In terms of the cost of CNC-machined parts, the primary driver is often the machining time. This can exceed material costs, setup costs, and even the expenses of custom finishing processes such as anodizing or plating.

As a result, this secret can reduce the cost of CNC machining by minimizing processing time as much as possible. One of the best methods is through a process known as manufacturing design.

The more engineers can optimize their designs to reduce cutting time, the more economical their parts will be.

Here are 10 CNC machining cost reduction techniques.

1. Rounded interior angle ≤ 3:1

The wider the radius, the less cutting is required for the tool to remove material.

In contrast, a narrow corner radius requires both a small tool to process the material and more cutting - usually at a slower speed to reduce the risk of deflection or tool breakage - resulting in more processing time.

To optimize the design, use an inner corner radius with an L: D ratio (length to diameter) of 3:1 or less. In addition, if possible, try to keep the internal corner radius unchanged. This helps reduce the use of cutting tools, but it increases complexity and can significantly increase running time.

2. Avoid machining deep hole workpieces

Components with deeper inner cavities are often time-consuming and expensive to manufacture.

The reason is that these designs require the use of fragile cutting tools that are prone to breakage during the machining process.

To avoid this situation, in order to achieve the required specifications, it is necessary to gradually "step by step" and "step by step" decrease, or other forms of machining such as wire cutting or wire EDM can be used; however, these may be equally expensive.

As a best practice, we recommend parts with a maximum length of 4 times the depth. Any component larger than this will significantly increase its manufacturing cost.

3. Limit the use of excessively small tolerances

Generally speaking, several surfaces of a component are crucial to its functionality. The more size requirements there are in the design (such as curvature, hole diameter, and chamfer), the higher the cost of the parts.

To eliminate unnecessary costs, it is crucial to allocate values only for the key features and surface of the task. Other less important functions should be controlled by the model (with a standard tolerance of+/-0.005).

Additionally, try defining a single dimension, such as the intersection of two faces or the center of a hole, and then determine other dimensions from here.

According to customer specifications, our usual tolerance accuracy is between 0.005-0.001.

4. Avoid thin-walled machining

Thin walled CNC parts have a tendency to vibrate, which slows down the machining speed. They can also cause distortion, making it difficult to maintain tolerances. The result may increase costs.

In order to reduce processing costs, the minimum width of the thin wall should be 0.794mm.

If very thin walls are required, using other manufacturing methods such as metal sheet manufacturing is usually more economical.

5. Optimize holes

When it comes to drilling, two factors that can increase costs are drilling depth and drilling size.

Usually, increasing the thread length in a hole is difficult to keep the bolt tighter. In fact, all screw connections are completed by the first two or three threads. Therefore, you do not need to make the diameter of a hole more than three times its length (if possible, keep it shorter). Going deeper will only increase the risk of tap breakage and prolong the processing time.

In addition, using standard tap sizes can help reduce costs. For example, 4-40 taps are more common and generally easier to obtain than 3-48 taps. In the same way, avoid very small threaded holes if possible. Any part smaller than 4mm needs to be manually processed, which increases a lot of time and risk.

6. Utilize standard drill bit sizes

Maintain the standard size of the holes, quantity or letter drill bit size. In this way, you don't need end grinders or reamers to complete non-standard sized holes. This helps reduce machine time to lower costs.

If you are not familiar with the dimensions of drilling machines and end mills, avoid using measurement methods of 0.492 or 3.841 millimeters.

7. Use inexpensive materials

Generally speaking, soft metals have lower machine costs compared to hard materials for the following reasons:

In most cases, raw materials are more economical

Soft materials, for example. Aluminum 6061 is easier to cut, which means shorter processing time.

Harder materials require more expensive cutting tools and are more prone to damage and wear, which may increase project costs.

If materials like aluminum 6061 are too soft for your parts, then find a more machinable low-carbon steel to replace them.

8. Avoid completing multiple tasks

This applies to surface roughness requirements that are high, as well as surface changes such as chemical coating (sometimes referred to as chromate) or anodizing.

Mixing will only increase a lot of costs. For example, several steps have been added to the part that requires the completion of mixed anodizing and chemical film. This also applies to specifying the smoothness in an area.

In terms of surface smoothness, it is best to require uniformity.

9. Divide complex parts

In some cases, complex parts can be cheaper if they are designed and machined as individual parts, and then welded or bolted together.

This is especially true for parts with deeper holes, as they require several hours of processing time to remove material, plus additional material costs.

The same applies to components that require operation on multiple surfaces, which can increase clamping and tool alignment time.

10. Large batch production

Although modern CNC machine tools can perform multiple operations simultaneously, they still require programming and installation.

Mass production helps improve production efficiency and reduce the cost of each product.

During the production phase (up to 10000 pieces), CNC machining can provide the highest cost-effectiveness.