Abstract
Microforming from sheet metals is a technology with high potential and increasing interest in modern factories. The combination of bulk forming technologies in micro-scale together with the easier handling of metal strips allows the high rate production of products with small dimension and is suited for commercial fields like electronics and micromechanics. The need of an efficient FEM aided process design must face the problem of material behavior in microforming, affected by size-effects and not obeying continuum mechanics. A reliable FE model allows the production of a database allowing, additional to process optimization, the design of online process control and the reduction of manufacturing defects, strongly affecting micro-productions because of the high deviations in such processes. In this work, a method for the design of a FEM model of a microforging process is proposed, developed in the commercial software MSC Marc including the modelling of local size effects in the form of variable friction. An increased friction factor is assumed, where typical microforming size effects are expected to take place. Stainless steel and copper-beryllium alloys are studied with the thickness of 300 µm. The microforged geometry consists in 6 parallel protrusions with a width of 200 µm. The experimental study is then performed, by varying punch forces, firstly in a simplified configuration with two protrusions and finally with the complete geometry in a multi-stage microforming process, respectively validating and verifying the developed simulation model.











Similar content being viewed by others
References
Vollertsen F, Biermann D, Hansen HN, Jawahir IS, Kuzman K (2009) Size effects in manufacturing of metallic components. CIRP Ann 58(2):566–587
Engel U, Eckstein R (2002) Microforming form basic research to its realisation. J Mater Process Technol 125–126:35–44
Sanchez AJ (2010) Handling for micro-manufacturing. In: Qin Y (ed) Micro-manufacturing engineering and technology. Elsevier, Oxford, pp 298–313
Hirota K (2007) Fabrication of micro-billet by sheet extrusion. J Mater Process Technol 191(1):283–287
Stellin T, Merklein M, Engel U (2012) Experimental and numerical investigation on a full forward extrusion process from metal strip. In: Noll H, Adamovic N, Dimov S (ed), Proceedings of the 9th international conference on multi-material micro manufacture, Research Publishing, pp 163–166
Ghassemali E, Jarfors AE, Tan M-J, Lim SCV (2013) On the microstructure of micro-pins manufactured by a novel progressive microforming process. Int J Mater Form 6(1):65–74
Chang CC, Kuo WL (2008) Effects of process parameters on filling of grooves in micro metal imprinting. Adv Technol Plast 2008(9):1884–1889
Grobbink SJ, Klaseboer G, Post J, Huetink J (2010) Investigations on the predictability of coining stainless steel AISI 410. In: Proceedings of the 10th international conference on numerical methods in industrial forming process, NUMIFORM 2010. American Institute of Physics, 1252 1, pp 956–963
Ravenswaaij R, van Tijum R, Hora P, van den Boogaard T, Engel U (2013) Towards zero-defect manufacturing of small metal parts. In: IDDRG 2013 conference proceedings. Zurich: Institute of Virtual Manufacturing, ETH Zurich, pp 87–92
Merklein M, Kuppert A (2009) A method for the layer compression test considering the anisotropic material behavior. IntJ Mater Form 2:483–486
Hochholdinger B, Grass H, Lipp A, Hora P (2001) Determination of flow curves by stack compression tests and inverse analysis for the simulation of hot forming. In: 7th European LS-DYNA conference. Salzburg, DYNAmore GmbH
Swift HW (1952) Plastic instability under plain stress. J Mech Phys Solids 1:1–18
Voce E (1948) The relationship between stress and strain for homogeneous deformation. J Inst Met 74:537–562
Hockett JE, Sherby OD (1975) Large strain deformation of polycrystalline metal at low homologous temperatures. J Mech Phys Solids 23:87–98
Stellin T, van Tijum R, Merklein M, Engel U (2014) Study of microforging of parallel ribs from metal strip. Key Eng Mater 611–612:565–572
Stellin T, Merklein M, Engel U (2013) Investigation on a microextrusion process of parallel protrusions from metal strip. In: Jun M, Park S (ed), Proceeding 8th international conference micro manufacturing, Victoria, Canada, pp 169–174
Stellin T, Merklein M, Engel U (2015) Experimental study of a microforming process of parallel ribs from metal strip. In: Annoni M, Fassi I, Wiens GJ, Dimov S (eds), Proceedings 4M/ICOMM, Research Publishing, pp 218–221
Acknowledgments
The work leading to these results has received funding from the European Community’s Seventh Framework Programme under Grant Agreement No. FP7-285030.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Stellin, T., van Tijum, R. & Engel, U. Modelling and experimental study of a microforging process from metal strip for the reduction of defects in mass production. Prod. Eng. Res. Devel. 10, 103–112 (2016). https://doi.org/10.1007/s11740-015-0644-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11740-015-0644-5