Orbital Boring

[Mr. M]

Okuma has a function (and I'm sure fanuc does also) where you can cut a non round or in groove with a face grooving tool. It is pretty cool watching that kind of stuff.

[jlw™]

Mazak supports it and calls it skiving or shaping depending on who you talk to. I have one machine with the software on it but no way to program it with out heavy edits.

[Sticky]

Funny we were doing this by hand on boring mills with the rotatory dial types back in the late 80's and early 90's, but it was being used back as early as WWII by places doing different things for the Military.

 

I think you are talking about a boring mill. Those have been around since the early 1900's. This is different in that the X&Y axis interpolate while syncing with the spindle C axis.

 

[Sticky]

Another fanuc implementation, starts at 7:26:

 

[Sticky]

Grob also does it using Siemens:

 

 

[crazy^millman]

Funny been in front of all 3 of those machines and watched the GROB do it recently on some parts for a customer. I still think a true turning process is superior to this approach in the long run. Time will tell if the machine can hold the .002 profile day in and day out for the next 5 years.

[Guest]

Funny been in front of all 3 of those machines and watched the GROB do it recently on some parts for a customer. I still think a true turning process is superior to this approach in the long run. Time will tell if the machine can hold the .002 profile day in and day out for the next 5 years.

 

Good point. I think if you're doing production, lathe to mill is gonna get the job done faster and better. But if it's a low volume item... no reason not to do it.

 

JM2CFWIW

[crazy^millman]

Good point. I think if you're doing production, lathe to mill is gonna get the job done faster and better. But if it's a low volume item... no reason not to do it.

 

JM2CFWIW

 

We know the people who see things like this and then want to do it day in and day out for the next 5 or 10 years and sorry on the best machine this is added wear and tear that is really not needed IMHO. Once a day maybe or once a week or in a pinch okay, but that is a lot of mass moving quickly that if you had a true spinning axis designed to follow the laws of physics you keep the wear curve heading in a better direction. I have done my share of crazy in a pinch things, but I want to see a machine doing this day in and day out for 5 years and the ball bar test throughout those years and see how that machine compares to one not taking a beating like the machine doing it will. Then 10 years and if it is holding tenths I will say okay I was wrong and a very well designed piece of equipment.

[civiceg]

False brinelling ftw. 

[Matthew Hajicek - Singularity]

Yeah, the travels on that last video are pretty short.  I've heard of people destroying their lead screws with short surfacing paths.

[civiceg]

There was a thread on here, DMG I believe, about frying a ballscrew by peel milling with too large of an endmill for the given slot. Physics wins.

[Watcher]

http://www.emastercam.com/board/topic/35669-mori-seiki-nv5000-using-peel-mill/?fromsearch=1

[Newbeeee™]

In my mind this is why we have never tried/used microlifts.

Granted we're 75% ally and the rest 303/304/316 stainless and don't machine any inco-nasty's, but the idea of a microlift worries me...

[Newbeeee™]

Yeah, the travels on that last video are pretty short.  I've heard of people destroying their lead screws with short surfacing paths.

We blew a leadscrew on one of the machines.

I believe it was due to a job that always went on that machine (we have 4 the same make/model but this job for some reason always went on #2 machine).

Cheap repair - just got x+y reballed.

But I'm sure it was down to peel milling and small movement and high feed/combination.

[Sticky]

A lot of the reason why screws will wear from short movements on newer machine is the insane accel decel values. Turn you accel decel down to half and watch your ballscrews last as long as the rest of the machine.

[Matthew Hajicek - Singularity]

I've been doing HFM on 17-4 and Ti and the paths seem to work just fine without microlifts.  It doesn't seem to shorten the life of the cutter or anything, and it executes faster.  I do have a part coming up where I have to cut some .040" wide by .275" long slots in the end of some thin walled tube; I'll have to keep false-brinelling in mind.

[Matthew Hajicek - Singularity]

Can't find any discussion of it online, but I'd guess that a linear motor machine would handle this sort of thing much better; no ball screws to false-brinel, you'd only have to worry about your ways / guides if they have rollers that might false-brinel.

[Newbeeee™]

Can't find any discussion of it online, but I'd guess that a linear motor machine would handle this sort of thing much better; no ball screws to false-brinel, you'd only have to worry about your ways / guides if they have rollers that might false-brinel.

I loved the idea of the Moog Hydrapoint design. Hydraulic linear actuators so no screw or backlash. Slap glass scales on it and away you go!

[mkd]

I loved the idea of the Moog Hydrapoint design. Hydraulic linear actuators so no screw or backlash. Slap glass scales on it and away you go!

Until you had to run one with two layers of ear protection.

Those puppies musta had the loudest hydraulic pumps on the planet. Not to mention they consume more power sitting, than cutting. Servo -valve...maybe not the best design choice....maybe. wink.

 

now a closed loop electric servo motor to hyd. pump to linear actuator... that might be a workable.

[Matthew Hajicek - Singularity]

You're still going to have bearings in your electric pump.

[mkd]

You're still going to have bearings in your electric pump.

I'm thinking pure torque reversals would be relatively unfelt to motor bearings compared to using a screw to swing a table around.

correct me if i'm wrong.

 edit: oh yeah, in the pump. gotcha. wonder what the better pump design would be? Vane/swashplate variable/ piston/....

[Matthew Hajicek - Singularity]

If you make your pump such that hydraulic fluid leakage lubes all the moving parts I think that would protect pretty well from false-brinelling since everything would be wet / submerged at all times. 

[MIL-TFP-41]

All about application and ROI. The gig I had where we used this...we cut annulus grooves at 10-12X dia's deep in hydraulic manifolds using devib boring bars. No way could these parts be chucked in a lathe efficiently. Saved countless hours on machine time & custom tooling that used to be used to interpolate the grooves. Sure the potential for machine wear is there. Tho by the time you count the hours and days and months saved...machine wear becomes a minimal cost (till the day comes where ballscrews have to be replaced & the job was due yesterday...yea that never happens)

[SlaveCam]

We are getting new machines that support orbit machining (Mazak HCN). I would like to hear numbers based on actual experience about attainable tolerance and roudness for "easy-to-machine" steels (finish cut). For example, the hole diameter is 5" (120mm) and SFM is about 820FPM (250m/min), what IT tolerance grade should we expect regarding diameter and roundness?