How to lap the seal faces with simple and cheap equipment 1

[atpcoltd]

Hi,
Please help me and let me know ,is there any way to do lap on the seal faces with silicon carbide or tungsten carbide material ,with no exact lapping machine or not ,if so please let me know the equipment we should find.

Thanks and Best Regards.

 

[JJPellin]

For many years, it was common to hand lap faces on an as-needed basis. We still have the equipment we used for this. It consists of a cast iron lapping plate with a deeply cut, cross-hatch pattern on the surface. The plate is precisely lapped flat on an industrial lapping machine. The cast iron plate is "charged" with diamond lapping compound using a small roller. This embeds the diamond particles into the cast iron. The excess is wiped off. The seal face is placed on the lapping plate, face down. The seal face is moved about the plate, with no downward pressure. I usually move it in an alternating figure-8 pattern. Tungsten Carbide takes quite a while to lap this way. Silicon Carbide takes even longer. A skilled technician can lap a face using this method to within 3 helium light bands.

Johnny Pellin

 

[atpcoltd]

Dear JJPellin's :

Thanks of your recommend for the cast iron plate ,actually we have made a cast iron plate size 500mm and thickness of this plate is 40 mm and we send it to a factory and they grinding both sides ,now we are going to send it for making some cross hatch pattern ,but we do not know the sizes of these pattern we have to make on it ?
Could you please let me know size of deep of serrations on working surface?
and if we make the spaced at 25 mm is it good ?
if not please let me know which size should i chose ?
Thanks in advanced

 

[JJPellin]

I do not know what the ideal depth and spacing of the grooves should be. But, I can describe the grooves in my lapping plate. My plate has grooves that are approximately 2 mm wide by about 2 mm deep. They are spaced about 10 mm between grooves. The two sets of lines are not at a 90 degree angle. They are at about a 60 degree angle. So, the small lands formed by the grooves diamond shaped with the points of the diamond having and angle of about 60 degrees and the sides of the diamond having an angle of about 120 degrees.

When I answered the original question, I was not expecting you to construct a lapping plate from scratch. They can be purchased as a complete unit, ready to use. But if you are determined to make your own, this pattern should work.


Johnny Pellin

 

[CHoff07]

I'm skeptical of the "flatness" of the lapping plate you'd be able to make in the shop without prior experience. Your milling table may be flat but flat enough to achieve 2-3 He light bands, I doubt it.

If your homemade plate does not give you the results you're looking for I suggest contacting a company like Lapmaster to see if you can buy just a plate for hand lapping. I'm not affiliated with them but I am aware of a major seal manufacturer that uses their products.
As for cost, I have no idea.