No matter which industry you belong to, selecting the right materials is one of the most important components to determine the overall function and cost of parts. Here are some quick tips for choosing the right material.
CNC machining can produce high-precision parts for almost any application. It allows very small tolerances for part dimensions and complex designs. But like any manufacturing process, material selection is a key component that determines the overall function and cost of a part: the designer has defined the important material characteristics of design - hardness, rigidity, chemical resistance, heat treatment and thermal stability.
Rapid processing can process various metal and plastic materials and other customized materials that can be provided on request.
Metal
Generally speaking, softer metals (such as aluminum and brass) and plastics are easy to process, and it takes less time to remove materials from part blanks, thus reducing processing time and processing costs. Hard materials, such as stainless steel and carbon steel, must be processed with slower spindle RPM and machine feed rate, which will increase processing time compared with soft materials. Generally speaking, the processing speed of aluminum is 4 times faster than that of carbon steel, and the processing speed of stainless steel is half that of carbon steel.
Metal type is a key driver in determining the total cost of parts. For example, the cost of 6061 aluminum bar is about half of the cost of aluminum plate; The cost of 7075 aluminum bar can be 2 to 3 times that of 6061 aluminum bar; The cost of 304 stainless steel is about 2 to 3 times that of 6061 aluminum and about twice that of 1018 carbon steel. Depending on the size and geometry of the part, the cost of materials may account for a large part of the total price of the part. If the design cannot guarantee the performance of carbon steel or stainless steel, please consider using 6061 aluminum to minimize the material cost.
Plastic
If the design does not require the rigidity of metal, plastic materials can become cheaper substitutes for metal. Polyethylene is easy to process, and the cost is about 1/3 of 6061 aluminum. The cost of ABS is usually 1.5 times that of acetal. The cost of nylon and polycarbonate is about three times that of acetal. While plastic may be a cost-effective alternative to materials, remember that depending on geometry, plastic may have difficulty achieving tight tolerances and that parts may warp after processing due to the stresses created when removing materials.
When choosing the metal or plastic suitable for your parts, you need to consider the following issues:
What will your parts be used for?
The end use of the part to be machined using CNC will have the most significant impact on material selection. For example, if you use parts outdoors or in a humid environment, use stainless steel instead of carbon steel so that the parts do not rust.
Design specifications such as stress load, tolerance and fastening type (welding, rivet) will also affect your choice of materials. Specifications such as military and aerospace components or FDA regulatory environment will also affect your choice of materials.
Is the weight of the part important?
Generally speaking, if metal is needed, standard aluminum alloys like 6061 are a good low-density choice, which can reduce weight. If strength can be weighed, plastics like ABS can help further reduce weight.
Strength and heat resistance
There are many different methods to measure material strength, including tensile strength, material hardness and wear resistance. Selecting materials of different types and strengths that combine your design requirements will enable you to select the best materials for your parts.
Also, very low or high temperatures will limit your use of certain materials. Environments with large temperature fluctuations are particularly important because some materials can expand or contract significantly even with small temperature changes.
