Download - Chapter 5, Part B
1
Facility Layout: Manufacturing and Services
Chapter 5, Part B
2
Facility Layout
Facility layout means planning: for the location of all machines, utilities, employee
workstations, customer service areas, material storage areas, aisles, restrooms, lunchrooms, internal walls, offices, and computer rooms
for the flow patterns of materials and people around, into, and within buildings
3
Locate All Areas In and Around Buildings
Equipment Work stations Material storage Rest/break areas Utilities Eating areas Aisles Offices
4
Characteristics of the Facility Layout Decision
Location of these various areas impacts the flow through the system.
The layout can affect productivity and costs generated by the system.
Layout alternatives are limited by the amount and type of space required for the
various areas the amount and type of space available the operations strategy
. . . more
5
Characteristics of the Facility Layout Decision
Layout decisions tend to be: Infrequent Expensive to implement Studied and evaluated extensively Long-term commitments
6
Manufacturing Facility Layouts
7
Materials Handling
The central focus of most manufacturing layouts is to minimize the cost of processing, transporting, and storing materials throughout the production system.
Materials used in manufacturing include: Raw material Purchased components Work-in-progress Finished goods Packaging material Maintenance, repair, and operating supplies
8
Materials Handling
A materials-handling system is the entire network of transportation that:
Receives material Stores material in inventories Moves material between processing points Deposits the finished products into vehicles for
delivery to customers
9
Materials Handling
Material-Handling Principles Move directly (no zigzagging/backtracking) Minimize human effort required Move heavy/bulky items the shortest distances Minimize number of times same item is moved MH systems should be flexible Mobile equipment should carry full loads
10
Materials Handling
Material-Handling Equipment Automatic transfer devices Containers/pallets/hand carts Conveyors Cranes Elevators Pipelines Turntables AGVS
11
Basic Layout Forms
Process Product Cellular Fixed-Position Hybrid
12
Process (Job Shop) Layouts
Equipment that perform similar processes are grouped together
Used when the operations system must handle a wide variety of products in relatively small volumes (i.e., flexibility is necessary)
13
Characteristics of Process Layouts
General-purpose equipment is used Changeover is rapid Material flow is intermittent Material handling equipment is flexible Operators are highly skilled . . . more
14
Characteristics of Process Layouts
Technical supervision is required Planning, scheduling and controlling functions are
challenging Production time is relatively long In-process inventory is relatively high
15
Product (Assembly Line) Layouts
Operations are arranged in the sequence required to make the product
Used when the operations system must handle a narrow variety of products in relatively high volumes
Operations and personnel are dedicated to producing one or a small number of products
16
Characteristics of Product Layouts
Special-purpose equipment are used Changeover is expensive and lengthy Material flow approaches continuous Material handling equipment is fixed Operators need not be as skilled . . . more
17
Characteristics of Product Layouts
Little direct supervision is required Planning, scheduling and controlling functions are
relatively straight-forward Production time for a unit is relatively short In-process inventory is relatively low
18
Cellular Manufacturing Layouts
Operations required to produce a particular family (group) of parts are arranged in the sequence required to make that family
Used when the operations system must handle a moderate variety of products in moderate volumes
19
Characteristics of Cellular ManufacturingRelative to Process Layouts
Equipment can be less general-purpose Material handling costs are reduced Training periods for operators are shortened In-process inventory is lower Parts can be made faster and shipped more quickly
20
Characteristics of Cellular ManufacturingRelative to Product Layouts
Equipment can be less special-purpose Changeovers are simplified Production is easier to automate
21
Fixed-Position Layouts
Product remains in a fixed position, and the personnel, material and equipment come to it
Used when the product is very bulky, large, heavy or fragile
22
Hybrid Layouts
Actually, most manufacturing facilities use a combination of layout types.
An example of a hybrid layout is where departments are arranged according to the types of processes but the products flow through on a product layout.
23
New Trends in Manufacturing Layouts
Designed for quality Designed for flexibility - to quickly shift to different
product models or to different production rates Cellular layout within larger process layouts Automated material handling U-shaped production lines . . . more
24
New Trends in Manufacturing Layouts
More open work areas with fewer walls, partitions, or other obstacles
Smaller and more compact factory layouts Less space provided for storage of inventories
throughout the layout
25
Planning Manufacturing Facility Layouts
Two Categories of Software Tools Computer aided design (CAD)
Allows 3-D, full-color views of facility design Allows virtual walk-throughs Ex. – ArchiCAD, AutoSketch, AutoCAD
Computer simulation Can simulate proposed system layout in operation
and measure its performance Ex. – ProModel, VisFactory, SIMPROCESS
26
Process and Warehouse Layouts Product Layouts Cellular Manufacturing Layouts
Planning Manufacturing Facility Layouts
27
Planning Manufacturing Facility Layouts
Process Layouts Primary focus is on the efficient flow of materials The wide variety of potential product routings
through the facility can be evaluated using computer simulation
Warehouse Layouts Primary focus is the fast storage and retrieval of
inventory items Decisions about aisle size/placement and location
of each inventory item can be evaluated using computer simulation
28
Planning Manufacturing Facility Layouts
Product Layouts Primary focus is on the analysis of production lines The goal of the production line analysis is to:
Determine how many workstations to have Determine which tasks to assign to which
workstation Minimize the number of workers & machines used Provide the required amount of capacity
Line balancing is a key part of the analysis
29
Planning Product Layouts
Line Balancing Procedure1. Determine the tasks involved in completing 1 unit2. Determine the order in which tasks must be done3. Draw a precedence diagram4. Estimate task times5. Calculate the cycle time6. Calculate the minimum number of workstations7. Use a heuristic to assign tasks to workstations
30
Planning Product Layouts
Line Balancing Heuristics Heuristic methods, based on simple rules, have been
developed to provide good (not optimal) solutions to line balancing problems
Heuristic methods include: Incremental utilization (IU) method Longest-task-time (LTT) method … and many others
31
Planning Product Layouts
Incremental Utilization Method Add tasks to a workstation in order of task
precedence one at a time until utilization is 100% or is observed to fall
Then the above procedure is repeated at the next workstation for the remaining tasks
Pro – Appropriate when one or more task times is equal to or greater than the cycle time
Con – Might create the need for extra equipment
32
Planning Product Layouts
Longest-Task-Time Method Adds tasks to a workstation one at a time in the order
of task precedence. If two or more tasks tie for order of precedence, the
one with the longest task time is added Conditions for its use:
No task time can be greater than the cycle time There can be no duplicate workstations
33
Example: Armstrong Pumps
Line BalancingArmstrong produces bicycle tire pumps on a
production line. The time to perform the 6 tasks in producing a pump and their immediate predecessor tasks are shown on the next slide.
Ten pumps per hour must be produced and 45 minutes per hour are productive.
Use the incremental utilization heuristic to combine the tasks into workstations in order to minimize idle time.
34
Example: Armstrong Pumps
Line Balancing Tasks that Time toImmediately Perform
Task Precede Task (min.) A -- 5.4
B A 3.2 C -- 1.5 D B,C 2.8 E D 17.1 F E 12.8
Total = 42.8
35
Example: Armstrong Pumps
Line Balancing – Network (Precedence) Diagram
A
C
B ED F
36
Example: Armstrong Pumps
Line Balancing – Cycle Time
= 45/10 = 4.5 minutes per pump
Productive Time per HourCycle Time = Demand per Hour
37
Example: Armstrong Pumps
Line Balancing – Minimum Number of Workstations
Minimum Number ofWorkstations
= [(42.8)(10)]/45 = 9.51 workstations
(Total Task Time)(Demand per Hour)= Productive Time per Hour
38
Example: Armstrong Pumps
Line Balancing – Incremental Utilization HeuristicWS Tasks Mins./pump #WS’s
Incr.Util. 1 A 5.4 5.4/4.5=1.2= 2
60.0% 1 A,B 5.4 + 3.2 8.6/4.5=1.9= 2
95.0% 1 A,B,C 8.6 + 1.5 10.1/4.5=2.2= 3
49.8% 2 C 1.5 1.5/4.5=.33= 1
33.3% 2 C,D 1.5 + 2.8 4.3/4.5=.96= 1
95.6% 2 C,D,E 4.3 + 17.1 21.4/4.5=4.8= 5
95.1% 3 E 17.1 17.1/4.5=3.8= 4
95.0% 3 E,F 17.1 + 12.8 29.9/4.5=6.6= 7
94.9% 4 F 12.8 12.8/4.5=2.8= 3
94.8%
39
Example: Armstrong Pumps
Line Balancing – Utilization of Production Line
= 9.51/10 = .951 = 95.1%
Minimum Number of WorkstationsUtilization = Actual Number of Workstations
40
Planning Product Layouts
Rebalancing a Production Line Changes that can lead to production lines being out of
balance or having insufficient/excess capacity are: Changes in demand Machine modifications Variations in employee learning and training
41
Planning Cellular Manufacturing Layouts
Cell Formation Decision Which machines are assigned to manufacturing
cells Which parts will be produced in each cell
42
Planning Cellular Manufacturing Layouts
Fundamental Requirements for Parts to be Made in Cells
Demand for the parts must be high enough and stable enough that moderate batch sizes of the parts can be produced periodically.
Parts must be capable of being grouped into parts families.
43
Planning Cellular Manufacturing Layouts
More-Complex Issues to be Resolved If all the parts cannot be cleanly divided between
cells, how will we decide which are to be the exceptional parts?
If inadequate capacity is available to produce all the parts in cells, which parts should be made outside the cells?
44
Planning Cellular Manufacturing Layouts
Cell Formation Procedure1. Form the Parts-Machines Matrix.2. Rearrange the Rows.
Place the machines that produce the same parts in adjacent rows.
3. Rearrange the Columns. Place the parts requiring the same machines in
adjacent columns.4. Use the rearranged parts-machines matrix to identify
cells, the machines for that cell and the parts that will be produced in that cell.