Application of the Taguchi Optimization Method in Order to Improve the Quality of the Conical Mini-Parts Obtained by Forming Process

Mini forming is an appropriate technology to manufacture small metal parts, as these are required in many industrial products resulting from mini-technology. This paper work want to underline the fact that even in down scale there are problems regarding deviation from the required dimensions. One of the problems is scaling effects, which occur in tribological aspects such as the friction coefficient, which increases with decreasing specimen size. Simulations investigations into mini forming process were carried out and mini conical parts have been obtained with different geometries. . The main objective is to observe and quantify behaviour of the mini parts during forming process and geometry deviations that affect the final product. The material used in this analysis is copper - zinc alloy with anisotropic properties. During forming process of conical mini-parts, the material record important variation along the part length and generate important shape deviation. This phenomenon causes deviations of sidewall angle, superior diameter, inferior diameter, mini part height, and connection radius between the part bottom and sidewall. There are multiple factors that affect the geometry deviations: sidewall angle, friction coefficient, tools gap, punch radius, and punch speed. The Dynaform 5.9.1 software was used to simulate the forming process. The part obtained after each simulation was analyzed and measured to quantify the deviation from the desired geometry on the final conical mini-part. In the final part of this paper some conclusions regarding geometry deviation of conical mini-parts obtained by forming are presented.

This paper develops an efficient and fast optimisation procedure for the cup drawing process in order to produce a defect free deep drawn cup. The finite difference technique is used as the solution engine for the deep drawing problem in the optimisation procedure. A procedure that minimises the Blank Holder Force (BHF) scheme is proposed, which searches for a linearly varying BHF scheme that minimises the maximum punch force while avoiding tearing and wrinkling. The optimised linear BHF scheme resulted in an improved cup forming when compared to that produced by the constant BHF scheme. The BHF scheme is optimised for different cases of drawing ratios and die coefficients of friction. It was found that the slope and the intercept of the linear BHF scheme increase in a nearly linear manner with the increase of the drawing ratio. A general equation is deduced for the optimum BHF at any drawing ratio for the cup under study. The proposed optimisation strategy can be applied to BHF schemes other than the linear one and with different objectives. [Received 3 March 2006, Accepted 10 January 2007]

Due to the trend of miniaturization on electrical devices, medical devices, and energy, etc., the need for micro and mini metal parts is increasing at a tremendous rate. In order to realize the potential of the mini-parts and take advantages from the mini-forming process, innovative modifications of the forming process must be developed. These modifications are particularly important with respect to the mini-parts forming, which offers an excellent opportunity to produce high accurate mini parts and to reduce manufacturing costs and time. However, severe modifications of the material thickness occur during forming of mini-parts. This paper presents a study concerning the material thickness variation during forming process of mini-parts. The main objective is to understand the material behaviour during forming of mini-parts. The material used in this analysis is copper - zinc alloy with anisotropic properties. During forming process of conical mini-parts, the material become very thin around the punch radius and become thicker at the upper end of the part. This phenomenon cause forming problems such: material fracture, wrinkling, part diameter variation, springback etc. There are multiple factors that affect the material thickness variation during forming process as: side wall angle, friction coefficient, punch radius, and punch speed. The Dynaform 5.9.1 software was used to simulate the forming process. The part obtained after each simulation was analyzed and measured to quantify material thickness variation on the final conical mini-part. To analyze the behaviour of the material during deep drawing process the obtained results for different conical mini-parts were compared. In the final part of this paper some conclusions regarding the material thickness variation during forming of conical mini-parts are presented.

Numerical simulation conducted by Finite Element Method is one of the most powerful tools for analyzing metal forming processes. Among them, Hydromechanical Deep Drawing (HDD) is, probably, the process which has gained the major interest in industries in the last few years. In this paper a numerical study of HDD of a can box is presented. The influence of geometrical features of a pressure chamber in terms of the gap with the punch is discussed, together with the main process parameters, such as counter-pressure and Blank Holder Force (BHF). The pressure path was found to be the key parameter for a successful HDD. The pressure, in fact, has to be increased very quickly in the first part of the process in order to obtain a minimum friction between the blank and the die entrance radius. The BHF is determined by the pressure path and so a simple way for understanding the correct force was developed. The results are presented in terms of thinning and wrinkles of the final product. Thickness was found to decrease in the first half of the simulation and then it remains constant; wrinkles take place in the last steps of the simulation and they depend on the BHF and on sheet metal anisotropy. The FEM commercial code Pam Stamp 2000 with Aquadraw function was utilized.

A database oriented process control design algorithm for improving deep-drawing performance

Mechanical response of common millet (Panicum miliaceum) seeds under quasi-static compression: Experiments and modeling

Numerical modelling of textile materials is important for developing new forming processes of textile reinforcements for composite parts, namely to decide on forming tool geometry and forming process parameters such as blank holder forces. A numerical model reduces the application of trial-and-error, which significantly reduces costs and material resources. The magnitude and distribution of blank holder forces play a decisive role in the quality of the formed textile. In general, no or even low blank holder forces will lead to wrinkles in the useful part of the preform. This reduces the mechanical quality of composite parts reinforced by textiles. In contrast, excessive blank holder force will cause damage to the textile. To observe these effects in complex forming situations, a material model has to be found which takes all forming modes of textile materials into account. A meso-scale model for biaxial reinforced weft-knitted fabrics is introduced, in which present yarns are simplified and discretized by beam elements. A single yarn is considered as a chain of multiple beam elements. Methods of modelling the complex geometry of the reinforced knitted structure are presented. The models are suitable for virtual mechanical tests and large scale forming simulations.

To predict the quality of a process outcome with given process parameters in real-time, surrogate models are often adopted. A surrogate model is a statistical model that interpolates between data points obtained either by process measurements or deterministic models of the process. However, in manufacturing processes the amount of useful data is often limited, and therefore setting up a sufficiently accurate surrogate model is challenging. The present contribution shows how to handle limited data in a surrogate modeling approach using the example of a cup drawing process. The purpose of the surrogate model is to classify the quality of the drawn cup and to predict its final geometry. These classification and regression tasks are solved via machine learning methods. The training data is sampled on a relatively wide range varying three parameters of a finite element simulation, namely sheet metal thickness, blank holder force, and friction. The geometrical features of the cup are extracted using domain knowledge. Besides this knowledge-based approach, an outlook is given for a data-driven surrogate modeling approach.

Experimental validation of IS2062 deep drawing component

The deep drawing process consists in realizing parts with complex shapes like different kind of boxes, cups, etc., from a metal sheet. These parts are obtained through one or several stamping steps. The tool setup motion of the stamping process is difficult to obtain. It requires practice and special knowledge on the process. The design is long and difficult to optimize. It is expensive in machining tool operations because it needs many trials and modifications on the tool before obtaining the right shape and the good working of the tool. The mains reasons of these difficulties come from the strain heterogeneity, the spring back after the tool removing and the decrease of thickness. There are many influent parameters for this kind of process. They modify directly the shape of the part. These parameters can be listed in three different categories: Firstly, the parameters linked to the tool geometry like the die enter radius, the punch diameter and the clearance between die and punch. Secondly, the parameters linked to the manufacturing conditions like the stamping speed, the lubricant and the blank holder force. And thirdly, the parameters linked to the flank geometry.

In sheet metal forming processes, formation without fracture is related to sheet metal formability. Parameters such as tool geometry, blank holder force, and lubricant are changed in order to push the formability of material to its maximum capacity. Lubricants play an important role in sheet metal forming processes. Depending on the type of lubricant, the formability of the sheet metal can be increased, the surface quality of the product can be improved, and the tool life can be extended. In this study, nanoparticles were added to solid lubricants, and the effect of nanolubricants on sheet metal formability was investigated with Erichsen test. Test specimens were observed by SEM, and the nanoparticle effect was investigated by EDX mapping. In addition, the optimum nanoparticle concentration was determined, and the effects of the nanoparticle on solid lubricants were compared with other lubricants which were used in sheet metal forming. As a result of the study, it was observed that the nanoparticle additive increased the formability by 13%. Results showed that the formability of the sheet metal increased up to certain nanoparticle concentrations, but it decreased above this limit.

The most common problem in area of sheet metal forming technology is a problem of achieving accurate and repeatable shapes of drawn and bent parts. This phenomenon is caused by the elastic springback. Springback can be defined as an elastically-driven change of shape of the deformed part upon removal of external loads. Several technological parameters influence amount of springback, between these belong friction coefficient, blankholder force, different geometry of tools, etc. In this paper is presented this topic, and also numerical simulation of this process. For an experimental process were used two high-strength steels. Steel with TRIP effect and dual phase steel DP 600. Numerical simulation was performed in the static implicit code Autoform. Results were compared and discussed.

In this work the significance of important parameters such as Blank temperature, Blank hold force on limiting drawing ratio (LDR) of IS513 CR3 steel sheets during warm deep drawing was determined. Influence of these parameters was analyzed at three different forming speeds. Experimental results proved that the blank temperature has a higher influence on LDR compared with other parameters especially at low forming speed.

The industrial production of parts with precision holes for various applications requires high manufacturing accuracy. The dimensional verification of precision holes with complex geometry remains a critical challenge in modern manufacturing, particularly in ensuring reliability and process efficiency. ExistingCMMprocedures are largely optimised for circular holes and lack validated methodologies for complex-shaped apertures. A new methodology for assessing the dimensional accuracy and inspection efficiency of epicycloid-shaped holes using CMMs is proposed: manufacturing surface samples with epicycloid-shaped holes using a Water Jet machine, conducting measurements on a ZEISS CONTURA CMM, optical validating measurement accuracy using microscopy on a Keyence VHX system and processing data through image segmentation of the hole, analysing results, and establishing dependencies of measurement accuracy and time on operational parameters. The dependencies of the mean deviation of epicycloid-shaped hole dimensions on the stylus movement speed and the number of measurement points have been established. Key findings indicate that the speed of the stylus significantly influences the accuracy of the measurement, while the number of probing points plays a secondary role. To address the limitations of conventional evaluation techniques, a new geometric complexity coefficient is proposed to quantify deviations from ideal shapes. This coefficient comprehensively characterises deviations from the ideal geometric shape and includes the length of the curve that forms the hole. The proposed methodology enables the optimisation of measurement parameters for complex-shaped holes and improves inspection efficiency on industrial production lines. This approach contributes original insights into the metrological assessment of non-standard geometries, addressing a significant gap in existing literature.

In cup-drawing, an element of metal whose initial diameter exceeds the mean cup diameter is under conditions of true radial drawing, which is combined with plastic bending under radial tension when it reaches the die profile, whereas other elements will be subject to stretch-forming under biaxial tension, which will be combined with bending under tension if they fall within the punch profile.In this part an analysis of the stresses and strains in the region of true drawing is attempted, taking into consideration the effects of bending, thickness changes, strain-hardening, blank-holding force, die-profile friction, and tool geometry, but not of anisotropy in the material. Theoretical punch load-travel diagrams, process work, maximum punch loads and strains are compared with recorded experimental results over a wide range of tool design, operating conditions, and materials.It is suggested that the theory can be applied with confidence in predicting punch loads and strokes and in prescribing power and strength ratings for deep-drawing presses.