Setup Changes Research Articles

Development of Rough Cutting Method with Plunge Milling Using 5-axis Control Machine Tool

This paper deals with the rough cutting method using 5-axis control machine tool and the tool path generation method to machine complicated shapes efficiently such as overhanging shape that requires the inclination of cutting tool. In general, conventional rough cutting methods employ the contour milling with 3-axis control. However, these rough cutting methods were not always efficient, because several set-up changes were required to machine complicated shapes. The study proposes the new rough cutting method for 5-axis control machining, which uses a plunge milling that has been used only for 3-axis control machining. Consequently, the rough cutting with the high efficiency of plunge milling and the flexibility of 5-axis control can be realized. In order to achieve the method, it is necessary to generate the tool path in consideration of the tool interference with not only the target shape but also the remained part. Therefore, the study developed the tool path generation method by expanding the method which uses the 2-dimensional configuration space technique. Finally, the developed method is implemented to the original CAM software. As a result, it is experimentally found that the system enables the rough cutting of complicated shapes with 5-axis control with only one set-up.

A learning approach to enhancing machine reconfiguration decision-making games in a heterarchical manufacturing environment

Business process management (BPM) emerges as a promising guiding principle and technology for integrating existing assets and future deployments. BPM provides mechanisms to transform the behaviours of disparate and heterogeneous systems into standard and interoperable business processes, aimed at effectively facilitating the conduct of factory system integration. On the shop floor, BPM requires machine-level controllers to be architected in a heterarchical fashion. Past work by the authors introduced a heuristic non-cooperative game theoretic planning technique for an autonomous machine controller to frame a decision about an impending reconfiguration (i.e. setup change) in a heterarchical manufacturing environment. The work described in this paper extends the authors’ previous work by employing a reinforcement learning approach for specifying the payoffs in reconfiguration games through capturing the effects of a sequence of reconfiguration decisions. Consequently, the controller can autonomously learn the long-term implications of decisions, and ultimately improve its decision-making process in manufacturing.

A quasi steady state approach to race car lap simulation in order to understand the effects of racing line and centre of gravity location

Using an established seven-degree-of-freedom (7DOF) model of an open wheel race car, a new quasi steady state lap simulation method is described. The method is based on optimal control techniques. It produces a GG speed diagram as an interim result, and is shown to have a low computational expenditure when compared with the current transient optimal control method. This paper shows a validation step, reports a case study using the new method, and compares the result with a transient optimal control method. The sensitivity of the optimal line for simulation studies is discussed in terms of a centre of gravity location change. Both simulation methods show improvements in lap time owing to a 6 per cent centre of gravity set-up change. The difference in optimal lines caused by a 6 per cent CG change rearward is shown to be so small that a driver is unlikely to find the information useful. In light of this observation, the computational effort required to generate a new optimal line for each set-up change may be misspent

Highly efficient manufacture of groove with sharp corner on adjoining surfaces by 6-axis control ultrasonic vibration cutting

Abstract Rapid machining means the extreme reduction of the machining lead-time required in completing a product from the blank shape. One of the ways in which machining lead-time could be reduced drastically is by avoiding too many setup changes. This paper presents a new machining method to create a groove with sharp corner on adjoining surfaces in one setup. Grooves with sharp corner (GSC) on adjoined curved or overhanging surfaces are at present impossible to manufacture by conventional machining in one setup or even by the existing numerical control (NC) machining method especially if it is adjacent to the obstruction. The obstruction tends to hamper the flow of machining operation, thereby requiring two or more setups as well as additional expensive fixtures to machine such a product. In the study, the GSC on adjoined curved or overhanging surfaces will be manufactured by 6-axis control milling using a non-rotational tool with the application of ultrasonic vibrations (USV) in one setup. The study also describes the machining method as well as the development of software for 6-axis control milling and the effect of ultrasonic vibrations in multi-axis machining. Based on the experimental results, the effectiveness of the new manufacturing method as well as the developed CAM software has been experimentally confirmed in the study.

Iterative approach to operation selection and sequencing in process planning

This paper considers the problem of selecting and sequencing operations in process planning for the objective of minimizing the sum of operation processing costs and machine, set-up and tool change costs. The main constraint is the precedence relations among operations. To represent the precedence relations and alternative operations, a tree-structured precedence graph is suggested. Based on the graph, the entire problem is decomposed into two subproblems: operation selection and operation sequencing. Then, three iterative algorithms are suggested that solve the two subproblems iteratively until optimal and near-optimal solutions are obtained. The algorithms are illustrated using an example part, and to show the performances of the algorithms, computational experiments were done on randomly generated test problems. The results show that the algorithms suggested work well for the test problems.

Daily stereotactic ultrasound prostate targeting: inter-user variability.

We analyzed the inter-user variability of patient setup for prostate radiotherapy using a stereotactic ultrasound-targeting device. Setup variations in 20 prostate cancer patients were analyzed. Users were a radiation oncologist, a medical physicist, four radiation technologists (RTT) and a radiologist. The radiation oncologist, radiologist, physicist and two RTTs were experienced users of the system (>18 months of experience); two RTTs were users new to the system. Gold standard for this analysis was a control CT acquired immediately following ultrasound targeting. For inter-user variability assessments, the radiation oncologist provided a set of axial and sagittal freeze-frames (standard freeze-frames) for virtual targeting by all users. Additionally each user acquired individual freeze-frames for target alignments. We analyzed the range of virtual setups in each patient along the principal room axes based on standard and individual freeze-frames. The magnitude of residual setup error and percentage of setup change for each user was assessed by control CT/planning CT comparison with individual virtual shifts. A total of 184 alignments were analyzed. The range of virtual shifts between users was 2.7+/-1.4, 3.6+/-1.1, and 4.4+/-1.4 mm (mean+/-SD) in x, y and z-direction for setups based on standard freeze-frames and 3.9+/-2.6, 6.0+/-4.7, and 5.4+/-2.7 mm for setups based on individual freeze-frames. When only virtual shifts of experienced users were analyzed, the mean ranges were reduced by up to 2.4 mm. Average magnitude of initial setup error before ultrasound targeting was 14.3 mm. Average improvement of prostate setup was 63.1+/-23.4% in experienced and 35.14+/-37.7% in inexperienced users, respectively (p<0.0001). Only 5 of 184 (2.7%) virtual alignments would have introduced new larger setup errors (mean 3.2 mm, range 0.2 to 9.5 mm) than the magnitude of the initial setup error. We conclude that ultrasound guided treatment setup for patients treated for prostate cancer can be performed with high inter-user consistency and does lead to improved treatment setup in more than 97% of attempted setups. Experienced use is correlated with a reduced range of setups between users and higher degree of setup improvement when compared with users new to the system

A decomposition method for multi-product kanban systems with setup times and lost sales

We consider kanban controlled production systems with three or more different products processed on a single manufacturing facility. Customers for a product arrive according to a Poisson process. If a customer's demand cannot be met from stock, the customer leaves and satisfies his demand elsewhere (lost sales). Between the production of different products setup changes must be performed that take a significant time. Setup times and processing times are product-specific and follow exponential distributions. A production run continues until the target inventory level given by the number of kanbans for the product has been reached (exhaustive processing). Then the manufacturing facility is set up for the next product according to a fixed setup cycle. The exact model is mathematically intractable even for smaller systems. Therefore, we propose a decomposition-based approximation method for estimating steady-state performance measures

Eclipse-RP: A new RP machine based on repeated deposition and machining

This paper presents a newly developed rapid prototyping (RP) machine. The design of this machine is based on the Eclipse parallel mechanism invented by the authors. One of the advantages of the Eclipse mechanism as compared to Gough-Stewart-based parallel mechanisms and applied to machining processes is that the spindle can tilt to 90 degrees and enables five-face machining without any set-up change of the workpieces. This advantage has been fully utilized in designing the new RP machine. The RP process consists of four stages: (1) post-machining feature extraction, (2) the slicing of the deposition feature, (3) repeated deposition and machining of each sliced layer, and (4) post-machining. Whole stages are executed in one machine structure without any set-up change. Using the Eclipse-RP and standard test parts, remarkable gains in productivity are obtained, namely 2.5 times reduction in time and 8 times reduction in cost.

A decomposition method for multi-product kanban systems with setup times and lost sales

We consider kanban controlled production systems with three or more different products processed on a single manufacturing facility. Customers for a product arrive according to a Poisson process. If a customer's demand cannot be met from stock, the customer leaves and satisfies his demand elsewhere (lost sales). Between the production of different products setup changes must be performed that take a significant time. Setup times and processing times are product-specific and follow exponential distributions. A production run continues until the target inventory level given by the number of kanbans for the product has been reached (exhaustive processing). Then the manufacturing facility is set up for the next product according to a fixed setup cycle. The exact model is mathematically intractable even for smaller systems. Therefore, we propose a decomposition-based approximation method for estimating steady-state performance measures.

Sheet metal bending: Forming part families for generating shared press-brake setups

Sheet metal bending press brakes can be set up to produce more than one type of part without requiring a setup change. To exploit this flexibility, setup planning techniques are needed so that press-brake setups can be shared among many different parts. This paper describes algorithms for partitioning a given set of parts into setup-compatible part families that can be produced on the same setup. First is presented a greedy algorithm to form a part family using a bottom-up approach that makes use of the mixed-integer linear programming formulation for generating shared setups for each part family. Second is presented a mixed-integer linear programming formulation to generate a shared setup for a given set of parts if such a setup exists. By producing many different types of parts on the same setup, it is expected that there will be significant reductions in the number of setup operations, improved machine tool utilization, and more cost-effective small-batch manufacturing.

A simulation of the effects of set-up error and changes in breastvolume on conventional and intensity-modulated treatments in breastradiotherapy

The effect of interfractional patient movement on dosimetry has beeninvestigated for breast radiotherapy. Errors in patient set-up and changes inbreast volume were simulated individually to determine how each contributes tothe total dosimetric error. Two treatment techniques were investigated: aconventional treatment and an intensity-modulated treatment delivered usingcompensators. Six patients were investigated and anterior-posterior (AP) andsuperior-inferior (SI) displacements were simulated by displacing theisocentre in both directions by 2, 5 and 10 mm. A model of the breast wasdeveloped from the six patients to simulate changes in breast volume. In thismodel, the breast was described as a set of semi-ellipses. The volume of thebreast was changed by varying the magnitude of the semi-major and semi-minoraxes. Anisotropic changes in breast volume were also investigated. Thedosimetric error was evaluated for each dose plan by calculating the volumeoutside the 95-105% dose range resulting from the simulations. A number ofparameters describing the size and shape of the breast were also investigatedto determine whether a susceptibility of outline sets to interfractionalpatient movement could be predicted. A parameter describing the increase inthe breast volume outside the 95-105% dose range was calculated for AP andSI set-up errors of ±3 mm and changes in breast volume of 5%.Results revealed that set-up errors were likely to cause larger increases inthe volume outside the 95-105% dose range than changes in breast volume fortypical set-up errors and changes in breast volume that occur duringtreatment. The magnitude of the set-up errors and changes in breast volumewere observed to be dependent on the shape outline set. Statisticallysignificant linear correlation was observed between the increase in the volumeoutside the 95-105% dose range and several of the evaluation parameters.

Concurrent analysis of machining sequences and fixturing set-ups for minimizing set-up changes for machining mill-turn parts

In a typical machining process for producing a mill-turn part, milling operations and turning operations are required. If both milling machines and turning machines are utilized, the part may need to be moved between the two types of machines. In addition, the fixturing set-ups may need to be changed when different portions of the part are machined. In this research, a concurrent analysis model for analysing machining sequences and fixturing set-ups is presented. The purpose is to determine a good machining sequence by evaluating the machine changes and the fixturing set-up changes. A feature-based fixturing analysis method is developed for calculating the fixturing parameters for machining prismatic features and rotational features of a mill-turned part. A branch-and-bound method is developed to analyse the feasible machining sequences to find the best sequence with the minimum number of machine changes and fixturing set-up changes. A software system is implemented and example parts are tested and discussed.

Search heuristics for operation sequencing in process planning

The operation-sequencing problem in process planning is considered to produce a part with the objective of minimizing the sum of machine, setup and tool change costs. In general, the problem has combinatorial characteristics and complex precedence relations, which makes the problem difficult to solve. Six local search heuristics have been developed based on simulated annealing and tabu search to obtain good solutions for practical-sized problems within a reasonable amount of computation time. Application of the algorithms is illustrated using an example part. Also, computational experiments were done on randomly generated problems and the results show that the tabu search-based algorithms are better than the simulated annealing-based algorithms on overall average. In particular, one of the tabu search algorithms suggested here gave optimal solutions for most small-sized test problems within very short computation times.

Branch and fathoming algorithms for operation sequencing in process planning

This paper focuses on the operation sequencing problem in process planning, which is the problem of determining the sequence of operations required for producing a part with the objective of minimizing the sum of machine, set-up and tool change costs. In general, operation sequencing in process planning has been a difficult optimization problem, since it has combinatorial characteristics and complex precedence relations. This paper first suggests a precedence-directed graph to describe the precedence relations among operations with a compact form. Then, using the directed graph, the authors develop optimal and heuristic branch and fathoming algorithms that can give optimal and near optimal solutions respectively. Application of the two algorithms is illustrated using an example part. Also, to show the performance of the suggested algorithms, computational experiments were done on randomly generated problems and the results show that the heuristic algorithm gives optimal solutions for all the generated problems with much shorter computation time.

A simulated annealing-based optimization algorithm for process planning

Computer-aided process planning (CAPP) in the past typically employed knowledge-based approaches, which are only capable of generating a feasible plan for a given part based on invariable machining resources. In the field of concurrent engineering, there is a great need for process planning optimization. This paper describes an approach that models the constraints of process planning problems in a concurrent manner. It is able to generate the entire solution space by considering multiple planning tasks, i.e. operations (machine, tool and tool approach direction), selection and operations sequencing simultaneously. Precedence relationships among all the operations required for a given part are used as the constraints for the solution space. The relationship between an actual sequence and the feasibility of applying an operation is also considered. An algorithm based on simulated annealing (SA) has been developed to search for the optimal solution. Several cost factors including machine cost, tool cost, machine change cost, tool change cost and set-up change cost can be used flexibly as the objective function. The case study shows that the algorithm can generate highly satisfying results.

What should you do before you start to use your new computer, or once you’ve bought it, how do you keep from breaking it?

After you have purchased your new or refurbished computer and before you attempt to plug it in and turn it on, read all supplied documentation. This may be the time to ask for advice from an experienced user to assist your initial setup. Remember that your computer is a device, which is sensitive to extremes of heat, cold, magnetic fields, and rapid changes in its electrical supply. Buy and use a quality surge suppressor. A quality unit should have a Underwriters Laboratories (UL) 1449 rating of less than or equal to 330 V and be rated at 240 joules minimum. Higher quality units provide sufficient outlets to avoid the need for a web of extension cords, and some provide a jack to suppress voltage spikes transmitted through the telephone connection. If at all possible, do not plug your computer into outlets shared by other devices with a large current draw, such as heaters, air conditioners, or appliances. As you unpack your computer, carefully record all serial and model numbers of all components. Store the model and serial numbers with copies of your original receipts and documentation in a secure location. Save the boxes and packing materials in the event you need to transport the computer. Choose a location for the computer that is accessible, comfortable, and away from potential damaging agents, such as sources of water, food, and smoke. Provide an area for the central processing unit that is well ventilated and out of direct lines of traffic. A computer, like any other tool, has to be accessible or it will not be used. Electrical components are fragile, not only to environmental and power supply extremes, but also to external shocks or bumps. Just as a mere light bulb can fail if jarred while it is on, jolts and bumps can damage the sensitive components of a computer while the hard disk is spinning. Buy quality diskettes or removable media. Remember to store diskettes or removable media away from strong sources of heat or magnetic fields. Use only a felt-tipped indelible marker to write on labels, which have already been affixed to diskettes; otherwise, use ballpoint pens to write only on labels that are not on diskettes. Immediately after you have set up and turned on your computer begin to think of the inevitable day it will not work as designed. With prior planning you should be prepared for the common emergencies. Your computer may not work properly if it suffers a mechanical failure, which is fortunately uncommon. The most common difficulties can be traced to userintroduced problems, such as inadvertent configuration or setup changes, inoculation with viruses, or addition of new programs or components that change critical settings. Emergency planning begins with the creation of diskettes to allow you to start or boot your computer without the information stored on a fixed disk. Use new quality diskettes to create an emergency boot disk containing operating system information, an emergency disk to recover in the event of failure from virus infestation, and, finally, a disk to allow use of the CD-ROM drive. To create a basic Windows 98 or Windows 95 emergency boot disk:

Corn Residue Retention by a Combination Chisel Plow

Using combination chisel plows in corn (Zea mays L.) residue can reduce surface residue cover to below levels that will protect the soil against erosion. Equipment operation and setup changes can alter the residue amount incorporated into soil. We evaluated the operational effects of using a combination chisel plow, equipped with coulter gangs, on corn residue cover on two silt loam soils. Variables included timing of chiseling, point selection, speed and depth of chiseling, and coulter‐gang engagement. Chisel plowing left 21 to 46% residue cover in the fall, and 13 to 33% residue cover in the spring. Differences were negated when overwintering losses after fall chiseling were considered. Only three of the eight spring chiseling treatments left &gt;30% residue cover: (i) the DMI Tiger‐C point with coulter‐gang engagement, (ii) the DMI Tiger‐C point without coulter‐gang engagement, and (iii) the 406‐mm sweep with gang engaged. Ranking of residue‐retention coefficients for the chisel points was as follows: 406‐mm low‐crown sweep (0.42–0.53) ≈ DMI Tiger‐C specialty point &gt; 51‐mm chisel point (0.33–0.40) &gt; 102‐mm twisted shovel (0.17–0.25). Depth of chiseling did not affect residue retention. Slowing the speed of operation from 6.4 to 3.2 km h−1 (resulting in 27–42% increased residue retention) had more effect than slowing from 9.6 to 6.4 km h−1 (19–24%). Primary tillage of corn residue using a combination chisel plow can provide adequate (&gt;30%) soil surface protection from erosion processes. Residue‐cover levels following secondary tillage and planting operations will likely fall below 30%.

Sheet Metal Bending: Generating Shared Setups

Contemporary process planners for sheet metal bending solve the process planning problem for individual parts. Quite often, many different parts can be produced on shared setups. However, plans generated by current process planning systems fail to exploit this commonality between setups and try to generate optimal setups for individual parts. In this paper, we present an algorithm for multi-part setup planning for sheet metal bending. This algorithm takes a set of parts and operation sequences for these parts, and tries to find a shared setup plan that can work for every part in the set. Setup changes constitute a major portion of the production time in batch production environments. Therefore, multi-part setup planning techniques can be used to significantly cut down the total number of setups and increase the overall through-put.

Generating resource based flexible form manufacturing features through objective driven clustering

The development of a new feature based technique for automated manufacturability evaluation (ME) of machined parts is reported in this article. Key to this approach is a new type of feature called a resource based flexible form manufacturing feature. This type of manufacturing feature incorporates available factory resources and permits unlimited variations in the geometric form as dictated by tool accessibility. A ME system based on this new feature definition is overviewed. Through a process of automatic feature recognition, a manufacturing feature based description of a part is generated which is then used as a form of high level operation plan on which accurate estimates of production cost and time can be made. This paper focuses on the feature recognition algorithm, which is termed Objective Driven Clustering. The recognition algorithm consists of generating feature primitives, which are operational subplans for subregions of a part. Subsequently, primitives are intelligently selected and grouped in a clustering process that uses heuristics, constraints and a user defined evaluation objective to form manufacturing features. The methodology accommodates parts with complex surfaces and interacting form features. It is also sensitive to a variety of part, factory and evaluation related parameters including the evaluation objective, accessibility, part material, D&T, available machines and tools, tool cost, tool change time and setup change time. A prototype system Arizona State University Manufacturability Evaluator (ASUME) used in validating the methodology is discussed.

Using operational planning horizons for determining setup changes

We consider operational planning horizons required for managing shop floor resources. Our concept of horizons is different from those developed in the literature for aggregate production planning; the focus is on operational-level decisions. Our problem is of scheduling machine setup changes and we conduct the study on a system implemented at a manufacturing facility. This system schedules machine setup changes at a particular stage of manufacturing. We identify a horizon parameter, l, which impacts the number of setup changes made. Short horizons increase the number of setup changes while reducing the work-in-process, whereas long horizons reduce the setups while increasing the work-in-process. We develop a metric for assessing the setup change schedules made by the system and use this to show that l is related to certain shop floor characteristics. We conclude that these characteristics should be used to determine l.