Abstract
In the study of microforming meeting the needs of miniaturization of parts to be formed, the size effects are important parameters to be considered seriously. The objective of the investigation is to establish an explicit friction model in micro/mesoscale to calculate the coefficient of friction (COF) considering size effects, which is very helpful in analysis of microforming processes. With the open–closed pocket assumption, a scaling factor was adopted to describe the size effects on tribological behaviors in microforming. Based on the general Wanheim/Bay friction law, a relationship between the real contact area and the forming load was obtained considering the microscopical contact interface and the pressure induced by the trapped lubricant liquid. An explicit equation was developed including fraction of real contact area, scaling factor, and properties of lubricant. The effects of scaling factor and lubricant properties were discussed by analyzing its effects on the fraction of real contact area and coefficient of friction. With the developed model, the coefficient of friction was calculated and introduced into the finite element simulation of micro-upsetting deformation using ABAQUS software. When the scaling factor is less than 9, the size effect of friction becomes the main reason which affects the shape parameter in micro-upsetting deformation. Comparisons show that simulation results are in good agreement with that of experiments, which means that the developed model is suitable for analyzing size effects of friction in microforming.
Similar content being viewed by others
References
Geiger M, Kleiner M, Eckstein R, Tiesler N, Engel U (2001) Microforming. CIRP Ann Manuf Tech 50:445–462
Engel U, Eckstein R (2002) Microforming—from basic research to its realization. J Mater Process Technol 125–126:35–44
Jeswiet J, Geiger M, Engel U, Kleiner M, Schikorra M, Duflou J, Neugebauer R, Bariani P, Bruschi S (2008) Metal forming progress since 2000. CIRP J Manuf Sci Technol 1:2–17
Fu MW, Chan WL (2013) A review on the state-of-the-art microforming technologies. Int J Adv Manuf Technol 67:2411–2437
Shen H, Gong C, Hu J, Yao Z (2012) Numerical and experimental study on bi-direction deformations in laser micro forming of two-bridge actuators. Int J Mach Tool Manuf 54–55:66–72
Liu H, Wang H, Shen Z, Huang Z, Li W, Zheng Y, Wang X (2012) The research on micro-punching by laser-driven flyer. Int J Mach Tool Manuf 54–55:18–24
Tan X (2002) Comparisons of friction models in bulk metal forming. Tribol Int 35:385–393
Masters IG, Williams DK, Roy R (2013) Friction behaviour in strip draw test of pre-stretched high strength automotive aluminium alloys. Int J Mach Tool Manuf 73:17–24
Engel U, Messner A, Tiesler N (1998) Cold forging of microparts—effect of miniaturization on friction. In: Chenot JL et al (eds) Proceeding of the First ESAFORM Conference on Materials Forming, 17–20 March 1998. Sophia Antipolis, France, pp 77–80
Tiesler N, Engel U, Geiger M (1999) Forming of microparts—effects of miniaturization on friction. In: Geiger M (ed) Advanced technology of plasticity, Proceeding of the Sixth International Conference on Technology of Plasticity, vol. II, 19–24 September 1999, Nuremberg, Germany, Springer, Berlin, 1999, 889–894
Vollertsen F, Hu Z, Schulze Niehoff H, Theiler C (2004) State of the art in micro forming and investigations into micro deep drawing. J Mater Process Technol 151:70–79
Guo B, Gong F, Wang CJ, Shan DB (2010) Size effect on friction in scaled down strip drawing. J Mater Sci 45:4067–4072
Vollertsen F, Hu Z (2006) Tribological size effects in sheet metal forming measured by a strip drawing test. CIRP Ann Manuf Tech 55:291–294
Brinksmeier E, Riemer O, Twardy S (2010) Tribological behavior of micro structured surfaces for the micro forming tools. Int J Mach Tool Manuf 50:425–430
Manabe K, Koyama H, Nouka H, Yang M, Ito K (2005) Finite element analysis of micro cup drawing process using tool and blank models with surface roughness. In: Bariani PF (ed) Advanced technology of plasticity, Proceeding of the Eighth International Conference on Technology of Plasticity ICTP 2005, 9–13 October 2005, Verona, Italy, 2005
Manabe K, Shimizu T, Koyama H, Yang M, Ito K (2008) Validation of FE simulation based on surface roughness model in micro-deep drawing. J Mater Process Technol 204:89–93
Jeon J, Bramley AN (2007) A friction model for microforming. Int J Adv Manuf Tech 33:125–129
Engel U (2006) Tribology in microforming. Wear 260:265–273
Pfestorf M, Engel U, Geiger M (1998) Three-dimensional characterization of surfaces for sheet metal forming. Wear 216:244–250
Peng LF, Lai XM, Lee HJ, Song JH, Ni J (2010) Friction behavior modeling and analysis in micro/meso scale metal forming process. Mater Design 31:1953–1961
Bay N (1987) Friction stress and normal stress in bulk metal-forming processes. J Mech Work Technol 14:203–223
Wanheim T, Bay N, Petersen AS (1974) A theoretically determined model for friction in metal working processes. Wear 28:251–258
Nellemann T, Bay N, Wanheim T (1977) Real area of contact and friction stress—the role of trapped lubricant. Wear 43:45–53
Author information
Authors and Affiliations
Corresponding author
Appendix
Appendix
Symbols | Meaning |
---|---|
λ | Scaling factor |
R | Radius of contact circular |
s | Width of rim in contact area OLPs |
α RC | Fraction of real contact area |
α c | Fraction of closed lubricant pockets |
α o | Fraction of open lubricant pockets |
S | Total contact area |
S 1 | Area with CLPs |
S 2 | Rim area in contact area with OLPs |
γ 0 | Angle of an isosceles triangle |
h | Height of an isosceles triangle |
t | Bottom side length of an isosceles triangle |
V | Volume of lubricant trapped in the closed pockets |
P | Normal pressure under dry friction |
P 0 | Real contact pressure of the flattened roughness peaks |
P l | Lubricant pressure |
P m | Normal pressure under lubrication condition in microforming |
τ | Friction stress at the whole surface |
τ 0 | Friction stress at flattened roughness peaks |
τ m | Friction stress at whole surface under lubrication condition |
K | Lubricant tangent bulk modulus |
K 0, K 1 | Anti-pressure strength parameters |
K 1 | Higher order coefficient |
f | Friction factor |
μ 0 | Coefficient of friction under dry friction |
μ mic | Coefficient of friction under lubrication condition in microforming |
Rights and permissions
About this article
Cite this article
Wang, C., Guo, B., Shan, D. et al. Tribological behaviors in microforming considering microscopically trapped lubricant at contact interface. Int J Adv Manuf Technol 71, 2083–2090 (2014). https://doi.org/10.1007/s00170-014-5657-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00170-014-5657-2