Metal Forging
Chapter 3.13
Forging



Metal is shaped to a desired form through
plastic deformation
Types: open die, impression die, ring
rolling, rotary swaging, cold heading
Terms: upset forging, draft, parting line,
flash, gutter, rib, web
Typical Characteristics





Controlled grain structure is primary benefit
High strength (high strength to weight ratio)
Seldom have internal blemishes
Size is limited by facilities
Machining operation required in most cases
Bralla
ASM Metals Handbook Vol.9
http://www.heungkuk.co.kr/hk_eng_prod_forg.html
Economics




Economically viable in large quantities for
impression die parts or small quantities for
open dies parts (but lots of skilled labor)
Tooling cost – may be high for impression
die
Labor cost – may be high for open die
Finishing costs can be moderate
Design Recommendations

Parting line choice is critical






Ideal – in one plane perpendicular to die motion (pg.
3.185)
Economical – one flat die, one w/ impression (Fig
3.13.6)
Minimize side thrust forces – keep parting line < 75
degrees from principal plane (pg. 3.185)
No undercuts (pg. 3.185)
Use parting line to control grain (Fig. 3.13.7)
Flow horizontally if possible (Fig. 3.13.7)
Design Recommendations





Draft angle per material (Table 3.13.2)
Avoid ribs and bosses that are high and narrow,
webs that are thin w/ variable thickness (Fig.
3.13.9)
Fillets and rounds (Table 3.13.3)
Consider machining allowances (pg. 3.190)
Tolerances: length and width, die wear, die
closure, match, straightness, draft, radii (pg.
3.191)