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Guhring Mill / Drill Huge Issues with Breakage and Tool Life

f40lm

Plastic
Joined
Mar 20, 2017
Hello all,

I'm new to this forum and coming to the forum with a crucial issue to our shop (desperate). We are going through Guhring mill / drills at an alarming rate. I have inherited this process and it has always been known to be a tool breaker, but it is at a serious point where we need to look at cost savings. Since start of production this year we have consumed 720 drill bits at a cost of $38,000 and 320 end mills at a cost of $5,500.

It is an outer race with a spline. Two oil holes are milled and drilled into this outer race from the spline side. The material is SAE 1060 Rockwell C 26-36

This operation runs 1,900 parts per shift, 2 shifts a day, 5 days per week. There are 3 robodrills that perform this operation 2x per part. Based off of that, each machine performs each operation 1,267 times per shift.

The operation is appears to be a 2mm depth of cut with a 2mm mill to form a pilot and then a 2mm drill operation thru cut which appears to be about 6mm in travel.

Machine: Fanuc Robodrill Alpha-T14iE

Operation 1: Carbide Mill 2.0mm Guhring 16,000rpm at 190 mm/min 2mm depth of cut Guhring

Operation 2: Carbide Drill 2.0mm Guhring 14,000rpm at 720mm/min 6-8mm thru cut Guhring



Does anyone think this existing tool can be saved with feeds/speeds or if I should pursue a different tooling supplier?
 
Hello all,

I'm new to this forum and coming to the forum with a crucial issue to our shop (desperate). We are going through Guhring mill / drills at an alarming rate. I have inherited this process and it has always been known to be a tool breaker, but it is at a serious point where we need to look at cost savings. Since start of production this year we have consumed 720 drill bits at a cost of $38,000 and 320 end mills at a cost of $5,500.

This operation runs 1,900 parts per shift, 2 shifts a day, 5 days per week. There are 3 robodrills that perform this operation 2x per part. Based off of that, each machine performs each operation 1,267 times per shift.

The operation is appears to be a 2mm depth of cut with a 2mm mill to form a pilot and then a 2mm drill operation thru cut which appears to be about 6mm in travel.

Operation 1: Carbide Mill 2.0mm Guhring 16,000rpm at 190 mm/min

Operation 2: Carbide Drill 2.0mm Guhring 14,000rpm at 720mm/min

The material is SAE 1060 Rockwell C 26-36

Does anyone think this existing tool can be saved with feeds/speeds or if I should pursue a different tooling supplier?
O l.10ml.k kk y n mm m l l k g ukh k lujmym

Sent from my SM-G900V using Tapatalk
 
Sooo, I presume you are milling, drilling concrete? Need more info to figure out what you have going on.

It is an outer race with a spline. Two oil holes are milled and drilled into this outer race from the spline side. It is SAE 1060 Rockwell C 26-36. Not concrete lol.

Mill: Guhring

Drill: Guhring

Operation is ran on a Fanuc Robodrill Alpha-T14iE

Please let me know what other information is needed. I am heavily into automation, not familiar with machining.
 
I would shop around on drill price, and compare some tools. Sounds like you've got enough volume to get some good info as to what the best tool is for what you are doing.

Do these drills have a predictable tool life? Can they be sent out for regrind at that size? If both answers are yes, I would look at that as a way to reduce costs also.
 
Guhring makes excellent products. How are the drills failing? Outside corners of lips burning up or are chunks being taken out along the cutting lips? Also, it sounds like this isn't any worse or better than it has ever run?
 
Try more feed? Looking at the recommended f&s, it seems the speed is right in the middle, but feed is about half. Unless I overlooked something.

edit- referring to the drill
 
I would shop around on drill price, and compare some tools. Sounds like you've got enough volume to get some good info as to what the best tool is for what you are doing.

Do these drills have a predictable tool life? Can they be sent out for regrind at that size? If both answers are yes, I would look at that as a way to reduce costs also.

I am not sure on that. Just started looking into this project so I will have to check with the supplier. That is a great suggestion though. I will definitely pursue it and get back to everyone.

Guhring makes excellent products. How are the drills failing? Outside corners of lips burning up or are chunks being taken out along the cutting lips? Also, it sounds like this isn't any worse or better than it has ever run?

From what I saw earlier today is the lips burning up but I will verify more tomorrow. According to the operators the drills are very intermittent. They will run 2000 parts without any changes or have it where they break on the first 1-10 parts. They swear it varies by the lot of them. They showed me two different lots where the shank looked like a drastically different color. I dont know much about this stuff, but I found that odd.

Try more feed? Looking at the recommended f&s, it seems the speed is right in the middle, but feed is about half. Unless I overlooked something.

edit- referring to the drill

I agree on the feed being to slow. It looks like you should be going 2-3 times the feed on the drill.

Excuse my ignorance, where can I find recommended speeds and feeds for this setup? Machinery handbook? NVM, found the data sheets


The price we are paying is around $52.40 per unit. You all are saying that is way too high?
 
I agree on the feed being to slow. It looks like you should be going 2-3 times the feed on the drill.

Can you show me calcs how you determined 2-3x faster? Not having much luck with the data sheets and my bad knowledge lol
 
Double and triple check to make sure the tools are running true, in all holders. If they aren't, you will get results all over the place....... damhik
 
First, if you guys really are on track to buy about $160,000 worth of drills this year the Guhring dealer should fly whoever he needs in to meet with you and look at the operation in person and give you however many free drills necessary to figure it out...seriously.

Also, is the end mill just going straight down in the z axis to spot a flat for the drill? That doesn't always produce a nice flat smooth surface for the drill, so you may have to swipe across the part in the x or y axis. Plus you may have to use a spot drill (not center drill) before drilling to yield the most reliable drill performance.

In general, chipped lips/point means too high feed and if the outer corners of the lips are melted the speed (RPM) is too high.

Definitely get the distributor in there, though.
 
Hello all,

I'm new to this forum and coming to the forum with a crucial issue to our shop (desperate). We are going through Guhring mill / drills at an alarming rate. I have inherited this process and it has always been known to be a tool breaker, but it is at a serious point where we need to look at cost savings. Since start of production this year we have consumed 720 drill bits at a cost of $38,000 and 320 end mills at a cost of $5,500.

It is an outer race with a spline. Two oil holes are milled and drilled into this outer race from the spline side. The material is SAE 1060 Rockwell C 26-36

This operation runs 1,900 parts per shift, 2 shifts a day, 5 days per week. There are 3 robodrills that perform this operation 2x per part. Based off of that, each machine performs each operation 1,267 times per shift.

The operation is appears to be a 2mm depth of cut with a 2mm mill to form a pilot and then a 2mm drill operation thru cut which appears to be about 6mm in travel.

Machine: Fanuc Robodrill Alpha-T14iE

Operation 1: Carbide Mill 2.0mm Guhring 16,000rpm at 190 mm/min 2mm depth of cut Guhring

Operation 2: Carbide Drill 2.0mm Guhring 14,000rpm at 720mm/min 6-8mm thru cut Guhring



Does anyone think this existing tool can be saved with feeds/speeds or if I should pursue a different tooling supplier?

First: Start your holes with Mikron Cross Pilots instead of an end mill. mikron cross pilot - Google Search

Second: Dump the Guhring and replace with a NACHI or - if the hole is shallow enough - an MA Ford Twister.
 
First, if you guys really are on track to buy about $160,000 worth of drills this year the Guhring dealer should fly whoever he needs in to meet with you and look at the operation in person and give you however many free drills necessary to figure it out...seriously.

+1 To this.

Use the phrase "considering a change in tooling manufacturer" and watch them charter a flight for a C level with an apps engineer to be in your shop the same week. If this is a typical job for your shop, you're spending millions a year in tooling - whoever you're buying from should have a guy sleeping on a cot in the back corner, just to make sure you're getting optimal performance from consumables. Our supplier has 2 guys here, full-time, on their dime.

If you need to put the screws to them, tell them the tool rep from XYZ Company said their bits would last 50% longer (because all sales people always say that.)

Seriously - do your homework, yes - but wring every last ounce of effort you can get out of your supplier's engineers too. That's their job.
 
The two tools you listed have longer flute lengths than needed, so the first thing I'd do after reviewing tool supplier is get appropriate lengths of cut. You'll save money right there and improve the stability of the two operations.

I agree with other comments on using a spotting drill and checking out Nachi. You should also check out the Robodrill spindles and ensure they're in good shape, and also the toolholding. Programming a slower speed/feed for the spot drill prior to it creating a full diameter seat for the main drill might extend its life without compromising part throughput, especially if it cuts down on breakage.
 
At that rate of consumption I would have Guhring in my shop at the machine doing the test cuts/recommendations. over $45,000 of tools in under 3 months is pretty significant.
 








 
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