Choose the most suitable material
When designing and machining parts, choosing the right material is the most important way to save money. The most suitable material is not necessarily the most expensive. You should choose the most appropriate material based on the purpose and function of the part.
Many materials are almost identical in terms of performance, but the price varies greatly. You can check if these alternative materials meet the functional requirements. For example, using the commonly used mold ejector pin instead of SKH51 material can save 50%~70% of the cost.
On the other hand, softer materials like 6061 aluminum are easier to cut and therefore have a shorter processing time. Harder materials, on the other hand, require more expensive tools and are prone to damage and wear of tools. As a result, harder materials lead to longer machining times and increased tool wear rates, which in turn increases machining costs.
Try to avoid using 90° inner angles
Acute angles or 90-degree inner angles increase the number of machining steps and time, which increases costs. In fact, most of the inner corners don't need to be 90 degrees, and the rounded corners don't affect the functionality.
If a fillet is used in the design, the machine can machine the part continuously. CNC machining tools such as milling cutters, end mills, etc., will automatically leave rounded inner corners. A small, narrow corner radius requires more toolpaths and special small tools, which will increase machining time and require tool changes. Conversely, the large inside corner radius allows larger tools to cut efficiently.
For the best design, make sure that the L:D ratio (length to diameter) of the inside corner radius is 3:1 or less. In addition, keeping all inner corners with the same radius can reduce machining time.
Minimize internal cavities
Designing metal or plastic parts with deep cavities is often time-consuming and difficult to machine. When creating cavities, a large amount of material needs to be removed, which not only wastes material, but also makes it difficult to remove chips, and may require special processes such as wire-cut EDM or counterbore EDM to reach depth. These all add to the cost.
The depth of the pocket in the design should be limited to 4 times the length as much as possible, and the ideal design depth should be 2~3 times the diameter.
Avoid thin-walled designs
Machined parts with thin walls will take more time to process because they are very fragile and difficult to maintain precise tolerances and are prone to vibration or deformation. Slow processing speeds, special processing techniques, and high scrap rates all contribute to higher prices for thin-walled parts.
Thick-walled parts are more stable and less costly. In order to keep processing costs low, avoid thin-walled designs. The wall thickness of metal parts should be greater than 0.8mm, and the wall thickness of plastic parts should be greater than 1.5mm.
Use standard outlet sizes
When a machined part is designed with threaded holes, the hole depth and thread size affect the total price. In general, increasing the thread length in the fixture will not make the part stronger, so there is no need to penetrate holes greater than 3 times the hole diameter and minimize the thread length. If the thread length is 3 times the diameter, it may increase the risk of breakage and require more machining time. Very small threads need to be tapped by hand, which also increases the price.
Avoid complicated parts
Machining oversized, miniature, or complex designs often requires specialized tooling, multi-axis CNC machines, or custom fixtures, all of which add to the total cost.
In some cases, especially for complex parts that need to be machined on multiple faces, you may want to try splitting the part into two or more independent parts and then welding or bolting them separately, which may reduce costs.
Avoid excessive surface treatment
The surface finishing of CNC machined parts is mainly to obtain aesthetics, corrosion resistance, wear resistance, or other properties. However, these surface treatment processes (e.g., heat treatment, sandblasting, special coatings, anodizing, etc.) add to the total cost. Therefore, the surface treatment process should be carefully selected according to the actual needs.
If the goal is to reduce the total cost, choosing a standard machined surface is a quick and cost-effective option, often used for non-display applications (e.g. mounting brackets). The standard surface finish is typically 125 RA (3.2 RA m).
Avoid overusing tight tolerances
Although we have the ultra-precision machining equipment and production experience to meet the tolerance requirements of ±0.001mm, we still recommend avoiding excessive use of tight tolerances for non-special purpose parts. Because the tighter the tolerances, the more operations and time required, which means that the costs increase significantly.
Bulk Orders
Although modern CNC lathes and milling machines operate more efficiently, they still require engineers to program and set up. The number of parts ordered has a big impact on the unit price. If you order 10000 parts vs. order 10 parts, the price will be very different. Mass production of the same parts can significantly improve the productivity and cost-effectiveness of CNC machining.
Plan production in advance
Develop product blueprints, advance design work, and finalize designs before production. This will give CNC machining suppliers enough time to source raw materials, make production plans, and deliver on time. According to our years of production experience, a longer lead time can reduce the overall cost by 4%~6%.