are available for CNC design parts, catering to different skill levels and specific needs. 

Some popular choices include Computer-Aided Design (CAD) software like SolidWorks, Autodesk Inventor, and Fusion 360, which offer robust tools for creating detailed 3D models of parts. Additionally, Computer-Aided Manufacturing (CAM) software such as Mastercam, Fusion 360 CAM, and CAMWorks are commonly used to generate toolpaths and NC code for CNC machining.

These software packages often integrate seamlessly with CAD software, providing a comprehensive solution for designing and manufacturing CNC parts.