Orbital Boring

[absolute technologies]

Has anyone used MasterCam to program Toshiba's Orbital Boring option or Okuma's Turn Cut function for a vertical or horizontal machining center?

 

We would like to bore a spherical diameter on a vertical machining center (see attached pic). Our CNC jig grinder won't do it other than a plunge type form grind and some parts' OAL are rather long where you would need a large swing lathe to fixture it. I've done these before on a vertical mill using a form tool and circle interpolation however some parts require a close true position and surface finish where I would like to rough it with a form tool then finish bore it. I saw a couple of weeks ago a vertical machine that had that option but don't remember the builder. YCM has it on their Fanuc controlled machine. It looks like Toshiba's patent isn't quite expired yet however they let it lapse from not paying the maintenance fees or maybe Okuma, YCM and others are licensing it from them.

 

Thanks!

Len Dye

Spherical Diameter.pdf

[crazy^millman]

Treat it like a 5 Axis toolpath even though it is really just a 2 axis toolpath from the machine standpoint with the Spindle being a controlled axis in this process. Define the tool as the custom with the relief like the lathe tool you will be using. Match the radius to the insert you will be using I assume .032 for roughing and .0156 for finishing. Then modify the post to output the correct codes that keeps the tool normal to the milling axis at each point of contact. Trick will be getting constitent output through out the cycle to have the Spindle keep the tool where you expect it. I have seen make macros to do this and some builders have a defined process. Once you have the process dialed in and understand how to define it to run on the machine should be pretty straight forward, but getting there will take some work. Best of luck and let us know how it turns out.

[The Cathedral]

I tried programming it once as a macro on an Okuma and I couldn't get the spindle positioning to keep up. Of course it was an older machine so maybe a newer one is more capable. 

[absolute technologies]

I tried programming it once as a macro on an Okuma and I couldn't get the spindle positioning to keep up. Of course it was an older machine so maybe a newer one is more capable. 

yes with the newer machines with the faster response/acceleration of the spindle it looks like the spindle gets up to about 250 RPM's where back in the day when Toshiba 1st came out with this it may have been like 100 RPM, which was ok on the large Horizontal Boring Mills.

 

Cheers!

Len Dye

[mkd]

Facing head on the HBM would sorta do it driven off the W axis. Expensive setup.

 Main trouble being backlash when reversing direction on CL of radius. Form tool would probably win.

[absolute technologies]

Back in the 80's I ran a new Devielg horizontal boring mill that had the NCTP50 Boring Head (same as G &L) where the boring head threaded on to the front of the machine and the main spindle would rotate the boring head and the Z-axis quill movement had 4" of travel inside the boring head that moved the boring bar tip to do profiling with Z-axis CNC commands and the W-axis saddle moving in & out of the part to create any type of profiled bore. However that's like a $100K attachment on a machine that's over $1M, not exactly the solution I'm looking for. A U-axis boring head retrofit to a machine isn't out of the question but it would be hard to justify verses a secondary operation.

 

What we're looking to do is integrate these types profiled bores into the typical machining operations on medium size vertical mills. Okuma has an orbital boring function called True-Cut but they don't do it unless the machine has chilled ball-screws and scales because X & Y are moving pretty fast and long cycle times will eventually will heat up and wear the drive system out. The scales are needed for the accuracy improvements. It'd be interesting to see how accurate the geometry of the bores are. As you can imagine there's a lot going to maintain accuracy and with faster electronics of today it should only get better. One would think thou the builder could get it to work better/faster RPM than opposed to writing a user macro.

 

Here's a snippet of G-Code and the Okuma True-Cut white paper for anyone interested. The G-Code looks simple enough for the Postmasters of the world (not me). It looks like once your in G165 mode (continuous CW circular motion mode) all your X-axis values are defining the bore profile incrementally from where you called the code. 

 

 

 

Cheers!

Len Dye

Okuma Turn-Cut.pdf

[YoDoug®]

I have started a simple post for Okuma Turn cut from a basic 2 axis Okuma lathe post. I stripped out all of the extra not needed BS. I use a manual entry for all of the prepatory start and finish commands and just program the lathe turning paths in between. Then I post as a SSB program and call that from my main mill program. The post still needs some work but it relatively close. I do not work on Turn-cut enabled machines very often so it is not a priority. If I ran one every day I would probably finish the post. We have one customer that has Turn-Cut on one of three machines on a Fastems cell. They do different operations in different machines. In the Turn-cut machine they finish using Turn-cut and probe results. They even have logic set up to re-cut undersize parts. 

[crazy^millman]

Back in the 80's I ran a new Devielg horizontal boring mill that had the NCTP50 Boring Head (same as G &L) where the boring head threaded on to the front of the machine and the main spindle would rotate the boring head and the Z-axis quill movement had 4" of travel inside the boring head that moved the boring bar tip to do profiling with Z-axis CNC commands and the W-axis saddle moving in & out of the part to create any type of profiled bore. However that's like a $100K attachment on a machine that's over $1M, not exactly the solution I'm looking for. A U-axis boring head retrofit to a machine isn't out of the question but it would be hard to justify verses a secondary operation.

 

What we're looking to do is integrate these types profiled bores into the typical machining operations on medium size vertical mills. Okuma has an orbital boring function called True-Cut but they don't do it unless the machine has chilled ball-screws and scales because X & Y are moving pretty fast and long cycle times will eventually will heat up and wear the drive system out. The scales are needed for the accuracy improvements. It'd be interesting to see how accurate the geometry of the bores are. As you can imagine there's a lot going to maintain accuracy and with faster electronics of today it should only get better. One would think thou the builder could get it to work better/faster RPM than opposed to writing a user macro.

 

Here's a snippet of G-Code and the Okuma True-Cut white paper for anyone interested. The G-Code looks simple enough for the Postmasters of the world (not me). It looks like once your in G165 mode (continuous CW circular motion mode) all your X-axis values are defining the bore profile incrementally from where you called the code. 

 

 

 

Cheers!

Len Dye

 

My thoughts are this is still never going to be better than the natural process and method to manufacture these shapes. There is German company doing this on a part for one customer. Went on and on about this part being a 15 minute part. I laughed and at them laughing to the customer. No way it is a 15 minute part were my exact words. If that part can be machined with all the features it has and made good day in and day out then I need to find a different profession. I think it is at 80 minutes and after 12 months and a lot of $$$$$ they may finally have a process that is day in and day out ready. I didn't feel it should take as long as it was, but 15 minutes I couldn't see it. I like your thinking and get where you are going with this, but yes the equipment has to be best of the best. Foundation, Environment and other extremely important factors needs to be considered for this as well. Normally these types of bore are ground in and ground in for a reason. You can hit the grind tolerances and finishes needed and have t be a repeatable process day in and day out then more power to you. Yes technology has made some good strides, but that comes with a price and not something I see a majority of places stepping up to any time soon. Please keep us posted and I need to stop by and see how you guys are doing over there.

[GoetzInd]

U-Axis head will be about a 35K investment for an HSK63 sized machine. I am working on a project that uses a couple of them right now.

 

Mike

[mkd]

any reason form-grinding with an air spindle wouldn't work?

 Obviously rough with a milling cutter, then grind. There must be some companies that specialize in this. Probably one that could provide a semi-turn key solution, i'd guess.

[absolute technologies]

any reason form-grinding with an air spindle wouldn't work?

 Obviously rough with a milling cutter, then grind. There must be some companies that specialize in this. Probably one that could provide a semi-turn key solution, i'd guess.

We have a CNC Jig grinder here but it will not do profiled type path. A CNC Jig Grinder with an encoder on the spindle and software similar to Orbital Boring would do it but it would have similar limitations as Orbital Boring does with the speed of the X & Y movement while keeping the keeping the spindle oriented to the X & Y position but with grinding you wouldn't need as much of RPM compared to boring would be an advantage. Our CNC Jig Grinder will do a plunge grind with the form dressed into the wheel however the surface finish from form grind isn't much better than circular interpolation with a staggered tooth form tool on VMC using cutting oil. Holding diameter size and form would be about the same for both processes. In this particular part shown the biggest problem I see is how gage the true position of the spherical diameter with such a small radius segment CMM just isn't going to measure it accurately. I've done some inspection similar with a ball bearing the same size as the SR with flats on it so you can get the bearing inside and square it back up so you can make some mechanical measurements is far more accurate.

 

Cheers!

Len

[MIL-TFP-41]

At my previous gig we used Turn-Cut quite a bit. It is very cool to watch. Coupled with some Sandvik silent bars were were cutting some very deep bores & annulus grooves.  We were able to achieve roundness within .001 spinning some decent RPM's. Size wasn't affected by RPM's however roundness was.  We used NX to drive the machines there, with the right post guru I am sure Mastercam could do it.

 

A kind of interesting read about Toshiba and their orbit boring function...basically Toshiba promised their machine could do this function but couldn't deliver. Toshiba lost $7,000,000 over the deal. Case of a salesman selling things they couldn't deliver....

http://caselaw.findlaw.com/tx-court-of-appeals/1402378.html

[absolute technologies]

 

A kind of interesting read about Toshiba and their orbit boring function...basically Toshiba promised their machine could do this function but couldn't deliver. Toshiba lost $7,000,000 over the deal. Case of a salesman selling things they couldn't deliver....

http://caselaw.findlaw.com/tx-court-of-appeals/1402378.html

yeah Toshiba isn't known for playing nice. Some of you may remember during the Reagan days where Toshiba Machine and Kongsberg controls where exporting 9-axis & 5-axis machines to Russia when they weren't supposed to import more than 2-axis machines. Well, the Russians where fully machining their submarine propellers and all the sudden we can't hear or identify the Russians subs. It was said the illegal export cost the Western world billions of dollars in new sonar listening capabilities and several years to recover. There were sanctions against Toshiba products in the US and some Congressmen smashed a Toshiba radio on the Capitol steps

[GoetzInd]

Interesting read...

 

 

Mike

[Brad Lisle]

Very interesting read. Fortunately, Okuma was able to engineer their own and has proven that it does work.

 

Attached is a sample roundness calculation you can expect to achieve. As you can see the higher the acceleration the less accurate the roundness becomes.

 

Hope this helps

[crazy^millman]

Brad what is the happy medium of speed and feed? I agree it is all relative and comes down to the specific application, but has a rule of thumb been worked out? I think this is more suited to applications where SFM doesn't need to be high to achieve good surface finish results. Harder metals or larger diameters would be the ideal situation for this technology is my thoughts. What are you seeing for implementation process and methods being used? Very interesting process, but still think traditional methods in most cases out weigh this method day in/out for years. Time will tell, but no getting around the laws of physics. For every action there is a reaction. You start making machines work hard in certain areas more than others and wear will be come a factor.

[absolute technologies]

for us being able to integrate contoured boring into a normal mill operation could have big advantages, provided the quality is equal. Not only are you saving the labor of an operation and the setup time thereof, more importantly you're saving the queue time in the build schedule. In addition it could minimize the scrap, this jig grind operation is the one of the last operations, if you lose just 1 part here you can lose your profit for whole lot run. Being the high cost to make complex cylinders, smaller lot sizes and smaller profit margins nowadays with the advancing of this technology it's looking pretty doable to me now. I wouldn't be to concerned about wearing the machine out either because we're only looking to do it only a couple times a year on one machine.

 

Thanks for the input Guys!

 

Cheers!

Len Dye

[Brad Lisle]

Here are a few extras for you to enjoy.

 

This feature can be extremely useful for select applications. As Ron mentioned, it is better suited for lower SFM materials. Though keep in mind the larger the bore diameter the higher the SFM can be achieved with the spindle RPM restrictions. As for wear, I don't believe this would cause any more wear to the machine than any dynamic toolpath, if you use this option for finish passes only. That is why Okuma requires certain options such as full ball screw cooling.

Turn Cut.zip

[cncchipmaker]

Could you use a full radiused keyway cutter? Possibly fixture it on a lathe?

[Brad Lisle]

yes you could, but you would not get as nice of a surface finish as a turned surface. You could also fixture into a lathe, but the whole purpose of this type of option is to eliminate the need for an additional operation that involves extra programming, setting up, fixturing, available machine time/scheduling. plus the simple fact, every time you take a part off the machine and put it back on there is potential tolerance or true position errors. There will always be more than one way to achieve the end results, what way is better is still up for debate. This just brings another tool to the box. With the highly complexity of todays parts being engineered, it is imperative to be able to achieve much tighter tolerances than before.

[mkd]

[Guest]

I believe the Cs Contour option on FANUC controls will do this. I have not done it myself (yet) but it's a good application for this option.

 

Or you could get a Matsuura CUBLEX and turn it AND do all the milling in the same setup on the same machine.

[GoetzInd]

 

 

I believe the Cs Contour option on FANUC controls will do this. I have not done it myself (yet) but it's a good application for this option.

It will. I've seen it done.

 

Mike

[Matthew Hajicek - Singularity]

At Dunwoody in '96 one of my classmates (Cyprian Troyer IIRC) was predicting not only this technology but also the same sort of thing applied to non-round profiles.  He was figuring that it would be more efficient to keep the cutting edge always engaged with the work, but also knew that it would be decades before the hardware would be able to keep up with the desired toolpath.

[crazy^millman]

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.