Milling – Ripping Cutters

[Oompa LumpaParticipant @oompalumpa34302]

[Oompa LumpaParticipant @oompalumpa34302]

Could anyone with experience of these roughing out cutters give me their opinion, their experience – of them?

I have a couple in 12mm and before I try to maim myself, or worse, destroy good work, could someone give me an idea of feed/speed for say 8082 aluminium?

Thanks,

graham.

[Oompa LumpaParticipant @oompalumpa34302]

Sorry, I meant to post this in Tools and Tooling, my apologies.

[Anonymous]

Rippa milling cutters use less power per cubic unit of metal removal and produce small curly pieces of swarf which are easier to remove, but leave a worse finish that normal mills.

I'm not sure what 8082 aluminium is, but I have done a lot of CNC machining with 12mm diameter 3 flute HSS rippas on 6082. Parameters were 4000rpm, feedrate 900mm/min, DOC 4mm and stepover 67%. If I was doing it now I'd be inclined to drastically increase the DOC and proportionally reduce the WOC, to make better use of the cutting edges. For the inside of electronics enclosures, which is what I was machining, the finish is perfectly acceptable.

Regards,

Andrew

[Oompa LumpaParticipant @oompalumpa34302]

Andrew, thank you, very helpful.

Naturally I meant 6082 aluminium, but then I also meant this question to be posted in tools and tooling. Best not mess with the actual cutter itself until I remember where I am and what I am supposed to be doing!

graham.

[Involute CurveParticipant @involutecurve]

Graham It depends a lot on your setup and strategy is it CNC with ball-screws, if so I have a lot of experience with this stuff, Climb mill, stepover should be either 70% or 25% these angles give the cutter tooth the best entry angle, in addition it also gives the best exit angle as the tooth leaves the work the chip becomes unsupported and tends to bend and break off, this can damage the tooth, depth of cut I often go full width at 70% stepover and twice width at 25%, so for a 12mm HSS ripper machining a pocket in 6082 I would go with 12mm depth OC 8.4 SO circular ramp in at 3deg 3500 rpm 850mm fr, profiling I would go 3mm SO 24 depth same speed and feed.
However as you know, none of this is cast in stone you have to know your machine and its capabilities, also is it about metal removal rate or finish either way I would finish with a normal endmill for best finish.

A lot of the above comes from advice via Sandvik, I have a paper from them I could forward to you via email.

HTH

Shaun

[michael coleParticipant @michaelcole91146]

Ripper cutters are available in both fine and rough grades. I use mine to cut steel and cut turning up the SFM and Feed intil i get nice purple chips flying off. The fine cutters leave a OK finsh for items you are not going to handle.

[Author]

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