Avoid Mistakes in CNC Design

Jack Lie CNC machining expert

Specialize in CNC Milling, CNC Turning, 3D Printing, Urethane Casting, and Sheet Metal Fabrication Services.

Once you upload your CAD file to our quotation system, our engineering tea will analyse our design and provide you the most cost-effective solution. As CNC machining has ability to produce various geometry parts, there are still some critical element we should consider. Limiting parts complexity and unnecessary features will reduce final milling or turning time, and finally reduce the production cost. We notice these 5 recurring issues in CNC machining designing process, in order to avoid these common mistake, and improve designing of manufacturing, shorten operation time, reduce final manufacturing cost.

Avoid Unnecessary Machining Features

The most frequent mistake in CNC designing is create parts area without machine cutting necessary. These unnecessary machining will increase parts producing time, and finally increase the final production cost.

As we can the following example, one the left, this design specifics thee critical circular geometries in the middle area, requires the square holes features machining in middle and then removing surrounding materials, finally reveal finished parts. This approach will add significant machining time to cut remaining materials. In a simpler design, we can see the illustration at right, CNC machines only need to cut required feature form the block, this approach will eliminate need of additional, wasteful machining process on excess materials. The design change in this example will reduce almost half of cutting process time. So keep your CNC design simple will avoid extra operation time, pointless machining and added manufacturing cost.

Avoid Small or Raised Text

Once we produce our customers designed parts, there are always requirement of parts number, description, and company logo on parts surface. All these text will increase parts appearance for company reputation. However, this process will also add final cost, and the smaller text, the higher cost. In reason of very small end-mills can only cut text operation at a very slow speed, which will finally increase operation time and therefore the final cost. So in CNC design process, you can accommodate lager text, increase operation time fast significantly. In addition, select recessed text rather than raised text once possible, which only requires milling away less materials to create letters, numbers or graphic on parts surface.

Avoid Tall and Thin Walls

Any features on wall in CNC designing process are tricky, any unreasonable design will give rise to final CNC manufacturing issues. As most cutting tools in CNC machines are made of hard and rigid materials like tungsten carbide and high-speed steel. In cutting process, all these tools will deflect or bend slightly by machining forces, same as the block materials. Then result to some issue like rippled surfaces and poor tolerance, in some case, these force will break, chip or bend the material walls.

Once you design tall wall on your parts as our maximum height of 50mm, you should add its thick to increase the rigidity of materials. Thin walls of 0.5 mm or less are easily to break down, flex or warp in machining process. Otherwise, it doesn’t mean to design wall too thick in reason of high speed of cutting tools at 10,000 to 15,000 RPM. Our experienced for walls design is width to height ratio of 3 to 1. In addition, add some draft to walls as angle of 1 to 5 degrees rather than standing vertical. This will make machining process easier.

Avoid Small Pocket Features

As in CNC parts design, we always need to incorporate small square corners or internal corner pockets to reduce parts overall weight or assemble other pieces. While in actual CNC manufacturing process, all these features are too small for our cutting tools to operate. Once you need to create these features, we will pick away materials at corner area with smaller cutting tools, which result to apply five to eight different small cutting tools. In this process, operation time will be increase by different tools alternation, and finally raise your project cost. In order to avoid this, you should determine the really critical pocket features. If these pockets are just for reducing parts weight, you should adjust your design to avoid unnecessary cutting process. Keep you corner design at large dimension, apply various big cutting tools and less operation time.

Reconsider Design for Molding

As we always receive injection-molded parts design for prototyping before our machining service purchasing. In this case, different manufacturing processes have various design requirement and results. Thick machined features will suffer sink, wrap, porosity problems once molded. A molded parts with ribs, pockets and other features will prolong operation time. The most important points is parts designs should be optimized for manufacturing process.

CNC machining is the quickest, efficient and most cost-effective way of prototypes and production manufacturing, it is a popular choice for designers and engineers. Avoid these common design mistakes in this tip will improve your parts design, shorten operations time, and reduce your final production cost.