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Chapter 6
Process Selectionand
Facility Layout
Saba Bahouth – UCO
Saba Bahouth – UCO 2
Forecasting
Product andService Design
TechnologicalChange
CapacityPlanning
ProcessSelection
Facilities andEquipment
Facility Layout
WorkDesign
Process Selection as Part of System Design
Deciding on the way the production of goods or services will be organized
Saba Bahouth – UCO 3
Process Choice Decisions
Three Types of Goods and Services
Custom, or make-to-order, goods and services are generally produced and delivered as one-of-a-kind or in small quantities, and are designed to meet specific customers’ specifications. Examples: ships, weddings, certain jewelry, estate plans, buildings, and surgery.
Option, or assemble-to-order, goods and services are configurations of standard parts, subassemblies, or services that can be selected by customers from a limited set.Examples: desktop computers, Subway sandwiches, vacation in tour, BBA
Standard, or make-to-stock, goods and services are made according to a fixed design, and the customer has no options from which to choose. Examples: appliances, shoes, sporting goods, credit cards, on-line Web-based courses, and bus service.
Saba Bahouth – UCO 4
The Big Picture
Types of Goods and Services
Custommake-to-order
Optionassemble-to-order
Standardmake-to-stock
Types of Processes
1. Projects
2. Job-Shop
3. Batch
4. Repetitive/(Assembly Lines)
5. Continuous
Types of Layout
1. Fixed Position Layout
2. Process/Functional Layout
3. Product Layout
4. Combination
Layout
Saba Bahouth – UCO 5
Job shop: Small scale production
Batch: Moderate volume production
Repetitive/assembly line: High volumes of standardized goods or services
Continuous: Very high volumes of non-discrete goods
Types of Processes
Job-Shop(intermittent process)
Process/Functional Layout
Repetitive(assembly line)Product Layout
Continuum
Make to OrderHigh variety, low volume
Low utilization (5% - 25%)General-purpose equipment
Make to StockLow variety, high volume
High utilization (70% - 95%)Specialized equipment
Batch Continuous
Product Layout
Flexible equipment
Projects
Saba Bahouth – UCO 6
Saba Bahouth – UCO 7
Batch
Repetitive
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Volume, Variety and Process Matrix
Different Attributes only(Low Variety) (such as grade, quality, size, thickness, etc.) Long runs only
Process/Functional focus (Intermittent)
projects, job shop(machine, print, carpentry)
Kinko’s
Repetitive(autos, motorcycles)
Honda
Product focus(steel, glass)Nucor Steel
Different Products:(High Variety) One or few units per run, high variety(allows customization)
Different ModulesModest runs, standardized modules
Mass Customization
(difficult to achieve, but huge rewards)
Dell Computer Co.
Poor strategy
Low-Volume Repetitive Process High-Volume
(Batch)
Saba Bahouth – UCO 9
0.1 min 0.7 min 1.0 min 0.5 min 0.2 min
Assembly-Line Balancing
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Assembly-Line BalancingAssembly-Line Balancing• An assembly line is a product layout dedicated to combining the
components of a good or service that has been created previously.
• Assembly line balancing is a technique for grouping tasks to balance the workload on workstations.
• Cycle time (CT) is the interval between successive outputs.
• Min. number of WS needed = Sum of task times/Cycle time = t / CT
• Individual WS efficiency = t / CT
• Assembly Line Efficiency = t / (N*CT)
0.1 min 0.7 min 1.0 min 0.5 min 0.2 min
Saba Bahouth – UCO 11
• 5 workstations: CT = 1 minute; 1 assembly every 1 minute.
• 3 workstations: CT = 1 minute; 1 assembly every 1 minute.
• 1 workstation: CT = 2.5 minutes; 1 assembly every 2.5 minutes.
Maximum Allowed Cycle Time:MACT = A / R
where A = Available time to produce the output (Hrs/day or Min/day)
R = Required output Rate (units/day) (be careful with time units)
Example: [8hrs/day] / [160units/day] = 0.05 hrs/unit or 3 minutes
Assembly-Line Balancing
0.1 min 0.7 min 1.0 min 0.5 min 0.2 min
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Funnel Analogy of Bottlenecks
Saba Bahouth – UCO 13
Little’s LawJ.D. Little (1961) developed a simple formula that explains the relationship between flow time (T), throughput (R) and work-in-process (WIP), which is known as Little’s Law.
WORK-IN-PROCESS (WIP) = THROUGHPUT (R) * FLOW TIME (T)
Assume: Throughput = 30 units/hr Flow time = 20 minutes or 1/3 hr Therefore WIP= 30 units/hr x 1/3 hr = 10 units
Consider a voting facility that processes an average of 50 people per hour and that on average, it takes 10 minutes for each person to complete the voting process.
WIP = R*TWIP = 50 voters/hr*(10 minutes/60 minutes per hour)WIP = 8.33 voters
Saba Bahouth – UCO 14
Solved Problem
An accounts receivable manager processes 200 bills per day with an average processing time of 5 working days. What is the average number of bills in her office? What if she reduces the time from 5 to 1 day using better technology?
Solution:
Saba Bahouth – UCO 15
Automation: Machinery that has sensing and control devices that enables it to operate with minimal input from an operator.
– Fixed automation– Programmable automation
Automation
• Machine technology – NCM for drilling, cutting, etc• Automatic identification systems (AIS) – Bar codes, toll pass• Process control – Glass temperature – QA charts• Vision system - Replacing human inspection: level in medicine
bottles• Robot – Imitation of human arm for boring and dangerous jobs• Automated storage and retrieval systems (ASRS)• Automated Guided Vehicles (AGV)• Flexible manufacturing systems (FMS) – One computer system
controlling several machines and material handling• Computer-integrated manufacturing (CIM) – One computer
system spanning over engineering, inventory, manufacturing, warehousing and shipping
Saba Bahouth – UCO 16
Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system
• Process/Functional layout
• Product layout
• Combination layout
• Fixed-Position layout (Projects)
Facilities Layout
Saba Bahouth – UCO 17
Gearcutting
Mill Drill
Lathes
Grind
Heattreat
Assembly
111
333
222
444
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111 3331111 2222
222
3333
111
444111
333333333
44444
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3322
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Process/Functional Layout
Saba Bahouth – UCO 18
Process/Functional LayoutA process/functional layout consists of a functional grouping of equipment or activities that do similar work.
Examples: offices, hospitals.
Advantages of product layouts include a lower investment in general purpose equipment, flexibility, and the diversity of jobs inherent in a process layout can lead to increased worker satisfaction.
Saba Bahouth – UCO 19
Product LayoutA product layout is an arrangement based on the sequence of operations that are performed during the manufacturing or service.
Examples: Subway sandwich shops, automobile assembly lines.
Advantages of product layouts include lower work-in-process inventories, shorter processing times, less material handling, requires lower labor skills, and simple planning and control systems.
Saba Bahouth – UCO 20
Gearcutting
Mill Drill
Lathes
Grind
Heattreat
Assembly
111
333
222
444
222111444
111 3331111 2222
222
3333
111
444111
333333333
44444
3333
3322
222
Process/Functional Layout
• Cellular Production• Group Technology
Saba Bahouth – UCO 21
-1111 -1111
222222222 - 2222
Asse
mbl
y
3333333333 - 3333
44444444444444 - 4444
Lathe
Lathe
Mill
Mill
Mill
Mill
Drill
Drill
Drill
Heat treat
Heat treat
Heat treat
Gear cut
Gear cut
Grind
Grind
Cellular Manufacturing Layout
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Group Technology / Cellular Layout
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Drill Polish
Work Cell
Forming a Cell
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A U-Shaped Production Line
1 2 3 45
678910
In
Out
Workers
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Advantages• Can handle a variety of
processing requirements• Not particularly vulnerable
to equipment failures• Equipment used is less
costly• Possible to use individual
incentive plans
Process/Functional Layouts
Disadvantages• 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
Saba Bahouth – UCO 26
Advantages• High rate of output• Low unit cost• Labor specialization• Low material handling cost• High utilization of labor/equipment• Established routing and scheduling• Easy accounting and purchasing
Product Layout
Disadvantages• Creates dull, repetitive jobs• Poorly skilled workers may neglect
maintenance and quality• Fairly inflexible to changes in volume• Highly susceptible to shutdowns• Needs preventive maintenance• Individual incentive plans are
impractical
Saba Bahouth – UCO 27
• Warehouse and storage layouts• Retail layouts• Office layouts• Service layouts must be functional and aesthetically pleasing
Service Layouts