The Identification of an Adequate Stressing Level to Find the Proper Running-In Conditions of a Lubricated DLC-Metal-System

Joachim Faller,Matthias Scherge

doi:10.3390/lubricants8090088

Joachim Faller, Matthias Scherge

Open Access

https://doi.org/10.3390/lubricants8090088

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Abstract

Using a tribometer equipped with a high-resolution wear measurement unit (RNT), the running-in of a diamondlike carbon (DLC) iron spray coating contact was analyzed and optimized. The optimization comprised an initial parameter field with different load and speed levels to find key operation points. These points were used to compose a dedicated running-in parameter field. The analysis underlined the importance of identifying the adequate stressing conditions. With respect to our concept of the running-in corridor, a high-power running-in has to be preferred to obtain a tribological system with low friction, small total wear and wear rate, high system stability, and low sensitivity to external changes.

Highlights

There is no straightforward path to identify running-in procedures in order to ensure excellent tribological performance during the lifetime of mechanical systems such as combustion engines, gear boxes, compressors, or pumps [1,2,3,4]
The measurements were performed using a flat pin made of iron-plated aluminum and a steel disk coated with diamondlike carbon (DLC)
The following approach to receive a running-in with the conditions described above can be deduced:

Summary

Introduction

There is no straightforward path to identify running-in procedures in order to ensure excellent tribological performance during the lifetime of mechanical systems such as combustion engines, gear boxes, compressors, or pumps [1,2,3,4]. It is necessary to analyze and understand the very first minutes or hours of operation to come up with a sound recipe for a controlled running-in. To reach this goal, high-resolution and real-time friction and wear tests have been performed using the lubricated pairing of iron-plated aluminum versus diamondlike carbon. The technical term ”running-in“ describes the first stage in the lifetime of a tribological system, and is connected with the expectation that friction and wear rate rapidly develop low and constant values as required for modern lubricated systems. For example, gearbox applications are in focus, a steady coefficient of friction of 0.08 and a wear rate of more than 100 nm/h do not characterize the running-in as successful

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