Metal forming Flashcards by Hannah Trimble

what are the basikc deformation processes for metal

rolling
forging
extrusion
drawing

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what temperature is cold working preformed at

Ambient tempurature

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what are the advantages of cold working

greater accuracy
close tolerances
better surface finish
higher strength and hardess
grain flow allows desirable directional properites
no heating equired
may eliminate secondary operations

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disadvantages of cold working

high force/power required
starting workpeice must be free of scale/dirt
ductility/strain hardening limit amout of forming that can be completed
anneling may be required for further deformation

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at what tempuratures is hot working preformed

above the recrystaization tempurature

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what is the recrystalization tempurature

typically 50% of melting pointy in kelvin scale
a tempuratre where no strain hardening occurs and new grains areformed with mmo strain

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what are the advantages of hot working

shape can be altered significantly
low force/power required
metals that cant handle cold work can be hot worked
strength properties are generally non directional
no work hardening occurs

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disadvanages of hot working

lower dimensional accuracy
high energy required
work surface has oxidation/scale
poor surface finish
shorter tool life

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at what tempuratures is warm working preformed

preformed above the amdient tempuare but below the recrystalization

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what are the advantages of warm working

lower force/power then cold working
more intricate geometry possible
need for anneling may be reduced/eliminated

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what is rolling

a processes in which the thicknessb of the work is reduced by compressive forces
most rolling is hpot rolling due to the large amount of deformation required
cold rolling can be preformed in the final stages of rolling

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what is forging

a deformation processes in which the the work is pressed between 2 dies

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forging facts

most forging is preformed hot
cold forging is used for certian products

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what is the difference between a forge hammer an a forging press

forging hammer uses impact loads
forging press applies gradual pressure

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what are the 3 types of forging operations

open die forging
impression die forging
flashless forging

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what is open die forging

material is compressed between 2 flat dies
allows material to flow out in the x direction
creates simple shapes

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what is impression die forging

preformed with dies that contain negive of desired shape
flash is formed as the metal nears its final position

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impresson die forging facts

several steps required
not capable of close tolerances
seprate cavities required for each step

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advantages of forging over maching

highe production rates
conservation of metal
greater part strength
favorable grain orrientation

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what is flashless forging

metal being foorced into a completly enclosed die caviity
no flash is formed

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what is important when it comes to flashless forging

material volume must equal die cavity volume

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what is coining

special application of flashless forging
fine details are impressed onto top and bottom surfaces of workpeice

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what is upset forging

a cylindrical workpeice decreases in length but increases in diameter

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what is a common use of upset forging

forming heads on nails/bolts

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what is extrusion in metals

material is forced to flow through a die opening with the the cross section shape the same as the die opening

what are the 3 types of metal extrusion

direct indirect impact

what is direct extrusion

the material is fored through the die opening by the ram

what is the main problem with direct extrusion

the significant amount of friction between the material and the walls of the container

what is indirect extrusion

the die is mounted on a. hollow ram and ram forces the material into the ram

hot extrusion advantages

reduces ram force increases ram speed reduces grain flow characteristics

what is impact extrusion

ram impacts the part at a high speed for a shot distanceas

what is drawing

similar to extrusion but the metal is pulled through a die

what are the 3 types of drawing

wire bar tube

what are the advantages of drawing

close dimensional control good surface finish improved strength and hardness economical for mas production

what are the advantages of sheet metalworking

good dimensional accuracy good surface finish high strenghth relitivly low cost with mass production

what are the 4 types of sheet metalworking

cutting bending drawing other forming

what are the 4 types of cutting

shearing blanking punching laser

what are the 3 stages of cutting

plastic deformatiobn penetration fracturwe

what is shearing

a sheet metal cutting operation along a straight line between 2 cutting edges

what is blanking

cutting sheet metal along a closed outline where the fallen peice is desired peice

what is the peice that is cut out dring blanking called

blank

what is punching

similar to blanking but the peice cut is scrap

what is cut off

seperating part with no excess waste

what is parting

seperating a part with excess waste

what is peircing

a punching operation in which a hole is cut out

what is slotting

simillar to periceing but a rectangular hole is cut

what uis notching

cutting a portion of metal from the edge of the sheet

what i ssemi notching

cutting a portion from inside the sheet

what is trimming

a cutting operation to remove excess metal from an established shape

what is shaving

shearing opration wth very small clearences

what is perforating

simeltanious punching operation

what is laser cutting

cutting using a highly cioncentrated beam of light

what is v bending

a punch looking like a v presses in to make a v shape

what is edge bending

pressure is held to part of the peice while the rest is bent with pressure being added

what are th esteps od the bending process

bend allowance bending force spring back

what is the neutral axis

a theoretical lime that stays the same during the bend

what is spring back

the elastic energy in the metal wanting to move back to original flat shape

what are 2 ways to comensate for spring back

overbending bottoming

what some bending operations

hemming seaming curling

what is the drawing process for sheet metal

pressure is applied evenly on the blanka press add more force to bring the peice down into a hole to create the shape

hwat are sone common defects n drawn parts

wrinkling at flange wrinking at wall tearing earing surface scratches

what is reverse drawing

a secondary drawing process where part is flipped over

what is emosing

creates rassed letters or ridges

what is lacing

a combination of cutting and bending

what is the guerin process

uses a think rubber pad to form sheet over block

what are some advantages of the Guerin process

low tool kcost form block can be made out of alot of different products rubber pad can be used on may different peices process attractive in small quantity production

what is the disadvantage of the guerin process

onlly relivily low forces can be applied

whatv is hydroforming

similar to the Guerin process but the rubber pad is switched o wiyh hydraloc fluid

what are the advantages of hydroformin

good for high production setup can be used more then once deeper draws can be achieved uniform pressure creates uniform wall tickness and prevents thickness

what is the disadvanteage of hydroforming

relitivly high tool cost

what is strectch forming

metal stretched and symoltaniously bent

what is roll bending

large metal sheets are formed into curved sections using rollers

what is roll formming

continuios bending in which opposing rules produce long sections

what is spinning

a method in which the material is clamped and rotated in which it is gradually shaped around a mandrel

Metal forming Flashcards

(74 cards)