HELP! Makino Duo64 work pick-up tension/d-roller issue... false wire break alarm

amyjohnson · Oct 1, 2020

Hey everyone looking for some help with an issue I'm having on a Makino Duo64 Wire EDM:

My machine was displaying a wire break alarm at the beginning of the cycle immediately following the M06 line. The wire wasn't broken, it'd run an M07 and then begin to rewire -- rinse and repeat. I went through the entire machine picking away at all the variables one at a time, played it safe by re-verifying my part zero, and so far nothing has worked.

I ended up adjusting the powder clutch most recently. I ran the clutch adjustment cycle and closely followed the owner manual, and I had my tension gauge repeating 250g for the 3rd check and 850g for the 4th check. I ran this twice to be extra careful. I just went to go edge find my Y-axis and found that it was barely repeating within .0005". I paid closer attention and found that the d-roller (powder clutch) wasn't rotating during the pick-up cycle and I could hear the k-roller (lower roller) tugging at the wire during the cycle. Typically, the two rollers are both rotating during pick-up cycles and I was wondering if anyone else has had this issue after a powder clutch adjustment.

Also, hopefully the false wirebreak alarms will be solved by the clutch adjustment, however, if not... Does anyone have any suggestions on what could be leading to this false detection? I have been pecking away at the issue one variable at a time, I even removed the tube leading from the front of the machine to the wire collector and performed all PM on the gears and wire flushing in the back of the machine, I've sifted through all the consumables and had another tech overview my program. I'm sort of at a loss here. Thanks for any input!

-Amy

Brian Pfluger · Oct 13, 2020

Amy,

It sounds like you are performing the correct key maintenance items on the machine (self-help is the best, but can be frustrating

). Have you tried contacting the Makino Technical Support Team at 1-888-625-4664? From your post, it appears that your issues are more maintenance related. How well has the machine been maintained and have you been following the recommended maintenance intervals identified in the Training Workbook (do you even have this book)? Additionally, what is the machine condition and machining hours on the main Rollers (D-Shaft Roller, K-Roller, L&M Rollers), and what type and size wire are you using?

I recommend looking at the following items:

D-Shaft Roller:
This is the main dual V-Groove rubber Tension Roller that is on the Upper Head. This roller should be cleaned and flipped over once a month to extend its service life, and please be sure to use warm soapy water to clean this roller as other cleaners can dry-out and degrade the life of the roller. As this Roller begins to wear, a groove the size of the wire will progressively be formed into the rubber. Once this groove becomes too deep, it must be replaced, as the roller can no longer properly grip the wire and maintain the correct tension. A common sign that the D-Shaft Roller service life is spent is False Wire Break issues like you are experiencing, as the machine is sensing the slippage of the wire across the D-Shaft Roller (kind of like a car spinning its tires - no traction).

H & I Rollers:
These are the (x2) smaller rollers that are located just below the D-Shaft Roller on the Upper Head. One of these is a rubber roller that spins and keeps tension on the wire to hold it against the D-Shaft Roller (prevents the wire from coming off the D-Shaft Roller) and also aids in feeding the wire during AWT. This roller should NOT spin freely when the machine is sitting idle, as it too will suffer a deep wire wear groove into the rubber until it can not longer grip the wire and will require replacement. The other roller is metal and required monthly cleaning, as this roller is the induction pick-up for wire touch sensing. Please clean and inspect this metal roller, and I would expect to see an improvement in your pick-up cycle accuracy and repeatability.

K-Shaft Roller:
This is the ceramic roller located in the Lower Head. This roller should spin freely when installed in the housing, but this roller assembly also contains some items that require maintenance and eventual replacement. When this roller is removed and installed in the machine there MUST be both a Flat Washer and Lock Washer used on the locking screw...if there is not a flat washer and lock washer then the position and alignment of the roller can be incorrect. There are also bearings, seals, and grease caps on this roller assembly that require cleaning and maintenance, and the bearings should see the shortest service life (usually replaced within a 3 year time period).

L&M Rollers:
These are the (x2) ceramic pinch rollers in the rear of the machine. These rollers do wear over time and will see the same type of wire groove worn into them. These rollers can be flipped around once (provide x2 indexes total), and this is typically performed around a 6,000 Machining Hour interval, which provides a total service life of 12,000 hours. When flipping these rollers over, the rollers do need to be indicated in (indicator and mag-base are needed) to within a 0.0005" TIR. These rollers also have bearings that can wear out and should be inspected, but they are typically replaced at the same time as the rollers.

I hope some of this is helpful to you!

-Brian

amyjohnson · Oct 15, 2020

Brian Pfluger said:
Amy,

It sounds like you are performing the correct key maintenance items on the machine (self-help is the best, but can be frustrating ). Have you tried contacting the Makino Technical Support Team at 1-888-625-4664? From your post, it appears that your issues are more maintenance related. How well has the machine been maintained and have you been following the recommended maintenance intervals identified in the Training Workbook (do you even have this book)? Additionally, what is the machine condition and machining hours on the main Rollers (D-Shaft Roller, K-Roller, L&M Rollers), and what type and size wire are you using?

I recommend looking at the following items:

D-Shaft Roller:
This is the main dual V-Groove rubber Tension Roller that is on the Upper Head. This roller should be cleaned and flipped over once a month to extend its service life, and please be sure to use warm soapy water to clean this roller as other cleaners can dry-out and degrade the life of the roller. As this Roller begins to wear, a groove the size of the wire will progressively be formed into the rubber. Once this groove becomes too deep, it must be replaced, as the roller can no longer properly grip the wire and maintain the correct tension. A common sign that the D-Shaft Roller service life is spent is False Wire Break issues like you are experiencing, as the machine is sensing the slippage of the wire across the D-Shaft Roller (kind of like a car spinning its tires - no traction).

H & I Rollers:
These are the (x2) smaller rollers that are located just below the D-Shaft Roller on the Upper Head. One of these is a rubber roller that spins and keeps tension on the wire to hold it against the D-Shaft Roller (prevents the wire from coming off the D-Shaft Roller) and also aids in feeding the wire during AWT. This roller should NOT spin freely when the machine is sitting idle, as it too will suffer a deep wire wear groove into the rubber until it can not longer grip the wire and will require replacement. The other roller is metal and required monthly cleaning, as this roller is the induction pick-up for wire touch sensing. Please clean and inspect this metal roller, and I would expect to see an improvement in your pick-up cycle accuracy and repeatability.

K-Shaft Roller:
This is the ceramic roller located in the Lower Head. This roller should spin freely when installed in the housing, but this roller assembly also contains some items that require maintenance and eventual replacement. When this roller is removed and installed in the machine there MUST be both a Flat Washer and Lock Washer used on the locking screw...if there is not a flat washer and lock washer then the position and alignment of the roller can be incorrect. There are also bearings, seals, and grease caps on this roller assembly that require cleaning and maintenance, and the bearings should see the shortest service life (usually replaced within a 3 year time period).

L&M Rollers:
These are the (x2) ceramic pinch rollers in the rear of the machine. These rollers do wear over time and will see the same type of wire groove worn into them. These rollers can be flipped around once (provide x2 indexes total), and this is typically performed around a 6,000 Machining Hour interval, which provides a total service life of 12,000 hours. When flipping these rollers over, the rollers do need to be indicated in (indicator and mag-base are needed) to within a 0.0005" TIR. These rollers also have bearings that can wear out and should be inspected, but they are typically replaced at the same time as the rollers.

I hope some of this is helpful to you!

-Brian

Hey Brian,

Thanks a lot for the reply! I performed an entire PM service and went through everything on the Training Workbook. It ended up being a combination of things. I went through the guides and ended up soaking the L & M rollers to get a little bit more life out of them. They've far exceeded their lifecycle. The pinch roller adjustment had been set to run .012" wire in the back of the machine, I've been running .010". I've ordered new ones and it seemed to resolve the D-roller issue during the edgefinding cycle as well as the false wirebreaks. As for the lack of repeatability during edgefinding and the real wirebreaks I was experiencing, the silicon-covered cables attached to the upper head were corroded and not producing a ground when I tested it with a rod. A service tech was able to make it in and look over that entire assembly and get it up and running. Again, I really appreciate the reply and am putting the resolution on here so that hopefully it may help someone else out with the same issue.

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HELP! Makino Duo64 work pick-up tension/d-roller issue... false wire break alarm

amyjohnson

Plastic

Brian Pfluger

Cast Iron

amyjohnson

Plastic

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