Strategies for production of parts textured by grinding using patterned wheels Eraldo Jannone da Silva a, *, Joa ˜o Fernando Gomes de Oliveira (1) a , Bruno Barbosa Salles b , Ricardo Santoro Cardoso b , Vinicius Ricco Alves Reis a a University of Sa ˜o Paulo – USP, School of Engineering – Sa˜o Carlos – EESC, Department of Production Engineering, Sa˜o Carlos, SP, Brazil b ThyssenKrupp Metalu ´rgica Campo Limpo – Research & Development, Campo Limpo Paulista, SP, Brazil 1. Introduction With the constant pressure for lower emissions in the automotive industry the world is searching more and more for engineering solutions that could improve the performance of internal combustion engines. One of the approaches is to increase load capacity in the hydrodynamic bearings, so the size of some of the engine components can be reduced, diminishing the energy loss, material consumption and inertia. This can be accomplished by introducing surface engineered textures on the bearing surfaces. Bruzzone et al. [2] published a CIRP keynote paper in 2008 on the advances in engineered surfaces for functional performance with a comprehensive view of the surfaces functionalities and processes that can be applied for texturing. One of the topics discussed on that publication was the application of textures for the improvement of lubrication showing good perspectives. Among the CIRP keynote, a considerable number of papers have been published on the influence of micro texturing on the lubrication performance of surfaces. Previous research [3] showed that the use of small cavities uniformly distributed over the sliding surface offers the best tribological results for hydrodynamic bearings. Simulation studies [4] show that short grooves with sinusoidal profile perpendicular to the movement give the most performing lubrication results for traditional automotive applica- tions. One common conclusion of most papers in this area is that a group of pockets can perform as a set of micro-bearings on the surface. Therefore, the challenge is to produce these pockets at low cost and feasible manufacturing cycle times. Current approaches to produce functional surfaces include, but are not limited to: etching, lithography and laser machining. The last is the most cited process, but with major drawbacks including: fine tuning of process parameters to control metal recast, burr formation, low production rate and high hardware investment as well as more complex operational training and safety require- ments. Alternatives for producing functional surfaces using traditional machining processes are presently sought. Grinding with patterned wheels by dressing arises as a potential alternative by combining its inherent finishing process character- istics, its capacity of cutting hard materials, with relative low process technical requirements, low investment and short cycle times. The proposed scheme developed by [1] in CIRP 2010, in which user defined patterns can be imprint on the wheel surface during dressing and later transferred to the part, promotes a freedom of choices for transferring patterns to the workpiece during regular grinding. Initial results of the technique were very encouraging, with setup and process times similar to conventional grinding. A deeper evaluation on process control requirements would be a natural next step in the development of this solution and for its application in industry. The research presented here is a partnership with a crankshaft producer aiming at the evaluation of the impact of ground pockets in hydrodynamic bearings for automotive applica- tions. This is the objective of the present research: to develop grinding strategies that would allow a full control of the pocket features. The following sections of this paper will present the main characteristics of the developed strategies and the resulting surface features, a method for grinding control of the texture properties and the main conclusions. 2. Characteristics of the developed process Details on the developed method can be found in [1]. Basically, the production of textured workpieces is realized by using a patterned grinding wheel and integer angular speed ratio between workpiece and wheel when grinding. In this paper the term pattern is used for the features generated on the wheel surface by dressing and textures or pockets for the features ground on the workpiece. The synchronization between both part and wheel for accomplishing the grinding process was described in the same 2010 paper and don’t require any additional hardware. The CIRP Annals - Manufacturing Technology xxx (2013) xxx–xxx A R T I C L E I N F O Keywords: Dressing Grinding wheel Part texturing A B S T R A C T The functionalization of surfaces by introducing pre-engineered textures is a new requirement from industry. Surfaces more prone to promote micro-lubrication are being designed by engineers and incorporated into the components specification. The major challenge is to develop manufacturing methods able to produce these textures in a repeatable and economically viable way. The aim of this research work is to develop grinding strategies based on the method proposed in [1] for producing textured surfaces by grinding. The characteristics of the produced textures are measured and evaluated using new proposed parameters. The obtained results show the potential of this process solution for the production of micro pockets for hydrodynamic bearings application. ß 2013 CIRP. * Corresponding author. E-mail address: eraldojs@sc.usp.br (E.J. Silva). G Model CIRP-1076; No. of Pages 4 Please cite this article in press as: Silva EJ, et al. Strategies for production of parts textured by grinding using patterned wheels. CIRP Annals - Manufacturing Technology (2013), http://dx.doi.org/10.1016/j.cirp.2013.03.123 Contents lists available at SciVerse ScienceDirect CIRP Annals - Manufacturing Technology journal homepage: http://ees.elsevier.com/cirp/default.asp 0007-8506/$ – see front matter ß 2013 CIRP. http://dx.doi.org/10.1016/j.cirp.2013.03.123