Untersuchungen zum Rundkneten von Mikrobauteilen

The demand for miniature components, as well as the requirement for high functional density paired with high precision, is increasing steadily from year to year. For example, saving resources and cost-effectiveness can be mentioned as reasons for this trend. This high demand paves the way for the development of new manufacturing processes or for the research and adaptation of existing processes for the purpose of miniaturization. Due to the specific advantages, such as the generation of residual compressive stresses in the components or the ability to produce complex geometries with adapted properties, the suitability of rotary swaging for micro manufacturing has been explored in recent years. Rotary swaging is very well-established in the macro range, especially in the automotive industry, and has also been explored. However, because it is well known that scaling a process from the macro to the micro range cannot always be readily accomplished, it is of particular interest to fill the knowledge gap of downsizing related to the swaged parts. The focus of the presented investigations was the understanding of the process in general as well as the phenomenon occurring in the component, the determination of the process limits and thus the productivity and the characterization of the products. A simulation of the process with the FE method showed the complexity of the material behavior, from which, for example, explanations for the occurrence of certain types of failure or for the hardening of the components can be derived. Furthermore, an unfavorable material flow was identified as the most common cause of failure in the micro rotary swaging process. Measures to control it were developed and experimentally investigated. An increase in the output rate without significant deterioration of the component quality was a target. This work shows that rotary swaging has a high potential for micro manufacturing, since different materials, ferrous and non-ferrous metals, can be easily formed and thus very high component strengths can be achieved

Application of Stochastic Regression for the Configuration of Microrotary Swaging Processes

In micromanufacturing, a precise adjustment of manufacturing, handling, and quality control processes constitutes an essential factor for success. The continuing miniaturization of workpieces and production devices results in ever decreasing tolerances, whereas machines and processes become increasingly more specialized. Thereby, the so-called size effects render the direct application of knowledge from the area of macromanufacturing impossible. In this context, this paper describes the application of the μ-ProPlAn method for the configuration of an infeed rotary swaging process for microcomponents. At this, the cause-effect relationships between relevant process parameters are analyzed using stochastic regression models, in order to determine cost-efficient process configurations for the manufacturing of bulk and tubular microcomponents

Investigations on the rotary swaging of micro-components

The demand for miniature components, as well as the requirement for high functional density paired with high precision, is increasing steadily from year to year. For example, saving resources and cost-effectiveness can be mentioned as reasons for this trend. This high demand paves the way for the development of new manufacturing processes or for the research and adaptation of existing processes for the purpose of miniaturization. Due to the specific advantages, such as the generation of residual compressive stresses in the components or the ability to produce complex geometries with adapted properties, the suitability of rotary swaging for micro manufacturing has been explored in recent years. Rotary swaging is very well-established in the macro range, especially in the automotive industry, and has also been explored. However, because it is well known that scaling a process from the macro to the micro range cannot always be readily accomplished, it is of particular interest to fill the knowledge gap of downsizing related to the swaged parts. The focus of the presented investigations was the understanding of the process in general as well as the phenomenon occurring in the component, the determination of the process limits and thus the productivity and the characterization of the products. A simulation of the process with the FE method showed the complexity of the material behavior, from which, for example, explanations for the occurrence of certain types of failure or for the hardening of the components can be derived. Furthermore, an unfavorable material flow was identified as the most common cause of failure in the micro rotary swaging process. Measures to control it were developed and experimentally investigated. An increase in the output rate without significant deterioration of the component quality was a target. This work shows that rotary swaging has a high potential for micro manufacturing, since different materials, ferrous and non-ferrous metals, can be easily formed and thus very high component strengths can be achieved

High productivity micro rotary swaging

Rotary swaging is an incremental forming process with two main process variations plunge and infeed rotary swaging. With plunge rotary swaging, the diameter is reduced within a limited section whereas the infeed rotary swaging enables a diameter reduction over the entire workpiece length. The process is now subject to intensive investigation for manufacturing of micro parts. By increasing the process speed, failures occur particularly due to inappropriate material flow. In plunge rotary swaging, the workpiece material can flow radially into the gap between the dies and thus the workpiece quality suffers. In infeed rotary swaging the workpiece material flows against the feeding direction and can provoke bending or braking of the workpiece. Therefore, additional measures to control both the radial and the axial material flow to enable high productivity micro rotary swaging are investigated. The radial material flow during plunge rotary swaging can be controlled by elastic intermediate elements that enable an increase of productivity by factor three. A spring-loaded clamping device that enables an increase of the productivity by factor four can temporarily buffer the axial material flow in infeed rotary swaging against the feeding direction

High productivity micro rotary swaging

Rotary swaging is an incremental forming process with two main process variations plunge and infeed rotary swaging. With plunge rotary swaging, the diameter is reduced within a limited section whereas the infeed rotary swaging enables a diameter reduction over the entire workpiece length. The process is now subject to intensive investigation for manufacturing of micro parts. By increasing the process speed, failures occur particularly due to inappropriate material flow. In plunge rotary swaging, the workpiece material can flow radially into the gap between the dies and thus the workpiece quality suffers. In infeed rotary swaging the workpiece material flows against the feeding direction and can provoke bending or braking of the workpiece. Therefore, additional measures to control both the radial and the axial material flow to enable high productivity micro rotary swaging are investigated. The radial material flow during plunge rotary swaging can be controlled by elastic intermediate elements that enable an increase of productivity by factor three. A spring-loaded clamping device that enables an increase of the productivity by factor four can temporarily buffer the axial material flow in infeed rotary swaging against the feeding direction

Material flow control in plunge micro rotary swaging

In rotary swaging, the material flow is not fully controlled by closure of the forming dies. This is especially noticeable in plunge rotary swaging of rod, where the workpiece is positioned into the forming zone und processed locally. As result, an uncontrolled elongation of the workpiece in axial direction takes place and an axial position shift of the workpiece relative to the dies occurs. This is a special challenge in production of linked micro parts, where single parts are interconnected in order to enable the handling as a strip and thereby a roll-to-roll production. The axial shift influences not only the subsequent positioning of neighbouring parts, but also the final geometry of the currently processed part. The presented investigation analyses the material flow during plunge micro rotary swaging on basis of in-process measurements of the workpiece shift on both sides of the forming zone as well as with the help of contour measurements of the processed parts. It is shown that the measured shift is strongly influenced by the workpiece clamping and fixation and that it can be controlled by applying low axial forces to the workpiece on one or both sides of the forming zone. Further, the geometry of the workpiece can be affected by these measures

Wire Joining by Rotary Swaging

AbstractA new wire joining process for wires with sub-millimeter diameters applying the rotary swaging was investigated. The basic idea is to join two wire ends by a tube segment. In the study different material combinations using steel (AISI304) and copper (CW004A) were examined. Further the realization of a form-locked joint was investigated. The formed samples were tested by optical microscopy and tensile testing and compared to spot welded samples

2D-simulation of Material Flow During Infeed Rotary Swaging Using Finite Element Method

AbstractFE simulation was applied to study the material flow during infeed rotary swaging. The neutral plane according to the process parameters was investigated and compared with experimental results. A single forming stroke was analyzed precisely by using small time points of 10-4s. For analysis the essential steps between the first contact of wire and forging die and the last contact before the die opens again are represented. In that range the feed velocity is eliminated and the neutral plane can be observed as spatial velocity at nodes in the axial direction equal 0mm/s. During a single stroke the location, the geometry and the orientation of the neutral plane is changing

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool materials in the form of a flat product. The graded deposits were subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled materials. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel

Development of micro rotary swaging tools of graded tool steel via co-spray forming

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool material in the form of a flat product. The graded deposit was subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled material. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel