PROCESSING MATERIALS

Processing Materials Materials are processed to make them more useful --- changing from one form to anotherMaterials are processed to make them more useful --- changing from one form to another Value is added by each processValue is added by each process  Primary Industry –Produces basic industrial materials used to make “basic industrial materials” –Iron ore steel structures, Crude oil chemicals plastics –Rubber (latex) is heated with sulfur --- Vulcanization Cottonthread Woodpaper Steelstructures Animal Hides shoes

Industrial Materials  Wood –Hard wood --- broad leaves --- deciduous, e.g. maple, oak –Soft wood --- thin leaves --- coniferous, e.g. pine –Plywood (a manufactured board) is made from wood chips and saw dust.  Metals –Metals, e.g. iron are used to make heavy structures, automobiles, planes and tools etc. –Alloys are the combination of two or more metals –Brass Copper + Zinc, Bronze Copper + Tin, Pewter Tin, Antimony and Copper –Ferrous metals --- more than 50% iron –Stainless steel containing chromium resists rusting

Industrial Materials  Ceramics –Objects obtained from clay like materials such as plaster, cement, limestone and glass --- pottery, fiber glass, sockets, switches –They are heated (fired) to around 2000 F in an oven called kiln –Glazing is coating them with glass-like materials –High strength ceramics are used in planes, automobiles –Soda lime glass sand, lime and sodium oxide at around 2500 F  Plastics –Long chain molecules --- polymers –Thermoplastics --- soften when heated and harden when cooled again, e.g. polythene bags, PVC bags –Thermoset --- do not soften when heated. They rather char and burn instead, e.g. bakelite, Formica and plastic cups

Industrial Materials  How Steel is Made –Iron ore (iron oxide) is melted with limestone and coke in a blast furnace –Molten iron cools and hardens into pig iron –Impurities are removed as slag –Hot metal is turned into steel in basic oxygen furnaces (BOFs) –Steel is also made in open-hearth furnaces and electric furnaces –Huge blocks of molten steel are called ingots --- bars, rods and sheets –Changing molten steel directly into basic shapes --- continuous casting

Processing Materials Forming --- changing shapeForming --- changing shape Separating --- removing a partSeparating --- removing a part Combining --- joining materials togetherCombining --- joining materials together Conditioning --- changing internal propertiesConditioning --- changing internal properties

Forming Processes  Casting –Castings are made from molds --- ice cubes, walk on a beach, cake pan –One-piece and two-piece molds –Slip is the liquid clay poured into a two-piece mold  Pressing –Pressing is like casting with a plunger –Meat can be pressed into shape with hands –Powdered metal pressed and heated --- sintering  Forging –Heating a metal and hammering into a shape --- blacksmith, coins –Hydraulic and mechanical presses use powerful rams --- thousand tons of force

Forming Processes  Extruding –Soft metal pressed/squeezed through an opening, e.g toothpaste –End products do not require much more shaping and machining  Blow Molding –Air blows the plastic into a mold, e.g plastic bottles  Vacuum Forming –A vacuum pulls the warm, soft plastic down –The plastic clings to whatever it is drawn against, e.g. blister packaging

Separating Processes  Shearing –Using knife-like blade for separating –When the force gets high enough, the material breaks along the line of the cut  Sawing –Separating with a blade that has teeth –Cutting wood along the direction of the grain --- Ripping –Cutting wood across the direction of the grain --- Crosscutting –Handsaws used for wood have 6-10 tpi –Metal is cut by hand using a hacksaw --- usually 18 tpi –Machine saws and table saws