OPTIMIZATION OF PRESS-FIT PROCESSES
Abstract
The press-fit process is an efficient, low-cost method for joining parts. The parts that must be joined interfere with each other’s occupation of space; therefore, contact dimensions and their tolerances influence the quality of the assembly. The traditional method for the selection of contact dimensions and their tolerances is based on engineering experience. The idea of the research work presented in this paper is to optimize the press-fit process at an early stage of development process, involving prediction and optimization of the joining force and consequently the prediction and minimization of the rejection rate. Accordingly, several finite-element (FE) simulations of the press-fit process for predicting the joining forces were conducted, considering input-parameter variations (material properties: yield stress, hardening exponent; geometry: shaft diameter, guide diameter of the core, functional diameter of the core; friction coefficient). Based on FE simulations and 47 different input-parameter-variation results, the empirical model for predicting the joining force using the response-surface methodology (RSM) was obtained. By using RSM and a stochastic Monte Carlo simulation, the rejection rate was also determined. The predicted and the actual rejection rates for selected process parameters were 1.4 % and 1.5 %, respectively. Consequently, the press-fit process can also be optimized to reduce the rejection rate using the same Monte Carlo simulation. The results of the analysis show that the rejection rate can be reduced from 1.4 % to 0.2 %.
References
2 F. Mahi, U. Dilthey, Joining of Metals, in Reference Module in Materials Science and Materials Engineering, Elsevier 2015, doi:10.1016/B978-0-12-803581-8.03785-1
3 A. G. Razzell, S. B. Venkata Siva, P. S. Rama Sreekanth, Joining and Machining of Ceramic Matrix Composites, in Reference Module in Materials Science and Materials Engineering, Elsevier 2016, doi:10.1016/B978-0-12-803581-8.03915-1
4 P. Groche, S. Wohletz, M. Brenneis, C. Pabst, F. Resch, Joining by forming – A review on joint mechanisms, applications and future trends, J. Mater. Process. Technol. 214 (2014) 10, 1972–1994, doi:10.1016/j.jmatprotec.2013.12.022
5 K. Martinsen, S. J. Hu, B. E. Carlson, Joining of dissimilar materials, CIRP Ann. – Manuf. Technol. 64 (2015) 2, 679–699, doi:10.1016/ j.cirp.2015.05.006
6 S. Kleditzsch, B. Awiszus, M. Lätzer, E. Leidich, Numerical and analytical investigation of steel–aluminum knurled interference fits: Joining process and load characteristics, J. Mater. Process. Technol. 219 (2015), 286–294, doi:10.1016/j.jmatprotec.2014.12.019
7 R. Kiebach, K. Engelbrecht, K. Kwok, S. Molin, M. Søgaard, P. Niehoff, F. Schulze-Küppers, R. Kriegel, J. Kluge, P. Vang Hendriksen, Joining of ceramic Ba0.5Sr0.5Co0.8Fe0.2O3 membranes for oxygen production to high temperature alloys, J. Memb. Sci. 506 (2016), 11–21, doi:10.1016/j.memsci.2016.01.050
8 M. Pawlicki, T. Drenger, M. Pieszak, J. Borowski, Cold upset forging joining of ultra-fine-grained aluminium and copper, J. Mater. Process. Technol. 223 (2015), 193–202, doi:10.1016/j.jmatprotec. 2015.04.004
9 T. N. Chakherlou, B. Abazadeh, Investigating clamping force variations in Al2024-T3 interference fitted bolted joints under static and cyclic loading, Mater. Des. 37 (2012), 128–136, doi:10.1016/ j.matdes.2011.12.037
10 J. Mucha, Finite element modeling and simulating of thermo¬mechanic stress in thermocompression bondings, Mater. Des. 30 (2009) 4, 1174–1182, doi:10.1016/j.matdes.2008.06.026
11 S. Salehghaffari, M. Panahipoor, M. Tajdari, Controlling the axial crushing of circular metal tubes using an expanding rigid ring press fitted on top of the structure, Int. J. Crashworthiness 15 (2010) 3, 251–264, doi:10.1080/13588260903209099
12 M. Bambach, A finite element framework for the evolution of bond strength in joining-by-forming processes, J. Mater. Process. Technol. 214 (2014) 10, 2156–2168, doi:10.1016/j.jmatprotec.2014. 03.015
13 M. Lorenzo, C. Blanco, J. C. P. Cerdán, Numerical Simulation and Analysis via FEM of the Assembly Process of a Press Fit by Shaft Axial Insertion, Springer 2013, 787–795, doi:10.1007/978-94-007-¬4902-3_82
14 G. A. Pantazopoulos, A. I. Toulfatzis, Fracture Modes and Mechanical Characteristics of Machinable Brass Rods, Metallogr. Micro¬struct. Anal. 1 (2012) 2, 106–114, doi:10.1007/s13632-¬012-¬0019-7
15 S. Božič, D. Šircelj, Measuring of stress-strain behaviour of steel 1.0718 and aluminium alloy at different temperature range, Mach. Technol. Mater. 6 (2011), 36–40
16 R. C. Hibbeler, Statics and Mechanics of Materials, 4th Edition, Pearson 2014
17 A. Van Beek, Advanced engineering design: Lifetime performance and reliability, TU Delft 2006
18 G. Gantar, K. Kuzman, Optimization of stamping processes aiming at maximal process stability, J. Mater. Process. Technol. 167 (2005) 2–3, 237–243, doi:10.1016/j.jmatprotec.2005.05.027
19 T. de Souza, B. F. Rolfe, Characterising material and process variation effects on springback robustness for a semi-cylindrical sheet metal forming process, Int. J. Mech. Sci. 52 (2010) 12, 1756–1766, doi:10.1016/j.ijmecsci.2010.09.009
20 A. Michael, M. Scholting, E. Atzema, Characterisation and modelling of the stochastic behaviour of deep drawing steels, VII International Conference on Computational Plasticity COMPLAS VII E. Oñate and D. R. J. Owen (Eds) CIMNE, Barcelona, 2003, 1–20
21 R. H. Myers, D. C. Montgomery, C. M. Anderson-Cook, Response Surface Methodology: Process and Product Optimization Using Designed Experiments, 3rd Editio, John Wiley & Sons 2009
22 R. Y. Rubinstein, D. P. Kroese, Simulation and the Monte Carlo Method, John Wiley & Sons, Inc., Hoboken 2007, doi:10.1002/ 9780470230381
