Choosing of materials Higher Product Design

Which one? Wide selection out there Can be time consuming to select the most appropriate one. To avoid problems as material failure it is worth taking on a systematic approach to identify which one is more appropriate in terms of properties, cost and any manufacturing restrictions there may be.

Systematic Approach Material Failure This is used to avoid material failure to the selection of materials Factors to consider which ones are relevant to aid in this choice: Properties Costs Complexity Design requirements Availability Number to be produced Effect on environment Social factors Material Failure Materials can fail in many different ways, including by buckling, excessive plastic flow, fatigue and fracture, wear, or corrosion.

Property 1 Strength This is the ability to stand up to any force that will be applied to it without bending, shattering or deforming. To resist tensile, compressive or shear force.

Property 2 Elasticity /stiffness This is the ability to absorb force and flex from different directions temporarily under force and be able to return to its original shape after the force is removed.

Property 3 Plasticity This is the ability for a material to change its shape permanently.

Property 4 Ductility This is the ability for the material to change its shape, deform itself, by stretching, bending or twisting it along the length. Must be strong as well as malleable.

Property 5 Tensile strength This is the ability of the material to stretch without breaking or snapping.

Property 6 Malleability The materials ability to be reshaped in all directions, without cracking.  

Property 7 Toughness This is a characteristic of the material that does not shatter or break when it is put under stress. Material that is not tough is brittle.

Property 8 Hardness This is the materials ability to resist scratching, indentations or wear and tear

Property 9 Conductivity This is when the material can conduct electricity

Suitability of materials Mechanical – ability to resist and support a force. Physical – looking at size, density and surface texture Thermal – ability to withstand temperature change Chemical – how a material reacts to corrosion and chemicals Electrical – how a material conducts or resists electrical currents Optical – ability to transmit and alter light Acoustical – ability to absorb and transfer sound

Testing the material Testing can be done in simulated conditions Useful to see how the material will perform in its expected environment. Answer: Is the material suited to the expected tasks? Does it meet the specification for the new product? How will sunlight and other external elements affect the material?

Cost implications Keep cost down is essential! Look for alternate, cheaper material that will perform just as efficiently. Ask: What material is required? What properties does it possess? How much does it cost? Is there another material that could do the job? How much is this one? Value Engineering: analytical approach to choose a material. Find ways a function can be achieved at reduced costs by substituting the material. Back to main menu