Processes used to form metallic materials Chapter 14 part 2 Processes used to form metallic materials

Upsetting AKA cold forming or cold heading Thickens or bulges the workpiece while shortening it by compression Combination of forging and extrusion Fastest process High volume production of nails, bolts and rivets Cold forms a head on the end of a metal rod by compressing it’s length in a die cavity

Consists of a die block and a punch Punch pushes precut stock through a hole Ejector pin in hole pushes part out when finished

Cold Forming Advantages Higher production rates Little or no scrap Close tolerances Good surface finish Increased part strength

Stamping Considered inexpensive and easy to make parts Cold forming Set of matched molds in a press Stock is shaped under pressure under one stroke from the stamping press Chipless process Highly used in the automotive industry

Stamping presses can also be used to: Punch Notch Pierce Trim

Embossing Produces raised areas on a flat sheet of metal Dog tags, id plates, license plates One side has raised printing, other side has indentation Uses 2 part matched die

Drawing Stretching and compressing to make a shape Several types Kitchen sinks, pans, car fenders Several types

Deep Drawing Female die pressed into sheet stock Stock stretches over male die or punch

Mating dies must match perfectly Stretch-draw Forming Mating dies must match perfectly Dies are expensive Would also have an upper die

Marforming Uses a thick rubber pad, metal retainer and a forming block Begins when upper platen holding the rubber pad moves down against the holding punch

Hydroforming Uses hydraulic fluid in place of rubber pad Workpiece is positioned on bottom die block Pressure chamber is lowered Punch is forced upward Pressure increases in the fluid chamber forcing workpiece around the punch

High speed process Parts as large as 25” dia and 12” deep Steel 3/8” thick Aluminum 1” thick

Expanding Increase the diameter of tubular parts Punch travels down into the part, pushing it against the sidewalls of the die Parts to be expanded 30% or less of the diameter of the workpiece can be done in one stroke More than 30% needs several strokes

Bulging Similar to expanding Make bellows or musical instruments Tube is placed inside a die (shaped like final part) Bulging punch is lowered into tube (rubber) Punch is compressed forcing material against the die Die has to be opened to get part out

Necking Reduce the diameter of the end of a tubular part CO2 cartridge Increased tensile strength in reduced area

Nosing Used to partially close the end of a tube Can also taper or round an end of the tube Similar to rotary swaging

Electromagnetic Forming Uses magnetic forces Magnetic coil creates a magnetic field that is passed through the workpiece The magnetic fields oppose each other This pushes the workpiece against a die Usually on round parts Can be used inside or outside Also used to join tubular parts

Contouring Magnetic force used to shape flat parts Coil looks like electric stove burner Coil is placed against a sheet Magnetic force pushes the sheet against a die Can not be used for complex shapes Pressure is constant, can’t have high pressure in one area and low in another Doesn’t work with holes in the part (interferes with magnetic flow)

Peen Forming Bombarding the surface of a part with small spheres called shot Shot made from: Cast steel Glass Ceramic particles Blasting creates overlapping indentations creating higher compression strength Peened areas will not crack Increases product life Engine valve springs

Explosive Forming Uses a female die, large water tank and an explosive charge Die, stock and charge are placed in water Air is removed from the die Charge is detonated, shock waves force stock into the die Size is only limited by the water tank

HERF (high-energy-rate forming) Variation of explosive forming Uses spark-generated shock wave

Spinning Stretching sheet stock over a spinning mold Cold or hot worked