Plant Layout

Plant Layout

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Layout Planning Manufacturing & Services • Deals with the physical arrangement of various resources that are available in the system with an objective to improve the performance of the operating system thereby providing better customer service.

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The Need for Layout Decisions Inefficient operations For Example:

High Cost Bottlenecks

Changes in the design of products or services

Accidents The introduction of new products or services

Safety hazards 11-12-2007

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The Need for Layout Design (Cont’d) Changes in environmental or other legal requirements

Changes in volume of output or mix of products Morale problems

Changes in methods and equipment

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Implications of layout Planning

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• Relationship between volume-variety –flow provides crucial input for layout planning. • As the flow becomes more cumbersome, the type of layout may significantly influence the ability of operations manager to effectively plan. • Table8.1 of Mahadevan

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Types of Layout • • • •

Process Product Group Technology Fixed Position

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Process Layout Milling Assembly & Test

Grinding

Drilling

Plating

Process Layout - work travels to dedicated process centers

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Functional Layout 22

3333

Assembly

4 44

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Heat treat

Grind

44

333Lathes

1111 2222

33

111

33 33

3 33

111333

Drill

22 2

Mill

222

33 33

444

222 111 444

33

222

111 Gear cutting

111 444

9

-1111

2222

3333

4444

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Lathe

Mill

Mill

Drill

Drill

Lathe Mill

Mill

Heat treat

Gear -1111 cut

Heat treat

Grind - 2222

Heat treat

Grind - 3333

Drill

Gear - 4444 cut

Assembly

Cellular Manufacturing Layout

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Process Layout • Arrangement of resources on the basis of the process characteristics of the resources available.

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Process Layout Examples • Car servicing • Hospital-Patient requiring various tests • Volume low & variety is more

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Product Layout • The resources are placed to follow exactly the visitation sequence dictated by the product.

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Product layout • The technique employed for product layout is known as line balancing • The resources required to achieve desired /targeted production rate. • Cycle time can be considered as a reciprocal of production rate.

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Product layout • Plant & machinery layout is designed to cater to continuous flow of Materials. • Use of mechanisation and automation can be planned. • Automobile Industry

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Advantages • Process • Sharing of specialised and costly equipment • More flexibility • Less vulnerable to breakdowns

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• Product • Standardised product and process routing • Operational control is simpler • High output rate is possible

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Disadvantages • Process • Large inventory build up • Excess material handling

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• Product • Less flexibility due to dedication of resources • Possibility of duplicating equipments leading to higher costs.

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Group Technology Layout • This is philosophy that seeks to exploit the commonality in manufacturing and uses this as a basis for grouping components and resources. This is also known as cellular manufacturing. • Pioneered by Russians • Mid volume & mid variety scenario • 70% of mfg. industry may fall under this category) 18-12-2007

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Advantages of Cellular Layout • • • • •

PPC becomes simpler Material handling becomes easier Traceability improves Employees are able to relate better. Helps in implementing SGA, Kaizen an JIT

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Cellular Layout- Examples • Reliance industries- HDPE & LDPE • Titan Industry • ABB( Industrial fans & blowers)

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Fixed Position Layout • The material remains in a fixed position , but the machinery, tool workmen etc are brought to the material

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Fixed Position Layout • Employed in large project type organisation • Example • ISRO • Helicopter • Nuclear engg. Division of BHEL

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• One worker and multiple machine layout

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Layout Design for Services • Critical factors • Degree of customer contact • Line visibility

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Performance Measures • The most fundamental measure for layout design is the distance travelled by customer order in the system.

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Performance Measures 1. Distance travelled by job in the SF 2. Space utilisation index 3. Matl. Handling costs 4. Lead time of the process 5. Ease of prodn. Control 7. No. of ownership changes

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• Kg Mts.

• Rs./month • Hrs per avg. product • Size of progress chasing staff • No. of times job changes hand.

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Automation • Automation: Machinery that has sensing and control devices that enables it to operate – Fixed automation – Programmable automation

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Automation • Computer-aided design and manufacturing systems (CAD/CAM) • Numerically controlled (NC) machines • Robot • Manufacturing cell • Flexible manufacturing systems(FMS) • Computer-integrated manufacturing (CIM)

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Functional vs. Cellular Layouts

Table 6.3

Dimension

Functional

Cellular

Number of moves between departments

many

few

Travel distances

longer

shorter

Travel paths

variable

fixed

Job waiting times

greater

shorter

Throughput time

higher

lower

Amount of work in process

higher

lower

Supervision difficulty

higher

lower

Scheduling complexity

higher

lower

Equipment utilization

lower

higher

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Other Service Layouts • Warehouse and storage layouts • Retail layouts • Office layouts

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Design Product Layouts: Line Balancing Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements.

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Cycle Time Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit.

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Determine Maximum Output OT Output capacity = CT OT = operating time per day D = Desired output rate OT CT = cycle time = D

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Determine the Minimum Number of Workstations Required N =

∑t

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(D)( ∑ t) OT

= sum of task times

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