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Factors Affecting CNC Machining Costs
Although 3D printing has become a hot topic in the mainstream media, expectations for it have not been too high in recent years, especially when it comes to making metal parts. CNC machining remains one of the most cost-effective manufacturing processes in on-demand production to date. When looking for custom CNC machined parts, the price from different manufacturers can be very differently, sometimes even a double the gap. Most of people felt confuse, what factors affecting the price of CNC machined parts? In fact, in CNC machining there is no fixed cost that can be universally applied to different CNC projects. This article will help you to understand some of the major factors affecting CNC machining costs, and provide you some advices about how to reduce the CNC machining costs for meet your project budget.
The most important factors affecting the costs of CNC machined parts is processing time, equipment, materials, design, manufacturing volume, tolerance and surface treatment, etc.
1. CNC machine and its configuration
CNC machine. CNC machine is a major investment before a machining project. For example, Haas (HAAS) machines are very popular in the United States, and the price of an entry-level CNC milling machine starts at $30,000. These expensive investments have to amortize into the cost of each part manufactured. Operation, maintenance and other related costs are also not a small expense. CNC machining uses expensive CNC machine tools, and the cost of the parts produced by it will be correspondingly higher.
Operations to machining custom parts include drilling, boring, turning and milling, most of operations are performed on a CNC mill or CNC lathe. At DDPROTOTYPE- a prototyping manufacturer in China, the machining cost for a 3-axis CNC milling machine (excluding operator wages) is $13 per hour, after add operator’s wages will be around $24 per hour. Prices for CNC turning is at $11 per hour, while machining costs for 5-axis CNC machining are $40 to $80 per hour or more.
Cutting tools. The material, coating and geometry of cuttingtools can affect the total cost of CNC machine also. For example, the cost of carbide-tipped cutting tool will be double of steel cutting tools, it is will be much harder, more heat-resistant and can work under extremely high speed. Cutting titanium alloy, you must use a special alloy cutting tools.
CNC milling is more expensive. Compared with CNC turning, CNC milling machines have more complex moving parts; are more difficult to set up, operate and maintaining; and can perform more complex operations, and cost will be higher accordingly.
Set-up costs. Set-up costs cover the costs incurred in preparation for the actual machining. All CNC machined parts begin as a 3D model. The 3D model is designed by design experts, using CAD (Computer Aided Design) software. The resources it takes to create a 3D model to be manufactured, make up a significant portion of the set-up costs. Set-up costs also include design optimization and CAM (Computer Aided Manufacturing) preparations for models to be manufactured, using the appropriate CAM software.
2. Materials
The material used to manufacture parts is one of the important factors affecting the cost, which involves to the cost of the raw material and the machinability of the raw material.
l The cost of raw material. The price of raw materials varies which depending on its value and rarity. Experienced purchasing engineers will have a detailed understanding of common processing materials, such as aluminum, copper, titanium, stainless steel, magnesium, zinc, ABS, Acrylic, POM, FRP, Nylon, PEEK, PVC, PC, PE, PU, PTFE.
Metal | |
Aluminum 6061 | $25 |
Aluminum 7075 | $80 |
Stainless steel 304 | $90 |
Plastic | |
ABS | $17 |
POM | $27 |
Nylon 6 | $30 |
Take the 6 “x 6” x 1 “dimensions for example, the cost of different materials.
Machinability of materials.In addition to the cost of raw materials, the difficulty of processing is another important determinant. The cost of CNC machining a part is proportional to the time it takes to machine it. Difficult-to-machine materials consume more resources also, such as more settings, fixtures, cutting fluids, electricity, and cutting tools. Metal materials tend to be more difficult to machine than plastic materials, but different material with different grade also. Such as ABS, PC, PMMA and AL6061 are very popular CNC materials as it is easy to cut, while the machinability of PEEK, magnesium, Teflon, stainless steel and titanium are slightly poor.
Design and Geometric Complexity.The design and geometry of the part significantly affects the cost of CNC machining. Obviously, the machining cost will be much higher for more complex part, sharp interior corners, thin-walls, deep cavities, non-standard hole and lettering, etc. Highly complex parts may require more advanced CNC machines, more machining time, multiple change the machining surface and setups, more quality inspections (tolerances, surface finish, etc.), setups, custom fixtures, etc, and all of this will affect the cost of the part.
Also, manufacturing large parts is more expensive because it requires more raw material, resources and machining time.
Quantity.The cost of single part can be effectively reduced through high volume manufacturing, which is the result of eliminating the cost of repeated setups. For the same part, CAD design, CAM and machine set up are all done at one time. If only used to make one prototype, all setup costs are allocated to this one part. If the same operations and setups are used for large volume of the same parts, the setup cost can be distributed across all parts, and maximize saving the cost. According to incomplete statistics, if the price of one part is $10, the price or manufacturing 1000pcs may be $1. Yes, the price difference is that big.
Tolerance of the part.Strict tolerances can be better meet the requirement of the design, but the cost of CNC machining is higher accordingly. Parts do not need to set too precise tolerances unless necessary. Usually, it is only necessary to keep tight tolerances at the interface of the part with other parts. It is should be pay attention that difficult to achieving tight tolerances inside a hole or cavity in a part. At DDPrototype, we usually follow standards DIN-2768-1-fine grade for CNC machined metal parts and DIN-2768-1-medium grade for CNC machined plastic parts.
Labor costing.There are many factors that determine labor costs, such as region, industry, senior level of skilled workers and so on. For CNC machining shop, most of time will have many parts with complex geometric shapes need do CNC machining, and in order to guarantee the quality and dimensional accuracy of the part, we will choosing to hire some senior and experiences machinists to operate the CNC machine. At the same time, the labor cost will be higher accordingly.
Surface treatment.If your part request additional surface treatment or finishing, the cost of the part will higher compare the part without any surface treatment or finishing, as it’s will request specific technologies and materials to achieve. Generally the surface treatment of the part included coating, anodizing, heat treatment, polishing, spraying, electroplating, passivating, silkscreen printing and so on.
Design.Complex features such as non-standard hole size, lettering and thin walls will lead the cost of CNC machining increased. Complex features require more programming time, specialized tools and multiple settings to machining the part, and the increase in running time will lead the CNC machining cost increased. We can simplify the design by eliminating the unnecessary function.
If your CAD drawing is accurate, detailed and complete? You may need an experienced engineer or machinist to help you with your designs to ensure your designs are machined as intended. This design consultation stage may add some initial cost to the project, but it can save a lot of unnecessary expenses in the long run, such as losses caused by design mistakes, losses caused by errors in tolerance setting, and so on.
Tips for reducing the cost of CNC machined part - how to reduce the cost of CNC machining?
After we understand the factors that affect the cost of CNC machining, and in order to reduce and minimize the costs of CNC machining, we should take following aspects into consideration.
1.Design and Complex geometry.
– Avoid the deep cavity structures
– Rounded inner corner
– Make sure the radius of the inner corner is at least 1/3 of the cavity depth
–Reduce the thin wall structure (the wall thickness of metal parts is better than 0.8 mm, and the plastic can be 1.5 mm)
–Limit depth length (maximum depth of thread is set to three times the hole diameter)
–Avoid small features with high aspect ratios
–Optimized for threaded holes
2. Tolerance
–Reduce the use of tight tolerances
–Standard tolerance used
–Eliminate all unnecessary tolerances from your design
3.Cutting tools
–Utilize standard drill bit
4.Surface treatment and finishing
–Avoid multiple surface treatments
–Select Machined Finishing
5.Others
–Choose a more economical location, such as Guangdong, China
–A CNC machining shop with skilled machinist is better
There are many factors that determine the price of CNC machined parts, but working with an experienced and skillful CNC machining service provider can help you solve many machining problems and providing you the high-quality parts. At DDPTOTOYPE, we have been dedicated to CNC machining services for more than ten years, and will provide you with more suggestions for optimizing designs. We are looking forward to hearing from you.