174
Sheet metal forming and blanking
W F
h d
s s R h
W mm mm mm N mm mm W
N m
Nm J
d U m
d d
= ⋅ ⋅ = ⋅ ⋅ +
⋅ ⋅ ⋅
⋅ ⋅ = ⋅ ⋅ +
⋅ ⋅
⋅ ⋅
− ⋅
= ⋅ ⋅ = = 2
3 2
3 1 2
1 1
2 3
60 0 8 0 8 350 1 2 1 9 1
2 0 1 40
2 3
18 385 9 0 04 490 3 490 3
1 2
π β
β π
. –
– .
. .
. – .
, .
. .
.
max
Exa m ple:
Fo r a d rawn cu p fro m 0.8 m m t h ick sh eet m et al m at erial n u m ber 1.0338 – R
m
= 350 N m m
2
wit h a d iam et er o f 60 m m an d a h eigh t o f 40 m m circu lar blan k d iam et er 115 m m , b = 1.9 t h e fo llo win g p ressin g wo rk fo r d rawin g wit h
a d o u ble-act io n p ress is req u ired :
Deep drawing without a blank holder is o n ly carried o u t if t h e p art d o es n o t t en d t o wrin kle, i. e. wit h t h ick sh eet m et al o r sm all am o u n t o f
d efo rm at io n wit h sm all d raw rat io b. Drawing defects
In o rd er t o elim in at e t h e p o ssibilit y o f p art s bein g reject ed , it is n eces- sary t o in vest igat e t h e scrap p ed p art s very t h o ro u gh ly an d t o id en t ify
t h ereby t h e cau ses o f an y d efect s an d t o t ake p reven t ive m easu res. So m e o f t h e m o st co m m o n d efect s are illu st rat ed in
Table 4.2.2 .
4.2.2 M aterials for sheet metal forming
Un alloyed an d alloyed steels as well as cop p er alloys, cop p er sh eet, an d ligh t alloys are all am on g th e com m on ly u sed m aterials in sh eet m etal
form in g tech n ology. Am on g alloyed steels, a d ifferen ce is d rawn between p h osp h or-alloyed steels, typ es of steel with ad d ition al h ard en in g after
h eat treatm en t bake-h ard en in g steels, ferritic ch rom iu m steels, au sten itic ch rom iu m n ickel steels an d cold -rolled sh eet with h igh er ten -
sile yield stren gth for cold form in g m icro-alloyed steels. Table 4.2.3
lists p op u lar m aterials with th e followin g sp ecification s:
– m at erial n u m ber, – t en sile st ren gt h R
m
[N m m
2
],
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
– lower yield stren gth R
eL
[N m m
2
] for sh eet m etals with an accen tu ated yield stren gth or 0.2 elon gation lim it R
p 0,2
[N m m
2
] for th ose with - o u t accen t u at ed yield st ren gt h ,
– u lt im at e elo n gat io n A []: eit h er relat ive t o an in it ial len gt h in t h e t en sile t est sp ecim en L
o f 80 m m A
80
o r t o L = 5 · d
A
5
, wit h an in it ial t en sile t est sp ecim en d iam et er o f d
, – field o f ap p licat io n .
175
Deep draw ing and stretch draw ing
Defect Possible Cause
Prevention, remedy
draw ing grooves tool w ear
replace draw punchfemale die, improve lubrication
tear marks on the base draw ing ratio b set too high
use a sheet metal w ith greater of the draw n part
draw ing gap too narrow deep draw ing capability or
curvature on draw punch employ multi-stage draw ing
or female die too small process extend draw ing gap
blank holder force too great check sheet metal thickness
draw ing speed too great increase die radii reduce
blank holder force reduce forming speed
vertical tear marks insufficient material in the
replace the female die on upper edge
defective area draw ing gap too w ide or draw ing edge
curvature too great
on rectangular parts, too much material at the corners
change the blank shape the corners are higher
recess material in the affected than the side w alls
areas trim the edge afterw ards vertical creases in the
blank holder force too low increase blank holder force
upper area of the body draw ing gap too great curvature
renew female die vessel w all, also in
at the female die too great conjunction w ith vertical
cracks crease formation
blank holder pressure too low increase blank holder pressure
at the flange other non-specific
incorrect blank shape correct blank shape check
defects faulty or asymmetrical material location
die and stops use suitable irregularly formed
unsuitable sheet metal sheet metals and lubricants
draw n parts incorrect lubricant
Table 4.2.2: Deep draw ing defects
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Unalloyed steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
St 12 10330
270...410 max. 280
28 automotive engineering
USt 13 10333
270...370 max. 250
32 automotive engineering
St 14 10338
270...350 max. 225
38 automotive engineering
Phosphor-alloyed steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
ZStE 220 P 10397
340...420 220...280
30 automotive engineering
ZStE 260 P 10417
380...460 260...320
28 car body w ork: doors,
hoods, roofs ZStE 300 P
10448 420...500
300...360 26
automotive engineering
Bake-hardening steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
ZStE 180 BH 10395
300...380 180...240
32 automotive engineering
ZStE 220 BH 10396
320...400 220...280
30 automotive engineering
ZStE 260 BH 10400
360...440 260...320
28 automotive engineering
ZStE 300 BH 10444
400...480 300...360
26 automotive engineering
Ferritic chromium steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
automotive engineering: bumpers, hub caps,
food industry, household, X 6 Cr 17
14016 450...600
250...270 20
appliances: deep-draw ing parts w ith high corrosion
resistance properties: sink unit panelling cutlery
hub caps, bumpers, X 6 CrM o 17 1
14113 480...630
260...280 20
car w indow frames radiator grille surrounds
automotive engineering: X 6 CrTi 12
14512 390...560
200...220 20
shock absorbers, exhaust system components
dairy, brew ery, food industry, soap industry and dyeing
plants: parts containers X 6 CrNb 17
14511 450...600
250...260 20
requiring w elding and w hich are exposed to
w eak acid solutions
176
Sheet metal forming and blanking Table 4.2.3: Summary of the more commonly used sheet metal materials
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
177
Deep draw ing and stretch draw ing
Austenitic CrNi steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
s3 mm household items,
A
80
: food industry: w ear-
X 5 CrNi 18 10 14301
500...700 min. 195 lengthw ise: 35;
resistant, deep- transversely: 40 draw able, w eldable
3s75 mm appliances, devices,
A
5
: 40 containers
s3 mm A
80
: chemical industry, paper
X 5 CrNi 18 12 14303
490...690 min. 185 lengthw ise: 35;
and textile industry: transversely: 40 cold extruded parts,
3s75 mm screw s, nuts
A
5
: 40
M icro-alloyed steels
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
ZStE 260 10480
350...450 260...340
24 automotive engineering:
car body parts ZStE 300
10489 380...480
300...380 22
automotive engineering ZStE 340
10548 410...530
340...440 20
automotive engineering ZStE 380
10550 460...600
380...500 18
automotive engineering ZStE 420
10556 480...620
420...540 16
automotive engineering
Copper and copper alloys
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
semi-finished products w ith SF-Cu F 22
2.0090.10 220...260
max. 140 42
very good w elding and brazing properties
all types of deep-draw ing CuZn 28 F 27
2.0261.10 270...350
max. 160 50
parts, all types of instruments and sleeves
CuZn 33 F 28 2.0280.10
280...360 max. 170
50 w ire mesh, radiator strips,
tubular rivets metal and w ood screw s,
printing cylinders, radiator CuZn 36 F 30
2.0335.10 300...370
max. 180 48
strips, zip fasteners, cup springs, hollow goods,
ball-point pen cartridges CuZn 37 Pb 0,5 F 29
2.0332.10 290...370
max. 200 50
deep-draw ing parts good hot and cold forming
properties: hot extruded CuZn 40 F 34
2.0360.10 min. 340
max. 240 43
parts, suitable for bending, riveting, upsetting and
flanging
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Table 4.2.3 continuation
Aluminium and aluminium alloys
M aterial R
m
R
p0,2
or Fields of application,
No. [Nmm
2
] R
eL
[Nmm
2
] A
80
[] examples
equipment construction, electrical installations,
electrical construction, high-frequency engineering,
Al 99,5 W7 3.0255.10
65...95 max. 55
40 aerials, coaxial cables
screening; aluminium foils in capacitors, as packaging
material, for heat insulation; household equipment
architecture, automotive engineering, metal goods:
sheet metals, strips, profiles, AlRM g 1 W 10
3.3319.10 100...140
35...60 23
rods, w ires, pipes, forgings, extremely good cold forming
properties, w eldable, highly seaw ater resistant
Al 99,9 M g 1 W 10 3.3318.10
100...140 35...60
23 dito
Al 99,85 M g 1 W 10 3.3317.10
100...140 35...60
23 dito
AlM g 2,5 G 25 3.3523.29
250...290 min. 180
7 car body w ork,
pull-tab can lids food industry, equipment
construction, automotive AlM g 3 W 19
3.3535.10 190...230
min. 80 20
engineering and shipbuilding, architecture: semi-finished
products, roofing, packaging, screw s, rivets
equipment construction, AlM n 1 F 12
3.0515.24 120...160
min. 90 7
refrigeration, technology, heat exchangers, roofing, panelling
mining, automotive engin- eering, aircraft construction,
AlCuM g 1 W 3.1325.10
max. 215 max. 140
13 mechanical engineering:
sheet metals, profiles, rods, pipes, forgings, screws, rivets
AlM g 2 M n 0,8 F 22 3.3527.24
220...260 max. 165
9 automotive engineering,
shipbuilding, equipment con- struction: parts resistant to
stress at high temperatures AlM gSi 0,8 F 28
3.2316.71 min. 275
min. 200 12
mechanical engineering, automotive engineering
architecture, mining, auto- motive engineering, ship-
AlM gSi 1 W 3.2315.10
max. 150 max. 85
18 building, mechanical
engineering, food and textile industries: all types of semi-
finished products, screw s
178
Sheet metal forming and blanking
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
4.2.3 Friction, w ear and lubrication during sheet metal forming
