ME215 Sunday CLEAN — Sheet Forming, Powder Metallurgy, Welding

Blanking

Shearing a closed contour from sheet metal where the sheared-out piece is the desired product.

Piercing

Shearing a closed contour from sheet metal where the sheared-out piece is scrap and the remaining strip is the product.

Bending

Strain-hardening sheet metal around a linear axis to change its geometry.

Drawing

Forming flat sheet metal into a 3D hollow shape using a punch and die without significant thinning.

Springback

Elastic recovery of sheet metal after bending forces are removed, altering the final angle.

Deep drawing

Drawing process where the depth of the cup significantly exceeds its diameter.

Hemming

Folding the edge of sheet metal back onto itself to reinforce the edge and improve safety.

Flanging

Bending the edge of sheet metal into a 90-degree or angled rim for joining or stiffness.

Coining

A pressing operation using high pressure to impart fine surface details and thickness variations.

Embossing

Pressing sheet metal to create raised or recessed patterns without significantly altering thickness.

Hydroforming

Using high-pressure fluid to form sheet metal or tubing into a complex die cavity.

Rubber pad forming

Using a flexible rubber block as one die half to form sheet metal around a rigid tool.

Shearing

Cutting sheet metal along a straight line using a punch and a die blade.

Slitting

Cutting wide sheet metal coils into multiple narrower strips using rotary circular blades.

Perforating

Punching a large array of closely spaced small holes into sheet metal.

Notching

Cutting material from the edge or corner of a sheet metal strip to shape the blank.

Lancing

Cutting a slit in the metal and bending the adjacent material up to form a tab or louvers.

Nibbling

Cutting a complex contour by punching a series of overlapping small holes.

Shaving

Shearing a very thin layer of material from the edge of a blank to improve dimensional accuracy and smoothness.

Trimming

Cutting excess scrap metal from the edges of a drawn or formed part.

Stretch forming

Stretching sheet metal beyond its yield point while wrapping it around a positive die.

Spin forming

Rotating a circular sheet blank against a form block using a rigid tool to create axisymmetric parts.

Explosive forming

Using an explosive charge in a liquid medium to rapidly shape high-strength sheet metal into a die.

Magnetic pulse forming

Using high-intensity electromagnetic fields to rapidly deform conductive sheet metal without physical contact.

Superplastic forming

Forming fine-grained alloys at elevated temperatures under low strain rates to achieve extreme elongations.

Minimum bend radius

The smallest radius to which sheet metal can be bent without cracking on the outer surface.

Bending allowance

The length of the neutral axis used to calculate the flat blank size required for a bent part.

Springback mitigation

Techniques like overbending or bottoming used to compensate for elastic recovery.

Draw beads

Ridges and grooves in a blank holder and die that control metal flow during deep drawing.

Blank holder force

The clamping pressure applied to the sheet edge to prevent wrinkling during drawing.

Thinning

The reduction of sheet thickness that occurs in areas subjected to high tensile stretching.

Wrinkling

A forming defect caused by compressive hoop stresses leading to buckling in unsupported regions.

Tear

A defect where sheet metal fractures due to excessive tensile stresses exceeding its ultimate strength.

Punch force

The maximum load required to drive the punch through or into the sheet metal.

Die clearance

The gap between the punch and die cutting edges, critical for clean shearing and burr minimization.

Powder production

The manufacturing of fine metallic or ceramic particles via chemical, mechanical, or atomization methods.

Atomization

Disintegrating a molten metal stream into fine droplets using high-pressure gas, water, or centrifugal force.

Reduction

Chemical removal of oxygen from metal oxides to produce metal powders.

Electrolytic deposition

Producing high-purity metal powders by electro-deposition from a solution or fused salt.

Blending

Thoroughly mixing metal powders of the same nominal composition to achieve batch uniformity.

Mixing

Combining metal powders of different compositions or with additives like lubricants and binders.

Compaction

Pressing loose metal powder inside a rigid die to form a cohesive green part.

Cold compaction

Pressing metal powders at room temperature to impart mechanical integrity and shape.

Isostatic pressing

Applying uniform hydrostatic pressure from all directions to compact metal powder uniformly.

Cold isostatic pressing

Compacting metal powder sealed in a flexible elastomeric mold using high-pressure liquid at room temperature.

Hot isostatic pressing

Simultaneously applying high temperature and uniform gas pressure to fully densify powder compacts or castings.

Sintering

Heating a green compact below its melting point in a controlled atmosphere to bond particles via diffusion.

Solid-state sintering

Sintering metal powders solely through atomic diffusion without the formation of a liquid phase.

Liquid-phase sintering

Sintering a powder mixture where one constituent melts, enhancing densification and particle rearrangement.

Green density

The density of the powder compact immediately after pressing and before sintering.

Green strength

The mechanical strength and handling integrity of an unsintered powder compact.

Sintering stages

The progression of neck growth, pore rounding, and pore shrinkage during thermal consolidation.

Infiltration

Melting a lower-melting-point metal into the interconnected pores of a porous sintered skeleton via capillary action.

Impregnation

Filling the open pores of a sintered part with oil, resin, or polymer for lubrication or sealing.

Sizing

A light pressing operation applied to a sintered part to improve dimensional precision and tolerances.

Repressing

Pressing a sintered part to increase density and mechanical strength.

Coining

Restriking a sintered component to impart surface details and tight dimensions.

Finishing

Post-sintering operations such as heat treating, machining, plating, or steam treating.

Porosity

The volume fraction of empty void space within a powder metallurgy compact.

Flow rate

The speed at which metal powder flows through a standard funnel under gravity, indicating handling behavior.

Apparent density

The density of loose powder poured into a container without external tamping or settling.

Compressibility

The ability of a metal powder to densify under applied pressure.

Green part

The fragile, unsintered component directly resulting from powder compaction.

Sintered neck

The solid-state bond formed between adjacent powder particles during the initial stages of sintering.

Dimensional change

The net shrinkage or growth that occurs in a powder metallurgy part during sintering.

Fusion welding

Joining metals by melting the base materials, often with the addition of a filler metal.

Solid-state welding

Joining metals through pressure, deformation, and atomic diffusion without bulk melting.

Shielded metal arc welding

Manual arc welding process using a flux-coated consumable electrode to shield the molten weld pool.

Gas metal arc welding

Semi-automatic arc welding using a continuously fed wire electrode and an external shielding gas.

Gas tungsten arc welding

Arc welding using a non-consumable tungsten electrode and an inert shielding gas, often called TIG.

Flux-cored arc welding

Arc welding using a continuous tubular electrode filled with flux, with or without external shielding gas.

Submerged arc welding

Arc welding process where the arc and molten pool are shielded by a blanket of granular fusible flux.

Electroslag welding

Vertical-position welding process using electrical resistance through molten slag to melt base and filler metals.

Gas welding

Oxyfuel welding process using combustion gases like acetylene to melt the base metals and filler rod.

Resistance spot welding

Joining overlapping sheet metals by applying clamping force and electrical current at localized points.

Resistance seam welding

Joining sheet metals continuously using rotating wheel electrodes and localized electrical current.

Flash welding

Resistance welding process where parts are brought into contact with high current to flash and melt interfaces before forging.

Friction welding

Solid-state joining process where heat is generated by mechanical friction between rotating and stationary parts.

Friction stir welding

Solid-state joining process using a rotating, non-consumable pin tool to plastically deform and weld materials.

Ultrasonic welding

Joining materials by applying high-frequency vibrational energy under pressure to create solid-state bonds.

Diffusion bonding

Solid-state joining process using high temperature and pressure over time to achieve atomic-scale coalescence.

Explosion welding

Solid-state welding driven by controlled detonating explosives to impact and bond metal plates together.

Forge welding

Ancient solid-state welding process where heated metals are hammered together to achieve coalescence.

Brazing

Joining metals using a filler metal with a liquidus temperature above 450 degrees Celsius without melting the base materials.

Soldering

Joining metals using a filler metal with a liquidus temperature below 450 degrees Celsius without melting base materials.

Filler metal

Additional metal added during welding, brazing, or soldering to fill the joint gap.

Flux

Chemical compound applied during welding or brazing to clean surfaces and prevent oxidation.

Heat-affected zone

The portion of the base metal that was not melted but experienced microstructural changes due to thermal cycles.

Fusion zone

The central area of a fusion weld where base and filler metals completely melted and mixed.

Weld bead

The solidified deposit of filler and melted base metal formed during a single weld pass.

Porosity

Trapped gas bubbles in the solidified weld metal caused by contamination or improper shielding.

Undercut

A weld defect where a groove is melted into the base metal adjacent to the weld toe without being filled.

Cracking

Structural fracture in the weld metal or heat-affected zone caused by high thermal stresses or metallurgical embrittlement.

Lack of fusion

A welding defect where the weld metal fails to fuse completely with the base metal or preceding weld passes.

Residual stresses

Internal mechanical stresses remaining in a welded component due to uneven thermal expansion and contraction.

Distortion

Permanent warping or angular change of a welded structure caused by localized heating and cooling stresses.

Preheat

Heating the base metal prior to welding to reduce cooling rates, thermal gradients, and cracking risk.

Post-weld heat treatment

Controlled thermal processing after welding to relieve residual stresses and improve mechanical properties.

Nondestructive testing

Inspection methods like radiography or ultrasonic testing used to evaluate weld integrity without damaging the part.

Radiographic testing

Using X-rays or gamma rays to detect internal defects and voids within a weld.