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Forming ProcessesForming Processes
GMP
Metal Forming/Press Operations
Forming processes are one of the most popular means of producing high volume products. Examples include appliance, aircraft, and automotive industries. – Major Reasons:
» Production costs are low
» Well suited for high production applications
» Process capabilities
» Processes are built into tooling
GMP
Tools
One of the basic tools used in these processes is a punch & die.– A punch is the portion of the tool attached to the ram of
the press and is inserted into the die.
– A die is usually the stationary portion of the tool attached to the press bed. It has a cavity to accept the punch.
GMP
Tools
Punch & die
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Tools
A progressive die is a tool capable of performing several operations from raw material to final product. These dies can be made from catalog items and divided into removable sections.
GMP
Tools
Die alignment and clearance– Uniform clearance
– General rule - 5-7% material thickness
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Tools
Punch & dies are capable of performing the following examples of cold working(CW) operations:– Blanking - cutting desired shape from strip, burrs left
on strip
– Piercing - leaving desired shape on strip, burrs on scrap
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Tools
Punch & die capabilities continued:– Forming & Bending
– Shearing
– Ironing
– Drawing
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Process Capabilities
Blanking vs. Piercing
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Tools
Forming & Bending
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Tools
Shearing
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Tools
Ironing
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Process Capabilities
Drawing
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Calculating Pressure for a Process (Tons)
General formula for a hole– Diameter of hole x Thickness of material x Ultimate
Tensile Strength (UTS) = Pressure in Tons
– Guidelines» Mild Steel = 80 - 60,000 psi, Brass = 60,000 psi,
Bronze = 40,000 psi, Copper = 30,000 psi
Alum = 20,000 psi
Example– 2” dia. hole in ¼ steel plate
» 2 x .250 x 80= 40 tons
GMP
Calculating Pressure for a Process (Tons)
General Formula - Profile – P= (L x 1/3) x material thickness x 60 (UTS)
– Example = Punch a 1”x 2” rectangle in ¼” brass» P= (6 x 1/3) x .250 x 60 = 29.7 ~ 30 tons
Machinery’s Handbook 23rd Edition
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Progressive Dies
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Progressive Dies
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Machine Tools- Presses
Classification– Manual
» Foot operated
– Light work -shearing
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Machine Tools- Presses
Mechanical – Max pressure near bottom of stroke
– Faster motion
– Operations - cutting, shallow forming, drawing, and progressive die operations
– Limitation - length of stroke set by design of mechanism = less flexibility
– Capacities up to 6,000 tons
GMP
Machine Tools- Presses Mechanical Press Drive Mechanisms
» Crank = Simple design - used for piercing, blanking, and drawing operations
» Eccentric/Cam = Short ram stroke which provides a dwell a bottom of stroke
» Knuckle Fast action and high mechanical advantage Applications include coining and sizing
» Toggle = Drawing presses to move the blank holder
» Screw = Slow action
GMP
Machine Tools- Presses
Hydraulic– Motion as a result of piston motion = longer or variable
stroke lengths can be programmed (within limitations of the piston).
– Steady pressure for operations such as deep drawing
– Single-slide
– Multiple-slide
– Capacities up to 50,000 tons
GMP
Machine Tools- Presses
Frame classification– Gap
» Open arrangement of press frame
» Excellent clearance around dies
» Can handle long and wide parts
– Arch» Lower portion of press near the bed is wide to accommodate
large sheet material
GMP
Machine Tools- Presses Frame classification continued:
– Straight side» Strong frame design—heavy loads are taken up in vertical
direction of massive frame
» Less of a tendency for punch & die to misalign
– Horn» Heavy shaft projecting from frame
» Used primarily for cylindrical work involving seaming, flanging, riveting, and embossing
GMP
Machine Tools- Presses
Frame classification continued: – Inclined
» Vertical design can be tilted back to allow parts and scrap to slide out
» Used on parts involving bending, piercing, blanking, etc.
– Turret Presses» Production of sheet metal parts having a variety of patterns,
holes, cutouts, etc. in various sizes
» Current presses are CNC controlled and combined into “machining centers”, capable of laser, forming, and water-jet operations.
GMP
Machine Tools- Presses
Frame classification continued: – Four Slide
» Complex forming of small to medium size parts
» Machine Basics 4-slides at 90 degrees controlled by cam to progressively
move through a cycle to achieve a final part Can be “tooled” with punches, cut-off tools,
lifting/shifting tools, and welding systems.
GMP
Machine Tools- Presses
Frame classification
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Machine Tools- Presses
Accessories