Chapter 10 Facility layout Flashcards
facility layout (layout planning) :
Deciding the best physical arrangement of all resources that consume space within a facility
Intermittent processing systems:
low volume of many different products
Repetitive processing systems:
high volume of a few standardized products
The 4 types of layouts:
Process layouts, product layout, hybrid layout, fixed-position layout
process layouts:
Group similar resources together based on
similar processes/functions
product layouts:
Designed to produce a specific product efficiently
hybrid layouts:
Combine aspects of both process and product layouts
fixed-position layouts:
Product is too large to move, and all resources must be brought to production site; e.g., shipbuilding
unique characteristics for process layouts are:
o resources used are general-purpose o facilities are less capital intensive o facilities are more labor intensive o resources have greater flexibility o processing rates are slower o material handling costs are higher o scheduling resources flow is more challenging o space requirements are higher
unique characteristics of product layouts are:
o resources are specialized
o facilities are capital intensive
o processing rates are faster
o material handling costs are lower
o space requirements for inventory storage are lower
o flexibility is low relative to the market
characteristics of hybrid layouts are:
• Combine elements of both product and process layouts
o Maintain some of the efficiencies of product layouts
o Maintain some of the flexibility of process layouts
• Group technology or cell layouts
o Identify parts of the process layout operation that can be
standardized and produce them in a product layout format
example: grocery stores
characteristics of fixed-position layout are:
- Used when product is large
- Product is difficult or impossible to move, i.e., very large or fixed
- All resources must be brought to the site
- Scheduling of crews and resources is a challenge
Steps in Design Process layout are:
- Gather information
- Develop a block plan
- Develop detailed layout
Steps in Design Process layout, Gathering information:
Identify space needed, space available, closeness measures
from-to matrix, REL, SLP
From-to matrix
A table that shows the number of trips or units of product moved between any pair of departments
REL chart:
A tool that reflects opinions of managers with regard to the importance of having any two departments close together
Steps in Design Process layout, Develop Block plan:
Use trial-and-error or decision support tools (load–distance model,
ALDEP, CRAFT)
Rectilinear distance: (used with load-distance model)
The shortest distance between two points measured by using only north–south and east–west movements.
ALDEP
automated layout design program
CRAFT
computerized relative allocation of facilities technique
Computer software packages for designing process layouts
Steps in Design Process layout, develop a detailed layout:
• Consider exact sizes/shapes of departments and work centers
including aisles and stairways
• Tools like drawings, three-dimensional models, and computer graphics software are available to facilitate this process
Special Cases of Process Layouts: Warehouse
Layouts
• Warehouse layout considerations
o Primary decision is where to locate each department relative to the dock.
• Storage areas of equal sizes
o Assign departments to locations in order to minimize the number of trips to the
dock.
• Storage areas of unequal sizes
o Step 1: Take the ratio of the number of trips relative to the storage area required.
o Step 2: Use the ratios from Step 1 to make assignments. Assign the department with the highest ratio closest to the dock. Next, assign the department with the second-highest ratio second closest to the dock. Continue in this manner until all departments have been assigned.
Special Cases of Process Layouts: Office
Layouts
• Office layout considerations
o Almost half of U.S. workforce works in an office environment.
o Human interaction and communication are the primary factors in designing office layouts.
o Layouts need to account for physical environment and psychological needs of the organization.
o Key trade-off is between proximity and privacy.
o Open concept offices promote understanding and trust.
o Flexible layouts incorporating “office landscaping” help to solve the privacy issue in open office environments.
Designing product layouts:
• Designing product layouts requires consideration of:
o Sequence of tasks to be performed by each workstation
o Logical order
o Speed considerations – line balancing
Steps in Designing product layouts:
Step 1: Identify tasks and their immediate predecessors.
Step 2: Determine output rate.
Step 3: Determine cycle time.
Step 4: Compute the theoretical minimum number of stations.
Step 5: Assign tasks to workstations (balance the line).
Step 6: Compute efficiency, idle time, and balance delay.
Steps in Designing product layouts, Step 1: Identify tasks and their immediate predecessors.
can list out the tasks or use a diagram
Steps in Designing product layouts, Step 2: Determine output rate.
Output rate is the number of units to be produced over a specific period of time.
The goal is to design a product layout that can produce the desired number of units with the fewest work centers and a balance of workload.
Steps in Designing product layouts, Step 3: Determine cycle time:
The amount of time each workstation is allowed to complete its tasks
Limited by the bottleneck task (the longest task)
Minimum cycle time = bottleneck
Maximum cycle time = sum of the task times
Steps in Designing product layouts, Step 4: Compute the theoretical minimum number of stations:
TM = number of stations needed to achieve 100% efficiency (every
second is used)
Always round up (no partial workstations)
Serves as a lower boundary for our analysis
Steps in Designing product layouts, Step 5: Assign tasks to workstations (balance the line) :
o Start at the first station and choose the longest eligible task following precedence relationships.
o Continue adding the longest eligible task that fits without going over the desired cycle time.
o When no additional tasks can be added within the desired cycle time, begin assigning tasks to the next workstation until finished.
Steps in Designing product layouts, Step 6: Compute efficiency, idle time, and balance delay:
Efficiency (%) is the ratio of total productive time divided by
total time.
Balance delay (%) is the amount by which the line falls short of 100%.
example: Balance delay (%) = 100% − 91.7% = 8.3%
other product layout considerations, Shape of the line (S, U, O, L):
Share resources, enhance communication and visibility, impact
location of loading and unloading
other product layout considerations, Paced versus unpaced lines:
Paced lines use an automatically enforced cycle time
Unpaced lines have more autonomy; product may be removed from assembly line
other product layout considerations, Number of product models produced:
Single-model lines – one version of a product
Mixed-model lines – many versions of a product
