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Clinching as a non-standard method for joining materials of dissimilar properties
... It has become an established mechanical joining process, especially in applications where thermal joining processes cannot be applied. A wide variety of materials with different levels of strength and ductility can be clinched nowadays [1]. Due to this fact, clinching has partially replaced thermal joining processes, especially in multi-material car body design. ...
The paper presents results of FEA-based optimisation of the tool design of a clinching process with a closed single-part die. The studied materials are the bake-hardening steel CR240BH, 1.5 mm thick, on the punch side and the die-cast aluminium alloy AlSi10MnMg, 2.95 mm thick, on the die side. The optimisation was aimed at suppression of cracks that appear at the bottom of the clinch joint in AlSi10MnMg in the case of using conventional tool designs. By varying geometry parameters of the tools it was possible to reduce crack probability, though along with slightly worse, but still acceptable geometry parameters of the clinch joint.
... Lastly, the crack phenomenon in the bottom of the joints is due to the generated tensile stress that can be prevented by eliminating the groove depth i.e., the flat bottom [14,15]. Additionally, these factors are influenced by the tool geometry, mechanical characteristics of the materials, plate thickness configuration, applied forces, and friction [14,[16][17][18][19][20]. ...
NEED—The effect of dimensional variability of sheet thickness (tolerance) and tool misalignment is poorly understood for the clinching process. Finite element analysis (FEA) is valuable but requires a lot of and is difficult to verify in this situation due to the asymmetrical geometry and nonlinear plasticity. OBJECTIVE—The objective of this work was to determine the effect of thickness tolerance, tool misalignment and sheet placement (top vs. bottom) in the clinching process, by use of analogue modelling with plasticine. METHOD—Experiments used a scaled-up punch and die, with plasticine as the analogue. Thickness tolerances were represented by sheet thicknesses of 11 and 7 mm, 12 and 8 mm, 8 and 12 mm and 13 and 9 mm for upper and lower sheets, respectively. Two types of lubricant were tested between sheets: glycerine and silicone oil. Angular variability was also introduced. Measured parameters were interlock (also called undercut) and neck thickness. Analogue results for deformation were compared with microscopy of metal clinching. FINDINGS—The results reveal that the multiscale analogue model is an efficient tool for studying the effect of dimensional deviation on a clinch joint. Thickness tolerance showed a critical relationship with interlock, namely a reduction to about half that of the nominal, for both maximum and least material conditions. Increased angular misalignment also reduced the interlock. Compared with glycerine, silicone oil tests showed reduced interlock, possibly the result of a lower coefficient of friction. ORIGINALITY—This work demonstrates the usefulness of analogue modelling for exploring process variability in clinching. The results also show that significant effects for sheet placement are ductility, lubricant (friction), thickness of samples and tool misalignment.
... Until the 1980s the technology was not widely used in industry [1]. Just in recent years has the interest in the use of clinching joining increased in industry, as clinching was successfully implemented to complement or even replace other joining techniques such as spot welding [2]. In the clinching process, two sheets of metal are joined using at most a die and a punch. ...
Clinching is one of the important new joining techniques, in which two plate metal parts are locally plastically deformed by mechanical interlock. Clinching is a mechanical joining method by using simple tools that consist of a punch, a die, and a blank-holder. The shapes of these tools are the most important parameters that control the final geometry of the clinch joints which in turn strongly affect the strength and quality of the final joint. In this study, finite element simulations are carried out to investigate some of the difficulties regarding the optimization of the process parameters, and major expected geometric parameters that will influence the strength, joinability, and the quality of the joint.
... These cracks may not affect the static strength, whereas the fatigue strength and fretting corrosion can be affected particularly under the dynamic loading. One of the main merits of the clinching process in terms of strength is the comparable fatigue strength over the resistance spot welding which is the most widely used spot joining process [46][47][48][49][50]. Therefore, eliminating the macro cracks as well as reducing the micro ones are so important challenges in the clinching process to strengthen the fatigue strength. ...
The mechanical clinching as an alternative joining process for fabricating lightweight aluminum to steel assemblies may face the challenges when joining low-ductility aluminum alloy to high-strength steel. Several researches have been focused on applying the electrically-assisted processes in various fields due to energy efficiency as well as practical simplicity, in order to improve the formability. This paper concentrates on the electrically-assisted mechanical clinching (EAMC) of AA6061-T6 aluminum to galvanized DP590 steel. To this end, a combination of experimental and numerical clinching tests was performed using extensible die at different penetration depths, in which controlling the material flow was obtained by applying newly defined chamfer ratio R C in order to guarantee the strong mechanical interlock. The joint section parameters, failure loads, and failure modes were measured. The effects of the geometrical features on material flow and mechanical strength of clinched joints were analyzed using a FE model. The results showed that the defined parameter R C greatly increased the strength with the use of the EAMC process, which came with a reduction in forming load.
... Clinching uses a form-friction interlock generated by the forming process to join dissimilar sheet materials (Kascak and Spišák, 2012). Eshtayeh et al. (2016) summarized the advantages of clinching: low purchasing and operating costs, no need for any supporting joint element and good fatigue property. ...
The production of pure steel and steel-aluminum (Al) bi-material body-in-white (BIW) in the same assembly line requires the use of joining techniques with high flexibility, and this is not currently possible with state-of-the-art mechanical joining techniques. This work therefore developed a hybrid joining technique, rivet resistance spot welding (RRSW). In this process, a special FEM-optimized rivet clamps the Al sheet on both sides, with one flat and one nearly flat surface. It functions as an adapter to weld the Al part with the other steel parts and separates the steel and Al parts to avoid contact corrosion. Experiments demonstrated that, with optimized rivet geometry and proper welding parameters, RRSW created steel-Al combinations in BIW that were of at least equal strength to, and usually stronger, than self-piercing riveting (SPR). RRSW’s corrosion resistance was also superior to SPR’s. To verify the sample level development, a steel roof was redesigned to use Al, and this was then welded to the adjacent steel parts using fully-automated spot welding unit. Using the same welding conditions as for the steel roof the RRSW quality was good. The same welding system can thus be used both for pure steel and for steel-Al multi-material BIW assembly. RRSW is therefore a flexible and economical joining method and a viable alternative to SPR.
... These joints have an adhesive layer between the sheets. These joints have higher strengths, but these joints need much more time because of the adhesive layer's drying is a time-consuming process [1,6,7]. ...
... These joints have an adhesive layer between the sheets. These joints have higher strength but they need much more time because the drying of the adhesive layer is a time-consuming process [4][5]. ...
... Until the 1980s, the technology was not widely used in industry [1]. Just in recent years has the interest in the use of clinching joining increased in industry, as clinching was successfully implemented to complement or even replace other joining techniques such as spot welding [2]. Unfortunately, this process is still early in its development despite rapid advances in recent years; much more research is required to reach the point where accuracy, high quality, and optimal strength of the joints become comparable to industry standard. ...
Clinching is a mechanical joining method using a simple toolset consisting of a punch, a die, and a blank holder. The shapes of these tools are the most important parameters that control the final geometry of the clinch joints and consequently the strength and quality of the latter. In order to save time and cost, these geometric parameters could be optimized by the use of finite element simulation. This paper reviews the published research related to the finite element modeling of the clinching process. In this study, a critical review of the latter had been carried out from different perspectives. The findings about difficulties facing the simulations of different clinching processes, the optimization of the process parameters, and the strength, joinability, and the quality of the joint were highlighted. In addition, future development, investigation, and more research are still needed to minimize problems and expenses in the industrial practical application of clinching.
... It has become an established mechanical joining process, especially in applications where thermal joining processes cannot be applied. A wide variety of materials with different levels of strength and ductility can be clinched nowadays [1]. Due to this fact, clinching has partially replaced thermal joining processes, especially in multi-material car body design. ...
The paper presents results of a FEA-based tool design optimisation for a clinching process with an open multiple-part die. The studied materials are the bake-hardening steel CR240BH (1.5 mm) on the punch side and the die-cast aluminium alloy AlSi10MnMg (2.95 mm) on the die side. The objective of the optimisation was to minimise probability of cracks that appear at the outer circumference of the bottom of the clinch joint in AlSi10MnMg. In the framework of the optimisation, it was possible to minimise crack probability by varying geometrical parameters of the tools though at the cost of slightly worse but still tolerable geometrical parameters of the clinch joint.
... Numerical researches involving the forming process and the strength of the joints made by pressing [5,6,7] represent a large contribution to the joints technology development. The determination of the tools geometry for the different material their thickness and its arrangement cause an increase in the use of computer simulation of forming process in order to reduce experimental studies [8,9,10]. The experimental research are usually related to the joints strength in shearing and tension test [11,12]. ...
The clinching joining technology is one of the most popular joining technologies by redrawing sheet material. The joining process parameters, the sheet material and its arrangements influences joints’ strength. Cylindrical axial-symmetrical joints formed by using rigid die and punch are still developed. The change of the rigid die on the die with movable segments affect the forming process and joint strength parameters. So there is a need to do experimental researches of the possibilities of joint formation by unchanged punch geometry and different die shape. In this article the forming process parameters (forming force, process energy consumption and its standard deviations) and joints strength parameters (maximum shearing force, total dissipated energy and dissipated energy up to 0.3 maximum force), according to the ISO 12996 standard, for the joints formed with using die with 2, 3 and 4 movable segments were presented. The punch geometry was unchanged and the minimum thickness of the embossment was also unchanged. For the die with 2 and 4 segments the load force direction influence on the joints strength was also presented.
... Until the 1980s the technology was not widely used in industry [1]. Just in recent years has the interest in the use of clinching joining increased in industry, as clinching was successfully implemented to complement or even replace other joining techniques such as spot welding [2]. In the clinching process, two sheets of metal are joined using at most a die and a punch. ...
Clinching is one of the important new joining techniques, in which two plate metal parts are locally plastically deformed by mechanical interlock. Clinching is a mechanical joining method by using simple tools that consist of a punch, a die, and a blank-holder. The shapes of these tools are the most important parameters that control the final geometry of the clinch joints which in turn strongly affect the strength and quality of the final joint. In this study, finite element simulations are carried out to investigate some of the difficulties regarding the optimization of the process parameters, and major expected geometric parameters that will influence the strength, joinability, and the quality of the joint.
Clinching is a mechanical joining method using more than one thin metal sheet together without additional components. The main advantage of this method over the spot welding method, which is used mainly in automotive and other sectors, is the possibility to connect different materials. Being a joining method based on the plastic deformation of the sheets, the main limitation of clinching is represented by the sheet material formability (ductility). In this paper, a literature survey is carried out for clinching research mainly related to finite element analysis of the clinched connections. This review process showed that main performance parameter of clinched connection is interlock length and it is effected from die parameters. It is also seen that, in order to strengthen the relationship between industrial applications and theoretical studies of clinch technology, it is necessary to carry out further research on some issues of the process, in particular to establish effective models for FEA simulations and to determine the parameters that are effective in the process, the sensitivities of the parameters to the mechanical behaviors of the clinch connection.
Clinching is a method for mechanically joining sheet metal of different thickness and properties in which the two plates to be joined undergo plastic deformation. The clinching process is established by connection or joining using simple tools: a punch and a die. This method has different characteristics compared to thermal joining methods, such as spot welding, including low purchase and operating costs, little preparatory work, safe and environmentally friendly, interesting mechanical properties, reproducibility, and durability. In this article, a brief review of traditional joining methods for dissimilar materials and the clinching process are illustrated in greater detail. In addition, the article looks to guide researchers for future work by identifying weaknesses of the current processes as well as potential for valuable contributions in the field of clinching.
Various materials are used in car body production which are not always possible to join by conventional joining methods such as resistance spot welding. Therefore ClinchRivet method seem to be possible alternative. The paper deals with evaluation of properties of the joints made by mechanical joining method – ClinchRivet. The joint is made with the using of a special rivet, which is pushed into the joined materials by the flat punch. Following materials were used for joining of this method: DX51D+Z and H220PD steel sheets. The ten-sile test for observing the carrying capacities and metallographicall analysis were used for the evaluation of joint properties. Some results of the tests of ClinchRivet joints were compared to the properties of the joints made by resistance spot welding.
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