Computer-aided design (CAD) is the initial but crucial step in any manufacturing process. The developed designs can then be transmitted to the top performance, precision manufacturing, and product development procedures, such as diverse types of CNC fabrication.

However, it is vital to highlight that, while CAD software solutions have made it efficient to create technical designs, designing and modelling for CNC fabrication still demands precision and quality. Let's read further to understand how to convert our design concepts into CNC fabrication without compromising the operational efficiency and, product quality & performance.

Top 8 Tips for Transforming Design Ideas Into CNC Fabricated Products

1. Standard Dimensions

   Standard sizes are available for all materials. It is critical to understand these standard stock dimensions. Also, part design should be adjusted to fit within typical stock sizes to reduce waste and increase material productivity. Consider the breadth, thickness, circumference, and height. Most providers standardize every one of these dimensions.

   In addition, utilizing conventional end mill diameters and drill sizes to create holes, slots, and pockets is a good practice when designing for CNC fabrication. Also, the material selection should be based on the most readily available alloys.

2. Emphasis on Critical Design Considerations

Prior to transferring the CAD drawing to the Computer-aided manufacturing (CAM) environment, confirm that it's complete and accurate. Ideally, the node count in the vector lines should be limited to the bare minimum without compromising the quality and precision of the design, and all necessary drawing elements should only get exported into the finalized file format. Moreover, the layers in the CNC software that could get selected inadvertently or dragged around must be locked.

3. Eliminate Any Overlapping Geometry

If the design has overlapped vectors, it will confuse the CNC machine, and the resultant motion would be back and forth in the same spot. It might work for certain laser etching designs, but it is rarely feasible. We need to remove duplicate object instances, if any .Moreover, lines that intersect slightly, for instance, arcs overlapping with regions of circles, and the objects aligned end-to-end, should be combined.

4. Refrain From Over-Tolerancing

Designers must allow for dimension tolerances only where needed. However, disproportionate tolerancing would increase production time and expense. Distinct CNC machines have varying tolerance standards. For example, a 4-axis CNC vertical milling machine would have different standard dimensions than a two- or three-axis CNC machine. Hence, precise tolerance constraints should be set only when essential to save time and money. Maintaining uniform tolerancing is also crucial since it reduces CNC machining time and improves product aesthetics.

5. Avoid Features That Are Difficult to CNC Fabricate While Designing

Superfluous design features and elements would complicate design fabrication. Realizing the machine's characteristics is generally advantageous when designing for CNC fabrication, as it allows designers to develop features that the machine can produce. Furthermore, particular components are purely aesthetic and cannot be fabricated precisely. Before deleting components for aesthetic purposes, examine the volume of material removal required and the procedure to be employed. We can contribute to the design by focusing on the precision of required attributes because one can incorporate the aesthetics through post-machining operations.

6. Understand the Significance of the Cut Width of CNC Cutting System's Tools

The cut depth and width serve as critical parameters while milling pockets, facing,  profiling, and other machining processes. Determining the cut width enables us to regulate better the material removal rate, feed rates & speeds, time duration for the operation completion, dimensional accuracy, and the surface finish. Ensure that the distance between tool paths is proportional to the tool's diameter. Also, machined corners are affected by the end mill's size, which influences how the components fit properly.

7. Prevent Designing Thinner Walls

While designing for CNC fabrication, avoiding extremely thin walls would lead to enhanced and accurate products. Since wall thickness is proportionate to material stiffness, reducing wall thickness would also reduce material stiffness, reducing feasible precision due to inherent disturbances during machining, resulting in inconsistent dimensions or a below-par surface polish. Metal walls must have a minimum thickness of 0.794 mm, and plastic walls must have a minimum of 1.5 mm. On the contrary, increasing the wall thickness of a part design aids in enhancing the rigidity and reducing machining time.

8. Add Radii for Internal Edges

Most cutting tools are tubular and cannot produce precise internal edges. Thus, it is critical to include radii while designing for CNC fabrication. Tool wear can be decreased by designing internal edges that are not overstrained. Designers can follow the rule of adding a radius equal to 130 percent of the milling tool radius. If the design requires 90° internal edges, include an undercut instead of decreasing the edge radius.

Conclusion

By implementing the above-discussed tips, designers and manufacturers can optimize the CAD models for producing quality parts and products with utmost dimensional accuracy, smooth surface finish, and best-in-class performance through CNC fabrication. Hence, we can transform several design concepts or prototypes developed on a computer into tangible products for real-world applications. 

Author:  Vincent Hua is the Marketing Manager at TSINFA. He is passionate about helping people understand high-end and complex manufacturing processes. Besides writing and contributing his insights, Vincent is very keen on technological innovation that helps build highly precise and stable CNC Machinery.