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Lecture

Tailoring friction and wear by laser microstructuring of automotive components

Tuesday (23.06.2020)
17:20 - 17:40 Room 2
Part of:


Today’s currency in traffic and transportation is carbon footprint. Thus, R&D focusses on reduction of friction. Additional research points to other environmental burden like lubricant savings. Tribological systems consist of two partners and a lubricant. Targeted manipulation of one partner’s surface leads to different tribological interactions. This paper presents an overview of various results of tribology-related industrial research activities, namely laser microstructuring. Well-engineered systems may energetically profit from modifying friction and wear related characteristics of their communicating surfaces by generating micro-scale structures. Laser structuring enables micro-scale modification of permanently strained powertrain components without influence of their macroscopic functionalities like sealing or heat dissipation. Various effects of microstructures are addressed: dimples as lubricant reservoirs, as generators of hydrodynamic effects or for surface wetting; vectored structures with lubricant channeling functionalities. The surface treatment family “laser texturing of tribologically interacting components” is characterized by its consequent concentration on (ultra)short-pulsed laser systems. Using longer-pulsed lasers typically result in non-avoidable thermal effects like burr, hardening, chipping, which contradict the desired behaviour. Additionally, some commercial established wavelengths lead to insufficient absorption when applied in the form of longer pulses. The use of (ultra)short pulses and/or shorter wavelengths significantly broadens the addressable spectrum of base and coating materials. Applying focussed laser pulses with durations of 500fs up to 10ps even to brittle materials leads to the generation of structures without burr and with defined, tightly tolerated depth. Tailoring diameter, depth and layout is based on the respective application and desired functionality. As an example, piston rings coated with diamond-like carbon coating were functionalized with a dimple grid or with a functional circumferential groove. This maintains the sealing characteristics of the piston ring, but reduces friction up to 25% by generating a hydrodynamic effect. Other components with slide contact functionalities can be functionalized as well. Another application is the replacement of conventional slide bearing in heavy machinery with the demand of recurring lubrication by laser structured ceramic bearings with lifetime lubricant reservoir.

Speaker:
Dipl.-Ing. Thomas Kuntze
Fraunhofer Institute for Material and Beam Technology IWS Dresden
Additional Authors:
  • Volker Franke
    Fraunhofer IWS
  • Leon Streit
    Fraunhofer IWS
  • George Pätzold
    Fraunhofer IWS

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