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Tangent Corner / Machining Al-7075 and deformations
« on: September 08, 2015, 08:08:53 AM »
Hi,
can someone please suggest proper way to machine Al-7075-T651 alloy to minimize/avoid deformation?
Stock ~1000x70x25mm, was clamped to the 6 standoffs using one M6 screw per standoff, which were then clamped to the table. When I machined one side and released it from the table, the part was bent (~4mm about the middle of the part lengthwise).
I've attached some pics illustrating machining strategy and the result.
1. profile part using 6mm single flute carbide endmill, flute length 25mm (6/1/25 cem): DOC0.5mm, F3000mm/min, S13800rpm
2. clear ~550x70x8-10mm area in zig-zag pattern, using 6/1/17 cem, DOC8-10mm, WOC1mm, F875mm/min, S12000rpm
3. rough using 6/1/17 cem, climb only, waterline: DOC2-17mm, WOC,Feed and Speed variable too keep relatively constant MRR and the machine happy
4. finish using 6/3/18 cem, waterline climb in X direction + contour in Y direction combined, max DOC/WOC 2mm, step-over 0.1mm, F4000mm/min, S24000rpm
Material was never too hot to touch - it was warmest after #2 (and I suspect that was the problem). I used some WD40 on all cuts.
I've done similar parts in Al-6082-T6 ~800x80x25 and Al-6060-? ~800x70x20, using different roughing strategy (waterline 0.5mm DOC), different clamping method (normal clamps on top) and the parts turned out straight.
Thanx,
Mihael
can someone please suggest proper way to machine Al-7075-T651 alloy to minimize/avoid deformation?
Stock ~1000x70x25mm, was clamped to the 6 standoffs using one M6 screw per standoff, which were then clamped to the table. When I machined one side and released it from the table, the part was bent (~4mm about the middle of the part lengthwise).
I've attached some pics illustrating machining strategy and the result.
1. profile part using 6mm single flute carbide endmill, flute length 25mm (6/1/25 cem): DOC0.5mm, F3000mm/min, S13800rpm
2. clear ~550x70x8-10mm area in zig-zag pattern, using 6/1/17 cem, DOC8-10mm, WOC1mm, F875mm/min, S12000rpm
3. rough using 6/1/17 cem, climb only, waterline: DOC2-17mm, WOC,Feed and Speed variable too keep relatively constant MRR and the machine happy
4. finish using 6/3/18 cem, waterline climb in X direction + contour in Y direction combined, max DOC/WOC 2mm, step-over 0.1mm, F4000mm/min, S24000rpm
Material was never too hot to touch - it was warmest after #2 (and I suspect that was the problem). I used some WD40 on all cuts.
I've done similar parts in Al-6082-T6 ~800x80x25 and Al-6060-? ~800x70x20, using different roughing strategy (waterline 0.5mm DOC), different clamping method (normal clamps on top) and the parts turned out straight.
Thanx,
Mihael