Processes used to for metallic materials

Hundreds of processes to shape or form metallic materials Many have been around for thousands of years Choosing a process depends on: Type of metal Production volume Cost Desired properties of finished part

Forging Hand forging Dates back to 4000B.C. How blacksmiths shape metal Heat until cherry red Hammer against an anvil to get desired shape Used by crafters working with wrought iron today

Applied to several processes Forging Applied to several processes Metal shaped by heavy presses and drop-forging hammers forcing heated metal into shape Little material is lost Shape is changed by repositioning metal during the process Grain of metal can be controlled making stronger/tougher part Used to make: bolts (without threads), rivets, connecting rods, gears

Simplest of all forging Open-Die Forging Simplest of all forging Heated workpiece is formed between flat dies that compact Dies don’t completely enclose Time consuming Quality depends on skill Limited application in high volume production

Cannot shape the part completely Creates flashing Material that squeezes out, excess Cannot shape the part completely Excess material has to be removed by machining Forged gear blanks can have up to 70% waste Teeth have to be machined

Closed-Die Forging Produces a near net shape part (close to final shape) Reduced waste Preheated metal completely encompassed by the die set Upper die repeatedly hammers the material, causing it to flow until it conforms to the shape of the die cavity

Majority of commercial forging More stock used to completely fill the die Dies can be made with a gutter (groove) Gutter is area for excess material to go

Coining Squeezing metal while it is confined in a closed set of dies Requires high pressure and precision dies Used to make coins and medallions Small details Causes metal to move from thinner to thicker areas

Blank is placed in die Movable punch cold works the material Can form fine detail Pressures as high as 200,000 psi

Rotary Forming Processes Uses rollers to squeeze and shape metal

Any ductile metal can be formed without heat Roller forming Any ductile metal can be formed without heat Forms straight stock into nearly any imaginable shape No dies Rollers progressively squeeze stock into desired shape Rollers grip and form, each set makes a small shape change Thickness remains fairly constant Only shape changes

Roller forming is a fast process Often combined with other processes Roller operation feeds into: cutting operation welding operation Another forming operation

Different types based on roller positions and number of rollers: Roll Bending Used to bend bar, rod, tube, angle and channel stock into circular, curved and cylindrical shapes Different types based on roller positions and number of rollers: Roll bender Two-roll machine Three-roll double-pinch machine Stretch forming

Thread Rolling Forms threads on fasteners Chipless cold-forming process (no waste) Blank (material) is rolled against grooved dies

Swaging AKA rotary swaging, radial forging Uses 2 or 4 opposing dies Dies strike material repeatedly

Extrusion Compresses metal beyond its elastic limit Continuous pressure Like squeezing toothpaste

Direct extrusion Ram forces stock through the die opening

Stationary mandrel extrusion Make hollow tubing Ram is attached to stationary mandrel Forces material through die opening from inside the material

Impact extrusion Used to make collapsible tubes Soft materials Slug placed in a die cavity then struck by a punch Metal flows back around the punch