gciriani
Materials
- May 5, 2004
- 52
In mass deburring, I try to predict the stock loss I need, by using as a proxy the material ratio curve of the surface roughness (Abbott Firestone curve), or BAC. I correlate the material loss to an approximation of the area below the BAC by using the DIN roughness parameters: Rpk, Rk, Rvk, MR1 and MR2. I’m having a hard time making the calculation when I incur in non-isotropic roughness (that is when roughness is different in different directions)
My approximation of the area below the BAC is the following
Area Roughness, AR = Rpk * MR1 * 0.5 + (MR1 + MR2) * 0.5 * Rk + Rvk * (1-MR2) * 0.5 + Rvk * MR2
AR approximates the area under BAC with 3 triangles and one rectangle whose sides are given by Rpk, Rk, Rvk, MR1 and MR2. However, if you look at this approximation in a volumetric way, it too simplistically implies that the part has roughness Rk etc in one direction, and is 100% smooth in the other perpendicular direction. Though inadequate it has given me some limited success in predicting for how long I need to keep my part in a centrifugal tumbler (CBF).
Let say that I start from AR = 10 and I know that my media can at most give me a finish of AR = 6. If after 10 minutes I am at AR = 9, I can infer that I need another 10 minutes to reach AR 8 and, another 10 to reach AR = 7 and so on. But as I said above the part is not smooth in the perpendicular direction, and I need to combine the two ARs (no pun intended).
Any suggestion on how to calculate a geometric 3D equivalent of AR, let say a Volume Roughness VR?
My approximation of the area below the BAC is the following
Area Roughness, AR = Rpk * MR1 * 0.5 + (MR1 + MR2) * 0.5 * Rk + Rvk * (1-MR2) * 0.5 + Rvk * MR2
AR approximates the area under BAC with 3 triangles and one rectangle whose sides are given by Rpk, Rk, Rvk, MR1 and MR2. However, if you look at this approximation in a volumetric way, it too simplistically implies that the part has roughness Rk etc in one direction, and is 100% smooth in the other perpendicular direction. Though inadequate it has given me some limited success in predicting for how long I need to keep my part in a centrifugal tumbler (CBF).
Let say that I start from AR = 10 and I know that my media can at most give me a finish of AR = 6. If after 10 minutes I am at AR = 9, I can infer that I need another 10 minutes to reach AR 8 and, another 10 to reach AR = 7 and so on. But as I said above the part is not smooth in the perpendicular direction, and I need to combine the two ARs (no pun intended).
Any suggestion on how to calculate a geometric 3D equivalent of AR, let say a Volume Roughness VR?