Need helpful ideas on how to reduce burrs on cross hikes with internal thread

[CncPrincess083096]

We have this part at my job that has multiple different operations and by time it gets to deburring it is such a hassle . Due to the current times my job is low on work so I have been bouncing around to all the different departments where i can work so I have seen every single operation. We makes thousands of these parts but it requires like 12 different tools to deburr and it doesn’t make sense to me . They are called barrel nuts we make the blanks in swiss machines then they go to turning an they thread the inside. Then they are sent to milling and the od gets cut into a hex with a cross hole on each side . The part where the cross hole meets the internal thread leaves nasty burrs that are causing a ton of stress to the deburring department . I am currently in deburring working o these parts and i just don’t think this is the best way to do it. I brought up re threading them and was told it can’t be done because it’s a single point thread and that the insert will break on the hole . Any ideas ? Thanks I’m advance

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[Jim Dawson]

I don't really understand why a tap could not be run through the part by hand as part of the debur operation. It might make sense to cross drill then thread. Maybe thread mill rather than single point on a turning machine.

But overall it sounds like an order of operation problem. Normally when I set up a job I plan the cuts to eliminate any burs during the process because I really hate deburring. Any final debur operation required is done in a vibratory deburring operation.

Without seeing the part it would be difficult to offer any meaningful advice.

[CncPrincess083096]

I don't really understand why a tap could not be run through the part by hand as part of the debur operation. It might make sense to cross drill then thread. Maybe thread mill rather than single point on a turning machine.

But overall it sounds like an order of operation problem. Normally when I set up a job I plan the cuts to eliminate any burs during the process because I really hate deburring. Any final debur operation required is done in a vibratory deburring operation.

Without seeing the part it would be difficult to offer any meaningful advice.

Thank you for your response ! After the take the part out of the mill it has a tap ran thru then again in deburring . All it does it push the burr from side to side it doesn’t break then put a reamer in it , a ball End mill , a mini buffing wheel , a wire brush , etc I don’t know of the top of my head what kind of material it is but it is definitely very hard. I was thinking the order of operations didn’t make sense but I was told it doesn’t work by someone who has been with the company for 4 decades so I’m assuming he has tried before ? I will try and get a picture tomorrow . Thank you again.

[Jim Dawson]

Sounds like ''This is the way we've always done it''

Make sure it's OK with the management to post a picture of a part. Sometimes they are sensitive about that kind of thing.

[machinehop5]

... talk with the customer's engineering dept to re-design the part for ease of mfg....Omit the hole, move the hole, finish drill on assemble, etc Cross holes in threads are always tough to de-burr.

[deadlykitten]

hy princess cross holes are tricky : if you deburr one hole, some burr will be removed, and the one that remains will go into the other hole

if you repeat this long enough, you will reach a point where the burr simply bends from side to side

cross holes and threading should be done on same machine, then repeat the operations in order to break the burrs, until only a tiny one remains, that can't be deburred, because it slides; if the burr is strong, it may break the threading insert, so it may be required to lower it's resistance, by using a different approach when drilling, in order to lower the cutting force when the holes intersect, by using a 2nd drill ( that will keep it's edge sharper for longer ), or a helix operation

it may be possible for the client to accept the part with this small sliding burr, otherwise, just like jim said, you may minimize it even more in a vibratory machine

i guess there is a machine that can do your part from stock, only that, perhaps, it is not in your shop ... so, without it, you move the parts from one machine to another, and go on a deburring-spree / kindly

[smartcolombyan]

During the swiss cross drilling operation, I'm sure there could be an added quick operation with a special tool that can help lower any additional manual deburring downstream. This could be a deburr tool like the heule or cogsdill with a small tooth insert to fit inside the side threaded holes and the tooth fit between the threads of the center thread. It might be easier to cut a chamfer where the threads meet with a back chamfer like tool where a pneumatic blower operation could push any chips out in an automated fashion.

[deadlykitten]

hy, i was thiking about your issue; what about, before threading, turn also a groove, aligned with the cross hole, with his diameter = thread max dia + a_small_clearance, and his width = cross hole dia + a_bit ?

this approach will increase the turning time, will require also a bit of finish operations ( for thread flancs, chamfers, crest dia, etc; a bit tricky because some operations are done in a reverse sense ), but the cross hole will never intersect the thread, because it is fully discontinued; however, this approach can be switched to a partially discontinue type, by making the groove diameter < thread max dia, but still > pitch dia

if approved, then try to minimize threading chips tendency to gather inside those grooves; if is not possible, then cut those grooves after the thread, not before

pls check attached sketch; if you wish for full dimensions, pls share your drawing / kindly