Process Management - Quality, Time and the Theory of Constraints - Pareto Presentation

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Quality, Time, and the Quality, Time, and the Theory of ConstraintsTheory of Constraints

Chapter 19Chapter 19

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IntroductionIntroduction

To satisfy their customers and to be To satisfy their customers and to be competitive, managers need to find cost-competitive, managers need to find cost-effective ways to continuously improve effective ways to continuously improve the quality of their products and to shorten the quality of their products and to shorten delivery time.delivery time.

This chapter describes how managers This chapter describes how managers streamline processes to improve quality streamline processes to improve quality and reduce delays.and reduce delays.

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Two Aspects of QualityTwo Aspects of Quality

1 Quality of design Quality of design measures how closely the measures how closely the characteristics of products or services meet characteristics of products or services meet the needs and wants of customers.the needs and wants of customers.

2 Conformance quality Conformance quality refers to the performance refers to the performance of a product or service according to design and of a product or service according to design and product specifications.product specifications.

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Two Aspects of QualityTwo Aspects of Quality

Actual Actual PerformancePerformance

Design Design SpecificationsSpecifications

Customer Customer SatisfactionSatisfaction

Quality Quality of Design of Design

FailureFailure

Conformance Conformance Quality Quality

FailureFailure

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Costs of QualityCosts of Quality

The The costs of quality costs of quality (COQ) refer to costs (COQ) refer to costs incurred to prevent, or costs arising as a result incurred to prevent, or costs arising as a result of, the production of a low-quality product.of, the production of a low-quality product.

These costs focus on conformance quality and These costs focus on conformance quality and are incurred in all business functions of the are incurred in all business functions of the value chain.value chain.

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1 Prevention costsPrevention costs--costs incurred in precluding --costs incurred in precluding the production of products that do not the production of products that do not conform to specifications.conform to specifications.

2 Appraisal costsAppraisal costs--costs incurred in detecting --costs incurred in detecting which of the individual units of products do which of the individual units of products do not conform to specifications.not conform to specifications.

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3 Internal failure costsInternal failure costs--costs incurred by a --costs incurred by a nonconforming product detected before it is nonconforming product detected before it is shipped to customers.shipped to customers.

4 External failure costsExternal failure costs--costs incurred by a --costs incurred by a nonconforming product detected after it is nonconforming product detected after it is shipped to customers.shipped to customers.

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Peoria Photo Corporation made 10,000 Peoria Photo Corporation made 10,000 photocopying machines in the year 2000.photocopying machines in the year 2000.

Peoria Photo determines the costs of quality Peoria Photo determines the costs of quality of its photocopying machines using a 7-step of its photocopying machines using a 7-step activity-based costing approach.activity-based costing approach.

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Costs of Quality (Steps 1 and 2)Costs of Quality (Steps 1 and 2)

Step 1Step 1: Identify the chosen cost object(s).: Identify the chosen cost object(s). The cost object is the 10,000 photocopying The cost object is the 10,000 photocopying

machines that Peoria Photo makes.machines that Peoria Photo makes. Step 2Step 2: Identify the direct costs of quality of : Identify the direct costs of quality of

the product. the product. The photocopying machines have no direct The photocopying machines have no direct

costs of quality.costs of quality.

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Costs of Quality (Step 3)Costs of Quality (Step 3)

Step 3Step 3: Select the cost-allocation bases to use : Select the cost-allocation bases to use for allocating indirect costs of quality for allocating indirect costs of quality to the to the product.product.

Peoria Photo classifies activities that result in Peoria Photo classifies activities that result in prevention, appraisal, internal failure, and external prevention, appraisal, internal failure, and external failure costs.failure costs.

(Information on the total quantities of each of these (Information on the total quantities of each of these cost-allocation bases used in all of Peoria’s operations cost-allocation bases used in all of Peoria’s operations is not provided.)is not provided.)

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Step 4Step 4: Identify the indirect costs of quality : Identify the indirect costs of quality associated with each cost-allocation associated with each cost-allocation base. base.

These are the These are the total costs total costs (fixed and variable) (fixed and variable) incurred on each of the costs of quality incurred on each of the costs of quality activities.activities.

(Information about these total costs is not (Information about these total costs is not provided.)provided.)

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Step 5Step 5: Compute the rate per unit of each : Compute the rate per unit of each cost-allocation base used to allocate cost-allocation base used to allocate indirect costs of quality to products. indirect costs of quality to products.

For each activity, the total costs calculated For each activity, the total costs calculated in Step 4 is divided by the total quantity of in Step 4 is divided by the total quantity of the cost-allocation base calculated in Step 3 the cost-allocation base calculated in Step 3 to compute the rate per unit for each cost-to compute the rate per unit for each cost-allocation base.allocation base.

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Peoria Photo chooses the number of inspection Peoria Photo chooses the number of inspection hours as the cost-allocation base for the hours as the cost-allocation base for the inspection activity in all of Peoria’s inspection activity in all of Peoria’s operations.operations.

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Cost of Quality and Cost of Quality and Value Value Chain CategoryChain Category Rate (Assumed) Rate (Assumed) Prevention costs:Prevention costs: Design engineering (R&D)Design engineering (R&D) $ 80 per hour $ 80 per hour Process engineering (R&D) Process engineering (R&D) $ 60 per $ 60 per hour hour Appraisal costs:Appraisal costs: Inspection (Manufacturing)Inspection (Manufacturing) $ 40 per $ 40 per hour hour Internal failure costs: Internal failure costs: Rework (Manufacturing)Rework (Manufacturing) $100 per hour$100 per hour

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Cost of Quality and Cost of Quality and Value Chain CategoryValue Chain Category Rate Rate (Assumed)(Assumed) External failure costs: External failure costs: Customer support (Marketing)Customer support (Marketing) $ 50 $ 50 per hour Transportation (Distribution)per hour Transportation (Distribution) $240 $240 per load Warranty repair per load Warranty repair (Customer Service) (Customer Service) $110 per $110 per hourhour

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Step 6Step 6: : Compute the indirect costs of quality Compute the indirect costs of quality allocated to the product. allocated to the product.

Peoria Photo first determines the quantities Peoria Photo first determines the quantities of each of the cost-allocation bases used by of each of the cost-allocation bases used by the photocopying machines.the photocopying machines.

This amount is multiplied by the cost-This amount is multiplied by the cost-allocation rate calculated in Step 5.allocation rate calculated in Step 5.

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Cost of Quality and Cost of Quality and Value Value Chain CategoryChain Category QuantityQuantity Prevention costsPrevention costs: : Design Design engineering (R&D)engineering (R&D) 20,000 hours 20,000 hours Process engineering (R&D) Process engineering (R&D) 22,500 hours 22,500 hours Appraisal costs:Appraisal costs: Inspection (Manufacturing)Inspection (Manufacturing) 120,000 hours 120,000 hours Internal Internal failure costs: failure costs: Rework Rework (Manufacturing)(Manufacturing) 50,000 hours 50,000 hours

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Cost of Quality and Cost of Quality and Value Chain CategoryValue Chain Category QuantityQuantity External failure costs: External failure costs: Customer support (Marketing)Customer support (Marketing) 6,000 hours 6,000 hours Transportation (Distribution)Transportation (Distribution) 1,500 loads 1,500 loads Warranty repair Warranty repair (Customer Service)(Customer Service) 60,000 hours60,000 hours

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What is the total cost for design engineering?What is the total cost for design engineering? 20,000 hours × $80 = $1,600,00020,000 hours × $80 = $1,600,000 What is the total cost for inspection? What is the total cost for inspection? 120,000 hours × $40 = $4,800,000120,000 hours × $40 = $4,800,000

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Cost of Quality and Cost of Quality and Value Chain CategoryValue Chain Category Total Costs Total Costs Prevention costs:Prevention costs: Design engineering (R&D)Design engineering (R&D) $1,600,000 $1,600,000 Process engineering (R&D) Process engineering (R&D) 1,350,000 1,350,000 Total Total $2,950,000 $2,950,000 Appraisal costs:Appraisal costs: InspectionInspection $4,800,000$4,800,000 TotalTotal $4,800,000$4,800,000

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Cost of Quality and Cost of Quality and Value Chain CategoryValue Chain Category Total CostsTotal Costs Internal failure costs: Internal failure costs: Rework (Manufacturing)Rework (Manufacturing) $5,000,000 $5,000,000 TotalTotal $5,000,000$5,000,000

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Cost of Quality and Cost of Quality and Value Chain CategoryValue Chain Category Total CostsTotal Costs External failure costs: External failure costs: Customer support (Marketing)Customer support (Marketing) $ 300,000 $ 300,000 Transportation (Distribution)Transportation (Distribution) 360,000 360,000 Warranty repair Warranty repair (Customer Service)(Customer Service) 6,600,000 6,600,000 Total Total $7,260,000$7,260,000

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Step 7Step 7: Compute the total costs of quality of : Compute the total costs of quality of the the product by adding all direct and indirect costs of product by adding all direct and indirect costs of quality assigned to it.quality assigned to it.

What are the total costs of quality?What are the total costs of quality?Prevention costsPrevention costs $ 2,950,000 $ 2,950,000

Appraisal costsAppraisal costs 4,800,000 4,800,000 Internal failure costsInternal failure costs 5,000,000 5,000,000

External failure costsExternal failure costs 7,260,000 7,260,000 TotalTotal $20,010,000$20,010,000

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Techniques Used to Analyze Techniques Used to Analyze Quality ProblemsQuality Problems

Three methods that companies use to identify Three methods that companies use to identify quality problems and to improve quality are:quality problems and to improve quality are:

1 Control chartsControl charts2 Pareto diagramsPareto diagrams3 Cause-and-effect diagramsCause-and-effect diagrams

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Control ChartsControl Charts

Statistical quality control (SQC), or statistical Statistical quality control (SQC), or statistical process control (SPC), is a formal means of process control (SPC), is a formal means of distinguishing between random variation and distinguishing between random variation and nonrandom variation in an operating process.nonrandom variation in an operating process.

A control chart is a graph of a series of A control chart is a graph of a series of successive observations of a particular step, successive observations of a particular step, procedure, or operation taken at regular procedure, or operation taken at regular intervals of time.intervals of time.

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Each observation is plotted relative to Each observation is plotted relative to specified ranges that represent the expected specified ranges that represent the expected statistical distribution.statistical distribution.

Only those observations outside the control Only those observations outside the control limits are ordinarily regarded as nonrandom limits are ordinarily regarded as nonrandom and worth investigating.and worth investigating.

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On the basis of experience, Peoria decides On the basis of experience, Peoria decides that any observation outside the arithmetic that any observation outside the arithmetic mean mean ± 2 ± 2 standard deviations should be standard deviations should be investigated.investigated.

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1 2 3 4 5 6 7 8 9 101 2 3 4 5 6 7 8 9 10

DaysDays

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For the production line, the last two For the production line, the last two observations signal that an out-of-control observations signal that an out-of-control occurrence is highly likely.occurrence is highly likely.

Given the ± 2Given the ± 2from the mean rule, both from the mean rule, both observations would lead to an investigation.observations would lead to an investigation.

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Pareto DiagramPareto Diagram

Observations outside control limits serve as Observations outside control limits serve as inputs to Pareto diagrams.inputs to Pareto diagrams.

A Pareto diagram indicates how frequently A Pareto diagram indicates how frequently each type of failure (defect) occurs.each type of failure (defect) occurs.

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Pareto DiagramPareto Diagram

Copies are Copies are fuzzy and fuzzy and unclearunclear

Copies are Copies are too too

light/darklight/darkPaper gets Paper gets

jammedjammed

Num

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N

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Def

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Def

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500

200

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Cause-and-effect DiagramsCause-and-effect Diagrams

The most frequently recurring and costly The most frequently recurring and costly problems identified by the Pareto diagram problems identified by the Pareto diagram are analyzed using cause-and-effect diagrams.are analyzed using cause-and-effect diagrams.

A cause-and-effect diagram identifies potential A cause-and-effect diagram identifies potential causes of failures or defects.causes of failures or defects.

As a first step, Peoria analyzes the causes of As a first step, Peoria analyzes the causes of the most frequently occurring failure, fuzzy the most frequently occurring failure, fuzzy and unclear copies.and unclear copies.

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Peoria identifies four major categories of Peoria identifies four major categories of potential causes of failure:potential causes of failure:

1 Human factorsHuman factors2 Methods and design factorsMethods and design factors3 Machine-related factorsMachine-related factors4 Materials and components factorsMaterials and components factors

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Methods andMethods anddesign factorsdesign factors

Human factorsHuman factors

Machine-relatedMachine-related factorsfactors

Materials and Materials and components factorscomponents factors

Multiple suppliersMultiple suppliers

New operatorNew operator Flawed part designFlawed part design

Poor maintenancePoor maintenance

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Relevant CostsRelevant Costs

Careful analysis of Peoria’s cause-and-effect Careful analysis of Peoria’s cause-and-effect diagram reveals that the frame of the copier diagram reveals that the frame of the copier is often mishandled as it travels from the is often mishandled as it travels from the suppliers’ warehouses to Peoria’s plant.suppliers’ warehouses to Peoria’s plant.

Mishandling causes the dimensions of the Mishandling causes the dimensions of the frame to vary from specifications, resulting in frame to vary from specifications, resulting in fuzzy and unclear copies.fuzzy and unclear copies.

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The team of engineers working to solve this The team of engineers working to solve this problem offers two alternative solutions:problem offers two alternative solutions:

1 Improve the inspection of the frames Improve the inspection of the frames immediately upon delivery.immediately upon delivery.

2 Redesign and strengthen the frames and the Redesign and strengthen the frames and the containers used to transport them to better containers used to transport them to better withstand mishandling during transportation.withstand mishandling during transportation.

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What must management do to evaluate each What must management do to evaluate each alternative?alternative?

Measure the total relevant costs and total Measure the total relevant costs and total relevant revenues. relevant revenues.

Additional Additional Additional Additional Inspection Cost Inspection Cost Redesign CostRedesign Cost DifferenceDifference

$200,000 $230,000 $30,000$200,000 $230,000 $30,000 Peoria determines the fixed and variable cost Peoria determines the fixed and variable cost

component of each activity involved.component of each activity involved.

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Variable AllocatedVariable Allocated CostsCosts Fixed CostsFixed Costs TotalTotal

Rework-hourRework-hour$ 40$ 40 $60$60 $100$100Customer-support-hrCustomer-support-hr $ 20$ 20 $30$30 $ 50$ 50Transportation/loadTransportation/load $180$180 $60$60 $240$240Warranty/repair hourWarranty/repair hour $ 45$ 45 $65$65 $110$110

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Only variable costs are relevant because Only variable costs are relevant because fixed costs are not affected.fixed costs are not affected.

Before making a decision, management Before making a decision, management must compare the incremental costs of must compare the incremental costs of each alternative against the corresponding each alternative against the corresponding incremental benefit.incremental benefit.

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Relevant BenefitsRelevant Benefits

Further Redesigning Further Redesigning InspectionInspection FramesFrames

Savings in rework costs: Savings in rework costs: $40 × 12,000 $480,000 $40 × 12,000 $480,000

$40 × 16,000 $640,000$40 × 16,000 $640,000 Savings in customer- support costs:Savings in customer- support costs: $20 × 1,000 $20,000 $20 × 1,000 $20,000 $20 × 1,400 $28,000$20 × 1,400 $28,000

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Further Redesigning Further Redesigning InspectionInspection Frames Frames

Savings in transportation costs for repair parts: Savings in transportation costs for repair parts: $180 × 250 $45,000 $180 × 250 $45,000

$180 × 350 $63,000$180 × 350 $63,000

Savings in warranty repair costs: Savings in warranty repair costs: $45 × 10,000 $450,000 $45 × 10,000 $450,000 $45 × 14,000 $630,000$45 × 14,000 $630,000

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Further Redesigning Further Redesigning InspectionInspection Frames Frames Relevant savings: Relevant savings: Rework costs Rework costs $480,000$480,000 $ $ 640,000 Customer-support costs 640,000 Customer-support costs 20,000 20,000 28,000 Transportation costs28,000 Transportation costs 45,000 45,000 63,000 63,000 Warranty repair costsWarranty repair costs 450,000 450,000 630,000 630,000 Total Total$995,000$995,000 $1,361,000$1,361,000

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ComparisonComparison

Further Redesigning Further Redesigning InspectionInspection Frames Frames Relevant Relevant savingssavings $995,000$995,000 $1,361,000 Additional $1,361,000 Additional costcost 200,000 200,000 230,000 230,000 Difference Difference$795,000$795,000 $1,131,000 $1,131,000

What should Peoria do?What should Peoria do? Redesigning the frames provides a $336,000 Redesigning the frames provides a $336,000

incremental benefit over further inspection.incremental benefit over further inspection.

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Nonfinancial MeasuresNonfinancial Measures

Nonfinancial measures can be categorized into:Nonfinancial measures can be categorized into:– Nonfinancial measures of customer-satisfactionNonfinancial measures of customer-satisfaction– Nonfinancial measures of internal performanceNonfinancial measures of internal performance

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Nonfinancial measures of customer satisfaction Nonfinancial measures of customer satisfaction include:include:

– Number of customer complaintsNumber of customer complaints– Defective units as a percentage of total units Defective units as a percentage of total units

shipped to customersshipped to customers– Percentage of products that experience early or Percentage of products that experience early or

excessive failureexcessive failure– On-time delivery rateOn-time delivery rate

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Nonfinancial measures of internal performance Nonfinancial measures of internal performance include:include:

– Number of defects for each product lineNumber of defects for each product line– Process yield (ratio of good output to total Process yield (ratio of good output to total

output)output)– Employee turnover (ratio of the number of Employee turnover (ratio of the number of

employees who left the company to the total employees who left the company to the total number of employees)number of employees)

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Evaluating Quality PerformanceEvaluating Quality Performance

Measuring the financial costs of quality and the Measuring the financial costs of quality and the nonfinancial aspects of quality have distinctly nonfinancial aspects of quality have distinctly different advantages.different advantages.

Financial measures are helpful to evaluate Financial measures are helpful to evaluate trade-offs among prevention costs, appraisal trade-offs among prevention costs, appraisal costs, and failure costs.costs, and failure costs.

They focus attention on the costs of poor They focus attention on the costs of poor quality.quality.

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Advantages of COQ measures:Advantages of COQ measures:– Consistent with the attention directing role of Consistent with the attention directing role of

management accounting, COQ focuses management accounting, COQ focuses attention on how costly poor quality can be.attention on how costly poor quality can be.

– Financial COQ measures assist in problem Financial COQ measures assist in problem solving by comparing different quality-solving by comparing different quality-improvement programs and setting priorities for improvement programs and setting priorities for achieving maximum cost reduction.achieving maximum cost reduction.

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– COQ provides a single, summary measure COQ provides a single, summary measure of quality performance.of quality performance.

Nonfinancial measures help focus attention Nonfinancial measures help focus attention on the precise problem areas that need on the precise problem areas that need improvement and also serve as indicators improvement and also serve as indicators of future long-run performance.of future long-run performance.

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Advantages of nonfinancial measures of Advantages of nonfinancial measures of quality:quality:

– Nonfinancial measures of quality are often easy Nonfinancial measures of quality are often easy to quantify and understand.to quantify and understand.

– Nonfinancial measures direct attention to Nonfinancial measures direct attention to physical processes and hence focus attention on physical processes and hence focus attention on the precise problem areas that need the precise problem areas that need improvement.improvement.

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– Nonfinancial measures provide immediate Nonfinancial measures provide immediate short-run feedback on whether quality short-run feedback on whether quality improvement efforts have, in fact, succeeded improvement efforts have, in fact, succeeded in improving quality.in improving quality.

– Nonfinancial measures are useful indicators Nonfinancial measures are useful indicators of future long-run performance.of future long-run performance.

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Time as a Competitive WeaponTime as a Competitive Weapon

Companies need to measure time in order to Companies need to measure time in order to manage it properly.manage it properly.

Two common operational measures of time Two common operational measures of time are:are:

1 Customer-response timeCustomer-response time2 On-time performanceOn-time performance

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Customer-Response TimeCustomer-Response Time

Customer-response time is the amount of time from Customer-response time is the amount of time from when a customer places an order for a product or when a customer places an order for a product or requests service to when the product or service is requests service to when the product or service is delivered to the customer.delivered to the customer.

The following are different components of customer-The following are different components of customer-response time:response time:

Receipt time Receipt time is the time it takes a Marketing is the time it takes a Marketing Department to specify a customer’s exact Department to specify a customer’s exact requirements to manufacturing.requirements to manufacturing.

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Customer-Response TimeCustomer-Response Time

Manufacturing lead time Manufacturing lead time is the amount of is the amount of time from when an order is ready to start on time from when an order is ready to start on the production line to when it becomes a the production line to when it becomes a finished good.finished good.

Delivery time Delivery time is the time it takes to deliver a is the time it takes to deliver a completed order to the customer.completed order to the customer.

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On-Time PerformanceOn-Time Performance

On-time performance refers to situations in On-time performance refers to situations in which the product or service is actually which the product or service is actually delivered at the time it is scheduled to be delivered at the time it is scheduled to be delivered.delivered.

On-time performance is an important element On-time performance is an important element of customer satisfaction because customers of customer satisfaction because customers want and expect on-time deliveries.want and expect on-time deliveries.

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Time Drivers and Costs of TimeTime Drivers and Costs of Time

A A time driver time driver is any factor where change in is any factor where change in the factor causes a change in the speed with the factor causes a change in the speed with which an activity is undertaken.which an activity is undertaken.

Managing customer-response time and on-time Managing customer-response time and on-time performance requires an understanding of the performance requires an understanding of the causes of delays and the resulting costs.causes of delays and the resulting costs.

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Two important drivers of time are:Two important drivers of time are:1 Uncertainty Uncertainty 2 Limited capacity and bottlenecksLimited capacity and bottlenecks The following are different components of The following are different components of

customer-response time:customer-response time: Receipt time Receipt time is the time it takes a Marketing is the time it takes a Marketing

Department to specify a customer’s exact Department to specify a customer’s exact requirements to manufacturing.requirements to manufacturing.

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Average waiting time Average waiting time is the average amount is the average amount of time that an order will wait in line before of time that an order will wait in line before it is set up and processed.it is set up and processed.

Average waiting time Average waiting time = = Average number of Average number of orders × (Manufacturing time)² orders × (Manufacturing time)² DividedDivided byby 2 × [Annual 2 × [Annual machine capacity – (Average number of machine capacity – (Average number of orders × Manufacturing time)]orders × Manufacturing time)]

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The longer the manufacturing time, the greater The longer the manufacturing time, the greater the chance that the machine will be in use the chance that the machine will be in use when an order arrives, and the longer the when an order arrives, and the longer the delays.delays.

The denominator in this formula measures The denominator in this formula measures unused capacity, or cushion.unused capacity, or cushion.

The smaller the unused capacity, the greater the The smaller the unused capacity, the greater the delays.delays.

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Theory of ConstraintsTheory of Constraints

The three main measurements in the theory of The three main measurements in the theory of constraints are:constraints are:

1 Throughput contribution Throughput contribution equal to revenues equal to revenues minus direct material costs.minus direct material costs.

2 InvestmentsInvestments equal the sum of material costs in equal the sum of material costs in direct materials inventory, work-in-process direct materials inventory, work-in-process inventory, finished goods inventory, R&D inventory, finished goods inventory, R&D costs, and costs of equipment and buildings.costs, and costs of equipment and buildings.

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3 Operating costs Operating costs equal to all operating costs equal to all operating costs (other than direct materials) incurred to earn (other than direct materials) incurred to earn throughput contribution.throughput contribution.

The objective of TOC is to increase throughput The objective of TOC is to increase throughput contribution while decreasing investments and contribution while decreasing investments and operating costs.operating costs.

TOC considers a short-run time horizon and TOC considers a short-run time horizon and assumes operating costs to be fixed costs.assumes operating costs to be fixed costs.

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The theory of constraints emphasizes the The theory of constraints emphasizes the management of bottlenecks as the key to management of bottlenecks as the key to improving the performance of the production improving the performance of the production system as a whole.system as a whole.

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Managing BottlenecksManaging Bottlenecks

The four steps in managing bottlenecks are:The four steps in managing bottlenecks are:1 Recognize that the bottleneck operation Recognize that the bottleneck operation

determines throughput contribution of the determines throughput contribution of the system as a whole.system as a whole.

2 Search and find the bottleneck operation by Search and find the bottleneck operation by identifying operations with large quantities identifying operations with large quantities of inventory waiting to be worked on.of inventory waiting to be worked on.

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Managing BottlenecksManaging Bottlenecks

3 Keep the bottleneck busy and subordinate all Keep the bottleneck busy and subordinate all nonbottleneck operations to the bottleneck nonbottleneck operations to the bottleneck operations. operations.

4 Take actions to increase bottleneck efficiency Take actions to increase bottleneck efficiency and capacity – the objective is to increase and capacity – the objective is to increase throughput contribution minus the incremental throughput contribution minus the incremental costs of taking such actions.costs of taking such actions.

Process Management - Quality, Time and the Theory of Constraints - Pareto Presentation

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