CNC prototyping cost drivers

In the following article, we’ll break down the costs associated with CNC prototyping, showing you exactly where cost matters and where costs can be reduced. A skilled manufacturing service such as GPT Precision Co., Ltd understands the ins and outs of CNC prototyping and can therefore deliver high-quality parts at competitive costs.
The first thing to realize is that the cost of CNC prototyping can vary widely, depending on what material you are working with, what tolerances your part requires, and how complex the part design is. By understanding each cost driver for CNC prototyping as well as other cost influencers you can determine how much you should be paying and what a competitive CNC-based prototyping service should cost.
There are several factors that are cost drivers for CNC prototyping. The most important ones are the following:

1. Design Complexity
One of the factors that affect the cost of CNC machining the most is part design. If your prototype has a straightforward design, with simple geometry, then it will be significantly cheaper than one with a more complex structure. This is based on the simple fact that a simple geometry is faster to machine than a complex one.

For example, if your prototype design integrates undercuts, many hole sizes, and a high level of detail, the machining time will be longer than a part that requires minimal cuts and milling. If cost is a key concern for your project, consider taking a look over your design and evaluating whether certain design elements are necessary and if they can be simplified to reduce machining time. Our design experts at GPT Precision Co., Ltd can also offer support to optimize your part design.

2. Tolerances
Another key cost driver for CNC prototyping is tolerances. In other words: how precise your product or prototype must be. CNC machining is one of the most high-precision manufacturing processes that exist today. But that doesn’t necessarily mean your part always requires the highest degree of precision. The tighter the part tolerances, the more costly the CNC machining process becomes, because of the added time it takes to achieve high levels of precision.

According to a study by the University of Illinois, the cost of CNC machining can increase by double between a rough tolerance of ±0.030 and a standard tolerance of ±0.005. Looking at tolerances of ±0.001? The cost can increase by up to four times. Considering this, do not be alarmed if you receive a shocking quote if you’ve asked for the tightest tolerances possible. Chances are, if you are ordering a prototype, it may not need the highest tolerances, which will enable you to scale back the costs of production.

3. Material choice
This should go without saying, but the choice of material will impact the overall cost of CNC prototyping. The cost of the raw material is often out of the hands of the CNC machining service, however different global regions have different costs. For instance, rapid prototyping services in China often have access to cheaper raw materials, which is why they can often offer lower production costs.

As a general rule, plastic materials are cheaper than metal. But that doesn’t narrow down very much, as there are many plastic and metals to choose from. For prototyping, plastics are often the most common option due to cost. Among CNC prototyping plastics, ABS is one of the most cost-effective. POM, PC, PA, and PMMA are also common. Looking at metals, aluminum alloys are usually the most cost-effective, which makes them popular for prototyping applications.

It is also worth noting that it is not only the cost of the raw material that influences cost: the machinability of the material also has an impact because less machinable materials take more time to process, which drives up cost.

4. Finishing choice
The fourth major cost driver for CNC prototyping is finishing. There are several post-processing options and each has a different price tag. Fortunately, there is also the option for no post-processing (aka “as-machined” or “as-milled”), which is viable for prototyping applications on a strict budget.

Finishing processes impart different characteristics for your prototype or final part, including aesthetic qualities like smoothness or gloss, and functional properties like better durability. If a surface treatment is needed for your CNC prototype, minimize the cost by choosing one, rather than multiple finishes.

CNC Prototyping Cost Influencers
In addition to the four aforementioned cost drivers, there are a handful of factors that influence the cost of CNC prototyping, though in less direct ways. These influencers also vary from service to service, so it may be worth discussing with your prototyping partner to understand their specific pricing model.