Design and Finite Element Analysis of a Hydraulic Pin-on-Disc Wear Testing Machine

Abstract

Wear is a leading cause of material loss and premature failure of mechanical components, and reliable laboratory wear testing is essential for selecting materials and coatings. This paper presents the design and finite element analysis (FEA) of a pin-on-disc wear testing machine in which the normal load is applied through a hydraulic cylinder instead of dead weights. The machine follows the configuration of ASTM G99 and is designed for a normal load of up to 200 N, a spindle speed of up to 1000 rpm, and a wear-track radius of 20–60 mm, using a ×10 mm pin against a ×165 mm hardened EN31 steel disc. Analytical design calculations give a nominal pin contact pressure of 2.55 MPa, a worst-case friction torque of 5 N•m and a required drive power of about 0.62 kW, which is met by a 0.75 kW motor with a variable frequency drive. A hydraulic cylinder of 25 mm bore reaches the 200 N test load at roughly 0.45 MPa and has a capacity of about 490 N at 1 MPa. Linear static FEA of the frame, loading arm, spindle and disc is used to verify structural adequacy, stiffness and safety factor. The results show that stresses and deflections remain far below permissible limits, so the structure does not compromise the accuracy of the wear measurement.

Introduction

The text presents the design and structural verification of a hydraulic pin-on-disc tribometer for studying friction and wear. Friction and wear are important because they strongly affect the service life, energy consumption, and maintenance cost of machines. Therefore, reliable and repeatable wear-testing equipment is needed.

The pin-on-disc test, commonly guided by ASTM G99, measures friction and wear by pressing a stationary pin against a rotating disc under a controlled normal load. Conventional machines generally use dead weights and levers, but these systems provide only stepwise load adjustment and require manual handling. The proposed machine replaces this arrangement with a hydraulic loading system, allowing smooth, adjustable, and potentially remote control of the test load.

Main design features

• Normal load: 10–200 N
• Spindle speed: 100–1000 rpm, controlled using a VFD
• Wear-track radius: 20–60 mm
• Maximum sliding speed: approximately 6.3 m/s
• Disc: hardened EN31 steel
• Spindle: EN8 steel
• Motor: 0.75 kW three-phase induction motor
• Hydraulic cylinder: 25 mm bore, requiring about 0.45 MPa pressure for the maximum load
• Friction measurement: load cell mounted on the pin arm

The design uses Archard’s wear law to relate wear volume to normal load, sliding distance, material hardness, and wear coefficient. For drive sizing, a worst-case friction coefficient of 0.5 was assumed. This produced a friction torque of about 5 N·m and frictional power of approximately 524 W, leading to the selection of a 0.75 kW motor after accounting for transmission losses.

Structural design and FEA

The frame and loading arm were designed to provide sufficient stiffness and minimize vibration and misalignment. Analytical calculations predicted a loading-arm bending stress of 8.63 MPa and a tip deflection of 0.029 mm.

Finite Element Analysis (FEA) was then performed to verify stresses and deflections in the frame, loading arm, spindle, disc, and pin. The FEA results were slightly higher than the analytical calculations because FEA accounts for local stress concentrations.

Conclusion

A pin-on-disc wear testing machine with hydraulic normal loading has been designed to the general practice of ASTM G99. A ×25 mm cylinder gives the required 200 N test load at about 0.45 MPa, with a capacity of about 490 N in reserve. Design calculations give a nominal contact pressure of 2.55 MPa, a worst-case friction torque of 5 N•m and a drive requirement of about 0.62 kW, met by a 0.75 kW motor with a VFD. FEA of the frame, loading arm, spindle and disc shows stresses far below the yield strength and a tip deflection of about 0.03 mm, confirming that the structure is adequate and will not affect measurement accuracy. Future work includes fabrication, calibration of the load cell and pressure transducer, thermal analysis of frictional heating, and validation of the machine against reference wear data for standard material pairs.

References

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Copyright

Copyright © 2026 Gautam Devidas Ingle, C. S. Padmavat, S. B. Janjal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.