Optimizing CNC Part Geometry – Design Considerations

CNC Machining is a crucial process in the custom manufacturing industry these days. It plays a pivotal role in the precise fabrication of intricate parts and enclosures. For engineers aiming to significantly enhance the quality and performance of their machined parts, it is important to address several key design considerations. These considerations are crucial for optimizing CNC part geometry. This ensures greater efficiency and better quality.

In this blog, we outline the key design considerations to keep in mind for optimizing CNC part geometry:

Material Selection

Firstly, you must remember that different materials react differently under the same machining conditions. Choose materials that are easier to machine with the tools available.

• Aluminum is highly machinable, lightweight, and corrosion-resistant, making it the ideal choice for projects with tight deadlines and budget constraints.
• Cold rolled steel, while strong and durable, can be more challenging to machine than aluminum but offers greater structural strength.
• Stainless steel is tougher to machine than aluminum and cold rolled steel. It’s often used in applications where durability is crucial.
• Plastic, meanwhile, is easy to machine but has to be handled carefully to avoid any deformation.

You can get in touch with your Protocase Account Manager to know more about the tools that we have on-hand. And, of course, we’re happy to also order additional tooling if your project requires it, for additional lead time and cost.

Geometric Complexity

While CNC machines can create highly complex geometries, it’s important to note that simpler designs can lead to quicker lead times, which then translates to lower costs. But at the same time, do not make sacrifices on the functionality of the part.

Symmetrical parts are easier to machine, requiring fewer steps and reducing the chances of errors. Symmetry helps in evenly distributing material removal and can simplify the creation of fixtures for holding the part during machining.

At Protocase, before the machining process, our engineering team evaluates each design using our internal complexity rubric. To help you get a deeper understanding of this rubric, we have a comprehensive guide that goes through the factors influencing the complexity level of your part. Download it from here.

Tolerances

In simple terms, tolerance refers to the degree of accuracy in the manufacturing of a part. We have an entire section dedicated to tolerances on our website.

Our ‘tolerances’ are the maximum limits for dimensional variation that we can tolerate before a part is considered out of specification.

In many cases, we can tighten these up. We are happy to discuss your specific tolerance requirements and find a solution that meets your needs without sacrificing our fast timelines.

Wall and Floor Thickness

The thickness of these features on a CNC milled part will dictate the rigidity of a part. This is an important consideration for the part’s structural integrity and functionality.

Features that are too thin relative to their overall size can result in issues such as chatter, out-of-tolerance parts and potential material breakage.

On the other hand, thicker walls reduce costs as you don’t need to remove as much material, plus the part stays more rigid for machining.

When a part is machined, it must be rigid enough to withstand the forces from the tooling needed to create the features.

Overhangs and Undercuts

Features like overhangs and undercuts can be complicated and expensive to machine as they may require specialized tooling and additional machining setups.

Where possible, redesign these features to be more accessible or utilize alternative manufacturing techniques. This will ensure a simpler, smoother and quicker process.

Holes and Slots

Holes and Slots can also add complexity. If possible, move holes or slots to the same face to achieve a faster and less complex machining process.

Corner Radii

The corner radius you choose will have a direct effect on the quality of the machining that can be achieved, as well as the amount of time it will take to machine a part. Using the largest radii possible for your design will both increase surface finish quality and reduce machining costs.

We have a blog which dives deep into the concept of corner radius in CNC machining, and will help choose the ideal corner radii for your requirements and budget.

Pockets

Deeper pockets can be challenging to machine due to limited tool reach and potential for tool deflection. To overcome these issues, limit the depth of pockets, or consider splitting the depth into multiple steps if the design allows.

Conclusion

By paying attention to these key considerations, you can ensure that your CNC part geometry is optimized for machinability. This will lead to efficient, cost-effective and high-quality finished parts.

If you still have questions, our CNC Engineering & Design Services team can help. Get in touch to talk about your design and requirements.

On the other hand, if you have a design ready and are eager to get started, fill out our Request-a-Quote form and get a quote within one business day.