Effects of Rolling Direction and Lubricant on Friction in Sheet Metal Forming

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Xiaojun Liu ◽  
Mathias Liewald ◽  
Dina Becker
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Alloy Sheet ◽  
Friction Behavior ◽  
Drawing Test ◽  
Strip Drawing ◽  
The Coefficient Of Friction ◽  
Surface Microstructures

Lubrication and friction at workpiece-tool interface play an important role in product quality control of sheet metal forming process. Surface microstructures of sheets have a great influence on the development of lubrication films. In order to investigate the effects of the rolling direction of aluminum alloy sheet and lubricant on the friction behavior in sheet metal forming, strip drawing test was used. The sample used was electric discharge texturing (EDT) surface. Lubricants, both with and without additives, were used. The strip drawing tests were performed at angles between the sliding and rolling directions of 0–90 deg. Variations in the sheet surface topography were analyzed by comparing the sheet surface microstructures and its 3D surface parameters before and after the strip drawing test. Results of the strip drawing tests indicate that the kind and amount of lubricant have great influences on friction at the interface, and the lubricant with additives benefits improving the friction behavior between the sheet and the tool. The EDT surface of the aluminum alloy sheet has an anisotropic frictional property during deep drawing process due to different angles between the sliding and rolling directions. When the sliding direction is parallel to the rolling direction, the coefficient of friction has the highest value. When the angle between the sliding and rolling directions increases, the coefficient of friction decreases. The surface microstructure of the sheets after the strip drawing test at different angles between the sliding and rolling directions has been modified, and its 3D surface parameters decrease significantly to a different degree.

scholarly journals Temperature induced friction increase in friction test and forming demonstrator for sheet metal forming

2021 ◽  
Author(s):  
Jan Filzek ◽  
Daniel Keil ◽  
Holger Schröder
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Transient Effects ◽  
Friction Test ◽  
Drawing Test ◽  
Machine Operators ◽  
Strip Drawing ◽  
Flat Strip ◽  
The Individual

High process stability is needed in sheet metal forming industry. This can be achieved by predicting and controlling the transient process and temperature variation, especially at start of production. In this connection, the temperature induced friction changing plays a significant role because it leads to product failures. The handling of the transient friction effects is currently done reactively, based on the individual experience of the machine operators. In future, those transient effects need to be controlled. This paper shows initially an analysis of the temperature induced friction increase in a well-known and proven flat strip drawing test. Different tribological systems were tested at tool temperatures between 20 and 80 °C. The temperature increase results in a higher friction of up to 77 %. Several influences on friction increase will be presented. These friction influences were verified afterwards with a heated forming demonstrator under laboratory conditions.

Dry Forming of Aluminium Sheet Metal: Influence of Different Types of Forming Tool Microstructures on the Coefficient of Friction

2015 ◽  
Vol 651-653 ◽  
pp. 516-521 ◽  
Author(s):  
Peter Scholz ◽  
Richard Börner ◽  
Ralf Kühn ◽  
Roland Müller ◽  
Andreas Schubert
Keyword(s):  
Sheet Metal ◽  
Coefficient Of Friction ◽  
Metal Forming ◽  
Process Chains ◽  
Different Types ◽  
Strip Drawing ◽  
The Coefficient Of Friction ◽  
Surface Microstructures ◽  
Forming Tools ◽  
Frictional Behaviour

In the sheet metal forming industry lubricants are applied in forming processes to expand the technological boundaries by reducing friction and wear. The friction between tool and sheet metal is crucial to the deep drawing process. Due to economic and ecological reasons the aim of the manufacturers is to reduce or even avoid the use of lubricants. Consequently, this approach enables both a shortening of the process chains and an essential saving of resources. The advantages of structured forming tools in lubricated processes concerning the reduction of the coefficient of friction by the appearance of lubricating micro pockets are well-known. However, without using any lubricant this effect does not work. In this case the contact area is reduced by structuring the forming tool which affects the tribological system.In this paper the influence of microstructures with different geometries and surface treatments (uncoated / a-C:H:Si-coating) on the coefficient of friction in dry metal forming of the alloy AA5182 is compared to the frictional behaviour of unstructured forming tools using lubricant as reference. Before coating, the forming tools are machined by milling to generate tribologically effective microstructures. With the use of a strip drawing plant the effects of different surface microstructures and materials on the coefficient of friction are investigated.

scholarly journals Strain Induced Surface Change in Sheet Metal Forming: Numerical Prediction, Influence on Friction and Tool Wear

2021 ◽  
Vol 5 (2) ◽  
pp. 29
Author(s):  
Yutian Wu ◽  
Viktor Recklin ◽  
Peter Groche
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Wear Behavior ◽  
Numerical Prediction ◽  
Wear Testing ◽  
Surface Roughening ◽  
Bead Geometry ◽  
Friction Behavior ◽  
Strip Drawing

In sheet metal forming, free deformation of the sheet takes place frequently without contact with forming tools. The pre-straining resulting from the free deformation leads to a surface roughening of the sheet metal. It is assumed that the roughening has an influence on friction and wear behavior of the following forming process as well as the painting quality after the manufacturing. In this paper, a numerical prediction based on a polycrystalline model is first proposed to predict the effect of surface roughing based on the material data of the as-received state of the sheet metal. Different states of strain are analyzed and the numerical result is validated through experimental evaluation. Besides the numerical prediction, the friction behavior after pre-straining is evaluated in strip drawing tests and the coefficient of friction (COF) is calculated. For interpretation of the measured COF, the surface roughness after the friction test and the surface image are evaluated by a transparent toolset. It is shown that the surface transformation as a result of pre-straining has a negative influence on the lubricating effect of the sheet metal and degrades the friction behavior. Finally, the influence of the strain-induced surface roughening on wear is discussed based on wear testing in strip drawing test with draw bead geometry.

scholarly journals Methods of determination of frictional resistances in sheet metal forming of car body sheets

2018 ◽  
Vol 19 (6) ◽  
pp. 756-760
Author(s):  
Tomasz Trzepieciński ◽  
Irena Nowotyńska
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Complex Function ◽  
Forming Process ◽  
The Coefficient Of Friction ◽  
Displacement Speed ◽  
Almost All ◽  
Lubrication Conditions

The friction phenomenon existed in almost all plastic working processes, in particular sheet metal forming, is a complex function of the material's properties, parameters of the forming process, surface topography of the sheet and tools, and lubrication conditions. During the stamping of the drawpieces there are zones differentiated in terms of stress and strain state, displacement speed and friction conditions. This article describes the methods for determining the value of the coefficient of friction in selected areas of sheet metal and presents the drawbacks and limitations of these methods.

scholarly journals Numerical modelling of microscopic lubricant flow in sheet metal forming. Application to plane strip drawing

2017 ◽  
Vol 112 (3) ◽  
pp. 203-237 ◽  
Author(s):  
Y. Carretta ◽  
R. Boman ◽  
J. Bech ◽  
N. Legrand ◽  
M. Laugier ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Lubricant Flow ◽  
Strip Drawing

scholarly journals Contact pressure and sliding velocity ranges in sheet metal forming simulations

2021 ◽  
Author(s):  
Joseba Cillaurren ◽  
Lander Galdos ◽  
Mario Sanchez ◽  
Alaitz Zabala ◽  
Eneko Saenz de Argandoña ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Contact Pressure ◽  
Sheet Metal ◽  
Coefficient Of Friction ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Sliding Velocity ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Friction Models

In the last few years many efforts have been carried out in order to better understand what the real contact between material and tools is. Based on the better understanding new friction models have been developed which have allowed process designers to improve numerical results in terms of component viability and geometrical accuracy. The new models define the coefficient of friction depending on different process parameters such as the contact pressure, the sliding velocity, the material strain, and the tool temperature. Many examples of the improvements achieved, both at laboratory scale and at industrial scale, can be found in the recent literature. However, in each of the examples found in the literature, different ranges of the variables affecting the coefficient of friction are covered depending on the component analysed and the material used to produce such component. The present work statistically analyses the contact pressure and sliding velocity ranges achieved during numerical simulation (FEM) of sheet metal forming processes. Nineteen different industrial components representing a high variety of shapes have been studied to cover a wide range of casuistic. The contact pressure and sliding velocity corresponding to typical areas of the tooling have been analysed though numerical simulation in each case. This study identifies the ranges of contact-pressure and sliding velocities occurring in sheet metal forming aimed to set the characterization range for future friction studies.

scholarly journals Modelling of Friction Phenomena Existed in Drawbead in Sheet Metal Forming

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5887
Author(s):  
Tomasz Trzepieciński ◽  
Andrzej Kubit ◽  
Romuald Fejkiel ◽  
Łukasz Chodoła ◽  
Daniel Ficek ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Rolling Direction ◽  
Back Propagation ◽  
Experimental Tests ◽  
Friction Model ◽  
Friction Reduction ◽  
Training Algorithms ◽  
Sheet Rolling

The article presents the results of friction tests of a 0.8 mm-thick DC04 deep-drawing quality steel sheet. A special friction simulator was used in the tests, reflecting friction conditions occurring while pulling a sheet strip through a drawbead in sheet metal forming. The variable parameters in the experimental tests were as follows: surface roughness of countersamples, lubrication conditions, sample orientation in relation to the sheet rolling direction as well as the sample width and height of the drawbead. Due to many factors that affect the value of the coefficient of friction coefficient, artificial neural networks (ANNs) were used to build and analyse the friction model. Four training algorithms were used to train the ANNs: back propagation, conjugate gradients, quasi-Newton and Levenberg–Marquardt. It was found that for all analysed friction conditions and sheet strip widths, increasing the drawbead height increases the COF value. The chlorine-based Heavy Draw 1150 compound provides a more effective friction reduction compared to a LAN-46 machine oil.

scholarly journals Tribological Performance of Environmentally Friendly Bio-Degradable Lubricants Based on a Combination of Boric Acid and Bio-Based Oils

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3892
Author(s):  
Tomasz Trzepieciński
Keyword(s):  
Boric Acid ◽  
Sheet Metal ◽  
Coefficient Of Friction ◽  
Vegetable Oils ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Low Carbon Steel ◽  
Environmentally Friendly ◽  
Low Carbon ◽  
The Coefficient Of Friction

Finding effective and environmentally friendly lubrication to use in sheet metal forming operations presents a substantial environmental and economic challenge to the automotive industry. This paper examines the effectiveness of different lubricants in the reduction of the coefficient of friction (COF) in the process of sheet metal forming of the low carbon steel sheets. These lubricants are based on a combination of boric acid (H3BO3) and edible vegetable oils, both of which are natural and environmentally friendly. To evaluate the friction characteristics of the lubricants in a forming operation, a strip drawing friction test is used. This test consisted in drawing a specimen in the form of a sheet metal strip between two non-rotating counter-samples with radii of 200 and 10 mm. The effectiveness of environmentally friendly lubricants in reducing the COF was compared to the traditional petroleum-based lubricants which are used in sheet metal-forming operations. The effect of lubricant conditions and tool surface roughness on the value of COFs is studied. It was found that palm oil in both configurations of countersample radius, both as pure oil and with the addition of 5 wt.% of H3BO3, was the most effective in lowering the coefficient of friction. In most of the conditions analysed, the addition of boric acid into vegetable oils leads to an increase in the lubrication efficiency by up to 15% compared to pure oils. The effectiveness of lubrication by olive and rapeseed oils in decreasing the frictional resistances clearly depends on the nominal pressure applied.

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