Grinding wheels for HSS

On Sat, 15 May 2004 21:48:26 -0700, "Harold & Susan Vordos"


Stellite is wonderful stuff - it grinds to a razor edge, it happily cuts at red heat and has extreme wear resistance. The few bits I own get more use than all the rest of my sizeable collection of carbide and HSS lathe tools.
The sad news is that the usual cutting tool grade is stellite 100 (Rockwell C62). Stellite 6 (Rockwell C42) is a hard facing grade for applications like guillotine blades where some hardness is sacrificed for more toughness and wear resistance. I've no information on the 98M2 grade.
In sorting thru junk piles Stellite is easily distinguished from HSS because it is totally non magnetic.
If you're lucky enough to find some stellite 100, Deloro recommend WA46J at 3,500 to 4,500 FPM for tool and cutter grinding. 8 deg front and side clearance, 12 to 20 deg top rake, nose radius 1/2 to 1/3 depth of cut. Grinding is slow because of the extreme wear resistance. It is not bothered by brazing temperatures so small chunks can be silver brazed to steel carriers to make stellite tipped boring tools or parting off cutters. EDM is the best way of slicing off custom sized chunks.
Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
big snip----

Absolutely true! Haynes Stellite is tougher at red heat than at room temperature.
Where have you located the cutting tool grade? I've not seen any Stellite cutting tools for sale from any of the supply houses. Could be I just don't know what I'm looking for, though. Sadly, about the time Stellite was really coming into its own, tungsten carbide, too, was being developed rapidly. I get the idea that the carbide insert concept was the winner, for obvious reasons (especially for NC or CNC applications, where you can replace a tip without losing orientation). That's a shame in a way, because there are applications where Stellite is superior to carbide.

As I said, I have no knowledge of the alloys, nor how they were to be applied. Ted, in particular, should be very pleased to hear what you had to say, considering his application choice for his Stellite 6 was in keeping with its design. His chisel seemed to benefit very well from his choice.

That's interesting, considering the information marked on the shanks I have are factory markings, but I am also aware that they are old stock, perhaps very old stock. In my mind, these go back to the late 50's, although I can't recall what lead me to believe that. As I said, I got them off ebay, and keep thinking that the seller had said that they had come from some old facility.

Interesting, the slower than normal surface speed for the wheel. Typical grinding is recommended at around 6,000 FPM. I think that speaks volumes about it's resistance to grinding, as you said. The slower speed would cause the wheel to act much softer than its rating. Someone running a faster wheel would be well off to use a softer grade, perhaps a G or H. That would be especially true if using a finer grit, which I am prone to doing. I prefer a 60 grit wheel for sharpening HSS toolbits. Cuts hotter, and somewhat slower, but I can grind tools with only one face, so they require almost no honing after shaping. The fine surface left by the finer wheel lends itself to better chip flow and a better looking tool in general.

HSS, too, lends itself to that very thing. I've even used silicon bronze filler to heliarc toolbits to shanks. Heat is not an object so long as you don't quench.
How I envy you your EDM! I'm stuck in the world of old technology, with a cutter grinder, and not much of one, available for such things. Better than nothing, but hardly an EDM!
Thanks for the great information, Jim.
Harold
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 16 May 2004 14:29:11 -0700, "Harold & Susan Vordos"

My small stock has been picked up at auto junk sales and model engineering shows - mostly as unidentified items mixed up with HSS tools. Stellite 100 items are usually marked as such.
My info comes from a very old (20y+) Deloro catalogue. Deloro is still very much alive and active but the emphasis now seems to be mainly on corrosion and wear resistant products as coating materials or investment castings.
A simple test to distinguish between the two types of products is to try machining it. Stellite 6 is machinable with the harder grades of carbide tips - Stellite 100 pretty much non machinable.
HSS is an alternative for brazed on tips but over enthusiastic brazing temperatures can come close to degradation of run of the mill HSS. High cobalt MoMax or M42 8% cobalt grades have a usefully larger temperature safety margin.
EDM is a very grand name for a jury rig spark eroder using a brass blade suspended from an old DC solenoid. It was done a very long time ago so details are a bit sparse. Power supply was about 80v fed thru a resistor and the solenoid coil to a stack of paper capacitors connected in parallel with the workpiece spark gap - can't remember how much - probably about 30uF. Workpiece was submerged in paraffin (kerosene) and current level was an amp or so.
Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.