Group technology and cellular manufacturing pdf

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Download Now Download Download to read offline. Group technology and cellular manufacturing Mar. Khulna university of engineering and technology Follow. Workparts with identical or similar routings are classified into part families. Then, the families can be used to form logical machine cells in a group technology layout.

Virtue Require less time than a complete parts classification and coding procedure. Production Flow Analysis Procedure. Scope of the analysis: The production flow analysis must begin defining the scope of the study population of parts to be analyzed. Data collection: The minimum data needed in the analysis are the part number and operation sequence. Additional data: lot size, time standards, and annual demand might be useful.

Sortation of process routings: Parts are arranged into groups according to the similarity of their process routings. To make this: a All operations or machines are reduced to code numbers; b For each part, operation codes are listed in the order they are performed c A sortation procedure is then used to arrange parts into packs.

PFA chart has been referred as part-machine incidence matrix. Production Flow Analysis Procedure 5. Cluster analysis: From the pattern of data in the PFA chart, related groupings are identified an rearranged into a new pattern that brings together packs with similar machine sequences. Weakness The data used in the technique are derived form existing production route sheets.

The routings may contain operations that are nonoptimal, illogical or unnecessary. Cellular Manufacturing Definition Cellular Cellularmanufacturing manufacturingisisan anapplication applicationofofgroup grouptechnology technologyinin which whichdissimilar dissimilarmachines machinesor orprocesses processeshave havebeen beenaggregated aggregatedinto into cells, cells,each eachofofwhich whichisisdedicated dedicatedtotothe theproduction productionofofaapart partor orproduct product family familyororlimited limitedgroups groupsofoffamilies.

Cellular Manufacturing 4. Composite Part Concept Definition Composite CompositePartPartConcept Conceptisisaahypothetical hypotheticalpart partfor foraagiven givenfamily familywhich which includes includesall allof ofthe thedesign designand andmanufacturing manufacturingattributes attributesofofthe thefamily.

An individual part in the family will have some features that characterize the family but not all of them. The composite part possesses all of them. Production cell design A production cell designed for the part family would include all the machines required to make the composite part.

Such a cell would be capable of producing any member of the family, simply by omitting those operations corresponding to features not possessed by the particular part. The cell would also be designed to allow size variations within the family as well as feature variations. Machine cell design.

Manufacturing cells can be classified according to the number of machines and the degree to which the material flow is mechanized between machines. Single machine cell: Consists on one machine plus supporting fixtures and tooling. This type of cell can be applied to workparts whose attributes allow them to be made on one basic type of process such as turning or milling.

Cellular Manufacturing 2. Group machine cell with manual handling: an arrangement of more than one machine used collectively to produce one or more part families.

Instead, the human operators who run the cell perform the material handling function. This layout is appropriate when there is variation in the work flow and to allow the multifunctional workers in the cell to move easily between machines.

Cellular Manufacturing 3. Group machine cell with semi-integrated handling: uses a mechanized handling system to move parts between machines in the cell. Flexible manufacturing system FMS : combines a fully integrated material handling system with automated processing stations.

Cellular Manufacturing Cell design Part movement Four types of part movement: 1. Repeat operation: a consecutive operation is carried out on the same machine so the part does not actually move. In-sequence move: the part moves from the current machine to an immediate neighbor in the forward direction. By-passing move: the part moves forward from the current machine to another machine that is two or more machines ahead. Backtracking move: the part moves from the current machine in the backward direction to another machine.

Cellular Manufacturing Movement Layout. Determine the workload and therefore the number of machines that must be included. Cellular Manufacturing. Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions.

Engineering design Reduction in new parts design Reduction in the number of drawings through standardization Reduction of drafting effort in new shop drawings Reduction of number of similar parts, easy retrieval of similar functional parts, and identification of substitute parts Layout planning Reduction in production floor space required Reduced material-handling effort.

Specification of equipment, tools, jigs, and fixtures Standardization of equipment Implementation of cellular manufacturing systems Significant reduction in up-front costs incurred in the release of new parts for manufacture Manufacturing: process planning Reduction in setup time and production time Alternative routing leading to improved part routing Reduction in number of machining operations and numerical control NC programming time Manufacturing: production control Reduced work-in-process inventory Easy identification of bottlenecks Improved material flow and reduced warehousing costs Faster response to schedule changes Improved usage of jigs, fixtures, pallets, tools, material handling, and manufacturing equipment Manufacturing: quality control Reduction in number of defects leading to reduced inspection effort Reduced scrap generation Better output quality Increased accountability of operators and supervisors responsible for quality production, making it easier to implement total quality control concepts.

Purchasing Coding of purchased part leading to standardized rules for purchasing Economies in purchasing possible because of accurate knowledge of raw material requirements Reduced number of part and raw materials Simplified vendor evaluation procedures leading to just-in-time purchasing Customer service Accurate and faster cost estimates Efficient spare parts management, leading to better customer service.

The parts are similar in their processing requirements, such as operations, tolerances, and machine tool capacities The primary objectives in implementing a cellular manufacturing system are to reduce: setup times by using part family tooling and sequencing flow times by reducing setup and move times and wait time for moves and using smaller batch sizes reduce inventories market response times In addition, cells represent sociological units that have more tendency to teamwork.

This means that motivation for process improvements often arises naturally in manufacturing cells. Manufacturing cells are natural candidates for just-in-time JIT implementation. Cell Design Design of cellular manufacturing system is a complex exercise with broad implications for an organization. The cell design process involves issues related to both system structure and system operation. Structural issues include: Selection of part families and grouping of parts into families Selection of machine and process populations and grouping of these into cells Selection of tools, fixtures, and pallets Selection of material-handling equipment Choice of equipment layout Issues related to procedures include: Detailed design of jobs Organization of supervisory and support personnel around the cellular structure Formulation of maintenance and inspection policies Design of procedures for production planning, scheduling, control, and acquisition of related software and hardware Modification of cost control and reward systems Outline of procedures for interfacing with the remaining manufacturing system in terms of work flow and information, whether computer controlled or not Evaluation of Cell Design Decisions The evaluation of design decisions can be categorized as related to either the system structure or the system operation.

Typical considerations related to the system structure include: Equipment and tooling investment low Equipment relocation cost low Material-handling costs low Floor space requirements low Extent to which parts are completed in a cell high Flexibility high Evaluations of cell system design are incomplete unless they relate to the operation of the system.

A few typical performance variables related to system operation are: Equipment utilization high Work-in-process inventory low Queue lengths at each workstation short Job throughput time short Job lateness low A major problem throughout the cell design process is the necessity of trading off against each other objectives related to structural parameters and performance variables.

For example, higher machine utilization can be achieved if several cells route their parts through the same machine. The drawbacks are increased queuing and control problems. System cost and performance are affected by every decision related to system structure and system operation. It is necessary to evaluate each important design parameter and relate its performance to pre-established criteria. For example, structural variables such as number of machines must be balanced against operational variables such as machine utilization and throughput time using analytical and simulation approaches.

Production flow analysis involves four stages: Stage 1: Machine classification. Machines are classified on the basis of operations that can be performed on them. A machine type number is assigned to machines capable of performing similar operations. Stage 2: Checking parts list and production route information.

For each part, information on the operations to be undertaken and the machines required to perform each of these operations is checked thoroughly. Stage 3: Factory flow analysis. This involves a micro-level examination of flow of components through machines. This, in turn, allows the problem to be decomposed into a number of machinecomponent groups. Stage 4: Machine-component group analysis. An intuitive manual method is suggested to manipulate the matrix to form cells.

However, as the problem size becomes large, the manual approach does not work. Therefore, there is a need to develop analytical approaches to handle large problems systematically. Try to group them. Step 1: Assign binary weight and calculate a decimal weight for each row and column using the following formulas:. Step 2: Rank the rows in order of decreasing decimal weight values.

Step 3: Repeat steps 1 and 2 for each column. Step 4: Continue preceding steps until there is no change in the position of each element in the row and the column. Try to group them by using Rank Order Clustering Algorithm.