One of the most common problems a design engineer faces when designing a product is how to select an appropriate material. Selecting a single material for a product from a huge variety of options is a difficult job which can be the difference between the success or failure of a design. To ensure material selection is done properly, the designer must follow the series of steps that are described below.
STEP 1: Define Required Mechanical Properties
There are around 22 mechanical properties that a designer should consider. To find out which mechanical properties are critical, engineering analysis must be done to identify design constraints like applied stresses, maximum weight, etc. Engineering analysis will tell the designer whether to consider ultimate tensile strength or to select yield point stresses, or if he should select a ductile or brittle material, and what minimum safety factor is required.
After considering the design constraints, the designer should now have a smaller range of materials that offer the required mechanical properties.
STEP 2: Identify Available Manufacturing Processes and Capability
The designer should now consider the manufacturing processes that are available. It is not uncommon for manufacturers to have lots of trouble producing a part because the designer didn’t think enough about the manufacturing process. For example, if you have selected Inconel, but cannot find manufacturer who is able to machine it satisfactorily, perhaps you should consider a more machinable material like stainless steel instead.
STEP 3: Review Required Manufacturing Properties
After narrowing down your list to materials that can be processed, the designer should now review the manufacturing properties of each material. This can include castability, machineability, weldability, melting temperature and fluidity. These properties will allow you to compare which materials will raise or lower the cost to produce the part.
STEP 4: Identify Available Materials
After applying the previous three filters, the designer should now have a very small list of materials, all of which have the required properties. Now he should filter the list for materials that are readily available. Selecting a material which is not available could result in delays to the project and extra cost for transporting it from a distant location.
STEP 5: Review Purchasing & Manufacturing Cost
Now the designer knows which materials can fulfill the design requirements and are available in the local market. Now the designer should estimate the cost of the product, including material purchasing and manufacturing costs, with each material. He can then select the material that will result in the minimum total cost for the product.
