c061 chap06 - foe web-process selection and facilitiy layout

1

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


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.


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


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


Batch

Repetitive


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)


0.1 min 0.7 min 1.0 min 0.5 min 0.2 min

Assembly-Line Balancing


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)



• 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



Funnel Analogy of Bottlenecks


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


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:


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


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


Gearcutting

Mill Drill

Lathes

Grind

Heattreat

Assembly

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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.


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.


Gearcutting

Mill Drill

Lathes

Grind

Heattreat

Assembly

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222

444

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44444

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• Cellular Production• Group Technology


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Lathe

Lathe

Mill

Mill

Mill

Mill

Drill

Drill

Drill

Heat treat

Heat treat

Heat treat

Gear cut

Gear cut

Grind

Grind

Cellular Manufacturing Layout


Group Technology / Cellular Layout


Drill Polish

Work Cell

Forming a Cell


A U-Shaped Production Line

1 2 3 45

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In

Out

Workers


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


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


• Warehouse and storage layouts• Retail layouts• Office layouts• Service layouts must be functional and aesthetically pleasing

Service Layouts

c061 chap06 - foe web-process selection and facilitiy layout

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