Page 43 - MetalForming June 2014

An example would be 5052-H32—strain hardened without thermal treatment to a 1⁄4-hard condition
T—Heat reated to produce stable tempers
T1—Cooled from hot working and naturally aged (at room temperature)
T2—Cooled from hot working, cold worked, and naturally aged T3—Solution heattreated and cold worked T4—Solution heattreated and naturally aged T5—Cooled from hot working and artificially aged (at
elevated temperature)
T6—Solution heattreated and artificially aged T7—Solution heattreated and stabilized
T8—Solution heattreated, cold worked and artificially aged T9—Solution heattreated, artificially aged and cold worked T10—Cooled from hot working, cold worked and artifi-
cially aged
Processing Planning
Aluminum-alloy type and temper are a prime concern for the process engineer and die designer. Formability—in terms of total elongation—varies with alloy type and temper (Table 2).
Determining an appropriate cutting clearance between punch and die depends on material type and thickness. Suggested punch-to-die clearances, in terms of percent of sheet thickness (t), also are provided in Table 2 for cutting, blanking and hole punching.
When punching and cutting aluminum, especially dead-
OVENS & FURNACES
Table 3—Minimum Bend Radii for Select Alloys and Material Thickness
soft alloys (O-temper), metalformers must closely follow the appropriate maintenance routines, and use sharp tool- ing. Dull edges on punches and dies can produce burrs sim- ilar to those caused by excessive clearance, with burr height being particularly problematic. A lubricant suitable for alu- minum stampings will help reduce tool wear and produce quality shear edges.
Bending aluminum requires special attention of the die designer. While for most steels the minimum bending radius relative to sheet thickness is approximately constant, pri- marily because ductility (total elongation) tends to be the lim- iting factor, this is not the case with aluminum. In general, the ratio of bend radius to sheet thickness will increase with sheet thickness (Table 3). MF
Note: Look for a special, in-depth article on bending, form- ing, deep drawing, cutting and punching of aluminum alloys, authored by Pete Ulintz and Stuart Keeler, coming in the July 2014 issue of MetalForming.
Tooling by Design
Alloy, Temper
0.016 in. thick
0.032 in. thick
0.064 in. thick
0.125 in. thick
3003-H16
0.5t
1t
1t
1.5t
5052-H34
0t
1t
1.5t
2t
6061-T6
1t
1t
1.5t
2.5t
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MetalForming/June 2014 41