Question

Selection of materials One of the most challenging task of materials engineer is the proper selection of the material for a particular job, e.g., a particular component of a machine or structure. An engineer must be in a position to choose the optimum combination of properties in a material at the lowest possible cost without compromising the quality. A number of questions need to be answered before a decision can be made as to the specification required of a material and hence a decision as to the optimum material for a particular task. The questions can be grouped under four general headings: 1. What properties are required? 2. What are the processing requirements and their implications for the choice of material? 3. What is the availability of materials? 4. What is the cost? Factors affecting the selection of materials: i) Material Properties The expected level of performance from the material - mechanical & physical i) Material Cost and Availability Material must be priced appropriately (not cheap but right) Material must be available (better to have multiple sources) iii) Processing Must consider how to make the part, for example: Casting, Machining, Welding. iv) Environment You need to choose one of the application from the list below (a), (b) or (c). Then, compare the materials properties, availability, processing method, cost, effect to the environment, etc for both assigned materials. At the end of the comparison, decide which materials you choose for the specific application, justify your answer. Answer your question in presentation slides (ppt) of 10 to 15 pages. a) car bumper: Polymer composite vs. metal alloy b) beverage container: Polymer vs. glass c) lawn chair: Aluminium vs. cast iron.

Answer 1

Title - Selection of Material

Solution : : Selection of Materials : TASK - Selection of Material for the design and development of Car Bumper structure Panel metal Alloy 1. What properties are required ? → The properties required by the car bumper structure Panel are 1) Mechanical strength 2) Low weight 3) Toughness - Shock, Energy Absorption capability 4) stiffness s) Good Formability 6) Joining Capability 7) Corrosion resistant Energy ecyclable Efficient, safe. 8) Re 7 -> 2. What are the processing requirements and their implications for the choice of material 2 1) The steel is the selected material for the car bumper structure pand which is developed a manufactured using forming methods. 2 Die Die & Punch is required for the Punching / Drawing application.

2 3) A layer of Electro coat (E-coat) is applied for anti-corrosive properties to be developed 4) As steel is good at for mability hence drawing of steel sheet required strength, stiffness within the structure. 5) Through cost of these forming devices & equipments is huge , we need to produce in a dot. ensures 3. What is the availability of material? 1) sted is the most important & usable material in the world. 2) Around major parts of the world produce sted & this has large reserves of steel. 3) Recycling Rate around 55% for the totally discarded stel 4) By 2050 primary steel making is to be remained dominant which involves CO2 - intensive processes. is 4. What is the cost 2. Roof structure is made out of mild sted. The cost of mild sted per kg is as follows: 0:56 $/kg Rs 42/kg as laser Also the processing cost adds up such welding for the bumper structure panel.

7 Pultrusion 3 ® Polymer composite: 1. What properties do polymer composite have ? 1) Good Flenural strength 2) Wear resistance 3) High specific stiffness 4) High fracture Resistance 5) Good abrasion resistance 6) Good Good corrosion resistance 7) Low cost 8). Highly viscous implications 2. What are the processing requirements of their for the choice of material ? 1) Plastic molding Heat Treating 2 ) 3) Powder Mettalurgy 4) Injection moulding 3) Rexin transfer Moulding Reaction Injection moulding 9 8) Compression moulding

4 3. What is the availability of material ? 1) plasti polymer is highly available of reserves around 63% the global 2) It is is recyclable too with around 23% of reusing capabilities: 3) Easily available and requires some flushing and filtration treatments. 4) Around 67% of products used these material for stiffness requirements 4. What is the cost of material e. --> 1) Cost is the com when costs of processing & filtration are taken into considerations. Concern 4 timer much costlier than the steak. 2 It is uncommon fabrication method, its 3) Due to their cost increases. mer Conclusion: Due to light weigh & flexibility, poly composites are considered better than the metal alloys if and only if it is easily available. Helps in achieving achieving more reduction in fuel fuel composition by light- weighting.

Summary - The selection of material for a particular task of engineering application depends upon many factors out of which, the properties required, cost, availability and manufacturing methods play an important role.