Small-lot Production Research Articles

A three-dimensional analytical cutting force model for micro end milling operation

In the present day manufacturing arena one of the most important fields of interest lies in the manufacturing of miniaturized components. End milling with fine-grained carbide micro end mills could be an efficient and economical means for medium and small lot production of micro components. Analysis of the cutting force in micro end milling plays a vital role in characterizing the cutting process, in estimating the tool life and in optimizing the process. A new approach to analytical three-dimensional cutting force modeling has been introduced in this paper. The model determines the theoretical chip area at any specific angular position of the tool cutting edge by considering the geometry of the path of the cutting edge and relates this with tangential cutting force. A greater proportion of the helix face of the cutter participating in the cutting process differs the cutting force profile in micro end milling operations a bit from that in conventional end milling operations. This is because of the reason that the depth-of-cut to tool diameter ratio is much higher in micro end milling than the conventional one. The analytical cutting force expressions developed in this model have been simulated for a set of cutting conditions and are found to be well in harmony with experimental results.

Influence of strip materials on behavior of incremental in-plane bending

Incremental in-plane bending that has been invented by authors is a new and flexible manufacturing technology for small-lot production of strip with various bending radii. The strip is bent incrementally by an inclined punch beating. The prototype incremental bending machine uses the numerical control technology and bends the strip flexibly. The strip material is an important condition for in-plane bending. The bending experiments are carried out and some experimental results such as beating force, bending radius, strain distribution are experimentally examined. The forming properties of in-plane bending are clarified in this study. Moreover, the approximate formulas for calculation the bending radius are proposed. The bending radius calculated by the proposed formula agrees with one of the experiments.

2P1-15 電子福祉機器における少量製造設計(講演,福祉機器設計)

Benefits-plan has supported the market of assistive device. But, electronic assistive devises are almost exempt from that plan. This market is very smaller than general market. Therefore, it is too expensive to make some metal mold castings. We need the manufacturing design technique of small-lot production for electronic assistive device. So we broke and broke down outstanding electronic assistive devices. With this analysis, we developed remote-control device and switch case by a multipurpose case.

Multiobjective optimization of robot motion for laser cutting applications

This paper focuses on the enhancement of automatic robot programming techniques for laser cutting applications. Such technology has already gained essential industrial acceptance, but its application for small lot production is limited by the tedious and time-consuming process of robot programming. Currently, even sophisticated graphical simulation systems do not allow optimization of robot motion using multiple criteria, nor does it take into account redundancy caused by the tool axial symmetry. The particular contribution of this paper lies in the area of multiobjective optimization of robot motions via graph representation of the search space and dynamic programming procedures. It presents algorithms that allow generation of smooth manipulator trajectories within acceptable time, simultaneously considering kinematics, collision and singularities constraints of the robotic system, as well as the limitations of the robot control units. The efficiency of the algorithms has been carefully investigated via computer simulation. The presented results are implemented in a commercial software package and verified for real-life applications in the automotive industry.

平板の面内逐次打点曲げにおける押込み量の影響

Incremental in-plane bending which has been invented by authors is a new and flexible manufacturing technology for small-lot production of sheet metal with various bending radii. The sheet metal is bent incrementally by an inclined-punch beating. The prototype incremental bending machine uses the numerical control technology and bends the sheet metal flexibly. The bending experiments are carried out and some experimental results such as beating force, bending radius, strain distribution are experimentally examined. The forming properties of in-plane bending are clarified in this study. Moreover, approximate formulas for calculating the bending radius are proposed base on the plane strain. The bending radius calculated by the proposed formula agrees with the one of the experiments.

신발 금형의 쾌속제작기술 개발 및 그 적용에 관한 연구

RP&M (Rapid Prototyping and Manufacturing) is the most appropriate technology for the small-lot production system, because the production cycle is getting shorter owing to various needs of the consumer. In this paper, rapid tooling technology is applied to the casting process. The casting process has the ability to reflect complicated shapes in one process. But it has not been widely used to make a die and mold because of the poor surface quality caused by air bubbles on the surface of the casting product. In this study, the porous casting mold is fabricated from a mixture of plaster and water-soluble binder. The porous casting mold can improve the characteristics of casting products with the help of the vacuum sealed casting process. The vacuum sealed casting process is an advanced technology that removes the air bubbles between the porous casting mould and the liquid metal, thus making the surface of the casting product finer. The purpose of this paper is to develop a high quality shoe mold using porous casting mold and to apply the RP&M technology to the shoe industry .

Low-Cost and High-Performance Micro-Fabrication Method Using Low Numerical-Aperture Optical Projection Lithography on Copper-Clad Plastic Boards

Combination of optical lithography patterning in the case of a thickly coated resist and electroplating using the resist replica is investigated for developing a new easy, low-cost and high-performance micro-fabrication method. In order to form patterns with a high aspect ratio and vertical side walls, low numerical aperture (NA) projection exposure is applied, and acrylic resist SU-8 is used due to its high transparency for the exposure light of near UV and visible light from violet to blue. When a lens with a low NA of 0.063 is used, a large depth-of-focus (DOF) of more than 200 µm is obtained for a 50-µm-wide and 100-µm-thick resist. If the focal position is adjusted suitably, 275-µm-thick patterns with vertical side walls and a high aspect ratio of more than 10 are obtained. These resist patterns are printed on copper clad plastic boards instead of silicon wafers. The copper-clad boards are directly available for electroplating without evaporating base metal layers on them. Thus, fabrication of micro nickel gears is demonstrated successfully. Since the new method uses low-cost optical lithography, it is applicable even for small production lots, and will be useful for fabricating various micro-parts.

Rapid fabrication of aluminum shoe mold using vacuum sealed casting process

Rapid prototyping and manufacturing (RP&M) is the most appropriate technology for the small-lot production system, because the production cycle is getting shorter owing to various needs of the consumer. Recently RP products, which are made of plastics, wax, and paper, were used to examine the design of samples. These samples, however, cannot be applied to the real mold because soft materials, such as plastics lack the necessary strength to be a mold. So the materials have been changed from RP products to a metal powder filled mold like an epoxy-metal powder composite mold or metal mold, which is called rapid tooling (RT) technology. In this paper, RT technology is applied to the casting process. The casting process has the ability to reflect complicated shapes in one process. But it has not been widely used to make a die and mold because of the poor surface quality caused by air bubbles on the surface of the casting product. In this study, the porous casting mold is fabricated from a mixture of ceramic powder and water-soluble binder. The porous casting mold can improve the characteristics of aluminum casting products with the help of the vacuum sealed casting process. The vacuum sealed casting process is an advanced technology that removes the air bubbles between the porous casting mold and the liquid metal, thus making the surface of the aluminum casting product finer. The purpose of this paper is to develop a high quality shoe mold using porous casting mold and to apply the RP&M technology to the shoe industry.

On Optimisation of Detail Recognition in a Process of Super‐Fast Grinding of Ceramics

AbstractMost of digital picture processing systems are used in mass production. While making use of intelligent systems of standard recognition, digital picture processing can be applied in lot production or small lot production, and their ability to learn enables them to recognize parts of di.erent shapes. In the present paper, a system based on fuzzy logic principles was introduced. It has an application in the automation of the feed of machined elements into the machine working space during machining of ceramics.

5102 作業動作認識に基づく作業支援システム : RFID を用いた作業位置の検出と物体の特定

The need of computer-aided work support systems is increasing for reliable work and efficient work training in small lot production of diversified products. We have proposed that machine recognition of human work is an important function for autonomous computer support system. In this paper, RFID (Radio Frequency Identification system) is considered as a device for identifying work objects, estimating work position and monitoring other information during human work. A prototype system, which has a RFID reader/writer mounted on a glove, is developed to detect the RFID tag without special operation. The result of detection test in assembling work shows that the system can be used for monitoring work sequences.

A study of the multi-stage flowshop scheduling problem with alternative operation assignments

In small-item large lot production, a single person had only single processing to do. A recent tendency of the production system is the multi-item small lot production. In this type of production system, one work person needs skills that are adaptable to multi-item articles. As the single work person needs more than one skill, one processing operation which comprises a job has come to be handled by several work persons. From the viewpoint of a job, one elementary operation has come to be processed by several alternative operation assignments. We discuss the problem of how to minimize the total elapsed time from the start up time to the completion of a job. In order to solve this problem, we analyze it theoretically under a simpler condition, then we propose an approximation algorithm based on the theoretical analysis applicable to a more general problem.

Tools of Change

This article discusses reconfigurable forming dies that increases the efficiency of small-lot production. Manufacturers have long desired single universal tools that could make many different shapes. Patents for reconfigurable “discrete-die” tooling—dies composed of movable elements such as pins or plates—date back nearly to the inception of the patent office. In forming large sheet metal parts, elastic springback can cause unacceptable part shape errors if the part is formed on a tool whose shape mirrors that of the finished part. Two approaches to tool shape correction have been developed for use with the reconfigurable tool. In one, an iterative technique calculates the correct die shape based on two initial guesses. In the other, a predictive technique uses finite element analysis to model and correct for elastic springback. Cost and benefit analysis has shown the attractiveness of reconfigurable tooling based on the initial investment alone. An even greater benefit could be realized through lowered assembly costs and shortened turnaround time for small production lots. Small-lot production shops are likely to profit by replacing fixed-shape forming tools with reconfigurable tools.

Functional Changes in the Technological Core of the Japanese Machinery Industry in Ota-ku, Tokyo

The industrial area in the southern part of inner Tokyo, of which the center is Ota-ku, developed in the second half of the 1960s, playing an important role as the technological core in the regional system of the machinery industry in the Tokyo metropolitan area. It coped with technological innovations such as microelectronics (ME) in the 1980s through its own efforts. Although the numbers of factories and employees have declined due to severe economic conditions since the 1990s, the function of the industrial area as the technological center has advanced. In addition to the first generation who founded their companies just after World War II based on their skillful machining technology, the younger generation has joined as managers or leading engineers. Most of the younger generation are highly educated and have learned ME technology as well as new management methods. Both groups have crystallized and upgraded the technological level of each factory. The renewed and vitalized factories are classified in the following three categories: processors of high-level of technology in response to various demands of machine manufacturers; manufacturers generating high-quality but very small lot products; and manufacturers of plot-type or those specialized in developing or testing for large machine manufacturers. These three types have common characteristics that are indispensable to each other and depend on numerous subcontracting processors in their vicinity. As a result, a strong industrial complex continues in Ota-ku with businesses upgrading their technology through mutual cooperation. Although a huge technological complex of the machinery industry existed in Ota-ku until the 1980s under the control of big manufacturers, this production system has been in the course of radical change since the 1990s. The technological complex with interfirm cooperation and interactive learning processes led by powerful small and medium enterprises is in transition to a horizontal relationship with big manufacturers. Most of the new generation was born and grew up in this area. They make their industrial community a substantial one through the interchange not only of business but also of social life involving the older generation. The industrial community has become a very important factor that sustains the strong technological complex. As a result of strengthening the technological complex, Ota-ku has increased its role as a regional innovation base for upgrading the Japanese machinery industry and as the core of its new regional division of labor system.

Path Optimization in a Multi-Robot Welding System

Multi-robot systems have been introduced actively in heavy industry in order to increase the productivity. However, since the configuration of workpiece is complex due to multi-kind small lot production especially in shipbuilding and in multi-robot systems robots are disposed as densely as possible in a working area to get high productivity, collision between adjacent robots could occur. Because the collision prevents effective production, collision occurrence should be avoided. This paper reduces the problem of minimization of total welding time subject to collision/deadlock avoidance among multi-robots to a path optimization one, and solves it through genetic algorithm (GA). Its effectiveness is shown by numerical simulations with practical workpieces. Furthermore, a two-step GA algorithm is proposed, where the welding path of the maximal loaded robot is optimized first and then those of other robots are optimized.

Validity of Adjusting Density of Material Fiber Mass in Twist Draft Spinning Frame

In order to add higher value to spun yarns, we have studied the application of a twist draft spinning to multi -kind small-lot production of functional yams. In twist draft spinning, a yarn is spun out directly from a large mass of material fiber and the yam count is controlled by spun yam tension. In this paper, we specially have regard to the linear de n-sity and twist rate of the yarn those are deeply concerned with quality of the yam. Through an analysis of the yam properties, it is found that the density of material fiber mass is the most effective parameter in properties of material fiber to adjust twist factor of the yarn. Furthermore, the linear density and the twist factor of the yam can be controlled independently by using spun yam tension and density of material fiber mass as adjusting parameters.

Rapid tooling approaches for small lot production of sheet-metal parts

Using Rapid Prototyping Techniques (RPTs) like Stereolithography or Selective Laser Sintering, the automotive industry produces plastic parts for prototypes faster and cheaper compared to the techniques used up to now. As a consequence of this process, the automotive industry increasingly demands to have sheet-metal parts also earlier than now at their disposal. This paper deals with rapid prototyping (RP) process chains to manufacture large sheet-metal forming tools. It gives an overview of technically possible solutions. After that, the paper deals more in detail with two of the approaches, namely layer milling and resin casting. It describes these manufacturing methods and presents the result of a case study which compares the approaches with the actually used production method.

Automatic Startup Operation of Plastics Extruder by Flexible Intelligence Machine Control

In process control, the need of multitype small-lot production becomes strong. But, due to strong nonlinearity and abrupt changes of plant dynamics, attempts to introduce quantitive model of plants and promote automated operations have been hindered. For this problem, we proposed the concept and the structure of the FIMC (Flexible Intelligence Machine Control) which is a controller with functions for acquiring control knowledge about the operation knowhow from the data furnished of expert operators in manual operation control hysteresis and eventually in automating operations based on control knowledge. In this paper, we show the design method and effectiveness of the FIMC applied to the startup operation of the plastics extruder.

Rapid hard tooling by plasma spraying for injection molding and sheet metal forming

Amidst the harsh competition over the development of new products around the world, rapid prototyping, especially rapid tooling methods have received widespread attention. Amongst the rapid hard tooling methods, thermal spraying can manufacture metal molds without limitation of pattern size. However, it has the disadvantage that only soft metals with low melting points such as zinc alloy can be sprayed to original mold, such as a rapid prototyping model or a natural material pattern, due to their lack of heat resistance and shrinkage of spray metals. So the wear resistance of spray tool is poor, it can be used only for trial or small-lot production. In this study, attempts were made to improve the heat resistance by using composite materials made of ceramic and metal powders as the sprayed original mold materials, and using stainless steel, tungsten carbide alloy, iron–nickel–chromium alloy with excellent wear resistance as spraying materials, respectively. The results show that injection molding spray mold and sheet metal forming spray die can be made by transferring from natural patterns and rapid prototyping models. As the durability and dimensional accuracy of the sprayed tools has sharply improved, the tools can be used for mass production.

Future steelmaking plant with minimized energy consumption and waste evolution

A view is presented on future BF-BOF type and EF type steelmaking plants. The former and the latter include, respectively, rationalized process steps for a mass production and small lot production of quality steels at reduced costs. Integration of the 2 types of plants is discussed for better synergy effects. Emphasis is placed on minimizing the consumption of primary energy and evolution of wastes such as dust, slag and gases, with a consideration given for maximized utilization of the wastes. Metallurgical key issues for future R & D to achieve improved productivity and wastes evolution are also suggested.

A Finite Element Based Die Design Algorithm for Sheet-Metal Forming on Reconfigurable Tools

Tooling cost is a major contributor to the total cost of small-lot production of sheet metal components. Within the framework of an academic/industrial/government partnership devoted to the development of a reconfigurable tool for stretch forming, we have implemented a Finite Element-based procedure to determine optimal die shape. In the reconfigurable forming tool (Hardt, D. E. et al., 1993, “A CAD Driven Flexible Forming System for Three-Dimensional Sheet Metal Parts,” Sheet Metal and Stamping Symp., Int. Congress and Exp., Detroit, MI, SAE Technical Paper Series 930282, pp. 69–76.), the die surface is created by the ends of an array of square pins, which can be individually repositioned by computer driven servo-mechanisms. An interpolating polymer layer is interposed between the part and the die surface to attain a smooth pressure distribution. The objective of the die design algorithm is to determine optimal positions for the pin array, which will result in the desired part shape. The proposed “spring-forward” method was originally developed for matched-die forming (Karafillis, A. P., and Boyce, M. C., 1992, “Tooling Design in Sheet Metal Forming using Springback Calculations,” Int. J. Mech. Sci., Vol. 34, pp. 113–131.; Karafillis, A. P., and Boyce, M. C., 1996, “Tooling And Binder Design for Sheet Metal Forming Processes Compensating Springback Error,” Int. J. Tools Manufac., Vol. 36, pp. 503–526.) and it is here extended and adapted to the reconfigurable tool geometry and stretch forming loading conditions. An essential prerequisite to the implementation of the die design procedure is the availability of an accurate FE model of the entire forming operation. The particular nature of the discrete die and issues related to the behavior of the interpolating layer introduce additional challenges. We have first simulated the process using a model that reproduces, as closely as possible, the actual geometry of the discrete tool. In order to optimize the delicate balance between model accuracy and computational requirements, we have then used the information gathered from the detailed analyses to develop an equivalent die model. An automated algorithm to construct the equivalent die model based on the discrete tool geometry (pin-positions) is integrated with the spring-forward method, to generate an iterative die design procedure that can be easily interfaced with the reconfiguring tool. The success of the proposed procedure in selecting an optimal die configuration is confirmed by comparison with experimental results.