Manufacturing Notes PDF

w1: what is manufacturing and what processes are used to make parts Two Perspectives on Manufacturing Technological Economical application of physical & chemical processes to alter the geometry,...

w1: what is manufacturing and what processes are used to make parts Two Perspectives on Manufacturing Technological Economical application of physical & chemical processes to alter the geometry, transformation of materials into items of greater value by one or properties, and/or appearance of a starting material to make parts or more processing and/or assembly operations product Manufacturing System Manufacturing System Macro View Micro View individual equipment and operators that perform processing and/or assembly operations on a starting raw material: managing the materials and processes - specific manufacturing machines - facilities - mill - people - lathe - equipment - operators - procedures - workpiece - cutting tools Manufacturing Support Systems increase productivity, but do not actually make the final product - people and procedures used to manage production operations Considerations Costs Rate Labour - Setup (equipment and tooling costs) - Parts per unit of time - Running (energy and labour costs) - speed of production - Waste/pollution (environmental costs) - cost decreases as quantity increases - cost increases as complexity and variety increase Geometric Complexity Accuracy Quantity/ production volume - Part shape - Achievable resolution, feature size, Product quantity to be made - Part size surface finish - low (1-100): custom - number of features - How accurate and consistent the - medium (100-10 000): jets, exotic - geometric transitions process is (variation) cars - holes/cores and non planar surfaces - high (10 000+): bottles, cars, phones, laptops Material Limits Quality Flexibility - physical limitation - Achievable resolution, feature size, - Scalability to different physical sizes - use standard materials: exotic high surface finish of parts strength materials are expensive - How accurate and consistent the - Compatibility with different part and difficult to process process is (variation) geometry - is the material or part quality good - Scalability to different production (net vs near net process) quantities - tolerance: allowable variation in dimensions or size, cost increases the more precise it is, high precision tools, or more time taken to cut, inspection costs, the different parts have to mesh together in the final design Limitations Manufacturing Plant Capability - What process can/can’t I use - Manufacturing plant capability - What materials can/can’t it work - Number of components with - What shapes can/can’t I make - How fast is it to design  - use standard part shapes and sizes to reduce cost - minimise part complexity Product variety - different product types of models produced in the plant - soft: slight changes, many common parts - colour of car - hard: great changes, few common parts - frame of car, sedan vs coupe etc - can’t manufacture many parts if all parts are different across different products due to cost Activity: Car Wheel high cost – alloy low cost – steel typical materials aluminium alloys [lighter] steel [heavier] annual production high (100k+) part or assembly part assembly (inner and outer disks) manufacturing process alloy casting: mould for general shape stamping: for general shape machining: trimmed and drilled lamination: for joining machining: trimmed and drilled mig-mag welding: for joining process scalable? yes, scalable to large quantities alternative manufacturing process? forging: for general shape [quick] machining: trimmed and drilled machining: trimmed and drilled Shaping Processes alter the geometry of the starting work material Solidification Process: casting and moulding - starting material is melted and solidified moulding (plastics) into a die casting (metals and ceramics) into a mould Deformation Process: Bulk - starting material is shaped by forces exceeding the yield strength of the material sheet metal forming or stamping forging extrusion Material Subtraction: Machining - excess material is cut away from a starting workpiece turning: material is cut from rotating workpiece using a single point cutting tool  drilling: material is cut from workpiece using a rotating drill bit cutting tool milling: material is cut from workpiece using a rotating milling cutter Material Addition Process: 3D Printing - material (powder, liquid, filament) is added together to form the final part shape particulate processing: starting materials are metal or ceramic powders which are pressed and sintered (heated near melting temperature) powder bed fusion process: laser fuses powder together additive manufacturing (AM) (3D printing) Material Joining Process - separate bulk material parts are joined to form the final shape adhesive bonding/glueing welding/brazing fastening with bolts Consideration vs Process machining sand casting additive manufacturing cost rate  quality flexibility Net Shape vs Near Net Shape consider combination of processes, is it near net shape, or does it need more processes to become the net shape depends on the requirements of the design, the finish, dimensions, extra design additives net shape: near net shape: make a part in one operation and requires no substantial further close to the final geometry, however, requires further operations to processing to achieve the required final part geometry and surface produce the final shape finish w2: Material Removal/Subtractive Manufacturing Conventional Machining definition uses a sharp and hard cutting tool to mechanically cut away material to shape and enhance finish of material or add extra details by forming chip factors - relative motion and trajectory between tool and workpiece (cutting speed and feed motion) to achieve various geometries/shapes - shape of cutting tool - strength of cutting tool material - cost of cutting tool - the higher the material removal rate, the more power and lower time on machine and tool, increase feed rate and speed to increase material removal rate - target material typically for metal, but plastic or ceramic materials may be used depending on machinability target stage typically performed after other basic near-net shape manufacturing processes such as casting, forging etc. advantages disadvantages versatile wasteful of material - different materials - costly to recycle - different art shapes - can reduce this by combining with other other processes (casting, forging) - different production quantities - typically no custom tools high dimensional accuracy good surface finish (net finish) few defects (very good quality) can be easily automated (CNC) more time consuming than other methods (low-medium rate) can have replaceable inserts can leave machining marks - cheap to change if they break - versatile, different materials can have different inserts cutting speed determines the productivity (limited by workpiece and depending on the material cutting materials) shape limited by tool access material machinability machining is harder if material is - very strong - very hard or very soft - very brittle or very tough - poor heat conductor - hardens while machining considerations  - cutting tools wear out or fail (break) over time due to higher loads when they: - undergo high structural and thermal loads - have increased cutting speed and increased feed rates - are made from materials of lower thermal or structural tolerance may not be as tough Machined Surface Finish can show visible machining marks factors: 1. geometric tool factors - nose radius (NR) & feed (f) (1) roughing (high feed, low speed): uses a sharp nose radius to get near-net shape by removing large amounts of material quickly (2) finishing (low feed, high speed): uses a round nose radius to get net shape (final dimensions, tolerance and surface finish) 2. how to eliminate vibrations/chatter of tool, machine, or workpiece – increase stiffness of setup – reduce feeds and depths to reduce forces – change cutter design to reduce forces – use a cutting fluid 3. process used Cutting Fluids Machining often requires use of cutting fluids (oil, water): 1. To remove heat 2. Lubricate the chip-tool interface 3. Wash away chips 4. Avoid part oxidation Contributes to: - chip removal - reduced stress on cutting tool - increased tool life - better part accuracy (reduced thermal expansion) - less surface damage Turning definition uses a lathe, single tip tool, to create a rotational part (circular cross section) process: 1. material is spinning (primary motion) 2. rotating tool moves horizontally (secondary motion) 3. creates divots into circular part factors - relative motion and trajectory between tool and workpiece (cutting speed and feed motion) to achieve various geometries/shapes - shape of cutting tool - types of lathes basic lathe bed: frame tool post: hold tools chucks: holds the workpiece tailstocks: supported workpiece OR other tools turret lathe CNC lathe tailstock replaced by turret that holds several tools Advanced programmable ‘Computer Numerical Control’ (CNC) of - tools rapidly brought into action by indexing the turret position, tool change and tool feeds - tool post can also be replaced by four sided turret to index four tools - saves changeover time advantages disadvantages Precision and Accuracy: Material Waste: - Turning can produce parts with very high precision and - Turning is a subtractive process, meaning material is accuracy, often to tolerances within thousandths of an inch. removed from the workpiece, which can result in significant Surface Finish: material waste. The process can achieve a very smooth surface finish, which is beneficial for parts that require high-quality Tool Wear and Maintenance: finishes. - Cutting tools in turning operations can wear out quickly, Versatility: especially when machining hard materials, necessitating Turning is suitable for a wide range of materials, including regular maintenance and replacement. metals, plastics, and composites. - It can produce a variety of shapes and features, such as Setup Time: cylindrical, conical, and spherical surfaces, threads, and - The initial setup for turning operations, particularly for grooves. complex parts, can be time-consuming. High Production Rates: - With the right setup and automation, turning can be a very Limited to Rotational Parts: efficient process for producing large quantities of parts - Turning is primarily suited for producing parts with quickly. rotational symmetry. It is not effective for non-cylindrical Automation Compatibility: parts. - Turning operations can be easily automated with CNC (Computer Numerical Control) technology, enhancing Surface Quality Limitation: efficiency and consistency. - While turning can produce good surface finishes, it may not Cost-Effective for Small to Medium Batch Sizes: be sufficient for parts requiring exceptionally high surface - For small to medium production runs, turning can be very quality without additional finishing processes. cost-effective compared to other manufacturing processes. Energy Consumption: - High-speed turning operations can consume significant amounts of energy, particularly when dealing with hard or tough materials. parameters + formulas calculate cutting speed; - 𝑑 = 4 𝑚𝑚 - 𝐷0 = 150 𝑚𝑚 - 𝑓 = 0. 3 𝑚𝑚/𝑟𝑒𝑣 - 𝑇𝑀 = 5 𝑚𝑖𝑛 - 𝐿 = 400 𝑚𝑚 π · 𝐷0 · 𝐿 use: 𝑇𝑚 = 𝑓·𝑣 : π · 𝐷0 · 𝐿 π · 150 · 400 𝑣 = 𝑇𝑚 · 𝑓 = 5 · 0.3 ≈ 125 633. 7 𝑚𝑚/𝑚𝑖𝑛 ≈ 126 𝑚/𝑚𝑖𝑛 Turning Operations Straight turning Contour turning Tool is fed in parallel to the axis of rotation of the work to form a Tool follows a contour that is not a straight line, thus creating a cylinder contoured form in the turned part Taper turning Facing Tool is fed at an angle with the axis of rotation of the work and Tool fed radially into the rotating work to create a flat surface on one create a tapered cylinder or conic shape end Form turning (forming) Chamfering Tool has a shape (form) that is imparted to the work by plunging the The cutting edge of the tool is used to cut an angle on the corner of tool radially into the work the cylinder, the tool can be fed both axially or radially. Remove sharp corners Drilling Cut-off (parting) Drilling by feeding drill into the rotating workpiece along its axis Tool fed radially into the rotating work to cut off the end of the part or form groove Threading Boring Used to cut external threads A single point tool is fed linearly, parallel to the axis of rotation, on the inside diameter of an existing hole in the part. It can enlarge the hole or produce a circular internal groove In effect, boring is an internal turning operation Knurling Forming operation used to produce patterns in the work surface. No cutting of material, just deformation Drilling definition drilling machine/press uses a drill bit, multiple points, to create a prismatic part (rigid non rotational cross section) process: 1. material is stationary 2. rotating tool moves along one axis 3. creates circular holes into part ↪ through hole: drill exits opposite side of work ↪ blind hole: drill does not exit opposite side factors that influence cost: - cutting speed (𝑣 in m/min or mm/sec) of tool edge moves relative to workpiece surface - can cause to much friction and heat - feed rate (𝑓𝑟 in mm/min or mm/sec) the tool is plunged into workpiece - depth of cut (𝑑 in mm) into workpiece types - the machine used: upright drill press radial arm drill press CNC drill simple more adjustability: horizontal and vertical more adjustability: horizontal and vertical, manually operated manually operated computer positioning limited adjustability: only vertical  advanced computer numerical control operated - drill bit used: - body of flutes, spiral grooves, used to guide chip removal, deliver cutting fluids - cutting points = number of flutes - reaming tapping - slightly enlarges a hole - cuts internal screw threads on an existing hole - enhances tolerance and surface finish (removes machine - tool: tap marks) - for threaded holes for fasteners - tool: reamer counterboring countersinking - used for hiding bolt/screw heads - creates stepped hole advantages limitations of conventional drilling: at depths of over 4 times the diameter of the drill bit: - chips can accumulate - cutting fluid flow restricted - interrupted cut drilling (pech drilling)  long/deep and narrow holes (small diameter) are difficult/impossible to drill conventionally: - due to drill bits being too fragile, and likely to break or wonder/skew - alternative: electro discharge hole drilling small holes (