Papers by Keyword: Micro Deep Drawing

Abstract: In order to make micro composite drills (Fig. 1), cemented tungsten carbide (WC-10Co) and high strength (AISI 4340) steel were successfully bonded by hot compaction diffusion bonding at a low temperature. The effects of holding time, pressure and temperature on microstructure and mechanical properties of the sintered carbides and bonding strengths of the bimetallic composites were examined, and a transitional layer was found at the interface as a result of elemental inter-diffusion. The optimal bonding parameters were determined to achieve the maximum bonding strength of 226 MPa of the WC-10Co/AISI 4340 steel joints, which is helpful in producing micro composite drills. Microforming is introduced to produce lighter and more energy effective products. In this study, Magnesium-Lithium (Mg-Li) alloy, new material in microscale, was chosen to superior formed micro-cup due to its ultralight weight with outstanding ductility. The dry and oil lubrication conditions were chosen as benchmarks to investigate effects of a novel oil-based nanoparticle lubricant in micro deep drawing (MDD) process of Mg-Li alloy. Finite Element (FE) modelling was conducted and the simulation results of the drawing force were in a good agreement with the experimental results. The formed cup quality with consideration on the surface roughness has been extensively evaluated and the results illustrated the quality improvement was substantial.

Abstract: In the last few decades, there is a global interest in micro products, and micro forming of metals is a promising micro manufacturing method. However, a comprehensive understanding of this process is absent. Therefore, this study aims to investigate micro deep drawing process via experimental and analysis work. Simulation results are in good agreement with the experimental data. The comparison between the finite element method (FEM) simulation and experimental results shows the feasibility of FEM simulation for micro deep drawing process. This research also lays a fundament of investigating micro forming process, especially micro deep drawing.

Abstract: Micro forming processes are very well suited for manufacturing of small metal parts in large quantities and micro deep drawing provides a great application potential for the manufacturing of parts with complex shapes. But size effects like changed tribology and material properties usually result in smaller process windows for micro forming operations. Process caused wear as well as large inaccuracy in manufacturing of micro forming tools is responsible for geometrical deviation of the tools from nominal size. Both influences can have essential impact on the process window size and process stability. A better understanding of the influence of tool geometry on process stability can help to improve and optimize process control in micro forming. In addition, a quantitative judgment of the impact of wear and manufacturing inaccuracy will be possible. Therefore, in this study, the impact of different tool geometries on the punch force in micro deep drawing was investigated. Significantly varied tool geometries were punch diameter, drawing gap, punch and drawing die radius and shape of the die edge. FEM simulations as well as experiments were used to determine tool geometry influence on the punch force of a micro deep drawing process. Hereby, it was possible to classify each geometry variation regarding its impact on the punch force and therefore on one important parameter of the process stability. Results show that the greatest impact on the punch force was caused by modifications of the punch diameter and variation of the drawing gap. Changes in punch or drawing die radii proved to be of minor importance.

Abstract: In macro forming a DLC-coating can increase durability and decrease wear of a deep drawing tool. Due to size effects, the behavior in micro range can differ from the behavior in macro range. To investigate durability and wear in micro deep drawing a blanking and deep drawing tool combination was developed, capable of maximum stroke rate of 200 parts per minute. Experiments with copper foil (E-Cu58) of 0.05 mm thickness were performed to produce cylindrical micro cups with a diameter of 1 mm using the lubricant Lubrimax Edel C. The tool material is stainless steel (German standard 1.2379). The punch has a diameter of 0.9 mm and the die diameter is 1.06 mm. To increase durability and decrease wear in micro deep drawing a DLC-coated tool is used. DLC-coated and uncoated tools are compared in long term test regarding wear behavior. Furthermore, the die radii of the tools are measured optically and cross-sections of the tools are made to analyze the microstructure. Experiments show, that the DLC-coating starts to delaminate during the first 5000 strokes. By analyzing the cross section it can be recognized a high density of scattered carbides and pores with different sizes up to 35 μm in the tool material are visible, causing delamination. Furthermore, higher load and stress in micro forming provides delamination. Thus a high influence on the durability of the DLC-coatings base material can be reported in micro range.

Abstract: This paper presents an explicit dynamic finite element method (FEM) in conjunction with the forming limit diagram (FLD) to analyze the forming limit for the various arc radii of punch in micro deep drawing of square cup. In the present study, the tensile test and friction test are performed to obtain the material parameters of the electro-deposited copper foil according to the ASTM standards. Importing these properties, the numerical analysis is conducted by the explicit dynamic FEM. The FLD in numerical simulation is used as the criterion of the forming limit in micro deep drawing of the square cup. The forming limit, deformed shape, punch load-stroke relationship, height of cup and thickness distribution of square cup, are discussed and compared with the experimental results. It shows that a good agreement is achieved from comparison between simulated and experimental results. When the arc radii of punch increase with R_p=0.2, 0.5 and 0.8mm, the limit drawing ratio increases from 1.90 to 2.03 and 2.10. The forming limit of square cup increases with an increase of the arc radii of punch. From this investigation, the results of this paper can be used as reference in the relative researches and applications of micro forming.

Abstract: This paper presents an explicit dynamic finite element method (FEM) in conjunction with the forming limit diagram (FLD) to analyze the forming limit for the SPCC foil in micro deep drawing of square cup. In the present study, the tensile, anisotropic and friction test are performed to obtain the material parameters of the alloy foil according to the ASTM standards. Importing these properties, the numerical analysis is conducted by the explicit dynamic FEM. The FLD in numerical simulation is used as the criterion of the forming limit in micro deep drawing of the square cup. The forming limit, punch load-stroke relationship, deformed shape and thickness distribution of square cup, are discussed and compared with the experimental results. It shows that a good agreement is achieved from comparison between simulated and experimental results. The limit drawing ratio in micro deep drawing of square cup is 2.08 in this paper. From this investigation, the results of this paper can be used as reference in the relative researches and applications of micro forming.

Abstract: In this paper, the influence of grain size and blank hold force on micro deep drawing stress and displacement are studied by self-made device. The results show that drawing stress decreases and elongation rate increases with the increase of grain size, the concentrated force area of cylinder-shaped part is transferred from the area punch fillet to die fillet area. Twin grain ratio and twinning degree near the punch fillet are increasing. Twin grain distribution becomes uneven with the increase of grain size. In micro deep drawing, the displacement increases with the increase of blank hold force, meanwhile, forming stress almost remains constant. The flange wrinkling can be inhibited.

Abstract: Superplastic deformation behavior of nanocrystalline nickel was investigated under equibiaxial tension at different strain rates and forming temperatures. The nickel sheets with a thickness of 0.1 mm were prepared by pulse electrodeposition process. The average grain size of the as-deposited nickel was 70 nm and equiaxed. To determine the optimum processing parameters relevant to micro deep drawing, uniaxial tensile tests were carried out at temperatures ranging from 370°C to 500°C and strain rates ranging from 10-4 to 10-3s-1. In the selected temperature and strain rate ranges, the elongation value is larger than 200%, which indicates good superplastic formability of the electrodeposited nickel. Equibiaxial forming was subsequently performed at 370°C and 450°C, using a punch with a diameter of 1mm. The effects of forming temperature, punch rates on deep drawing process were experimentally investigated. The results indicated that the nickel specimens can be readily drawn at 450°C and punch rates ranging from 0.1mm• min-1 to 5mm• min-1. TEM and SEM were also used to examine microstructures of the as-deposited nickel sheet and deformed nickel specimens. The observations showed that significant grain growth occurs even at low superplastic forming temperatures. Microstructure was found to depend on the stress state and level of deformation.

Abstract: The existing forming press uses a hydraulic actuator and high powered mechanical actuator, therefore occupying a large space because of its size. This type of system is inefficient for manufacturing micro size and precision products. As forming components are small in size, forming equipment must also be small in size because the forming die and load must be small. The micro forming manufacturing system is an ultra precision forming equipment the size of several micros to millimeters and precision of sub-micro to micrometer. This micro forming manufacturing system has the advantage of minimization in manipulating distance and working space. As equipment and tools become smaller in size, minute inertia force and high natural frequency can be obtained. Therefore, high precision forming performance can be obtained. This allows the factory to quickly provide the customer with goods because the manufacturing system and process are reduced. To construct a micro manufacturing system, many technologies are necessary such as high stiffness frame, high precision actuating part, structural analysis, high precision tools and system control. In this paper Research development about a micro metal forming manufacturing system has been developed. To coincide with the purpose to be more practical, we set the development of the equipment including micro deep drawing, micro punching and micro restriking process to the goal. To achieve this goal, the miniaturized micro metal forming manufacturing system is designed and made with miniaturized size system. A micro deep drawing process and system dynamic characteristic experiments are researched using this miniaturized micro forming system. A micro deep drawing experiment is performed using micro thin foil materials (Al-1100, SUS-304). If this miniaturized micro forming technology is used, efficient material practical use in the micro forming field which uses the micro metal thin foil is possible.

Abstract: The micro metal forming manufacturing system is essentially an ultra precision forming press that can manufacture various micro scale products from metal thin foil and bulk material. In this paper, the micro metal forming manufacturing system has been developed using a micro servo motor. A micro forming system has been developed in Japan with a micro press that is limited to the single forming process. However, a press with a multi forming process is needed and we set about performing research and development of assorted equipment, including investigation into micro deep drawing and the micro punching process. In order to achieve this goal, exploration into the micro forming process as related to the multi forming process must be preceded first. Material selection and analysis of the micro forming process are accomplished in this paper, and the basis research as to how to make the actual system is accomplished.