Punching Operations Research Articles

A DETAILED STUDY ON PROCESS FAILURE MODE AND EFFECT ANALYSIS OF PUNCHING PROCESS

An FMEA (Failure Mode and Effect Analysis) is a systematic method of identifying and preventing product and process problems before they occur. FMEAs are focused on preventing defects, enhancing safety, and increasing customer satisfaction. Ideally, FMEAs are conducted in the product design or process development stages, although conducting an FMEA on existing products and processes can also yield substantial benefits. FMEA is used in the manufacturing industry to improve production quality and productivity by reducing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design. It is a method that evaluates possible failures in the system, design, process or service . In this paper, Failure mode and Effect Analysis is done on the process of Punching. A series of punching operation is done on various work pieces and the defects are found. Based on the evidence found, the ratings are given and risk priority number is given. Based on the RPN, the preventive measures are given. The FMEA is a proactive approach in solving potential failure modes. These works serve as a failure prevention guide for those who perform the punching operation and works towards effective punching operation.

Computer Aided Process Planning for Freeform Surface Sheet Metal Features in Automotive Industry

This paper describes computer aided process planning for a freeform surface; sheet metal features. Automotive body panels are always manufactured using thin forming sheets; the developed CAPP system consists of two modules which are feature recognition module based on STEP AP203 and a process plan module; two additional modules for automotive panel CAPP system and cost estimation module are also incorporated in the system of punch and bending operation. Stamped or punched features in generative shape design are used to design automotive panels; the generative CAPP system is written in visual basic 2008 language and implemented in several case studies demonstrated in the present work. Feature recognition of punched; stamped internal features in free form surface recognized in base of data exchange files using STEP AP203 ISO-10303-21.

Simulations and experiments in punching spring-steel devices with sub-millimeter features

This work demonstrates the feasibility of meso-scale (100μm to mm) punching of multiple holes of intricate shapes in metals. Analytical modeling, finite element (FE) simulation, and experimentation are used in this work. Two-dimensional FE simulations in ABAQUS were done with an assumed material modeling and plane-strain condition. A known analytical model was used and compared with the ABAQUS simulation results to understand the effects of clearance between the punch and the die. FE simulation in ABAQUS was done for different clearances and corner radii of the punch, die, and holder. To complement modeling with real experiments and for the purpose of comparison, a set of punches and dies were made to punch out a miniature spring-steel gripper. Comparison of compliant grippers made by wire-cut electro discharge machining (EDM) and punching shows that realizing sharp interior and re-entrant corners by punching is not easy to achieve. However, the promise of realizing meso-scale parts with complicated shapes through punching is demonstrated in this work; and further work is identified and some strategies are suggested for improvement. The main contribution of this paper is in adapting the well-established punching and blanking operations to the meso-scale as a viable alternative to making miniature devices currently dominated by lithography-based techniques.

자동차용 비대칭 스트라이커의 순차이송금형 및 공정 개발에 관한 연구

For high production rate of parts requiring multiple operations such as punching, blanking, or other operations are generally done with progressive dies. However, progressive die is generally limited to use for sheet metal forming due to the technical difficulties in rod or bulk material. This study proposes a new technique of progressive die and forming process for asymmetric automotive door striker, which is conventionally manufactured with separate tandem processes using solid rod. In order to design forming process and die, FEM simulation was performed to divide proper intermediate processes and analyze its formability. As a result, Forming processes were divided into 3 stages with upper and side punches and also, workpiece feeding and location mechanism was designed and manufactured in this study. Finally, forming tryouts were carried out by using the manufactured progressive die to verify the forming quality and productivity.

Storing Clocked Programs Inside DNA: A Simplifying Framework for Nanocomputing

Abstract In the history of modern computation, large mechanical calculators preceded computers. A person would sit there punching keys according to a procedure and a number would eventually appear. Once calculators became fast enough, it became obvious that the critical path was the punching rather than the calculation itself. That is what made the stored program concept vital to further progress. Once the instructions were stored in the machine, the entire computation could run at the speed of the machine. This book shows how to do the same thing for DNA computing. Rather than asking a robot or a person to pour in specific strands at different times in order to cause a DNA computation to occur (by analogy to a person punching numbers and operations into a mechanical calculator), the DNA instructions are stored within the solution and guide the entire computation. We show how to store straight line programs, conditionals, loops, and a rudimentary form of subroutines. To achieve this goal, the book propose...

Numerical Simulation and Verification of Multi-Operation Sheet Forming Process for Stamping Parts of Spiral Step Surface

On the basis of in-depth simulation analysis of stress and strain, thickness and forming limit changes in the property sphere during the drawing process for the stamping part of the spiral step surface, combined with the comprehensive simulation analysis of flanging, punching and other operations for the parts, it is concluded that the most obvious non-uniform changes of sheet thickness occur in the drawing process and then in the flanging process. The possibility and the distribution of tension fracture in ironing and wrinkles in thickening has been predicted and the production feasibility of low-cost drawing process without the blank holder and multi-operation forming process for stamping parts of spiral step surface. The validity of multi-operation numerical simulation results has been verified by the actual measurement of finished product rate and product thickness in trial production.

Study on Deformation Mechanism of Tube Hydropiercing

The numerical simulation of tube hydropiercing process on a typical tubular component was conducted by employing the FEM code MARC in order to investigate the deformation mechanism of tube hydropiercing. The 3D FEM models have been established in both inward and outward punching operations. Based on the calculation results of the distributions and their changes of stress and deformation, a plastic bending deformation zone in the vicinity of the hole’s edge has been discovered, which differs greatly from that in the conventional sheet metal punching process. Influence of inner pressure on the quality of hydropierced hole was also investigated.

STEP-compliant process planning system for compound sheet metal machining

Compound punch-cutting machines are referred as machines that perform both punching and laser-cutting operations. Such machines can greatly increase the efficiency and flexibility of sheet metal manufacturing. Though there are computer-aided design (CAD) systems developed to take care of product design, and computer-aided process planning (CAPP) systems to generate optimal tool paths and plans and computer-aided manufacturing (CAM) systems for various manufacturing requirements, according to our literature search, there is no platform or system dedicated to compound sheet metal machining, which lead to problems such as low efficiency and high cost due to lack of optimal scheduling methods for the compound machining methods. This research attempts to develop a prototype STEP-compliant process planning system for supporting the compound punch-cutting machines. The system has interfaces to input CAD product data and output machine control codes. It integrates software modules for nesting optimization, cutting/punch path optimization and planning, simulation, and machining parameters set up. The focus of the paper is placed on investigating the problems and solutions of compound machining, the structure of the STEP-compliant system, and the definition of STEP-compliant product data models and interfaces for creating a STEP-compliant programming environment, where the above mentioned software modules are integrated.

Optimal process planning for a combined punch-and-laser cutting machine using ant colony optimization

A machine that performs both punching and laser-cutting operations is referred as combined punch-and-laser machine. Such a machine has been in the market for about two decades. Although process-planning tools have been used on such a combined machine, the optimization of process planning dedicated to combined machines, based on our literature search results, has never been directly studied. This work addresses the process-planning problem for the combined punch-and-laser machine by integrating knowledge, quantitative analysis, and numerical optimization approaches. The proposed methodology helps making decisions on following issues: (i) which type of operation should be applied to each feature, and (ii) what is the optimal operation sequence (tool path) to achieve the maximum manufacturing efficiency. The ant colony optimization (ACO) algorithms are employed in searching the optimal tool path. Sensitivities of control parameters of ACO are also analysed. Through applications, the proposed method can significantly improve the operation efficiency for the combined punch-and-laser machine. The method can also be easily automated and integrated with the nesting and G-code generation processes. Some issues and possible future research topics have also been discussed.

FeCrNiAl alloy intended for using as blade material fabricated by rapid solidification method

We explored fabrication of ribbons of the FeCrNiAl alloy by rapid solidification method and succeeded in producing ribbons of 0.6 mm width and 30 μm thickness. The obtained ribbon-shape product is prospective for usage as blade material. The as-solidified product, however, is too hard and brittle for the succeeding punching operation to be applied for a final-product shape. This was found to be due to existence of extremely fine particles of NiAl based B2 phase uniformly dispersed in the matrix. We, therefore, searched for a heat-treatment for improving ductility and found an appropriate one. By this heat-treatment ductility was improved to such an extent that the punching operation was applicable. We then searched for a heat-treatment for producing Al2O3 on the surface which facilitates a hard and sharp blade-edge, and found an appropriate one. This heat-treatment simultaneously hardens the matrix once softened to an extent sufficient for supporting the Al2O3 layers. The final product is suitable for applications as blades, such as razors.

Generic algorithm for sheet metal working tool selection, using curve matching and tree searching

Abstract There are thousands of products made with sheet metal parts. Irrespective of the size of the part to be produced, the first step involves cutting the sheet or strip into appropriate shapes by means of the physical process of shearing. A contoured part, whether it be circular or more complex in shape, is cut between a punch and die in a press, in a process known as blanking. The same process is also used to remove internal unwanted parts of a blank, but in this case the process is known as punching. Contoured parts may also be cut by repeated small punching operations in the process known as nibbling. This paper considers punching and nibbling processes. In modern sheet metal industries the selection of a suitable set of tools for punching and/or nibbling operations, is a cost issue for two reasons. Firstly, the tooling is in itself very expensive and secondly, if the tool capacity of the tool rack is exceeded, expensive set-ups are required to mount different tools in the rack and to reprogram the system. In this work, to ‘optimise’ the process of selecting a set of tools, a simulation technique is proposed. In the simulation different sets of tools are generated by running a simulation a number of times. The set of tools with the minimum cost function value is selected. Using the well known Monte Carlo technique, the planner should be able to decide how long to run this simulation in order to reach an acceptable economic set of tools.

Failure of Tungsten Carbide-Cobalt Lamination Dies: A Corrosion Evaluation

Abstract Sudden failures of cemented tungsten carbide (WC)-cobalt punching dies are rare but expensive. Corrosion of the cobalt matrix, or cobalt leaching, by water-based lubricants usually is considered the cause of such failures. The validity of this mechanism was evaluated by measuring the corrosion behavior of cobalt, WC, and WC-15% Co die material in water and seven made-up lubricants. In the worst lubricant, the cobalt matrix corroded at an estimated rate of 0.01% sodium chloride [NaCl]), aerated water of pH 7, the rate could be 80 mpy. Such a rate still was not high enough to explain die failures because of the short contact time between lubricant and sliding surfaces during punching operations. Excessive adhesive wear caused by low lubricity and resulting in removal of large wear particles may have been responsible. Such particles wedged between sliding surfaces may have exerted forces sufficient to cause breakage of the dies.

Formation of Holes in Engineering Ceramic Plates by Press-Working

The purpose of the present research is to establish a simple method of forming holes in brittle materials by a conventional press-working. By utilizing a specially designed blunted spherical punch, a small hole is formed at the center of the specimen at its first stage, and subsequently the hole is enlarged by a continuous punching operation. The present improved technique realizes a very low load for punching operation as well as a considerably low clamping stress for preventing serious radial cracks around the hole. Some punching works in engineering ceramic plates were performed by the method for various aspect ratios AR=3∼32(AR=D/t, D; the diameter of the hole and t; the plate thickness). As long as the AR value is larger than about 3, the present method proved to be very successful in forming holes in tough engineering ceramics such as alumina, silicon-nitride and toughend zirconia, as well as in making small holes less than 1 mm in diameter. The technique is also successful in forming many holes by a single operation.

Optimal strip sequencing strategies for flexible manufacturing operations in two and three dimensions

In this paper, optimal strip strategies are developed for a variety of two-dimensional and three-dimensional sequencing problems arising in flexible manufacturing. These strategies are appropriate for CNC drilling operations, NC punching operations, and circuit board population, for example. Seven different metrics are considered.

Method for Punching Holes in Brittle Sheet Materials. Modeling of Punching Operation and Basic Experiments.

The purpose of the present research is to establish a simple method of forming holes in brittle sheet materials by a conventional punching technique. By utilizing a specially designed round-top punch, a small hole is formed at the center of the sheet specimen at its first stage, and subsequently the hole is enlarged by a continuous punching operation. The present improved technique realizes a very low load for punching operation as well as a considerably low precompression stress for preventing serious radial cracks around the hole. The technique is also successful in forming many holes by a single operation.

Precision forging hollow parts in novel dies

Dynamically highly stressed mechanical-transmission parts such as gears and drive flanges can be economically produced by forging. Hollow parts, such as gears, are conventionally forged with a web at the centre which is punched out later and the bore then machined to the required dimension. These punching and machining operations cause material waste and increased cost. In order to forge hollow parts with an accurate bore and to eliminate problems caused by the web, the authors have explored a method for precision forging hollow billets. Because the highly-stressed centre-web region is eleminated when hallow billets are used, a more homogeneous stress distribution arises in the die, allowing more complex shapes to be forged. In this paper, advantages of using hollow billets for precision forging hollow components with accurate bores are discussed. General problems and requirements of dies for flashless forging are outlined and alternative designs are presented. Various hollow shapes which have been precision forged from hollow billets, in dies of novel design, are described.

Computer Aids to Data Quality Control

This paper reviews some of the recently developed computer methods for checking data quality. The work started in the USA and Canada, but a substantial project is now underway at Newcastle based on these methods. It is commonplace today to process very large quantities of data on computers, not only in censuses and surveys, but also in other applications. The object of this paper is to review computerised methods of ensuring good data quality. The procedures divide into three types. First, there are procedures to check the quality of data coding and key punching operations. Secondly, there are theories of logical and arithmetic edits, which can assist both in detecting erroneous records, and also in locating erroneous fields on these erroneous records. Thirdly, there are statistical checks which can be run on the data once it is input. The simultaneous application of these procedures can achieve very high quality at reasonable costs. A popular (in theory at least) method of controlling data quality is the use of double or triple entry, but in any case this clearly does not identify logical and arithmetic errors already existing on the data sheets. Minton (1969) drew attention to the defects in this type of verification procedure and devised a new approach outlined below, based on sampling of the processed data. Fellegi & Holt (1976) were the first to propose the use of theories of logical edits. Their system facilitates the verification of sets of edits, and enables these edits to be used to help to pinpoint errors. This paper will not be concerned with procedures which are not computer-aided, such as interviewer training systems for feedback of error types to field staff, etc. We shall also ignore aspects of survey design and of questionnaire design, which can be computer aided. Some statistician feel that errors in data can often be detected at the analysis stage, so that the data entry phase can be rushed through. We feel that this is a mistaken view, and that the procedures outlined below should have a widespread application.

Use of a computer for producing microbiological reports and for data storage and processing.

A simple 'fail-safe' system is described that produces microbiology reports on a computer teleprinter and stores results on the magnetic tapes and discs of a computer for instant retrieval and epidemiological analysis. The system, which has been in operation for over a year, involves the use of a modified conventional NCR request form. The top portion, which is completed manually by the laboratory staff, is coded by writing numbers in hatched boxes. The data thus written on to the bottom portion are transcribed by punch operators on to paper tape and this data input is verified by double punching. The reports are normally produced automatically by the computer terminal telprinter, but in case of mechanical failure the manually completed request forms can be returned to wards and outpatient departments. The system permits a wide choice of options for epidemiological analysis, and six programmes are described, one of which produces a digest of the overall percentage antibiotic sensitivities of organisms from various sites.

MICSYS, an information system using the digital computer for culture collections

A system is outlined for the collection of alphanumeric information and data on organisms in culture collections, for storage on magnetic tape, and for selective retrieval by a computer. Information is recorded on standard forms and transferred to cards by key punch operators. The generic and specific names of the organisms are automatically compared with reference lists to check for authenticity, synonymy, type, and correct spelling before the entry is recorded on magnetic tape. Minor errors in spelling are corrected. Existing information can be changed, added to, or deleted. Programs have been written to produce lists or catalogs of species in individual collections and of a group of collections. Other programs for selective retrieval of information can be written. The system has sufficient flexibility to enable the user to establish the kinds of information stored and to design according to his requirements the formats of selective retrieval operations.

The Odds Against Women

can life today, none remains more pervasive or more invidious than that directed against women. In industry, government and academia, women by and large are excluded from positions of power, as defined by salary, prestige and decisionmaking authority. There is as much sexual segregation in jobs now as sixty years ago, and although one-third of all women now work, most are still restricted to occupations defined as feminine. In some instances women have been allowed to take over such previously male occupations as elevator operators, or have been recruited for such monotonous new jobs as key punch operators. Occupations that segregate heavily have been growing faster than those that do not. Dale Hiestand, in his study of employment opportunities for minorities (Economic Growth and Employment Opportunities for Minorities, New York, Columbia University Press, 1964), shows that in occupations in which incomes increase most rapidly, the acceptance of women is very slow. On the other hand, men enter jobs in which income rises rapidly whether or not they have been traditionally female occupations. Men, for example, now comprise the majority of secondary school teachers, and the nursing profession now wants to recruit men because only then will wages and hours improve. Women now earn 40 percent of the bachelor degrees awarded, but their degrees aren't much help. Men right out of college are recruited for executive training, while women with the same qualifications are offered secretarial jobs. The American woman's share of the employment market has risen in recent years, but her share of professional and technical jobs has actually declined. Women are found predominantly in the less well-paid, uncompetitive jobs; they are more often overqualified in their work, and their median salary is below that of American men, both white and black. Sixty-six percent of employed women with from one to three years of college, 20 percent of employed women with a college degree, and 7 percent of employed women with one or more years beyond the first degree are sales ladies, office clerks, nursemaids and household cooks.