Deep undercuts - tools to use?

[Newbeeee™]

Hi All,

Customer just talking about adding undercuts to an existing part to reduce the weight.

It's 6082-T6 (very similar to 6061). We're trying to get them to do the weight reduction on the outside, but this will affect the form/fit/function, so they want it on the inside.

 

Best way to describe the part is it is an electronic enclosure, with lugs stuck out from the inside walls. These are mostly on corners, so are stuck out with an underneath radius (if this makes sense?).

 

The worse undercut detail on the part is radius 12.5mm (0.492"), with a radial/undercut cut depth of 6.6mm (0.260"). The length/depth of the tool (stickout) will need to be 70mm (2.756").

So picture (size for size) a tee cutter that's 25mm dia (0.984") head, with a 11.8mm (0.464") dia shank. This obviously is size for size and doesn't give any room for tool movement (ie feed straight in and straight back out to produce the dims).

Me thinking a tricky little number this, and will be talking to PH Horn in the morn to see what they have that could be modified (as I can't see anything off the shelf).

 

Anyone got any thoughts on this? I'm thinking carbide shank, 3mm max (.118") thickness cutting width (maybe even narrower), and a shank dia of 10mm (.394") to allow a little bit of tool movement. So that's 7D deep with say a 24mm dia (.984") head then...

Cheers

[K2csq7]

Do you have a screenshot?

I often design progressive tooling (2-3 different tools) starting with as big a tool as possible to remove a nice chunk, then a smaller tool for finishing alone....

[Guest]

This is where a 5 axis machine can be invaluable, by tipping the part you can shorten the length you need to actually reach many times.

[The Chipmaker]

On aggressive and deep undercuts I use slotmills. Without seeing the part its hard to see if that would work. Good luck.

[cincy k]

Try Internal Tool. http://www.internaltool.com/ They may have something that will work.

[Newbeeee™]

Thanks for the replies - just got back from buying another Chevalier VMC. So an expensive day today...

 

Attached is a piccy which hopefully makes it a little clearer. The two areas 'blacked' are the undercuts, which have the 12.5mm radius (and undercut by 6.6mm).

I spoke with PH Horn today - they are looking into modifying the shank and head of an existing tool. Won't be cheap but at least it's replaceable heads.

When asked if it *should* work ok, I got a 'urr, ummm' type reply with a bit of a look!

Cheers

[MrFish]

Internal tool or simtek t-slot cutters

 

simtek do a T-slot cutter with interchangeable heads in there Sigma line that is 28 OD and has a max cut depth of 6.5mm or a 32 OD with 8.5mm

[Newbeeee™]

Fishy,

Thanks for the heads-up. I have never heard of Simtek before - have you used them?

I can't see a sigma line but I'm asuming the below is the company?

Cheers

 

http://www.simtek.eu/simmill_groovemilling/simmill_px_sx_ux_vx/index_english.html

[MotorCityMinion]

Weight reduction huh. So she don't gotta be pretty. Material is is forgiving. Perhaps a 1" dia x 3" flute length hogger relieved where you need it. Multi pass away. RDOC = can't take the noise.

[MrFish]

Fishy,

Thanks for the heads-up. I have never heard of Simtek before - have you used them?

I can't see a sigma line but I'm asuming the below is the company?

Cheers

 

http://www.simtek.eu...ex_english.html

 

 

Yip thats them. Used them heaps. Very good product, have cut alot of 17-4ph stainless hardened to H900 and they work great, a pretty good test. Also cut some tapered splines with a custom 6 tipped simtek t-slot cutter in a 4th axis for the motor shafts on this http://martinjetpack.com/

 

Do some great little solid carbide boring bars for the lathe too.

 

I did here a rumor once that they company was started by some guys from PH horn, but they seem to have a much larger range of t-slot cutters than them and we found there coating and grind geometry to work alot better in the 17-4.

[Newbeeee™]

Had a long chat with the PH Horn tech today - he quoted modified tooling with a note which said 'no guarantee of function'....not too confident then!

[Ron Branch @ 5th Axis]

We use to sinker EDM parts like this for many companies at one place I worked. Was not cheap, but be suprised how much ti is going to cost trying to machine that out.

[Newbeeee™]

Yes, I put a proposal to them (customer) costing various versions mentioning edm for the most challenging bits.

Also linked the PH Horn youtube vid showing their tools, and pointed out the differences (ie larger shanks, less overhang, shallower depth of cut etc).

It looks like common sense is prevailing, and they are edging towards external weight loss - Phew - I think we dodged a bullet

[Mike Whitten CAD/CAM Contractors]

Hello newbeeee,

 

Have a look at an MSC line called "Shank Type Cutters". Go to the site and get to page 506 of the Big Book. You can also search for 00608729 (Ø1" x 1/8" width x 4-15/16 OAL). They are HSS or HSCO, 8tth and also staggered. They work very well, especially in aluminum as they are built with some nice geometry.

 

MIke

[crazy^millman]

Hey Mike how are you? Long time no see.

[Mike Whitten CAD/CAM Contractors]

Hello Ron,

 

Ooh..I am doing ok, just trying to figure out how to make money...you know. Other than that, things are very nice over here in Carson City. I just want to fish, hunt and ride dirt bikes as much as possible

 

I hope all goes well with you also.

 

Thanks,

[Newbeeee™]

Thanks Mike.

[Joe788]

Newbee, it sure looks like the bosses for the threaded holes are wayyyyy larger than they need to be. The undercutting would be a lot easier if they removed about 50% of the thickness from the area around the threaded holes. There's no need to have .250 wall thickness around a 4-40 (or whatever tiny size) hole like that.

[Newbeeee™]

Joe - 100% correct. I did say this to them as well. They're M3 threads and to be honest 60 thou wall is plently for what it's doing.

Trouble with reducing the mtl, is it dramatically reduces the seating area for the pcb, which means re-test/qual for vibration which is big bucks...