Can I surface grind a piece of tool steel with carbide brazed on it

bmklawt · Jan 25, 2021

I've only done surface grinding way back in shop class and although this may be a simple question I don't know the answer.
If I have a piece of flat tool steel with a piece of carbide brazed in it can I surface grind the the whole piece flat. The picture shows the carbide piece in red and the red arrow shows the surface I want to grind.

Your help is greatly appreciated,
Bruce

CarbideBob · Jan 25, 2021

So you want to grind the HSS and the carbide?
Regular stone surface grinding wheels will get very unhappy when they hit the carbide, as in very unhappy.
Diamond wheels will not like the HSS much but can be made to work, sort of an art, the right wheel bond and lots of coolant.
CBN resin bond wheels will cut both to some extent but still flood coolant.

How much do you want to remove? How big is it? Drawing does not say 1 inch or 3 feet long.
If normal sized I'd just stick it on the Blanchard with a diamond wheel and live with the the high wheel wear cost if only .005-.020 to be taken off since it looks to be nice and flat.
I light grind steel even dead soft 4140 with a diamond wheel on such just because the wheel change time is more expensive than the diamond lost.

Doing one and doing 1,000 become different attack strategies.
There is green wheels but I just so hate those things.
Bob
(Since I do this maybe I could help a Michigan member)

michiganbuck · Jan 25, 2021

Like bob said when an aluminum oxide wheel contacts carbide the carbide acts like a dresser and wears away the wheel, not the carbide.
A diamond wheel will grind both steel and carbide but will be slow and cause a lot of wear to the diamond wheel,
A green wheel will grind both steel and carbide but may not give the keenest edge on the carbide. I also don't like a green wheel for this kind of job.

With the SG you might best use an aluminum oxide wheel to get the steel flush with the carbide and then grind a little more with a diamond wheel. Grinding with coolant best when using the diamond wheel.
If the carbide is highest then diamond wheel down to the steel, and continue to grind a little steel.

Oh, and grinding or rubbing carbide with aluminum oxide will cause a lot of heat perhaps cracking the carbide or melting the braze holding it.

*If you had to grind .003 off that side and used a diamond wheel perhaps 100-120 or 220 grit diamond with using coolant it would be an ok job, but slower than you would grind just steel with an AO wheel. A 320 diamond wheel would be very slow. With any of those wheels grinding dry would overheat and be very slow.

Use strip braze cut to about exact size, flux, and a small sliver of silver, you can expect the braze height to be very constant (I think .005 but forget for sure) Once you get the braze height mastered you can braze and get only .002 of carbide to grind.

Water boil the brazed parts so that will remove the rock hard braze flux so you don't have to grind it off. (that boil will blacken the steel)

I would leave a little space at the sides of the carbide to fill with braze.

Make cherry red till the carbide seems to be floating, slide it a little, then hold it in place and take heat away to cool.

Don't get any fingerprints on the carbide, the steel, or the braze -> or it may not stick.

Bruce, will this be a one up/few up of a production job?

Carbide comes in different grades for cast iron/steel or aluminum. The cast-iron grade for wear resistance and a shock resistance/ the steel and aluminum grade for cutting steel or aluminum.

I would grind that carbide angle first with just the diamond wheel.

stephen thomas · Jan 26, 2021

I do it.
As everyone else has said it can be hard on your diamond wheel.

Back in the early daze of eBay one of my kid brothers bought me a DoALL D1030 for $50 at a HS shop auction. Looking online, 10 x 3 (hole) size wheels were cheap then because few small shop or hobbyists use them. So i stocked up on some Norton diamonds.
Among other things, i brazed 1-1/4” wide C2 to mild steel shanks for hand scraper insert blades & ground them all down flat to fit the handles & thin the carbide for spring & ease of sharpening.

With the increased presence of chinese tooling, new diamnod products are ever cheaper today. Still, if you have to pay new and hope to do this on a production basis it will be important to experiment & dial in the parameters of feeds, speeds, coolant, diamnond grit & matrix, etc or the cost per part could be high. If you merely want to do a few pieces and your dimond wheels are on hand for general purpose it will work fine. (It/grinding steel can ruin the dress if the wheel is square & true).

Use flood coolant & don’t crowd the wheel.

If it’s not clear, it is the steel, not the carbide that eats the diamonds. The diamonds (pure carbon) dissolves in hot steel.

Smt

bmklawt · Jan 26, 2021

The knife is 3" X .750 X .300,all I am allowed to say is the knife is off an extruder, there are 10 extruders with 4 blades each and they need to be ground down anywhere from .002 to .040 to get the knife edge back every day, very abrasive stuff. I thought about just solid carbide blades but the way the height is adjusted the carbide would snap when tightened down.
maybe I need to explore putting an insert into the knife

Milland · Jan 26, 2021

bmklawt said:
maybe I need to explore putting an insert into the knife

That sounds like a good plan. You could look at coatings too, depending on the abrasive nature of whatever you're cutting the right coating could really help.

michiganbuck · Jan 26, 2021

Is the sketch close to size, perhaps 7" long- 1 1/2" tall - 1/2 wide?
Are you looking for a blade design to use .. or is it a blade design to market?
Do you normally break or dull blades?
what material are you cutting?
Is it a high-speed whacking if the material it cuts..or just a flow feed of material?
You can private message me if this is secret.

CarbideBob · Jan 26, 2021

.040 is a lot.
Can it be taken less if both sides ground back? The flank wear maybe .040 but not so much if the front ground also?
Fourty thou flank wear is usually only a few thou. up front.
Replaceable insert design an option if usage high enough for a special one off insert. These are not cheap in 1 to 10s. Think 100 to 250 piece buys at the bottom.
Many ways to skin the cat and not enough information to give a good suggestion.
Along with Buck who is so way knowledgeable you can PM me anytime.
Not sure if I can be of any help here but it is sort of in my world and have a file cabinet full of "do not talk, do not tell" papers if that a concern.
Much more than the file cabinet done on a handshake or known as do not screw the customer.
For sure I may be no help at all as a supplier but always willing to toss out some ideas for free.
Bob

michiganbuck · Jan 27, 2021

Taking off the side it would be easy to surface grind the steel on both sides of the carbide with an AO wheel and then bring the carbide to flush the steel with the diamond wheel.
But .04 is a lot to take with each sharpening so that would reduce the width to waste the blade in only a few sharpenings. A carbide adjustable blade perhaps dovetail to the backside so being able to adjust upward so grinding only off the top and with not grinding steel.
Like bob said these would be very expensive in a few-up so finding an existing blade to use or one near size to alter would be best.
Barber Colman, Madison, Prat, Wetmore, are a few of the adjustable reamer manufacturers that made thin blades that can be modified to fit another purpose...or the cutter can be altered to fit the blade.

Carbide blanks can be bought, perhaps 3/32 x 3/8 x 6" long that can be easily parted to a needed length and even angled (for dovetail) at the side with only using a surface grinder., using a type I (common)diamond wheel.

Dovetail easily made to carbide with a surface grinder and a simple angled set of steel angled block-in blocks,

CarbideBob · Jan 27, 2021

A close up picture of the ".040" worn tool area might be helpful and not reveal any secrets.

Diamond wheels from China can be great and they can be terrible. Not so much badly made as badly matched to the job.
I have bought USA made diamond wheels from McMaster needing something overnight. They were shit and sit on the shelf with this note. "Emergency use only, no cuttie. Stick every part"
These made by a very good US maker but all so wrong for my uses. They must work for somebody but not me.
Herein lies the world of diamond grinding wheels. If you think carbide grades confusing or hard to match to a job .... this is much worse.
The wrong wheel and you will fight or go so slow. The right wheel to match your use and you don't know why people have a hard time, this is so friggen easy.
I hate grinding steel. I can peel off carbide at much higher MRR rates but that is because of many years of working it and not so much in HSS.

You say the body/shank is tool steel and needs to be adjusted. Is it some real high hard HSS or a more normal and very soft and flexible thing?
Dead soft 4140 is a "tool steel".
Seems you need to bend it for size control. I do know how the jacking, wedge or size shim is done but the fact that solid carbide seems bad says a bit.
Even without the flex you do not want to buy this in solid carbide if your volumes not very high, as in many thousands per year.

From the start it seems that you want to do this in house. I do so much love that and maybe we have tossed out somethings that will help you.
Bob

implmex · Jan 28, 2021

Hi All:
Would I be making a complete asshole of myself if I said to just set it up on the wire EDM?
That's the easiest way to solve the problem that I can think of, but it's useless advice if you don't have access to a wire.

This would not be a very expensive job, so would you consider just farming it out?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

CarbideBob · Jan 31, 2021

implmex said:
Hi All:
Would I be making a complete asshole of myself if I said to just set it up on the wire EDM?
That's the easiest way to solve the problem that I can think of, but it's useless advice if you don't have access to a wire.

This would not be a very expensive job, so would you consider just farming it out?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Skimming the top only .010-.040 as marked of on a part this long on a EDM would not be cheap?
I'll take your EDM and ante up a Blanchard if more than one part.

The OP seemed to be thinking wear land removal as a top grind alone.
Unless some real reason for this which I do not see that a big mistake but I have not seen a worn tool so maybe not right.

If the OP has never done such grind there is a real tough learning curve. But if it a large repeat it can be worth the time and wheels invested.
I do not think that there is "right" way to do this, many options, costs, delivery, tooling, equipment on hand.

Hopefully the OP will come back with what done and working for him. I hate to see questions and then go away. Once asked you are in.
Bob

michiganbuck · Jan 31, 2021

The red arrow side would be more of a challenge than grinding the narrow side, there at the narrow, a bench grinder could expose the carbide, and then the carbide easily ground with a surface grinder or even a carbide grinder.

On the red arrow side, an AO wheel on the SG could grind away the steel and then a diamond wheel gring mostly just carbide.

Yes, I would use a wet diamond wheel.

Hodge · Jan 31, 2021

I used to rework/grind chucker form tools with carbide inserts. Form tool itself was carbide. Top of tool carbide and steel. After grinding form back to a good edge tool had to be flipped up and top ground. Always used diamond wheel. Biggest issue was keeping a tight radius on the corner of the wheel. Had to keep the radius tight for proper chip breaking. I always kept a finger brake diamond dresser close at hand and thus kept a proper radius and clean grinding face. Even using a diamond wheel in this manner they will last a long time.
Hodge

Trueturning · Feb 1, 2021

michiganbuck said:
Like bob said when an aluminum oxide wheel contacts carbide the carbide acts like a dresser and wears away the wheel, not the carbide.
A diamond wheel will grind both steel and carbide but will be slow and cause a lot of wear to the diamond wheel,
A green wheel will grind both steel and carbide but may not give the keenest edge on the carbide. I also don't like a green wheel for this kind of job.

With the SG you might best use an aluminum oxide wheel to get the steel flush with the carbide and then grind a little more with a diamond wheel. Grinding with coolant best when using the diamond wheel.
If the carbide is highest then diamond wheel down to the steel, and continue to grind a little steel.

Oh, and grinding or rubbing carbide with aluminum oxide will cause a lot of heat perhaps cracking the carbide or melting the braze holding it.

*If you had to grind .003 off that side and used a diamond wheel perhaps 100-120 or 220 grit diamond with using coolant it would be an ok job, but slower than you would grind just steel with an AO wheel. A 320 diamond wheel would be very slow. With any of those wheels grinding dry would overheat and be very slow.

Use strip braze cut to about exact size, flux, and a small sliver of silver, you can expect the braze height to be very constant (I think .005 but forget for sure) Once you get the braze height mastered you can braze and get only .002 of carbide to grind.

Water boil the brazed parts so that will remove the rock hard braze flux so you don't have to grind it off. (that boil will blacken the steel)

I would leave a little space at the sides of the carbide to fill with braze.

Make cherry red till the carbide seems to be floating, slide it a little, then hold it in place and take heat away to cool.

Don't get any fingerprints on the carbide, the steel, or the braze -> or it may not stick.

Bruce, will this be a one up/few up of a production job?

Carbide comes in different grades for cast iron/steel or aluminum. The cast-iron grade for wear resistance and a shock resistance/ the steel and aluminum grade for cutting steel or aluminum.

I would grind that carbide angle first with just the diamond wheel.

No surprise from me that you know this all in and out. I always will take a question like that and ask, “why in heck would you need to do something like that?

After that comment I would want to go fishing instead.

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Can I surface grind a piece of tool steel with carbide brazed on it

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