Facilities Layout Layout : the configuration configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system
6-14 Process Selection and Facility Layout
Importance of Layout Decisions
Requires substantial investments of money and effort Involves long-term commitments
Has significant impact on cost and efficiency of short-term operations
6-15 Process Selection and Facility Layout
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
6-16 Process Selection and Facility Layout
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
6-17 Process Selection and Facility Layout
Basic Layout Types
Product layouts
Process layouts
Fixed-Position layout
Combination layouts
6-18 Process Selection and Facility Layout
Basic Layout Types
Product layout
Process layout
Layout that uses standardized processing operations to achieve smooth, rapid, highvolume flow Layout that can handle varied processing requirements
Fixed Position layout
Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed
6-19 Process Selection and Facility Layout
Product Layout Figure 6.4
Raw materials or customer Material and/or labor
Station 1
Material and/or labor
Station 2
Material and/or labor
Station 3
Station 4
Material and/or labor
Used for Repetitive or Continuous Processing
Finished item
6-20 Process Selection and Facility Layout
Advantages of Product Layout
High rate of output
Low unit cost
Labor specialization
Low material handling cost
High utilization of labor and equipment
Established routing and scheduling
Routing accounting and purchasing
6-21 Process Selection and Facility Layout
Disadvantages of Product Layout
Creates dull, repetitive jobs Poorly skilled workers may not maintain equipment or quality of output
Fairly inflexible to changes in volume
Highly susceptible to shutdowns
Needs preventive maintenance
Individual incentive plans are impractical
6-22 Process Selection and Facility Layout
A U-Shaped Production Line Figure 6.6
In
1
2
3
4 5
Workers
6 Out
10
9
8
7
6-23 Process Selection and Facility Layout
Process Layout Figure 6.7
Process Layout (functional) Dept. A
Dept. C
Dept. E
Dept. B
Dept. D
Dept. F
Used for Intermittent processing Job Shop or Batch
6-24 Process Selection and Facility Layout
Product Layout Figure 6.7 (cont’d)
Product Layout (sequential) Work Station 1
Work Station 2
Work Station 3
Used for Repetitive Processing Repetitive or Continuous
6-25 Process Selection and Facility Layout
Advantages of Process Layouts
Can handle a variety of processing requirements Not particularly vulnerable to equipment failures
Equipment used is less costly
Possible to use individual incentive plans
6-26 Process Selection and Facility Layout
Disadvantages Disadvantag es of Process Layouts
In-process inventory costs can be high
Challenging routing and scheduling
Equipment utilization rates are low
Material handling slow and inefficient
Complexities often reduce span of supervision
Special attention for each product or customer
Accounting and purchasing are more involved
6-27 Process Selection and Facility Layout
Cellular Layouts
Cellular Production
Layout in which machines are grouped into a cell that can process items that have similar processing requirements
Group Technology
The grouping into part families of items with similar design or manufacturing characteristics
6-28 Process Selection and Facility Layout
Functionall vs. Cellular Layouts Functiona 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 difficulty
higher
lower
Scheduling complexity
higher
lower
Equipment utilization
lower
higher
6-29 Process Selection and Facility Layout
Other Service Layouts
Warehouse and storage layouts
Retail layouts
Office layouts
6-30 Process Selection and Facility Layout
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.
6-31 Process Selection and Facility Layout
Cycle Time
Cycle time is time is the maximum time allowed at each workstation to complete its set of tasks on a unit.
6-32 Process Selection and Facility Layout
Determine Maximum Output OT Output capacity = CT OT
o p e ra t in g tim e p e r d a y
D = Desir Desir ed out output put r at ate e OT CT = cycl cy cle e t im e = D
6-33 Process Selection and Facility Layout
Determine the Minimum Number of Workstations Required
N =
t
(D)( t) OT = su sum m of task task times times
6-34 Process Selection and Facility Layout
Precedence Diagram Figure 6.10
Precedence diagram : Tool used in line balancing to display elemental tasks and sequence requirements 0.1 min.
1.0 min.
a
b c
0.7 min.
A Simple Precedence Diagram
d
e
0.5 min.
0.2 min.
6-35 Process Selection and Facility Layout
Example 1: Assembly Line Balancing
Arrange tasks shown in Figure 6.10 into three workstations.
Use a cycle time of 1.0 minute Assign tasks in order of the most number of followers
6-36 Process Selection and Facility Layout
Example 1 Solution
Eligible
Assign Task
1.0
a, c
a
0.9
0.9
c
c
0.2
0.2
none
-
2
1.0
b
b
0.0
3
1.0
d
d
0.5
0.5
e
e
0.3
0.3
-
-
Workstation 1
Time Remaining
Revised Time Remaining
Station Idle Time
0.2 0.0
0.3 0.5
6-37 Process Selection and Facility Layout
Calculate Percent Idle Time Idle time per cycle Percent idle time = (N)(CT)
Efficiency = 1 – Percent idle time
6-38 Process Selection and Facility Layout
Line Balancing Rules Some Heuristic (intuitive) Rules:
Assign tasks in order of most following tasks.
Count the number of tasks that follow
Assign tasks in order of greatest positional weight.
Positional weight is the sum of each task’s time and the times of all following tasks.
6-39 Process Selection and Facility Layout
Example 2
0.2
0.2
0.3
a
b
e
0.8
0.6
c
d
f
g
h
1.0
0.4
0.3
6-40 Process Selection and Facility Layout
Solution to Example 2
Station 1
a
b
Station 2
Station 3
e f
c
Station 4
d
g
h
6-41 Process Selection and Facility Layout
Parallel Workstation Workstationss 1 min.
30/hr.
1 min.
30/hr.
2 min.
30/hr.
1 min.
30/hr.
Bottleneck 30/hr. 1 min.
60/hr.
1 min.
30/hr.
1 min.
1 min. 30/hr. 1 min.
Parallel Workstations
30/hr.
60/hr.
6-42 Process Selection and Facility Layout
Designing Process Layouts Information Requirements: 1.
List of departments
2.
Projection of work flows
3.
Distance between locations
4.
Amount of money to be invested
5.
List of special considerations
6.
Location of key utilities
6-43 Process Selection and Facility Layout
Example 3: Interdepartmental Work Flows for Assigned Departments
Figure 6.12
30 1
A
170
B
3
10 0
C
2
6-44 Process Selection and Facility Layout
Author’s note:
The following three slides are not in the 8e, but I like to use them t hem for alternate examples.
6-45 Process Selection and Facility Layout
Process Layout Milling Assembly & Test
Grinding
Drilling
Plating
Process Layout - work travels to dedicated process centers
