Lecture 5: Fundamentals of Manufacturing Process & Materials PDF

Lecture 5 Fundamentals of Manufacturing Process & Materials  Types of Production The number of parts to be produced (such as the annual quantity) and the rate (the number of pieces made per unit time) are important economic considerations in determining optimum proce...

Lecture 5 Fundamentals of Manufacturing Process & Materials  Types of Production The number of parts to be produced (such as the annual quantity) and the rate (the number of pieces made per unit time) are important economic considerations in determining optimum processes and types of machinery required. A brief outline of the general types of production, in increasing order of annual quantities produced, are: 1. Job shops: Small lot sizes, typically less than 100, using general-purpose machines, such as lathes, milling machines, drill presses, and grinders, many now typically equipped with computer controls. 2. Small-batch production: Quantities from about 10 to 100, using machines similar to those in job shops. 3. Batch production: Lot sizes typically between 100 and 5000, using more advanced machinery with computer control. 4. Mass production: Lot sizes generally over 100,000, using special-purpose machinery, known as dedicated machines, and various automated equipment in a plant for transferring materials and parts in progress.  Selection of Manufacturing Processes Selecting the right process for manufacturing your product is crucial for achieving efficiency, quality, and cost-effectiveness. The selection of a particular manufacturing process depends on the geometric features of the parts to be made, including the dimensional tolerances and surface texture required, and on numerous factors about the workpiece material and its manufacturing properties. There is a constant demand for new approaches to production challenges and, especially, for manufacturing cost reduction.  Types of Manufacturing Processes There is often more than one method that can be employed to produce a part from a given material. The following broad categories of manufacturing methods are all applicable to metallic as well as nonmetallic materials: 1. Casting: Expendable mold and permanent mold. 2. Forming and shaping: Rolling, forging, extrusion, drawing, sheet forming, powder metallurgy, and molding. 3. Machining: Turning, boring, drilling, milling, shaping, broaching; grinding; ultrasonic machining; chemical, electrical, and electrochemical machining; and high-energy-beam machining. 4. Joining: Welding, brazing, soldering, diffusion bonding, adhesive bonding, and mechanical joining. 5. Finishing: Honing, lapping, polishing, burnishing, deburring, surface treating, coating, and plating. 6. Microfabrication and nanofabrication: Technologies that can produce parts with dimensions at the micro (one-millionth of a meter) and nano (one-billionth of a meter) levels; fabrication of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS), typically involving processes such as lithography, micromachining, etching, LIGA, and various specialized processes. Types of Manufacturing Processes Types of Manufacturing Processes Types of Manufacturing Processes Types of Manufacturing Processes Types of Manufacturing Processes Types of Manufacturing Processes  Selection of Materials An increasingly wide variety of materials are now available, each type having its own properties and manufacturing characteristics, advantages, limitations, and costs. The selection of materials for products (consumer or industrial) and their components is typically made in consultation with material engineers; design engineers may also be sufficiently experienced and qualified to assist. As new developments continue, the selection of an appropriate material for a particular application from a very large variety of materials has become even more challenging. There are continuously shifting trends in the substitution of materials, driven not only by technological considerations but also by economics.  Properties of Materials Mechanical properties of interest in manufacturing generally include strength, ductility, hardness, toughness, elasticity, fatigue, and creep resistance. Physical properties are density, specific heat, thermal expansion and conductivity, melting point, and electrical and magnetic properties. Chemical properties include oxidation, corrosion, degradation, toxicity, and flammability. These properties play a significant role in both hostile (such as corrosive) and normal environments. Manufacturing properties indicate whether a particular material can be cast, formed, shaped, machined, joined, and heat treated with relative ease. Another important consideration is appearance, which includes such characteristics as surface texture, color, and feel, all of which can play a significant role in a product’s acceptance by the public.  Types of Materials The general types of materials used, either individually or in combination with other materials, are the following: Ferrous metals: Carbon, alloy, stainless, and tool and die steels. Nonferrous metals: Aluminum, magnesium, copper, nickel, titanium, superalloys, refractory metals, beryllium, zirconium, low-melting-point alloys, and precious metals. Plastics (polymers): Thermoplastics, thermosets, elastomers. Ceramics, glasses, glass ceramics, graphite, diamond, and diamond-like materials. Composite materials: Reinforced plastics and metal-matrix and ceramic-matrix composites Nanomaterials: Carbon nanotubes, Fullerenes, Nanoparticles, Nanowires, and Quantum dots Shape-memory alloys (smart materials), amorphous alloys, semiconductors, and superconductors.  Process Selection Calculations Example: You're deciding between two manufacturing processes for producing a new plastic phone case design. Here's a breakdown of the cost structure for each process: Process A (Machining): Setup cost: $1000 per production run Material cost per unit: $5 per phone case Labor cost per unit: $2 per phone case Process B (Injection Molding): Molding tool cost: $20,000 (one-time cost) Material cost per unit: $3 per phone case Labor cost per unit: $1 per phone case You need to determine the "crossover point" - the minimum production batch size at which process B (injection molding) becomes more cost-effective than process A (machining).  Process Selection Calculations Solution: Define the variable cost per unit for each process: Variable cost (Process A) = Material cost + Labor cost = $5/unit + $2/unit = $7/unit Variable cost (Process B) = Material cost + Labor cost = $3/unit + $1/unit = $4/unit Identify the cost difference per unit between the two processes: Cost difference per unit = Variable cost (Process A) - Variable cost (Process B) = $7/unit - $4/unit = $3/unit Set up a formula to find the crossover point (batch size): Crossover point (batch size) = Molding tool cost / (Cost difference per unit) Apply the formula: Crossover point (batch size) = $20,000 / ($3/unit) = 6,666.67 units (round up to 6,667 units) Based on the calculation, using process B (injection molding) becomes more cost-effective than process A (machining) only when the production batch size reaches 6,667 units or more.  Material Selection Calculations Example: You're designing a lightweight drone frame. You need to choose a material that balances strength and weight for optimal flight performance. Here's a breakdown of two candidate materials: Material A (Aluminum): Density: 2700 kg/m³ Tensile Strength: 300 MPa (Megapascals) Material B (Carbon Fiber): Density: 1700 kg/m³ Tensile Strength: 400 MPa You need to determine the "specific strength" (strength-to-weight ratio) of each material to compare their suitability for the drone frame. The material with the higher specific strength will offer a better balance between strength and weight.  Material Selection Calculations Solution: Specific Strength Formula: Specific Strength = Tensile Strength / Density Calculate Specific Strength for Material A: Specific Strength (A) = 300 MPa / 2700 kg/m³ = 0.111 MPa/(kg/m³) Calculate Specific Strength for Material B: Specific Strength (B) = 400 MPa / 1700 kg/m³ = 0.235 MPa/(kg/m³) Based on the calculations: Material A (Aluminum) has a specific strength of 0.111 MPa/(kg/m³). Material B (Carbon Fiber) has a specific strength of 0.235 MPa/(kg/m³). Since Material B (Carbon Fiber) has a higher specific strength (0.235) compared to Material A (Aluminum) (0.111), it offers a better balance between strength and weight, making it a more suitable choice for the lightweight drone frame.