A cellular manufacturing layout is in direct contradiction to the traditional production line. In the production line, numerous workers are needed to service a single production line running from receiving of raw material to shipping of finished product. A breakdown in staffing or machinery in any part of the line nearly always resulted in the entire process being idled until the specific difficulty in the line was repaired, or re-crewed. With cellular manufacturing, production is divided among groups, or cells, of workers and production machinery. Thus, the breakdown of one cell, due to equipment malfunction or staffing problems, does not radically affect the rest of the production process.
Technology and cellular manufacturing have combined to streamline the production processes of numerous established and start-up manufacturing facilities worldwide. Lean systems, such as Kaizen, and Six Sigma, to name just two, though very often high in startup cost, provide both a short- and long-term benefit in reducing the waste common to the traditional production line. The bottom line in any manufacturing enterprise is profit. Cellular manufacturing has been proven to dramatically increase profits.
Cellular Manufacturing is a model for workplace design, and is an integral part of lean manufacturing systems. The goal of lean manufacturing is the aggressive minimization of waste, called muda, to achieve maximum efficiency of resources. Cellular manufacturing, sometimes called cellular or cell production, arranges factory floor labor into semi-autonomous and multi-skilled teams, or work cells, who manufacture complete products or complex components. Properly trained and implemented cells are more flexible and responsive than the traditional mass-production line, and can manage processes, defects, scheduling, equipment maintenance, and other manufacturing issues more efficiently.
A cell is a group of workstations, machines or equipment arranged such that a product can be processed progressively from one workstation to another without having to wait for a batch to be completed or requiring additional handling between operations. Cells may be dedicated to a process, a sub-component, or an entire product. Cells are conducive to single-piece and one-touch manufacturing methods and are often found as part of lean manufacturing applications. Cells may be designed for the office as well as the factory.
Though very technical and detailed, the concept of cellular production is basically simple; get a finished product from raw materials to shipment as efficiently, and as profitably as possible. Cellular manufacturing systems and layouts essentially separate the production line into segments, or cells, sometimes called modules. Each cell, consisting of both workers and production machinery, is dedicated to a particular component of the manufactured product. Ideally, workers and equipment comprising a particular cell are trained and configured to be able to take over the processes of another cell when necessary, thus minimizing downtime and wastage of raw material
Group technology or families-of-parts concepts are often used in cellular design. Group technology is the process of studying a large population of different workpieces and then dividing them into groups of items having similar characteristics. The process may be executed with the aid of a computer, and has been used to divide parts into groups for use with CAD/CAM processing. Family of parts is the process of grouping workpieces into logical families so that they can be produced by the same group of machines, tooling, and people with only minor changes on procedure or setup.
In production, setups and changeovers are faster because the same tools and fixtures can be used for similar parts. With group technology the workpieces and machining operations have to be classified. Once coded into classifications, processing information can be retrieved quickly.
There are many forms of cellular technology Straight line, U-shape, but equipment contained with the cell, or workstations, are normally configured in closely proximity to compress time and space. It is very important to ensure quick changeover from one product to the next for inducing cell velocity. For handling materials, robots, conveyors etc are used and sometimes it is also manual. If totally automated, then a supervisory computer is required to control movement between the individual pieces of equipment and the automated conveyance.
The goal of cellular manufacturing is having the flexibility to produce a high variety of low demand products, while maintaining the high productivity of large scale production. Cell designers achieve this through modularity in both process design and product design.
Process Design
Work is divided into discrete segments and each segment is assigned a work cell. This introduced the modularity of processes. In this way, if any segment of the process needs to be changed, only the particular cell would be affected, not the entire production line.
For example, if a particular component was prone to defects, and this could be solved by upgrading the equipment, a new work cell could be designed and prepared while the obsolete cell continued production. Also, this will help in reducing stalling time and will increase the capacity.
Once the new cell is tested and ready for production, the incoming parts to and outgoing parts from the old cell will simply be rerouted to the new cell without having to disrupt the entire production line.
In this way, work cells increase the flexibility to upgrade processes and allow changes in products to better suit customer demands while reducing or eliminating the costs of breakdown. Even though the machinery may be functionally dissimilar, the family of parts produced contains similar processing requirements or has structural similarities. Thus, all parts basically follow the same routing with some minor variations (e.g., skipping an operation). The cells may have no conveyorized movement of parts between machines, or they may have a flow line connected by a conveyor that can provide automatic transfer.
Product Design
It must match the modularity of processes. Even though the entire production system becomes more flexible, each individual cell is still optimized for a relatively narrow range of tasks, in order to take advantage of the mass-production efficiencies of specialization and scale. This means that a large variety of products can be designed to be assembled from a small number of modular parts, through which a high product variety as well as high productivity can be achieved. For example, a varied range of automobiles may be designed to use the same chassis, a small number of engine configurations, and a moderate variety of car bodies, each available in a range of colors. In this way, a large variety of automobiles, with different performances and appearances and functions, can be produced by combining the outputs from a more limited number of work cells.
Cells are usually larger than traditional workstations, but smaller than a complete department. Additionally, a cellular manufacturing layout requires less floor space as a result of the optimized production processes. Each cell is responsible for its own internal control of quality, scheduling, ordering, and record keeping. This way, responsibilities of tasks are assigned to those who are most familiar with the situation and most able to quickly fix any problems. The middle management no longer has to monitor the outputs and interrelationships of every single worker.
Implementation of Cellular Manufacturing System
The biggest challenge when implementing cellular manufacturing in a company is dividing the entire manufacturing system into cells. There are two types of issues;
- The “hard” issues of equipment, such as material flow and layout, and
- The “soft” issues of management, such as up skilling and corporate culture.
The hard issues are a matter of design and investment. The entire factory floor is rearranged, and equipment is modified or replaced to enable cell manufacturing. The costs of work stoppages during implementation can be considerable, and generally this rearrangement is preferred to be phased to minimize the impacts of such disruptions as much as possible.
The soft issues are more difficult to calculate and control. The implementation of cell manufacturing often involves employee training and the redefinition and reassignment of jobs. Each of the workers in each cell should ideally be able to complete the entire range of tasks required from that cell, and often this means being more multi-skilled than they were previously. For this reason, transition from a progressive assembly line type of manufacturing to cellular is often best managed in stages with both types co-existing for a period of time.
In addition, to make cells self-managing (to some extent), workers are expected to learn the tools and strategies for effective teamwork and management, tasks that workers in conventional factory environments are entirely unused to.
On the same lines, the management will also find their jobs redefined, as they must take a more “hands-off” approach to allow work cells to effectively self-manage. So they are supposed to learn to perform a more oversight and support role, and maintain a system where work cells self-optimize through supplier-input-process-output-customer (SIPOC) relationships.
Product start-ups can be more difficult to manage if assembly training was traditionally accomplished station-by-station on a fixed assembly line. As each operator in a cell is responsible for a larger number of assembled parts and operations, the time needed to master the sequence and techniques is considerably longer. If multiple parallel cells are used, each cell must be launched separately (meaning slower production ramp) or with equal training resources (meaning more in total). The consideration of the cell’s internal group dynamics, personalities and other traits is often more of a concern in cellular manufacturing due to the closer proximity and co-dependency of the team members; however properly implemented this is a major benefit of cellular manufacturing.
Benefits and Costs of Cellular Manufacturing System
Among the biggest benefits are these;
- Processes become more balanced and productivity increases because the manufacturing floor has been reorganized and tidied up.
- Part movement, set-up time, and wait time between operations are reduced, resulting in a reduction of work in progress inventory freeing idle capital that can be better utilized elsewhere.
- Helps eliminate overproduction by only producing items when they are needed.
- There is ample amount of cost savings and the better control of operations.
Along with the set up costs, there are also other costs associated with particular cells in cellular manufacturing. Sometimes different work cells can require the same machines and tools, possibly resulting in duplication causing a higher investment of equipment and lowered machine utilization. However, this is a matter of optimization and can be addressed through process design.
The cellular manufacturing system, often called lean manufacturing, is a fairly recent development in global manufacturing processes. One of the first, and today, the most common cellular, or lean manufacturing systems is the Kaizen system. Originally conceived by the Toyota Corporation in Japan, Kaizen utilizes technology and cellular manufacturing to reduce the waste of time, effort, money, and resources in the production process.