The importance of material selection in CNC machining goes beyond simply the design of a part. The material chosen must also be taken into consideration together with the machining process in order not to only determine the cost, function, and strength of a part but also its uses. This article will focus on selecting the right material for CNC machining by examining several key factors needed to be taken into consideration when choosing from the various materials available based on end use application, mechanical properties and cost.
The basis of material selection is an understanding of their intrinsic properties. There are three primary materials involved in CNC machining. They are metals, plastics, and composites. Each provides its own level of quality.
In CNC machining, metals like aluminum, stainless steel and brass are used which are chosen for their strength, heat resistance, malleability, and durability. Aluminum which is known for its light weight and corrosion resistance is used for many automotive and aerospace parts. For when you need high strength, stainless steel is an excellent choice. The addition of chromium and nickel gives this material its corrosion resistant properties and the molybdenum increases its strength. It is popular in medical devices and food processing equipment. Another popular form of metal that is used in the process of CNC machining is brass. This metal gives a nice, golden look to your parts and is very durable. It is also the most easy to machine so it is commonly used for decorative items and electrical components.
Other widely sleep are different plastics like ABS, polycarbonate and PEEK. Plastics are chosen for light weight, low cost and ease of working with. ABS is commonly used in computer keyboard and computers body panels. Polycarbonate is widely used in helmets, eye glass lenses. Polycarbonate is very good transparency better this when this small wall thickness. PEEK is extremely expensive, is chosen when high performance is required at high temperature or good chemical resistance is required.
Each of these materials has different advantages and disadvantages which are important to consider when deciding on which material is most suitable to use Composite materials are great also to reduce tools and molds used in manufacturing. Many of the tools used for molding metal or forming polymers are made from either steel or a polymer. Composites replace those rusty metal tools are replaced [sic] with a single composite mold. Additionally composite molds can be lighter than the heavily weight metal molds typically used to shape plastic. Composites offer other advantages over similar materials due to fabrication methods. Ashby says that modern manufacturing processes such as resin transfer molding “which… now produce large, complex structures directly” are much more suited for composites. Comparatively rolled steel or aluminum is much more difficult to shape into wavy, curling forms that are “inherently stable as, for example, corrugated paper” without forming a joint or fastening tools and parts together. Three reports published in recent issues of SAMPE Journal demonstrate that engineers designing structures have begun to benefit from incorporating composites and composites manufacturing processes. Because of their design flexibility as provided by lay-up processing, many different shapes and forms can be made to suite [sic] requirements. Annual automobile showings regularly display designs diametrically opposed to current and previous years’ cars. These completely new designs are what can be achieved by composites because of their excellent specific properties.
Consideration should also be given to environmental and regulatory compliance issues when selecting materials. In certain industries, such as food processing and healthcare, the right choices of materials are vital to meet with strict regulations governing safety and hygiene.
CONCLUSION
The selection of material is very important in CNC machining and the right type of material needs to be chosen for working with it for a project, because it may or may not make the project successful. Various features needs to be considered, including mechanical features, costs involved, requirements of the designing, machining and fabrication, permissible compliance criteria to ensure accurate machining, and machinability as well to make the project successful.