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Broaching on CNC mill?

fivendime

Aluminum
Joined
Dec 11, 2006
Location
Utah
How do you broach on a CNC mill? Anyone have pics of there set-ups/tool holders? I would like to know the best way to do this. The key ways would be apox. 1 1/2" to 2" wide and 8" to 10" deep key ways. Any way to do it on a mazac?

Will the spindle bearings be destoyed? Thanks for your help.

Adam
 
However, I've never heard of doing keyways that big before.
I assume that for a keyway taht big, you must have a huge ID.
Is there no way to approach the job using a horizontal head, or a different machine?

I could see ruffing the keyway out using a plunge mill, then following to clean up the corners, but I don't think that even a Cat50 will have the clamp force to overcome that bending moment of a 10" long keyway.

Just my .02

Doug.
 
broaching

5/10, if you were considering rotary broaching, those sizes are too large for standard tooling, maybe a shaper style operation would be best
 
How big is the bore? We use a right angle head to mill key-ways, but it takes a pretty large bore and I'm not sure it will reach 10 inches.

We also push broach key-ways with multiple passes and the spindle oriented on our CNC mills but nothing that big.
 
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I suppose you could do it with a cutter about 1/4" wide but I think that is not a good idea; using the spindle that is, you would be making so many strokes the chances are you could cause false brinelling in the spindle bearings.

I have seen the idea of broaching on a mill discussed several times with vehement opinions for and against; in aluminum for a 1/4" keyway it is probably okay but not really good practise.

One idea I had was to make a fixture that would clamp onto the spindle nose and have a bar with a cutter attached to this so the spindle is not being used.

Most Z axis servos can safely develop a couple of thousand pounds thrust and that would be plenty for driving a small slotting cutter to make whatever size keyway was needed.

It might be necessary to lock out the toolchanger or some serious damage might occur if the changer came in with the toolholder clamped on the nose.

I have also thought that an mechanism probably could be made that would fit in the spindle and have an index pin to locate a fixed housing (like an angle toolholder). This device would convert the spindle rotation into a sort of pecking action for a slotting tool; a semicircular motion about a horizontal axis so the tool came out and down then retracted and returned to the top. This would nibble the keyway as the Z axis came down so you would not create great long stringy chips. maybe something like this already exists.
 
Depending on the particulars of what you are trying to do this might be an option:

http://www.morriskeyseater.com/

I saw their setup at the Milwaukee tool show a couple years back it seemed like a very special purpose tool but if you have the right application it might be just the ticket.

Tim
 
I converted an old 630 mm Toyoda machining center with tired spindle bearings into a CNC shaper that will cut 3/4" wide keyways in stainless or monel all day long without complaining. Automatic toolchanging for bores with multi keyways really saves time over the manual shaper. Those Razorform tools work fantastic too.
 
The one part is apox. 14" OD, and a bore size of apox. 8" with a keyway of 1 1/2" wide and 9" long. So I don't think a right angle head would work. The "Razorform" tool looks good for small keyways. But not much help for a long keyway.

My worries are with the spindle bearings taking a beating, and how would you go about orient the cutter on a mill say at 90 degrees and at 180 degrees?


The reason for doing in on a mill or mazak is to save time on setups and to have the orientation correct.


Thanks
Adam
 
G&L(cnc types) HMCs had/has a couple of pages in the manual aboot broaching,I also remember it being brought up in class,I did not pay attention to the lesson,or have forgotten any specifics.
I like the above mentioned idea of using the W/saddle as apposed to the Z/spindle.
Gw
 
Here is a home made right angle attachment that we have mounted on our Haas VF-6 with a rotary table mounted to the table.
We use it to cut helical and straight oil grooves in bronze bushings.
It has two bearings on the outboard end with a 1.0 bore. The spindle has a .5 bore with a set screw to hold the end mill. A timing belt pulley is mounted in the spindle.
 

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Here is a home made right angle attachment that we have mounted on our Haas VF-6 with a rotary table mounted to the table.
We use it to cut helical and straight oil grooves in bronze bushings.
It has two bearings on the outboard end with a 1.0 bore. The spindle has a .5 bore with a set screw to hold the end mill. A timing belt pulley is mounted in the spindle.

That's pretty slick. Where there's a will, there's a way.
 
How many parts do you have to make? if it's only a few, then my suggestion would be wire edm. EDM will handle this job with no effort. Even with hard materials. You'll get great results on the first try as long as your edm guy knows what he is doing, and you won't risk your mazac's bearings.

Bruce
 
The one part is apox. 14" OD, and a bore size of apox. 8" with a keyway of 1 1/2" wide and 9" long. So I don't think a right angle head would work. The "Razorform" tool looks good for small keyways. But not much help for a long keyway.

My worries are with the spindle bearings taking a beating, and how would you go about orient the cutter on a mill say at 90 degrees and at 180 degrees?


The reason for doing in on a mill or mazak is to save time on setups and to have the orientation correct.


Thanks
Adam

You never mention the depth of the keyway ... nor do you state whether it is through or blind.

Also not stated are your tolerances and material.

I second Groovitude's suggestion of WEDM if the keyway is through and your material is conductive.
 








 
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