bearing area ratio

[dho]

the requirement:
Ra 2 to 4 microiches
Rz 40 micorinches max
Rp 8 microinches max
bearing ratio, shall be 70 - 90% when measured at a depth P = 0.25 Rz.

where/how i interpret the attached measurement about bearing area ratio?
thanks.

 

[MikeHalloran]

1. Read the book that came with the machine that printed the tickets you provided.
2. Ask whoever issued 'the requirement' for references or sources of instruction.


Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

what the heck are we talking about ?? Al ? Steel, composite ??

another day in paradise, or is paradise one day closer ?

 

[dho]

it is about surface roughness. no mater AL or steel.
BEARING, bears, supports. not ball BEARING.

 

[MikeHalloran]

I'm GUESSING that the 'bearing area' refers to the proportion of solid material to air at 1/4 of the Z depth of the surface, referring to a traditional profilometer plot. I.e., 'just' draw a line at 1/4xRz on the profile plot, then measure the axial length of the plot that's above the line and the length that's below the line, and report the ratio as a percentage.

One problem with that conjectural interpretation is that the result is not really a percentage of area, since you would be working with what is effectively a cross section profile of the surface, so the result would be a percentage of lengths.

One other problem is that the instrument you are using does not produce a profile plot.

Maybe it does so internally, and does all the measuring internally, and reports the measurement you seek as a number, but I can't tell.

... because you haven't even done us the simple courtesy of identifying the instrument you are using, so we could seek out the manual and read it for ourselves.



Mike Halloran
Pembroke Pines, FL, USA

 

[dho]

as i saw, most bearing area ratio curve plotted MR to Rt. the requirement is to Rz. so i was wonder if there is a machine, 2, or it can be interpreted from Rt to Rz (even i think not), 3, or the requirement is wrong.
thanks.