Cellular Manufacturing; Work Cells

Cellular Manufacturing (CM)

Cellular Manufacturing (CM) refers to a manufacturing system wherein the equipment and workstations are arranged in an efficient sequence that allows a continuous and smooth movement of inventories and materials to produce products from start to finish in a single process flow, while incurring minimal transport or waiting time, or any delay for that matter. CM is an important ingredient of lean manufacturing.

In order to set up a single process flow (or single product flow) line, it is necessary to locate all the different equipment needed to manufacture the product together in the same production area. This is in contrast with the traditional 'batch and queue' set-up wherein only similar equipment are put in the same area. Under a 'batch and queue' set-up, products that need to undergo processing under a certain equipment need to be transported to the area where the equipment are located. There they are queued for processing in batches. Such a system sometimes results in transport and batching delays. In a single process flow set-up, the products simply transfer from one equipment to the next along the same production line in a free-flowing manner, avoiding transport and batching delays.

The single process flow set-up described above is an example of a 'work cell'. A work cell is defined as a collection of equipment and workstations arranged in a single area that allows a product or group of similar products to be processed completely from start to finish. It is, in essence, a self-contained mini-production line that caters to a group of products that undergo the same production process. Cellular manufacturing involves the use of work 'cells', which is how it got its name.

Since differently-processed products need different work cells, a large company with diversified products needs to build several, different work cells if single process flows are desired. Given enough volume of products to work with, work cells have been proven by experience to be faster and more efficient in manufacturing than 'batch and queue' systems.

Because of the free flow of materials in cellular manufacturing, it has the ability to produce products just in time. This means that every unit processed at one station will get processed in the next station. As such, no inventories that have already undergone processing at one station will be left unprocessed in another station.

This prevents the build-up of non-moving inventories, which are products that have already incurred some production costs but can not generate revenues because they are stuck somewhere along the process. Aside from preventing non-moving inventories, process issues are immediately detected by just-in-time production, since defective products are seen earlier than if products are manufactured in large batches and queued.

One technique that cellular manufacturing can use to achieve 'just-in-time' production is the 'pull system', wherein required inventories and materials are requested or 'pulled in' by each station from the station preceding it. This 'pull' can originate from the end customer itself, thereby ensuring that the products manufactured are only those needed to satisfy a customer order. This prevents wastes from products not being sold.

It is not enough to simply arrange different equipment in sequence to make cellular manufacturing really work. Bottlenecks along the single process flow must be eliminated, usually by balancing the equipment capacities with each other. If bottlenecks exist, then the higher-capacity equipment within the line will be underutilized. Balancing equipment capacities may mean: 1) choosing 'right-sized' equipment that match each other; and/or 2) combining two or more smaller capacity equipment to match one larger-capacity equipment.

If properly implemented, the benefits of cellular manufacturing include: 1) higher production efficiency; 2) elimination of waste; 3) reduced inventory levels; 4) optimized use of floor space; 5) shorter production cycle times; 6) higher effective manufacturing capacity; and 7) improved customer response time. As a result, the over-all production cost becomes lower and profits become greater.

HOME