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Lapping with abrasives. What industries do it?

rmcphearson

rmcphearson

Hot Rolled
Joined
Jan 12, 2008
Location
Rochester, NY
What industries make use of lapping with abrasives and for what purpose?

I've used it to match valves/seats in small engines and I use it to maintain my reel mowers. Who else does it and why, specifically?

Thanks,
Roland
 
Anything that has to be finished to close limits. Gage blocks are always the first thing that comes to mind. Also things like hydraulic valves, pump bodies.
 
anything that needs the best precision possible. Hydraulic controls, including large earth movers to jet fighter jets. Many mechanisms that need to seal quickly and totally. Ring gages. Master disc Rings. Air Gage probes. Air Bearing fits for precision gages. Chemical mixing devices. Micrometer spindles and bearings. Granet surface Plates. Large Gate Valves. Angled Seat Valves. Paint gun nozzles. Fule Injector Seats and on and on and on.
 
Roller bearing outer races, reed valve seating areas (Curtis Air Compressor experience), RC engine cylinders, valves and seats, etc.. Too many more that I don't know about but basically anything that is very tight tolerance can use it.
 
optical transit, levels common to have tapered bearing. it gets lapped so female and male tapers match as well as seat that limits all weight locking the tapers together.
.
its fine enough i had to thin the lapping compound as it was too thick a paste to flow. when instruments tapped side to side holds position the tapers are lapped enough. usually magic marker it up and lap til its all showing even fit
 
Lapping dowel holes

rmcphearson said:
What industries make use of lapping with abrasives and for what purpose?

I've used it to match valves/seats in small engines and I use it to maintain my reel mowers. Who else does it and why, specifically?

Thanks,
Roland
Click to expand...
I always lapped the dowel holes in hardened tooling and die blocks for a light tap fit with a four ounce hammer. The closest tolerance job I ever worked on was .00005 gages. I hand lapped the special gages using a cast iron lapping plate. I still have the lapping plate. When I turned them in for inspection the inspector came to me and asked me how to measure the gages. I said your the inspector, his reply was I'll just send them back to you. So I went to Inspection with him and we measured the parts together. They passed!
 
Thanks again guys. Another question:
Are the grooves in lapping plates tapered/bevelled? I've never seen one in person. I imagine they are or at least there is a chamfer at the top corner to facilitate or draw the compound up to get between the plate and the workpiece. I can't find a good image of a cross section of a lapping plate.
 
The grooves catch the excess compound,
When you are lapping steel or iron the surface becomes flatter and harder, and it goes slower the further you lap as the piece work hardens.
When you want to cut fast, you have the lap wet with oil and the compound, but, a wet lap rolls up the edges.
So, when the work gets close, you let the lap get dry, or less wet. Then you finish and the edges get sharp, real cut you sharp.
When lapping a piece by hand on a plate, use a figure 8 motion and rotate the piece often in 1/4 turns, and try to work the piece over the entire plate, to help keep the plate flat.
 
no idea if its lapping, but i polish my car. also industial engines used to get lapped during break in by running them with an abrasive mixed into the lubricant (engine oil), no idea if thats done today, probably not needed.
 
Carbide inserts for aluminum cutting are often lapped.
Same with PCD segment tops.
Sometimes this lap is free abrasive flat and other times contained.
Is grinding with a 3000 grit wheel grinding or lapping?
Is removing .020 from 200 carbide inserts with 120 grit diamond on a Wolters in 5 minutes free abrasive slurry lapping or charged grinding?
And what about a Stahli that rotates the parts like a Speedfam or Woltres but uses diamond wheels for the top and bottom lapping plates?

If you polish flutes or chipbreakers with a nylon fiber PCD impregnated brush, lapping or just polishing.
If you do the same with a horsehair brush charged with diamond paste?
I guess this not lapping since there is no controlled "lap".
Bob
 
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