How is CNC machining cost calculated?

CNC machining costs may vary depending upon different factors as discussed below:

1. CNC Machine costs
Machining cost changes with the change of type of the machine. Mainly, there are two types of machines that are being used for manufacturing parts using CNC machining i.e. 3 axis and multi-axis machines. The machine cost is also dependent on various factors like the size & weight of the machine, speed, power, and machine configuration. The machining cost is calculated per hour and the approximate cost of 3 axis CNC machining is around 40$ per hour while for CNC turning machines it is about 35$ per hour. The hourly rate of CNC machining using multi-axis machines is comparatively more ranges between 75$ and 125$. Due to the involvement of more complex parts, CNC milling is more expensive than other types of machining operations. The machining expenditures increase with the increase in axes of the milling machines. For example, in the case of 5 axis machining, it costs more as compared to 3 axis machines.

2. Machining time
The time required for complete machining of any CNC machined part also plays a vital role in the calculation of the CNC machining cost. It is the rule of thumb, that the more time taken for machining more will have the cost of the machining which add up to the basic setup cost. Software like CAM, which requires a 3D CAD design model, can provide the estimation of the time required for the completion of the project. A project with a high level of complexity requires more hours to complete.

3. Labor
One of the advantages of CNC machining, as compared to manual machining, is that it reduces the number of laborers that are involved in manufacturing. The primary cost of the labor is of the expert designer who designs the 3D CAD design model for the machining which increases with the complexity of the desired product. This cost remains the same even you are required to manufacture more parts which reduce the per part machining price. Then, the additional cost is of the labor who operates the CNC machine which also increases with the increased hours required for complete machining of the part. The extra cost is added to the labor cost if manual work is done to assemble, finish, and post-process the parts. The extra labor cost is also added if the finished product is being delivered from the machine shop to the client at a different location.

4. Shape complexity and dimensions

The machining cost is also increased with the increase in complexity of the CNC machined parts. The parts with higher complexity may require more process operations, different tools, and more production time. The part features like sharp internal corners, deep cavities, or thin wall increases the CNC machining cost. The designs with simple features are easy to manufacture and also save manufacturing time. The parts with larger dimensions require more raw material and time to manufacture, so their cost will be higher as compared to the smaller parts.

5. Material costs
The material costs are also imperative in calculating the cost of CNC machining. The price of the final product made by a CNC machine depends upon the type of materials of which you are required to make the product. You may be required to make part of plastic or metal materials. As the plastic materials are cheaper and of less durability, the machining cost of plastic or aluminum material is less as compared to stainless steel. As in CNC machines, the material is removed from the solid blocks to make the 3D object. so, the required raw material will be more than the material of the final product. The machinists buy the materials in the form of solid blocks and calculate the expense of the product per block. The most commonly used metals in CNC machining are Aluminum, Stainless Steel, and Brass. Due to the economical prices and excellent machinability of aluminum, most machinists use aluminum in CNC machines. Stainless Steel and brass result in more cost due to poor machinability relative to aluminum. The titanium alloy is the most expensive of all these metals so the machining cost of this metal will be the highest because it may require some special tools to manufacture the parts. In case of the plastics, the price of the bulk material is less, tools required also cost less and less time is required to machine the plastics like Nylon, Delrin, and ABS.

6. Surface finishing
In the case of some products, surface finishing is required which also results in an increase in the price of the final products. In order to improve the aesthetic of the final product and remove any scratches made during the machining process, you may require to provide a good finish like polishing. Other finishing processes may also include coating, anodizing, painting, chroming, blacking, galvanizing, brushing, and water transferring. The inclusion of any of the se finishes will add the extra cost to the price of the final product.

7. Tooling cost
In some cases of manufacturing, standard tooling is not useful so custom tooling is required which also increases the manufacturing cost using CNC machines.

8. Tolerances
In manufacturing the products with tight tolerances, the cost will also increase because fabricating parts with tight tolerances requires complex machinery. Sometimes you may be required to make holes or cavities with tight tolerances which may develop burrs on the surface and will spend more time to reduce it.

9. Quantity
The volume of the order tremendously affects the cost of the final product. It is true that the overall cost will increase with the increase of required finished parts but the cost per part will decrease.