If you have completed the part design but are unsure which material to choose, then you have come to the right place. CNC machining can use various main types of materials: metal, plastic, ceramics, composite materials, and wood.

Each material has unique characteristics and challenges that can affect the characteristics of the final product and the entire manufacturing process. This article will explore the types of materials that can be processed and help you choose the appropriate materials for your product.

5 materials used in CNC machining

The main material categories used in CNC machining are metals, plastics, ceramics, composite materials, and wood. In these categories, there are a large number of unique materials, each with specific characteristics. The following guidelines represent general methods for selecting precision manufacturing materials, so you should consult experts when searching for specific properties.

#1 Metal

Metal is a common CNC machining material. CNC machining of metals is often used in aerospace, automotive, electronics, and even medical applications. Steel, aluminum, brass, copper, and titanium are all machinable metals.

(Related post: Aluminum Prototype Manufacturing: How do you determine the best method?)

#2 Plastics

Plastic is another common CNC machining material that manufacturers can use in refrigeration components, electronics, toys, sports, and other industries. Commonly used machined plastics include acrylic acid, polycarbonate, PVC, and even nylon.

(Related post: CNC processing plastic prototypes: is it a good choice?)

#3 Ceramics

Although CNC machining of ceramics is complex, it can indeed be used for some advanced applications. Space shuttle engine components, tank armor, and superconductors are some examples of machined ceramics. Due to its brittleness, advanced machining operations are required to produce durable and reliable ceramic parts.

#4 Composite materials

Composite materials are another highly challenging material for CNC machining. In fact, they usually require diamond tools and 5-axis CNC machines to complete. Machined composite materials are very useful for applications in the automotive, aerospace, and power generation industries.

#5 Wood

Next is the category of wood. The CNC processing of wood is usually limited to more artistic applications, such as furniture and decoration. However, it can also be used for certain structural applications.

As we pointed out, certain categories of materials are more difficult to process than others. You may want to know which properties determine machinability and whether specific materials are suitable for your project. To assist you in selecting CNC materials that are suitable for your project, we will provide a detailed introduction to the attributes you may need to consider.

Basic factors to consider when selecting materials

hardness

Hardness directly affects cutting speed and the type of tool material that can be used in CNC machining processes. Using very hard materials, such as titanium, can make machining more complex and require harder cutting tools.

Harder materials can also make the cutting process slower than usual, thereby increasing labor time. On the other hand, very soft materials such as polymers are prone to deformation during processing, requiring the use of special tools and slower working speeds to ensure the formation of chips, rather than simply causing plastic to flow around the tools.

Both of these may affect operating costs. Brass, aluminum alloy, low-carbon steel, and some polycarbonates are easy to process materials, so the processing cost is usually lower.

Heat input

Heat input is another key variable to consider, as the thermal conductivity, melting temperature, and thermal reaction of each material are different. For example, if the melting temperature is very low (such as tin), it is difficult to process the material without partial or complete melting.

The heat input from processing can also have more subtle effects on the hardness and strength of materials at the microstructural level. Another heat input factor to consider is the deformation of the heating material during softening, and residual stress can affect the shape of the product.

Based on the processed raw materials and available budget, annealing, using more suitable processing tools, and replacing coolants are potential solutions. For plastics, annealing can eliminate residual stress and limit deformation.

surface treatment

Surface finish is another key factor to keep in mind, as various materials produce very rough surface finish after processing. In addition to the beauty of the product, its functionality may also be threatened.

Parts with mating surfaces may not seal well or increase friction, which may not be necessary for certain applications. In addition, some ceramics and plastics, such as acrylic, will form a frosted surface after CNC machining, limiting their use as transparent windows.