Transcript CHAPTER 4
CHAPTER 4 Manufacturing Materials and Processes Learning Objectives • Define and describe given manufacturing materials, material terminology, numbering systems, and material treatment • Describe steel and aluminum material selection characteristics • Explain sustainability applications for steel and aluminum processing and manufacturing Learning Objectives • Identify a variety of manufacturing processes used to create plastic products • Explain sustainability applications for plastics processing and manufacturing • Discuss casting processes and terminology Learning Objectives • Explain the forging process and terminology • Describe manufacturing processes • Define and draw the representation of various machined features • Explain tool design and drafting practices • Draw a basic machine tool Learning Objectives • Discuss the statistical process quality control assurance system • Evaluate the results of an engineering and manufacturing problem • Explain the use of computer-aided manufacturing (CAM) in industry • Discuss robotics in industry Ferrous Metals • Contain iron • Cast iron Alloy containing 1.7% to 4.5% carbon Varying amounts of silicon, manganese, phosphorus, and sulfur • Steel Alloy containing 0.8% to 1.5% carbon Gray Cast Iron • • • • 1.7% to 4.5% carbon 1% to 3% silicon Easy to cast and machine Popular for: • Automotive cylinder blocks • Machine tools • Agricultural implements • Cast iron pipe White Cast Iron • Extremely hard and brittle • Almost no ductility • Highly resistant to wear Chilled Gray Cast Iron • Creates outer surface of white cast iron • Internal characteristics of gray cast iron • Surface advantage of white cast iron Alloy Cast Iron • Nickel, chromium, molybdenum, copper, or manganese alloy • Increased: • Strength • Wear resistance • Corrosion resistance • Heat resistance Malleable Cast Iron • Heat-treated white cast iron • Strong • Ductile • Shock-resistant • Easy to machine Nodular Cast Iron • Special casting process • Magnesium or cerium alloy • Strong • Ductile • Can be chilled Mild steel (MS) • Less than 0.3% carbon • Cannot be hardened • Common for forged and machined parts Medium Carbon Steel • 0.3% to 0.6% carbon • Harder than mild steel • Easy to forge and machine High Carbon Steel • 0.6% to 1.50% carbon • Can be hardened by heat treating • Difficult to forge, machine, or weld Hot-Rolled Steel (HRS) • Formed between rollers or forged when red-hot • Consistent grain structure Strong Ductile Cold-Rolled Steel (CRS) • Additional forming after initial hot rolling • Smooth, clean surface • Ensures dimensional accuracy • Increases tensile strength Steel Alloys • Chromium • Tungsten • Corrosion resistant • Hard for cutting tools • Wear resistant • Carbon • Manganese • Hard for cutting • Strong tools • Wear resistant • Vanadium • Molybdenum • Tough • Strong • Strong • Wear resistant • Non-brittle • Heat resistance Steel Castings • Generally stronger and tougher than cast iron • Common for machine parts Stainless Steel • Generally at least 10.5% chromium • Excellent corrosion resistance • Oxidation resistant • Heat resistant • Strong Stainless Steel Applications • • • • Restaurant and hospital equipment Architectural and marine applications Some aircraft applications Consumer products Steel Numbering Systems • American Iron and Steel Institute (AISI) • Society of Automotive Engineers (SAE) • Example: SAE 1020 10: type of steel 20: approximate amount of carbon (0.20% carbon) • Added letter between the first and second pair of numbers Heat Treating Steel • Heating followed by quenching hardens steel • Case hardening • Hardens the surface layer by carburization, often followed by quenching • Tempering • Annealing Hardness Testing • Brinell test • Brinell Hardness Number (BHN) • Rockwell hardness test • Example note: CASE HARDEN 58 PER ROCKWELL “C” SCALE. Nonferrous metals • No iron content • Copper • Aluminum Aluminum • • • • • • Corrosion resistant Lightweight Easily cast Conducts heat and electricity Easily extruded Very malleable Aluminum Alloy Numbering • Various designations • Example: 1030 • 1: 99% pure • 0: no control of specific impurities • 30: 99.30% aluminum Copper Alloys • • • • Easily rolled and drawn into wire Excellent corrosion resistance Great electrical conductor Better ductility than any metal except for silver and gold Brass • Alloy of copper (about 90%) and zinc (about 10% zinc) • Corrosion resistant • Strong • Ductile Bronze • Alloy of copper and tin • Tin increases: Hardness Wear resistance • Phosphor bronze Precious and Other Specialty Metals • • • • • • Gold Silver Platinum Columbium Titanium Tungsten Metallurgy • Practical use of metals and metalworking • Production of metal components for use in products • Alloy development • Material shaping • Heat treatment • Surface treatment Plastics and Polymers • Polymerization • Often molded into shape • Machined for tight tolerance situations or when holes or other features are required • Gears • Pinions • Society of the Plastics Industry, Inc. (SPI) identification coding system Thermoplastics • Heated and formed by pressure to a desired shape • Reheating changes the shape • Used for most plastic products Thermoplastics • Thousands of different thermoplastic combinations for specific applications • Common examples: Acrylic Acrylonitrile-butadiene-styrene Polyamide (nylon) Polyethylene Polypropylene Polyesters (ABS) Thermosets • Heated and formed by pressure to a permanent shape • Cannot be altered by heating after curing • Used when heat exists • More rigid and harder than thermoplastics • About 15% of plastics • Expensive • Brittle • Cannot be reformed Common Thermosets • • • • • Alkyds Melamine formaldehyde Phenolics Unsaturated polyesters Urea formaldehyde Elastomers • Stretch at least equal to their original length and return to their original length • Rubber • Occurs naturally in a number of plants • Produced synthetically Almost rubber twice as many products as natural Common Elastomers • Many different elastomers for specific applications • Butyl rubber • Chloroprene rubber (Neoprene) • Nitrile rubber • Polyurethane • Silicones Inorganic Materials • Carbon • Graphite • Can be molded by pressure • Low tensile strength • High compressive strength Inorganic Materials • Ceramics • Hard • Brittle • Resistant to heat, chemicals, and corrosion Inorganic Materials • Clay • Glass • Refractory • Used for high-temperature applications • Inorganic cements Composites • Reinforced plastics • Polymers combined with reinforcing material • Glass • Graphite • Thermoplastic fibers • Cotton • Paper • Metal Material Selection • Typically occurs during initial design or redesign • Requires knowledge of: • Material properties, characteristics, cost, and • • • • • availability Manufacturing processes and costs Part geometry External and internal forces applied to the parts and the assembly Product use and appearance Environmental considerations and sustainability Castings • The result of founding 1. A pattern is constructed that is the same 2. 3. shape as the desired finished product A mold is made by packing sand or other material around the pattern The pattern is removed from the mold and molten metal is poured into the hollow cavity Sand Casting • Most commonly used method of making castings • Two general types: • Green sand • Dry sand Cores • Baked clean sand mixed with binders, or • Ceramic products • Reduce casting • weight Save on machining costs Centrifugal Casting • No cores needed • Objects with circular or cylindrical shapes • Tubing • Pipes • Wheels Die Casting • Nonferrous metal castings • Zinc alloy • Brass • Bronze • Aluminum • Quick and economic • Fine detail and smooth finish Permanent Casting • Similar to sand casting and die casting • The mold can be used many times • Good finished qualities Investment Casting Forgings • Hot or cold materials • Material retains original grain structure • Strong and ductile Forging Methods • Hand forging • Smithing • Blacksmithing • Machine forging • Upset • Swaging • Bending • Punching • Cutting • Welding Metal Stamping • Uses a punch press • Holes created by punching through material • Mass production • Example: • Automobile body panels Hydroforming • • • • Tube hydroforming Sheet hydroforming High strength-to-weight ratios Can be more economical than metal stamping Powder Metallurgy (PM) • Uses metal-alloyed powders • Compacted under pressure in a die • Sintered • Metal Injection Molding (MIM) • Powder Forging (PF) • Quality, precision parts • Mass production Machine Processes • Machining • Used to manufacture metal and some plastic products • Machine tools • Machinist Drilling Machine (Drill Press) • • • • • • Machine-drill holes Reaming Boring Counterboring Countersinking Tapping Grinding Machine • Grinding • Honing • Lapping Lathe • Cut material by turning cylindrically shaped objects Screw Machine • Type of lathe • Mass-production • Variety of small turned parts • Screws • Threaded parts Milling Machines • Horizontal mill • Vertical mill • Work fastened to a table • Rotary cutting tool removes material Large variety of milling cutters End milling cutters Milling Machines Milling Machines • Universal Milling Machine • Table action includes x-, y-, and z-axis movement plus angular rotation • Multiaxis Milling Machines • CNC tools that move in four or more directions Saw Machines • Power hacksaw • Band saw • Circular abrasive or metal cutting wheels • Cut material to length • Machining operations Kerf Water-Jet Cutting • Cut almost any material • Cut material as thick as 12 in. (305 mm) or more • Hold fine tolerances • Do not produce a heat-affected zone Shaper • Horizontal, vertical, or angular flat surfaces • Being replaced by milling machines • Slow • Cuts only in one direction Chemical Machining • Uses chemicals to remove material accurately • Electrochemical machining (ECM) • Electrodischarge machining (EDM) • Electron beam (EB) cutting and machining • Ultrasonic machining • Laser machining Drill Features on a Drawing Ream Features on a Drawing Bore Features on a Drawing Counterbore Features on a Drawing Countersink Features on a Drawing Counterdrill Features on a Drawing Spotface Features on a Drawing Chamfer Features on a Drawing Fillet and Round Features on a Drawing Key, Keyseat, Keyway on a Drawing Threads on a Drawing • Many different forms of threads • Fasteners to hold parts together • Adjust parts in alignment • Transmit power Knurl on a Drawing Surface Texture (Surface Finish) • • • • Roughness Waviness Lay Flaws Additional Features • • • • Boss Lug Pad Dovetail • • • • Kerf Neck Spline T-slot Injection Molding Process • Most common process for creating thermoplastic products Extrusion Process • Continuous shapes: moldings, tubing, bars, angles Blow Molding Process • Hollow products: bottles, containers Calendering Process • Thermoplastic or thermoset plastics pass through a series of heated rollers • Sheet products • Vinyl flooring • Gaskets Rotational Molding Process • Polymer pellets in a heated, rotating metal mold • Rotation forms a thin coating against the sides of the mold • Large hollow objects • Tanks • Containers • Floats Solid Phase Forming Process • Detailed shapes: containers, electrical housings, automotive parts Thermoforming of Plastic • Similar to solid phase forming, but does not use a die • Thin-walled shapes • Containers • Guards • Fenders Free-Form Fabrication (FFF) of Plastic • Rapid prototyping • Stereolithography • 3-D Printing Casting Thermoset Plastics • Similar to permanent casting of metals Compression Molding and Transfer Molding • Common for thermosets • Uses a mold, specific amount of heated material, additional heat, and pressure Foam Molding and Reaction Injection Molding • Similar to casting, but uses an expanding foam material Vulcanization Process • Rubber products such as tires Manufacturing Composites • • • • Layering process Compression molding of composites Resin transfer molding Vacuum bag forming Rapid Prototyping (RP) • Stereolithography (SLA) • Computer controlled ultraviolet laser beam hardens a photo-curable liquid resin • Fused deposition modeling (FDM) • CNC extruder-head squeezes a fine filament of melted thermoplastic through a nozzle • 3-D printing • Print head dispenses a thermoplastic material in layers Tool Design • Machining operations require special tools to hold the workpiece or guide the machine tool • Jig • Fixture • Kinematics Computer-Integrated Manufacturing (CIM) • Computer and software controls most, if not all, portions of manufacturing • Brings together: • Computer-Aided Design and Drafting (CADD) • Computer-Aided Engineering (CAE) • Computer Numerical Control (CNC) • Computer-Aided Manufacturing (CAM) • Computer-Aided Quality Control (CAQC) • Robotics CAD/CAM integration • A direct link between the design and manufacture of a product • CAD used to create product geometry • 2-D multiview drawings • 3-D models • CAM generates instructions for CNC machine tools • • • • • Stamping Cutting Burning Bending Other operations Statistical Process Control (SPC)