Master Cylinder Piston – Case Study

Master Cylinder Piston – Case Study

The Challenge

A customer of ours was manufacturing master cylinder pistons made of 3415 case hardening steel using a Doosan Lynx 220-LSY CNC Lathe. The part required a surface finish of 12 Ra microinch (0.3 Ra) or better on the outside seal diameter. Before we got involved, the customer was sub-contracting another company to grind these parts down to achieve the required surface finish, since they could not achieve the correct surface finish using a turning insert.

Here was their original process:

  • Speed: 1900 RPM
  • Feed: 0.005”/rev (0.12mm/rev)
  • Finish achieved: 16-24 microinch Ra (0.4-0.6 Ra)

Our Solution

Once we assessed their operation, we recommended that they use an Elliott Tool Technologies S2488-00M Single Roll OD Burnishing Tool.

Here are the statistics of the new burnishing solution:

  • Speed: 1900 RPM
  • Feed: 0.0024”/rev (0.06mm/rev)
  • Radial load: 0.02” (0.5mm)
  • Finish achieved: 5-7 Ra microinch (0.12-0.17 Ra)

Final Results

The single roll burnishing tool produced a surface finish of 7 Ra microinch (0.18 Ra) or better. The parts could be made all in-house, eliminating the need for expensive sub-contracting to grind the pistons. The new process only required one set-up, saving our customer lots of time and money.