P. Mattfeld

Analysis of the Velocity Distribution of an Elliptic Surface Structure Manufactured by Machine Hammer Peening

Machine hammer peening (MHP) is an incremental forming process for surface structuring of technical workpieces or tools. Currently, MHP strongly attracts the attention of automotive and toolmaking industry. Recently performed research showed improved tribological characteristics in lubricated deep drawing in terms of a reduced friction coefficient due to a lubricant pocket effect and a reduced contact area. In order to design the MHP process to obtain an optimized load capacity of the fluid film, the velocity distribution has to be analyzed. Thus, an analytic approach for solving the Reynolds equation as a valid simplification of the Navier–Stokes equations for an elliptic geometry of a MHP structure is proposed in this work. The research assumes stationary hydrodynamic lubrication and is restricted to the longitudinal properties. Thereby, the influence of the structure geometry, the fluid film thickness, the sliding velocity and the dynamic viscosity on the fluid velocity distribution is researched by means of an analytic solution of the Reynolds equation. The derived formula is applied to contribute to the understanding in lubricated deep drawing with MHP structures, but is also transferable on further sliding contacts, e.g. bearing lubrication.

Evaluating the substitution risk of production systems in volatile environments

Today’s manufacturing companies are confronted with key challenges such as an increasing individualization and shorter product life cycles. Production systems are to be made resistant to substitutions in order to secure sustainable competitive advantages in such a volatile market environment. A production system runs at risk of being substituted if an alternative production system exists, which is at least equivalent in terms of economic, ecologic, social, and technological criteria with respect to current as well as possible future product programs. The research presented in this paper provides a systematic approach to assess the substitution risk of production systems regarding a current as well as possible future product programs. It comprises a methodology, which allows for a static and dynamic evaluation of production systems based on analytical cost models, scenario creation and real options analysis. By implementing a Monte Carlo simulation, various probability distributions of system parameters can be taken into account. The presented methodology focusses on economic and ecologic aspects. Finally, the methodology is applied to a case study.

Analysis of the fluid pressure, load capacity, and coefficient of friction of an elliptic machine hammer peened surface structure in hydrodynamic lubrication

Recently, the velocity distribution within an elliptical machine hammer peened (MHP) surface structure was discussed by solving analytically the Reynolds equation using Full-Sommerfeld boundary condition (Trauth et al. in Tribol Lett 60(19):1–13, 2015). However, in order to design the MHP process to obtain defined friction characteristics and load capacities of a fluid film, the pressure distribution has to be analyzed as well. Thus, in this contribution, the fluid pressure is discussed using Full-Sommerfeld first, then the previous work is extended by the Swift–Stieber boundary condition to account for cavitation effects. Thereby, the influence of geometry and process parameters on the fluid pressure, load capacity and coefficient of friction will be analyzed both using an approach based on absolute and dimensionless numbers. To asses the influence of lateral effects, the semi-analytic 1D results are compared to numerical 2D results based on the Raimondi approach. Thereby, a recommendation for a surface design manufactured by machine hammer peening is formulated.

Lebenszyklusorientierte Technologieplanung : Technologieauswahl unter Berücksichtigung des Produktlebenszyklus

Kurzfassung Die ökologische Bewertung von Technologien erfolgt bislang unter Berücksichtigung der Herstellungsphase eines Produkts. Effekte, die zu einer Reduktion der Umweltauswirkungen in weiteren Lebensphasen führen, werden vernachlässigt. Daher wurde ein Vorgehensmodell zur Bewertung von Technologien anhand der Umweltauswirkungen des gefertigten Produkts von der Herstellungsphase bis zur Entsorgungsphase entwickelt. Der Fokus liegt auf der Berücksichtigung von Wechselwirkungen zwischen den Lebensphasen.