Cellular manufacturing

CELLULAR MANUFACTURING

Cellular manufacturing refers to the utilization of work cells that specialize in the creation of families of parts or items made in medium amount.

Parts (and products) in this amount range are generally made in batches, and batch production need downtime for setup change overs and has high inventory carrying costs.

Cellular manufacturing depends on a methodology called group technology (GT), which reduces the lesser benefits of batch production by recognizing that although the parts vary, they also contain similarities.

At the point when these similarities are exploited in production, operating efficiencies get improved.

The improvement is commonly accomplished by getting the production around manufacturing cells.

Each cell is designed to produce one part family (or a limited number of part families), thereby following the principle of specialization of operations.

PART FAMILIES

A central feature of cellular manufacturing and group technology is the part family.

A part family is a gathering of parts that possess common geometric shape and
size, or in the processing steps utilized in their assembling.

It is not unusual for a factory that produces 10,000 various parts to make those parts into 20 to 30 part families.

In each part family the processing steps are same.

Cellular manufacturing
Two parts that are identical in shape and size but quite different in manufacturing: (a) 1,000,000 units/yr, tolerance 0.010 in., 1015 CR steel, nickel plate; and (b) 100/yr, tolerance 0.001 in, 18-8 stainless steel.

There are constantly differences between parts in a family, but the similarities are close enough that the parts can be assembled in the similar family.

Parts have the similar size and shape; however, their processing requirements are quite different because of differences in work material, production quantities, and design tolerances.

Several parts are with geometries that differ, but their manufacturing requirements are quite similar.

There are several ways by which part families are identified in industry.

Ten different parts with same manufacturing type

One method include visual investigation of all the parts made in the factory (or photos of the parts) and utilizing best judgment to bunch them into suitable families.

Another approach, called production flow analysis, uses information contained on route sheets to classify parts.

In effect, parts with similar manufacturing steps are grouped into the same family.

A third method, usually the most expensive but most useful, is parts classification and coding.

Parts classification and coding involve the identification of similarities and changes among parts and relating these parts by means of a mathematical coding scheme.

The classification is as follows:

(1) systems based on part design attributes,

(2) systems based on part manufacturing attributes,

(3) systems based on both design and manufacturing attributes.

Normal part design and manufacturing attributes utilized in Group Technology
systems are introduce.

Since each company create a unique set of parts and products, a characterization and coding system that might be acceptable for one company is not necessarily appropriate for another company.

MACHINE CELLS

To fully exploit the similarities among parts in a family, production should be organized using machine cells designed to specialize in making those particular parts.

One of the principles in designing a group technology machine cell is the composite part concept.

COMPOSITE PART CONCEPT

Members of a part family possess similar design and/ or manufacturing features.

There is usually a correlation between part design features and the manufacturing operations that produce those features.

Round holes are made by drilling; cylindrical shapes are made by turning; and so on.

Composite part concept:
Composite part concept: (a) the composite part for a family of machined rotational parts, and (b) the
individual features of the composite part.

The composite part for a given family (not to be confused with a part made of composite material) is a hypothetical part that includes all of the design and manufacturing attributes of the family.

The normally, an single part in the family will have some of the features that characterize the family, but not all of them.

A production cell intended for the part family would incorporate those machines needed to make the composite part.

Types of group technology machine cells
Types of group technology machine cells: (a) single machine, (b) multiple machines with manual handling, (c) multiple machines with mechanized handling, (d) flexible manufacturing cell, and (e) flexible manufacturing system. Key: Man manual operation; automated station.

Such a cell would be equipped of producing any individual of the family, simply by excluding those operations corresponding to features not possessed by the
particular part.

The cell would also be intended to allow for size variations inside the family as well as feature variations.

BENEFITS AND PROBLEMS IN GROUP TECHNOLOGY

The use of machine cells and group technology provide substantial benefits to companies that have the discipline and perseverance to implement it.

The potential benefits include the following:

(1) The standardization of tooling, fixturing, promoted by Group Technology (GT).

(2) Material handling is minimize due to the parts are moved in between a machine cell rather than the entire factory.

(3) Production scheduling is simplified.

(4) Manufacturing lead time is reduced.

(5) Work-in-process is reduced.

(6) Process planning is simpler.

(7) Worker satisfaction usually improves working in a cell.

(8) Higher quality work is accomplished.

There are many defect in implementing machine cells.

One obvious problem is rearranging production machines in the plant into the appropriate machine cells.

ADVANTAGES OF CELLULAR MANUFACTURING

Manufacturing cells are utilize to reduce product movement as well as materials, equipment and labor during the manufacturing process.

By reducing process duration and material handling, these cells help shops more easily meet customer demands regarding cost, quality and lead times.

Improvement in machine utilization.

DISADVANTAGES OF CELLULAR MANUFACTURING

Setup times or change over times may not always be significantly minimized just due to the components in the family bear apparent similarity.

Same observation about raw material and work in process inventories require to be follow up at the time of the design of the cells.

APPLICATIONS OF CELLULAR MANUFACTURING

Cellular Manufacturing System (CMS) is mostly utilized in multiple-product industries due to CMS is the management of cells for flexibility of production system.

Processes or machines are sequence in same groups, and products are categorized in proper production groups

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