Journal of Minerals & Materials Characterization & Engineering, Vol. 9, No.5, pp.461-470, 2010
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461
Effect of Draw Ratio and Sheet Thickness on Eari ng an d Drawability of
Al 1200 Cups
O.O. Oluwole1*, C.O. Anyaeche2 and O.V. Faola3
1Mechanical Engineering Department, University of Ibadan.
2Production Engineering Department,Universitry of Ibadan.
3Department of Metallurgical and Materials Engineering,
FUT, Akure, Nigeria.
*Corresponding author: [e-mail] [phone]
ABSTRACT
The effect of blank/punch diameter ratio (draw ratio) in deep drawing on earing for different
gauges of Al 1200 sheet was studied. Using 60, 62, 64 and 65mm diameter circle blanks and
33mm diameter punch die, fully annealed Al 1200 sheets of gauge thicknesses 0.6 to 2.0mm were
subjected to deep drawing on an ErrichsenR cup drawing machine.
The results showed that with increase in sheet thickness, the smaller is the draw ratio that would
draw the sheet. For 0.6-0.9mm sheet thickness, cups were drawn with draw ratios of 60/33 to
65/33. For sheet thicknesses of 1.2-1.58mm, only 60/33 and 62/33 draw ratios were observe to
draw cups. Earing was observed to generally increase with increasing draw ratio using the same
sheet thickness. It was also observed that for thinner sheets (0.6-0.9mm), using the same draw
ratio, earing increased with increasing sheet thickness. For thicker sheets (1.2-1.58mm) earing
was observed to decrease with increasing sheet thickness. After that, there was an increase for
deep-drawn 2mm thick sheet.
Higher draw ratios were observed to draw deeper cup depths with minimal earing. The depth of
cups drawn with 65/33 draw ratio was observed to be about 28% more than those drawn with
60/33 draw ratio with an increase in earing of only 0.84% for 0.6mm thick sheet and 1.2% for
0.9mm thick sheets. Earing was also observed to increase by 1.64% for the 2mm thick sheet that
had undergone grain growth over the fine grained one.
Key words: Earing; punch die/blank diameter ratio; deep drawing; Al 1200

462 O. Oluwole, O. Anyaeche and O.V. Faola Vol.9, No.5
1. INTRODUCTION`
Al 1200 is the grade of aluminium used for hollowware. When cold rolled, aluminium or its
alloys are recrystallised by ann ealing. New grains form with orientations that differ from those
present in the cold rolled condition[1]. Preferred orientation is much reduced but seldom
eliminated. Preferred o ri e nt at io n i n the plane of a sheet that is associated with textures may cause
a problem known as earing. Earing is wasteful of material because larger blank than necessary
must be used in deep drawing hollowware production. Moreover, it may lead to the production
problems due to difficulties in ejecting products after a pressing operation.
Much work has been done in the area of earing and texture[2,3]. Four ears usually form because
of non-uniform plastic deformation along the rim of deep drawn products if there is a desirable
balance between the rolling texture and the annealing textu r e ; h o we ver, eight small ears could be
formed or none at all. Because of this possibility of ann e a ling to produce a texture which could
minimize or eliminate earing, the care fu l c on tr o l of co ld ro ll an d planar anisotropy by annealing
schedules is normal undertaken[2,4,5] .
The effect of draw ratio on earing of Al 1200 during deep-drawing was studied in this work
using various sheet thicknesses.
2. MATERIALS AND METHOD
Starting materials were Al 1200 as cast in the form of sheets of starting thicknesses of 8mm,
7.34mm and 6mm obtained from Aluminium Rolling Mills Ota, Ogun State, Nigeria. The
average chemical composition is shown i n T a bl e 1 .
Table 1: Average Chemical Composition (Wt %) Of Aluminium 1200
Fe Si Mg Mn Al
0.53 0.225 0.025 0.025 Balance
The starting material was annealed at 460 for 6 hours. The annealed sheets were cold-rolled to
different thicknesses, 2, 1.58, 1.55, 1.51, 1.48, 1.17, 0.9, 0.84, 0.75 and 0.6mm. After cold –roll,
annealing temperatures were selected as suited to each degree of cold roll [5] to achieve H0
hardness. A HerausR industrial Muffle furnace was used for annealing and cooling was done in
air [4]. The annealed specimens were prepared for deep drawing by blanking them into 60, 62,
64, 65 and 70mm circle blank diameters. Using an ErrichssenR deep-drawing machine, a 33mm
diameter deep-drawing die was used in deep-drawing the prepared circle blanks into cups. Earing
developed at the rims of the cups were measured using standard measuring techniques [2]. This

Vol.9, No.5 Effect of Draw Ratio and Sheet Thickness 463
research work was carried out in the quality control laboratory of Aluminium Rolling Mills,
Ota,Ogun State, Nigeria.
3. RESULTS AND DISCUSSION
3.1 Results
The results obtained a re p r es e nt ed in Tables 2- 8. Table 2 shows the drawability of varying
thicknesses of Al 1200 cups with varying punch/blank diameter ratio. The result showed that
thicknesses of 1.17 -1.58 mm can be drawn by only draw ratio of 62/33 and 60/33 while smaller
gauges of 0.6-0.9mm could be drawn by draw ratios of 60/33 – 65/33.
Table 2: Drawability of Varying Thicknesses of Al 1200 cups with varying punch/blank ratio
Sample
Thickness (mm) Blank diameter (mm) 1s
t
Draw
2.0 60 Drawn
1.58 60 Drawn
1.58 62 Drawn
1.58 64 Broken
1.58 65 Broken
1.58 70 Broken
1.55 60 Drawn
1.55 62 Drawn
1.17 60 Drawn
1.17 62 Drawn
1.17 64 Broken
1.17 65 Broken
1.17 70 Broken
0.9 60 Drawn
0.9 65 Drawn
0.75 60 Drawn
0.75 62 Drawn
0.75 64 Drawn
0.75 65 Drawn
0.75 70 Broken
0.6 60 Drawn
0.6 65 Drawn
Table 3 shows variation of earing with varying draw ratio (plate thickness kept constant). The
same result is presented in Fig.3. It was observed that increasing draw ratio increased earing.

464 O. Oluwole, O. Anyaeche and O.V. Faola Vol.9, No.5
Table 3: Variation of Earing of Al 1200 cups with varying blank-diameter/ punch-die ratio (plate
thickness kept constant).
Test piece
thickness(mm) Blank Diameter(mm)
Earing %
0.60 65 1.2
0.60 60 0.39
0.75 65 3.43
0.75 64 3.24
0.90 65 4.65
0.90 64 2.85
0.90 60 3.9
1.55 62 2.23
1.55 60 1.87
2.0 60 4.84
The results of variation o f e a ring with varying plate thicknesses (draw ratio kept constant) are
presented in Table 4 and Fig. 4. While earing was observed to increase with increasing sheet
thickness for 0.6-0.9mm thick sheets, the reverse was true for 1.2-1.55 mm sheets. At 2mm
thickness, earing was observed to shoot-up again.
Table 4: Variation of Earing of Al 1200 cups with varying plate thicknesses (Blank-
diameter/p unch-die ratio kept constant)
Test piece
thickness(mm) Blank Diameter(mm)
Earing %
0.60 65 1.2
0.75 65 3.43
0.84 65 3.98
0.90 65 4.65
0.75 64 3.24
0.76 64 3.80
0.90 64 2.85
1.20 62 3.51
1.51 62 2.68
1.55 62 2.23
0.60 60 0.39
0.90 60 3.9
1.20 60 3.38
1.48 60 1.99
1.55 60 1.87
2.0 60 4.84

Vol.9, No.5 Effect of Draw Ratio and Sheet Thickness 465
Table 5 presents the variation of depth of drawn cup and earing with draw ratio for 0.6mm
sheets. The depth of cups drawn with 65/33 draw ratio was obse r ved to be about 28% more than
drawing with 60/33 draw ratio with an increase in earing of only 0.84%.
Table 5: Variation of Depth of Drawn cup and Earing with Blank-Diameter/Punch-Die Ratio for
Al 1200 cups using fully annealed 0.6mm thick Sheet.
Anneal-Time
(Hrs) at4600C
Temper
Designation
Draw Ratio
BlankФ/PunchФ
1
st
Draw 2ndDraw Earing(%)
1 0 60/33 22.4 28.3 0.02
2 0 60/33 21.1 28.0 0.72
3 0 60/33 21.5 28.0 0.30
4 0 60/33 22.6 28.5 0.39
1 0 65/33 28.0 35.8 0.36
2 0 65/33 27.9 35.8 2.5
3 0 65/33 28.0 35.9 1.4
4 0 65/33 28.0 35.8 1.2
The variation of depth of drawn cup and earing with draw ratio for 0.9mm sheets is presented in
Table 6. The depth of cups drawn with 65/33 draw ratio was observed to be about 28% more
than drawing with 60/33 draw ratio with about 1.2% increase in earing.
Table 6: Variation of Depth of Drawn cup and Earing with Blank-Diameter/Punch-Die Ratio for
Al 1200 cups using fully annealed 0.9mm thick Sheet.
Anneal-Time
(Hrs) at4600C
Temper
Designation
Draw Ratio
BlankФ/PunchФ
1
st
Draw 2ndDraw Earing(%)
1 0 60/33 23.0 28.9 3.5
2 0 60/33 22.8 29.0 3.9
3 0 60/33 23.0 28.8 3.9
4 0 60/33 23.0 28.8 3.9
1 0 65/33 27.8 36.4 9.3
2 0 65/33 27.9 36.3 5.4
3 0 65/33 28.0 36.5 3.9
4 0 65/33 27.8 36.6 6.1
Table 7 presents the variation in depth of drawn cups and earing with annealing time for fully
annealed 2mm thick sheet while Table 8 presents values of earing and depth of drawn cups for
over-annealed 2mm sheets. The result showed that earing increased with grain growth from over-
annealing.

466 O. Oluwole, O. Anyaeche and O.V. Faola Vol.9, No.5
Table 7: Variation of Depth of Drawn cup and Earing with increasing annealing Temperature
using 2mm thick Sheet.
Anneal-Time
(Hrs) at4000C
Temper
Designation
Draw Ratio
BlankФ/PunchФ
1
st
Draw 2ndDraw Earing(%)
1 0 60/33 23.3 28.0 4.3
2 0 60/33 23.3 28.0 4.3
3 0 60/33 23.2 28.2 2.6
4 0 60/33 23.0 28.8 3.4
Table 8: Variation of Depth of Drawn cup and Earing with increasing Annealing Time using
2mm thick Sheet.
Anneal-Time
(Hrs) at4600C
Temper
Designation
Draw Ratio
BlankФ/PunchФ
1
st
Draw 2ndDraw Earing(%)
1 0 60/33 22.4 28.2 4.1
2 0 60/33 22.3 28.0 7.5
3 0 60/33 22.5 28.4 5.1
4 0 60/33 22.4 28.1 4.2
Fig.1 shows broken cups drawn with 64/33, 65/33 and 70/33 draw ratios. Fig.2 shows earing in
some deep-drawn samples.
Fig. 1: Broken cups using 64, 65 and 70/33mm draw ratios
Fig. 2: Four sets of cups of varying thicknesses showing ears formed at the rims.

Vol.9, No.5 Effect of Draw Ratio and Sheet Thickness 467
3.2 Discussions
3.2.1 Drawability of different shee t th ick ness
For the sheet thicknesses tested (Table 2), it was observed that sheets of thicknesses within the
range 0.6-0.9mm were drawn by draw ratios 60/33 to 65/33.
For thicker sheets of 1.2-1.58mm, only 60/33 and 62/33 draw ratios were observe to draw cups.
Cups drawn with higher draw ratios were observed to break (Fig.1).
3.2.2 Earing variation with draw ratio and sheet thickness
Fig.3 shows the variation of earing with increasing draw ratio for different sheet thickness.
Earing was observed to gener all y increase with increasing draw ratio using the same sheet
thickness. The increase in earing with increase in draw ratio can be attributed to increased
material available for draw.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
59 60 61 62 63 64 65 66
Blank Diameter(mm)
Earing(%)
0.9mm thick sheet
0.75mm thick sheet
1.55mm thick sheet
0.6mm thick sheet
Fig. 3: Variation Trend of Earing with increasing Draw Ratio (Sheet Thickness
kept constant)
It was observed that for thinner sheets (0.6-0.9mm), using the same draw ratio, earing increased
with increasing sheet thickness (Fig.4). For thicker sheets (1.2-1.58mm) earing was observed to
decrease with increasing she et thickness; after which there was an increase for deep-drawn 2mm

468 O. Oluwole, O. Anyaeche and O.V. Faola Vol.9, No.5
thick sheet. This behaviour can be explained by th e t ext ure (pr efer red orientation) of the
material. Earing has been observed to increase generally with increasing planar anisotropy [2].
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
00.2 0.4 0.6 0.811.2 1.41.6 1.8
Sheet Thickness(mm)
Earing( %)
65 mm Blank Diameter
64mm Blank Diameter
62mm Blank Diameter
60mm Blank Diameter
Fig. 4: Variation Trend of Earing with increasing Sheet Thickness (Draw Ratio
kept constant).
3.2.3 Drawn-Cup depth and earing variation with draw ratio and thickness.
At 60/33 draw ratio, drawn cup depth was observed to increase with increasin g s heet thickness at
first draw for all thicknesses and at second draw for 0.6 and 0.9mm thick sheets (Tables 5-7).
There was not much gain in depth for deep-drawn 2mm thick sheets at second draw over the
0.6mm thick sheet.
Earing was observed to in cr ea se with in cr ea si ng sh ee t th ic kn es s, however, from 0.36% in deep-
drawn 0.6mm sheets to 3.9% in deep-drawn 0.9mm sheets and remaining about steady at 3.6%
for deep-drawn 2mm thick sheet.
At 65/33 draw ratio, drawn-cup depth was observed to increase with increasing sheet thickness at
second draw only for 0.6 and 0.9mm thick sheets. Earing was observed to increase as well with
increasing sheet thickness, from 1.7% in deep-drawn 0.6mm s h eets to 5.1% in deep-drawn
0.9mm sheets.

Vol.9, No.5 Effect of Draw Ratio and Sheet Thickness 469
The increase in drawn-cup depth with increasing thickness could be attributed to increased area
available for draw. The increase in earing is attributable to the texture of the material causing
ears (Fig.2).
65/33 draw ratio was observed to draw deeper cup depths compared with cups drawn with 60/33
draw ratio. This was expected because of the larger blank size available for draw. The depth of
cups drawn with 65/33 draw ratio was observed to be about 28% more than those drawn with
60/33 draw ratio with an increase in earing of only 0.84% for 0.6mm thick sheet and 1.2% for
0.9mm thick sheets.
3.2.4 Drawn-Cup depth and earing variation grain growth
Table 8 shows the results obtained from drawing with 2mm thick Al 1200 sheet that has
undergone grain growth. The results showed smaller cup depth at first draw compared to cup
drawn from fine grained 2mm thick sheet (Table 7). At second draw, cup depth was the same
depth as cups draw from the fine grained material. However, earing was observed to increase by
1.64% for the large grained material. The effect of grain growth causing the material to be less
ductile can be attributed to increased earing.
4. CONCLUSION
The following conclusions were drawn from this work:
The results showed that with increase in sheet thickness, the smaller is the draw ratio to draw the
sheet. For 0.6-0.9mm sheet thickness, cups were drawn with draw ratios of 60/33 to 65/33. For
sheet thicknesses of 1.2-1.58mm, only 60/33 and 62/33 draw ratios were observe to draw cups.
Earing was observed to gener all y increase with increasing draw ratio using the same sheet
thickness.
It was also observed that for thinner sheets (0.6-0.9mm), using the same draw ra ti o , e ar i ng
increased with increasing sheet thickness. For thicker sheets (1.2-1.58mm) earing was observed
to decrease with increasi n g sheet thickness after which earing increased for 2mm thick sheet
Higher draw ratios were observed to draw deeper cup depths with minimal earing. The depth of
cups drawn with 65/33 draw ratio was observed to be about 28% more than those drawn with
60/33 draw ratio with an increase in earing of only 0.84% for 0.6mm thick sheet and 1.2% for
0.9mm thick sheets. Earing was also observed to increase by 1.64% for the 2mm thick sheet that
had undergone grain growth over the fine grained one.

470 O. Oluwole, O. Anyaeche and O.V. Faola Vol.9, No.5
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