1. Determine the functional requirements of the part.
2. Identify common materials used for machining the part.
3. Consider related secondary processing.
Prioritize your part requirements:
1. Environmental: For many, this is absolutely the most important requirement. Environmental factors may include heat and cold resistance, flame retardancy, or UV and chemical resistance.
Depending on the application, your material may have to be food-grade or medical-grade. Consider the full range of applications for the part. For example, components of medical devices may have to withstand the extremely high heat of an autoclave or harsh chemical sterilization between uses.
2. Electrical: This can encompass a range of application-related factors. A part may need to be conductive or insulating. It may need to dissipate static electricity. In either case, choosing the right metal or plastic resin is crucial.
3. Mechanical: Strength comes in many forms. The part may need to fall anywhere on a continuum ranging from rigid to flexible. It may need tensile or compressive strength, or be able to resist impact. It may have to be wear-resistant or provide lubrication to function as a bearing. Materials that meet these requirements exist, and some are more efficient than others.
4. Size: While machining can produce parts of various sizes, part dimensions may be limited by the maximum available size of a particular stock material.
5. Cost: Cost can be a significant factor, often falling after essentials and good options.
Identifying Commonly Used Machining Materials
Over the years, our engineers have identified a selection of materials suitable for machining processes, and these materials have consistently been popular choices for our customers.
For metals, these include aluminum, brass, copper, stainless steel, and steel. In plastics, designers frequently choose polyetheretherketone (PEEK), ABS, acetal, nylon, polycarbonate, polyvinyl chloride (PVC), high-density polyethylene, and low-density polyethylene. Protolabs offers over 40 different grades of plastics and metals. Some key characteristics of the most popular machining materials include:
ABS and Acetal
1. ABS has high impact strength, low thermal conductivity, and a low coefficient of friction.
2. Acetal has high mechanical strength, good dimensional stability, and low moisture absorption. PEEK vs. Ultem
1. PEEK offers high abrasion resistance, low moisture absorption, and a low coefficient of friction.
2. Ultem (PEI) offers extremely high strength, stiffness, chemical resistance, and high dielectric strength.
Aluminum 6061 vs. 7075
1. 6061 offers excellent machinability, low cost, and versatility.
2. 7075 offers high strength, hardness, low weight, and heat resistance.
Finishing Options and Process Selection
In addition to material selection, related secondary finishing processes need to be considered. For example, if the chosen material is one of the available aluminum alloys (6061 and 7075), several available surface treatments need to be considered. Anodizing is better suited for durability, providing you with a cost-effective and high-quality all-in-one solution.
