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Fundamental Tool & Die Making techniques


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Bend Radius
Deep Drawn
Fine Blanking
Formula
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Slug pulling prevention
Tool die Design



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Strip layout

Jigs and Fixture Design Book



Geometric Tolerances


GDT
ISO tolerance for shafts
ISO tolerance for holes
Surface Roughness
Surface Texture


Quality Control Co

tAQL
Process Capability CPK
Sampling plan
AQL Level I, II, III


E

Common problems of Deep draw process

 

  

Metal fracture during deep drawing process
1. Deep drawing radii too small, creating resistance to metal flow to cause undue thinning or fracture. Correct by increasing die radius or by changing die entrance to conical or elliptical shape.
2. Clearance between punch and die too little, too great or uneven.
3. Blank holder pressure too great.
4. Lubricant inadequate or unsuitable.
5. Punch nose radius too small.

Wrinkles on top edge or flange
1. Blank holder pressure too tight.
2. Draw radius too large.
3. Punch nose radius too large.
4. Wrinkles on the side of cup or flange caused by burr on blank or by an unbalanced blank holder pressure.

Uneven top rim or flange
1. Nicks or burr along the periphery of the blank.
2. Punch die or blank locator not concentric. Too much material pulled into the die by off center forming punch preventing forming of an even cup depth or flange.
3. Blank holder exerting an unbalanced force on the blank, permitting the material flow unevenly into the die.

Flange wrinkled, Puckered.
1. Blank thickness wrong or out of tolerance.
2. Draw radius too large.
3. Clearance between punch & Die too large for the stock thickness.
3. Depth of previous drawn too short or redraw operation too deep. Or side wall of drawn cup being tinned down.

Fracture ay bottom of redrawn cup
1. Draw radius and blank holding surface scratched, nicked or galled. Restricting metal flow into the die.
2. Punch nose and draw radius too small.
3. Diameter Reduction too great.

Fracture in or at Flange of drawn cup.
1. Punch and die clearance too small.

Excess material at top of deep drawn shell
1. Material thickness too great or punch die clearance too small or uneven.
2. Punch nose radius larger than cup bottom radius, causes excess
sheet metal to flow up side wall.
3. Draw radius too large, permitting wrinkles to start that enlarge during redraw of cup.

 

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