Cellular manufacturing

Cellular manufacturing is a process of manufacturing which is a subsection of just-in-time manufacturing and lean manufacturing encompassing group technology. The goal of cellular manufacturing is to move as quickly as possible, make a wide variety of similar products, while making as little waste as possible. Cellular manufacturing involves the use of multiple 'cells' in an assembly line fashion. Each of these cells is composed of one or multiple different machines which accomplish a certain task. The product moves from one cell to the next, each station completing part of the manufacturing process. Often the cells are arranged in a 'U-shape' design because this allows for the overseer to move less and have the ability to more readily watch over the entire process. One of the biggest advantages of cellular manufacturing is the amount of flexibility that it has. Since most of the machines are automatic, simple changes can be made very rapidly. This allows for a variety of scaling for a product, minor changes to the overall design, and in extreme cases, entirely changing the overall design. These changes, although tedious, can be accomplished extremely quickly and precisely.'A cell is a small organizational unit...designed to exploit similarities in how you process information, make products, and serve customers. Manufacturing cells people and equipment required for processing families of like products. may have traveled miles to visit all the equipment and labor needed for their fabrication... After reorganization, families of similar parts are produced together within the physical confines of cells that house most or all of the required resources,...facilitating the rapid flow and efficient processing of material and information... Furthermore, cell operators can be cross-trained in several machines, engage in job rotation, and assume responsibilities for tasks previously belonged to supervisors and support staff activities such as planning and scheduling, quality control, trouble-shooting, parts ordering, interfacing with customers and suppliers, and record-keeping.''The first step involved creating cells in the assembly, electrical and chemical testing departments. In April 1984 six cells, identified by different colors, were established... All devices manufactured in cells are identified by the cell's color, and all feed-back from quality control is directed straight to the workers of the cell concerned... The second step, in summer, 1984, was to 'cellularize' manufacture of the analyzer subassemblies needed in the analyzer cells, and to test them if necessary. Production of the five sub-assembly cells consists exclusively of certain analyzer sub-units. The parts and materials are located in the cells... Material control between the cells is based on the pull system and actual demand. In the analyzer cells there is a buffer consisting of two pieces for each (roughly 25 different) sub-unit. When one piece is taken into assembly, a new one is ordered from the corresponding unit-cell. The order is made a magnetic button, which identifies the ordering cell (by color), unit (by code), and order date... When the manufacturing cell has completed the order, the unit is taken with the button to its place on the ordering cell shelf. Orders from the unit cells to the sub-cells are based on the same principle. The only difference is that the buffer size is six sub-units. This was implemented in August, 1984.' Cellular manufacturing is a process of manufacturing which is a subsection of just-in-time manufacturing and lean manufacturing encompassing group technology. The goal of cellular manufacturing is to move as quickly as possible, make a wide variety of similar products, while making as little waste as possible. Cellular manufacturing involves the use of multiple 'cells' in an assembly line fashion. Each of these cells is composed of one or multiple different machines which accomplish a certain task. The product moves from one cell to the next, each station completing part of the manufacturing process. Often the cells are arranged in a 'U-shape' design because this allows for the overseer to move less and have the ability to more readily watch over the entire process. One of the biggest advantages of cellular manufacturing is the amount of flexibility that it has. Since most of the machines are automatic, simple changes can be made very rapidly. This allows for a variety of scaling for a product, minor changes to the overall design, and in extreme cases, entirely changing the overall design. These changes, although tedious, can be accomplished extremely quickly and precisely. A cell is created by consolidating the processes required to create a specific output, such as a part or a set of instructions. These cells allow for the reduction of extraneous steps in the process of creating the specific output, and facilitate quick identification of problems and encourage communication of employees within the cell in order to resolve issues that arise quickly. Once implemented, cellular manufacturing has been said to reliably create massive gains in productivity and quality while simultaneously reducing the amount of inventory, space and lead time required to create a product. It is for this reason that the one-piece-flow cell has been called 'the ultimate in lean production.' Cellular manufacturing is derivative of principles of group technology, which were proposed by Flanders in 1925 and adopted in Russia by Mitrofanov in 1933 (whose book was translated into English in 1959). Burbidge actively promoted group technology in the 1970s. 'Apparently, Japanese firms began implementing cellular manufacturing sometime in the 1970s,' and in the 1980s cells migrated to the United States as an element of just-in-time (JIT) production. One of the first English-language books to discuss cellular manufacturing, that of Hall in 1983, referred to a cell as a “U-line,” for the common, or ideal, U-shaped configuration of a cell—ideal because that shape puts all cell processes and operatives into a cluster, affording high visibility and contact. By 1990 cells had come to be treated as foundation practices in JIT manufacturing, so much so that Harmon and Peterson, in their book, Reinventing the Factory, included a section entitled, 'Cell: Fundamental Factory of the Future'. Cellular manufacturing was carried forward in the 1990s, when just-in-time was renamed lean manufacturing. Finally, when JIT/lean became widely attractive in the service sector, cellular concepts found their way into that realm; for example, Hyer and Wemmerlöv’s final chapter is devoted to office cells. Cells are created in a workplace to facilitate flow. This is accomplished by bringing together operations or machines or people involved in a processing sequence of a products natural flow and grouping them close to one another, distinct from other groups. This grouping is called a cell. These cells are used to improve many factors in a manufacturing setting by allowing one-piece flow to occur. An example of one-piece flow would be in the production of a metallic case part that arrives at the factory from the vendor in separate pieces, requiring assembly. First, the pieces would be moved from storage to the cell, where they would be welded together, then polished, then coated, and finally packaged. All of these steps would be completed in a single cell, so as to minimize various factors (called non-value-added processes/steps) such as time required to transport materials between steps. Some common formats of single cells are: the U-shape (good for communication and quick movement of workers), the straight line, or the L-shape. The number of workers inside these formations depend on current demand and can be modulated to increase or decrease production. For example, if a cell is normally occupied by two workers and demand is doubled, four workers should be placed in the cell. Similarly, if demand halves, one worker will occupy the cell. Since cells have a variety of differing equipment, it is therefore a requirement that any employee is skilled at multiple processes. While there exist many advantages to forming cells, there are some obvious benefits. It is quickly evident from observation of cells where inefficiencies lie, such as when an employee is too busy or relatively inactive. Resolving these inefficiencies can increase production and productivity by up to and above 100% in many cases. In addition to this, formation of cells consistently frees up floor space in the manufacturing/assembly environment (by having inventory only where it is absolutely required), improves safety in the work environment (due to smaller quantities of product/inventory being handled), improves morale (by imparting feelings of accomplishment and satisfaction in employees), reduces cost of inventory, and reducing inventory obsolescence. When formation of a cell would be too difficult, a simple principle is applied in order to improve efficiencies and flow, that is, to perform processes in a specific location and gather materials to that point at a rate dictated by an average of customer demand (this rate is called the takt time). This is referred to as the Pacemaker Process. Despite the advantages of designing for one-piece-flow, the formation of a cell must be carefully considered before implementation. Use of costly and complex equipment that tends to break down can cause massive delays in the production and will ruin output until they can be brought back online. The short travel distances within cells serve to quicken the flows. Moreover, the compactness of a cell minimizes space that might allow build-ups of inventory between cell stations. To formalize that advantage, cells often have designed-in rules or physical devices that limit the amount of inventory between stations. Such a rule is known, in JIT/lean parlance, as kanban (from the Japanese), which establishes a maximum number of units allowable between a providing and a using work station. (Discussion and illustrations of cells in combinations with kanban are found in) The simplest form, kanban squares, are marked areas on floors or tables between work stations. The rule, applied to the producing station: 'If all squares are full, stop. If not, fill them up.'