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Easily grind on a CNC using electroplated wheels

Drip

Plastic
Joined
Apr 4, 2024
Location
Connecticut
Many shops don't have grinders, only CNC lathes or mills. I work as an application engineer for a small electroplated manufacturer and not a week goes by without me getting a request to grind on a CNC machining center. There are many reasons for these requests to grind - material type, accuracy, efficiency, etc. The beauty of plated wheels is that they don't require dressing, so they are easy to use on a CNC mill. Here are some of the things to pay attention to when grinding on a CNC:

Spindle speed - CBN electroplated works best at around 7000-8000 spfm, however, we have customers well below that who have had success. Diamond electroplated speeds are more forgiving - 4000-6000 sfpm generally is good.
Coolant - straight oil coolant is best for CBN, but water soluble will work. For electroplated diamond applications, water soluble is best
Finish requirement - Electroplated wheels generally give a rougher finish so oftentimes a rougher and finisher wheel is needed, but the cost of a strip and replate is only 60% of the cost of a new wheel so your abrasive costs, even with a two wheel setup, are low.

My intention would be to periodically post case histories. In the meantime, any questions, thoughts or comments will be answered promptly.
 
Can you show any examples of some grinding jobs done this way in a VMC? I have run into jobs where it could be a good solution, but the uncertainty factor has usually pushed us to go other directions.
 
Can you show any examples of some grinding jobs done this way in a VMC? I have run into jobs where it could be a good solution, but the uncertainty factor has usually pushed us to go other directions.
Yes, I willl post one or two in the next few days.
 
Another thing with electro plated wheels.
If you mount them indicated-in or dressed-in it is good to keep them on the original mount, and mark a line-up mark so they can go back on the spindle at the same 180/360(same place on a circle.)
 
Another thing with electro plated wheels.
If you mount them indicated-in or dressed-in it is good to keep them on the original mount, and mark a line-up mark so they can go back on the spindle at the same 180/360(same place on a circle.)
At mounting good to indicate to <.001 if you can..*(that is pretty easy)
For a production part two wheels is best so you are down waiting.
 
Another thing with electro plated wheels.
If you mount them indicated-in or dressed-in it is good to keep them on the original mount, and mark a line-up mark so they can go back on the spindle at the same 180/360(same place on a circle.)
The key to making plated work best is to run with as little runout as possible, so you make a good point. It's always good practice to indicate a plated wheel to .0005" runout max.
 
Are custom shape plated wheels available for grinding HSS dry? Can someone make a wheel blank and have it plated? What material works well for a wheel blank?
Apologies in advance for all the questions but......
 
Are custom shape plated wheels available for grinding HSS dry? Can someone make a wheel blank and have it plated? What material works well for a wheel blank?
Apologies in advance for all the questions but......
Plated wheels can be used dry but not recommended. Oil is best, water soluble next, and for very light stock removal with a small area of contact (like a mtd pt for deburring) you can use plated wheels dry. Plated blanks can be made and sent in for plating only, yes. Best material to use for a blank is 4140 steel. It's the standard.
 
What method of plating do you use? I used to get a bunch of blanks I made plated with diamond in a high vacuum chamber. As for stripping, I quit having that done as it does remove some of the blank, I would just make plenty of blanks and toss them when they wore out.

Keep in mind the way cover seals on VMCs are NOT designed for grinding swarf, and neither are the coolant systems as they lack filtering.
 
The method of plating we use is not in a high vacuum chamber. That utilizes braze. It's more expensive and is extremely limited in it's use. We use standard electroplating. We can get 10-15 replates on average from a blank. Our method of stripping removes no blank material. Grinding swarf would be a problem on a VMC if you were using the VMC for only grinding and if you were using it with a conventional vitrified wheel. What we are talking about in this thread is using a CNC mill for small runs of precision grinding with one layer of CBN or diamond, both of which wear attriciously. You are correct, though, the ground chip is smaller than what you get with a cutting tool so the coolant needs to be filtered correctly to protect the weighs etc. I will be commenting more on this subject so I'm glad you brought it up!
 
Keep in mind the way cover seals on VMCs are NOT designed for grinding swarf, and neither are the coolant systems as they lack filtering.

People have been afraid of grinding in standard CNC mills for years, but AB Tools sort of opened the path for a bunch of folks to start doing it once they demonstrated that many of their tools are ground in standard Haas (!) VMCs with no real ill effects over time.

There are about half a dozen customers in my region grinding on Speedios now. Not Brother recommended or anything, but it isn't like the Speedio Police are going to bust down your door. Everything from very high-end knife blades, to weirdo materials for fusion reactors, to Inconel nozzles for high pressure liquid injection into a combustion chamber.

One customer was originally very particularly concerned about protecting the ways on their M series 5 axis, and started working with vendors to cook up an elaborate multi-stage filtering setup with a price tag of well over $50k. I asked our service guys to write them a quote for full ball-screw and linear guides for X, Y, and Z (the A and C rotary have positive pressure, as does the spindle, so relatively immune from grinding sins).

Total Cost (freight, install, parts): $23k.

They decided not to buy the elaborate filtering system and have been grinding crazy materials in the machine since, with zero evidence of ill effects.
 
Yeah, I am aware of what AB Tools does, and that they send their rotaries in for rebuild every 3 to 4 years, and replace screws at regular intervals, which sounds like they do experience ill effects over time to me. I machined ceramics, quartz, and stone with a VMC for 19 years, with the last 15 using the same machine with zero issues related to what I was machining. My multi-stage filtration system cost around $400 so it can be affordable if you are willing to do a little work yourself. I filtered to sub-micron, if you wanted to stop at 20 microns you could nix $100 off that. When I filtered to 20 microns I would have to replace the ceramic seal in my coolant pump every year, once I started filtering to sub micron it was still working fine when I nixed that line of work 11 years later. There were many other benefits to the extra filtration too, I found it to be well worth the little bit of extra work. I made about 200 gallons of fines mud a year and cleaned the 20-micron filters every year or two and the 1-micron filter around every 6-9 months so the maintenance wasn't bad. How old the cartridge filters were and how they were prepped after washing made a big difference in how long before the flow decreased enough to make me clean them. If I wasn't machining so much calcium carbonate I think the filters would have lasted much longer.

I can't imagine grinding on a metal cutting machine without any type of bag or cartridge filtration, the cost to benefit ratio is just soooo lopsided. But then I also feel the same about metal cutting chips. Being a home shop with limited space I made a custom coolant system for my last machine when I got it, there was just no room for the 80 gallon tank in my shop. It uses two coolant tanks with a cheap bag filter between them. The coolant and chips come out of the machine, most chips are caught here and the coolant and fines get pumped into the filter which drains into a holding tank. Perfectly clean coolant goes to the machine so no issues with chips in my LocLine valves and anti-backflow valves, AND ZERO FINES TO DEAL WITH IN MY COOLANT TANK!!!! The $7 bag lasts a few months and takes 5 minutes to change, way less trouble than cleaning the fines out of my Brother's tank :ack2:
 
Yeah, I am aware of what AB Tools does, and that they send their rotaries in for rebuild every 3 to 4 years, and replace screws at regular intervals, which sounds like they do experience ill effects over time to me. I machined ceramics, quartz, and stone with a VMC for 19 years, with the last 15 using the same machine with zero issues related to what I was machining. My multi-stage filtration system cost around $400 so it can be affordable if you are willing to do a little work yourself. I filtered to sub-micron, if you wanted to stop at 20 microns you could nix $100 off that. When I filtered to 20 microns I would have to replace the ceramic seal in my coolant pump every year, once I started filtering to sub micron it was still working fine when I nixed that line of work 11 years later.

I did neglect to mention that pretty much everyone grinding in our machines has bag and/or cartridge filters, but only down to 10 microns. Not huge success finding coolants that can filter down beyond that without stripping, though options are out there. Everyone seems happy at 10 and nobody seems all that keen to go down a coolant rabbit hole to go beyond that.

Should also note that unlike AB who is grinding carbide, all day the processes happening on the fleet up here are a small part of the overall use case. 99% of the material removal is traditional machining/turning, with grinding happening on critical surfaces as basically a super-finishing operation. Complicates the filtering a bit as we still need to deal with regular chips. They also all go into it knowing sure, you might need new ball screws in 4-5 years...

But the cost/process savings are so absurd compared to specialty grinding equipment that it doesn't matter. Grinding in-machine is just a tool in the turret and another operation vs. buying an expensive specialty machine, setting it up, moving the parts over to it, the floor space, training, etc etc.
 
I did neglect to mention that pretty much everyone grinding in our machines has bag and/or cartridge filters, but only down to 10 microns. Not huge success finding coolants that can filter down beyond that without stripping, though options are out there. Everyone seems happy at 10 and nobody seems all that keen to go down a coolant rabbit hole to go beyond that.

Should also note that unlike AB who is grinding carbide, all day the processes happening on the fleet up here are a small part of the overall use case. 99% of the material removal is traditional machining/turning, with grinding happening on critical surfaces as basically a super-finishing operation. Complicates the filtering a bit as we still need to deal with regular chips. They also all go into it knowing sure, you might need new ball screws in 4-5 years...

But the cost/process savings are so absurd compared to specialty grinding equipment that it doesn't matter. Grinding in-machine is just a tool in the turret and another operation vs. buying an expensive specialty machine, setting it up, moving the parts over to it, the floor space, training, etc etc.
I understand that how much grinding you do will affect how much filtration capacity you need. If you only do a little then you don't need much, but I think you will still want it, I know I would. Hell, I only machine metal and plastic right now and want it. If you don't filter the fines out they will circulate in your coolant for quite a while. Our VMC coolant systems are turbulent enough that the fines won't settle out until we stop running the coolant overnight. At least run your coolant from the pump through a bag filter. It is low pressure so the housing can be cheap. You may need a better pump but that isn't too hard to fix. If doing any grinding it would be hard to not justify the trouble. If the company is too big to have any common sense then fine, they can afford the maintenance. Those of us who are a bit cheaper at heart may want to do something to protect our equipment. You know, spend $200 to make your waycovers, screws, and ways last longer.

For those interested contact your coolant mfgr to find out how fine you can filter it first. I use Trim 580xt and can go down to 25 microns.
 
I understand that how much grinding you do will affect how much filtration capacity you need. If you only do a little then you don't need much, but I think you will still want it, I know I would. Hell, I only machine metal and plastic right now and want it. If you don't filter the fines out they will circulate in your coolant for quite a while. Our VMC coolant systems are turbulent enough that the fines won't settle out until we stop running the coolant overnight. At least run your coolant from the pump through a bag filter. It is low pressure so the housing can be cheap. You may need a better pump but that isn't too hard to fix. If doing any grinding it would be hard to not justify the trouble. If the company is too big to have any common sense then fine, they can afford the maintenance. Those of us who are a bit cheaper at heart may want to do something to protect our equipment. You know, spend $200 to make your waycovers, screws, and ways last longer.

For those interested contact your coolant mfgr to find out how fine you can filter it first. I use Trim 580xt and can go down to 25 microns.
I'd love to see your setup.

I make a lot of fines apparently, and haven't figured out how a good filter system would work. I'm not that smart I guess! When I looked even the filter material was over $400 so I was clearly looking at the wrong things?

I run oil... so I suppose I can go as fine as is affordable?

I'm running a job right now that would be a fantastic job to dust the finish passes using grinding as endmills like to SING.
 
Many shops don't have grinders, only CNC lathes or mills. I work as an application engineer for a small electroplated manufacturer and not a week goes by without me getting a request to grind on a CNC machining center. There are many reasons for these requests to grind - material type, accuracy, efficiency, etc. The beauty of plated wheels is that they don't require dressing, so they are easy to use on a CNC mill. Here are some of the things to pay attention to when grinding on a CNC:

Spindle speed - CBN electroplated works best at around 7000-8000 spfm, however, we have customers well below that who have had success. Diamond electroplated speeds are more forgiving - 4000-6000 sfpm generally is good.
Coolant - straight oil coolant is best for CBN, but water soluble will work. For electroplated diamond applications, water soluble is best
Finish requirement - Electroplated wheels generally give a rougher finish so oftentimes a rougher and finisher wheel is needed, but the cost of a strip and replate is only 60% of the cost of a new wheel so your abrasive costs, even with a two wheel setup, are low.

My intention would be to periodically post case histories. In the meantime, any questions, thoughts or comments will be answered promptly.
Do you have any wheels or have any success grinding depths on cnc machines, aka facing with a cup wheel?
 
My experience facing hard stuff such as granite and porcelainized ceramics was that single-surface diamond tools quit working very quickly. It seems that the sharp points on the crystals were quickly ground off leaving flats that didn't cut well. For facing I used sintered diamond tools and dressed them as needed.

I shut down the custom switchplate side of my business in 2019 but will see if I have enough photos to show what I did. If nothing else I can show the coolant system I have on my Kitamura where I run all of the coolant through a bag filter before it goes into the storage tank. Think centralized coolant for one machine. I am too far behind on a job right now but will create a new thread showing what I can on this. If nothing else it is good food for thought.
 
People have been afraid of grinding in standard CNC mills for years, but AB Tools sort of opened the path for a bunch of folks to start doing it once they demonstrated that many of their tools are ground in standard Haas (!) VMCs with no real ill effects over time.

There are about half a dozen customers in my region grinding on Speedios now. Not Brother recommended or anything, but it isn't like the Speedio Police are going to bust down your door. Everything from very high-end knife blades, to weirdo materials for fusion reactors, to Inconel nozzles for high pressure liquid injection into a combustion chamber.

One customer was originally very particularly concerned about protecting the ways on their M series 5 axis, and started working with vendors to cook up an elaborate multi-stage filtering setup with a price tag of well over $50k. I asked our service guys to write them a quote for full ball-screw and linear guides for X, Y, and Z (the A and C rotary have positive pressure, as does the spindle, so relatively immune from grinding sins).

Total Cost (freight, install, parts): $23k.

They decided not to buy the elaborate filtering system and have been grinding crazy materials in the machine since, with zero evidence

Do you have any wheels or have any success grinding depths on cnc machines, aka facing with a cup wheel?
Yes, I would need more specifics as to your particular job, but we do have customers using cup wheels for facing. Important information needed would be wheel size, doc, total stock, etc.
 
Plated wheels can be used dry but not recommended. Oil is best, water soluble next, and for very light stock removal with a small area of contact (like a mtd pt for deburring) you can use plated wheels dry. Plated blanks can be made and sent in for plating only, yes. Best material to use for a blank is 4140 steel. It's the standard.
One other interesting fact that some people may not know...some skate sharpening machines use electroplated CBN wheels dry and a product called the Drill Doctor, for home sharpening drills, also uses CBN electroplated wheels dry.
 








 
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