DP Johnson, 2005 Dealing with Production Bottlenecks Mini-case Be Sure To Review Notes Area And...

DP Johnson, 2005

Dealing with Production Bottlenecks Dealing with Production Bottlenecks

Mini-caseMini-case

Be Sure To Review Notes Area Be Sure To Review Notes Area And Related Word DocumentAnd Related Word Document

Forward to InstructorsForward to Instructors

DP Johnson, 2005

Dealing with Production Dealing with Production Bottlenecks Bottlenecks

Mini-caseMini-case

The concepts and approach applied in these examples The concepts and approach applied in these examples come from the book “The Goal” by Eli Goldratt. This book come from the book “The Goal” by Eli Goldratt. This book

is required reading for anyone interested in manufacturing, is required reading for anyone interested in manufacturing, production operations and productivity improvementproduction operations and productivity improvement

The GoalThe Goal Every system was built for a purposeEvery system was built for a purpose Must define the system’s global goalMust define the system’s global goal Actions of and decision about Actions of and decision about

subsystems must be judged on subsystems must be judged on impact towards the global goalimpact towards the global goal

From “The Goal” by Eli Goldratt

ConstraintsConstraints Anything that limits a system from Anything that limits a system from

achieving higher performance vs its achieving higher performance vs its goalgoal

Critical ConstraintCritical Constraint• The active constraintThe active constraint• The one that is currently limiting the The one that is currently limiting the

systemsystemFrom “The Goal” by Eli Goldratt

Flow and ConstraintsFlow and Constraints

200

225

220

400

500

250

300

500

350

250

250

250

250

300 600

#’s are MaximumProduction RatesIn Units/Hour


300

300

300

400

500

300

300

500

1000

350

275

275

275

250

300 600

50% / 50% Split

#’s are MaximumProduction RatesIn Units/Shift

Five StepsFive Steps Identify the System’s ConstraintsIdentify the System’s Constraints Decide how to exploit the system’s Decide how to exploit the system’s

constraintsconstraints Subordinate everything else to the Subordinate everything else to the

above decisionabove decision Elevate the system’s constraintsElevate the system’s constraints If in the previous steps a constraint If in the previous steps a constraint

has been broken, go back to step 1has been broken, go back to step 1


Identify the System’s ConstraintsIdentify the System’s Constraints

Prioritize by impact on the Prioritize by impact on the goal – otherwise too much goal – otherwise too much triviatrivia

Specifically identify the active Specifically identify the active constraintconstraint

Find a numeric capacity value Find a numeric capacity value if possibleif possible


Decide how to exploit the system’s Decide how to exploit the system’s constraintsconstraints

Find ways to maximize output of Find ways to maximize output of bottlenecks – aka active constraintsbottlenecks – aka active constraints

Find ways to offload and maximize Find ways to offload and maximize effectiveness of this resourceeffectiveness of this resource


Subordinate everything else to the Subordinate everything else to the above decisionabove decision

Priorities for Priorities for • __________________• __________________• __________________

Do you need to run other resources Do you need to run other resources at full capacity?at full capacity?

Elevate the system’s constraintsElevate the system’s constraints Can you…Can you…

• Increase the capacity of the bottleneck?Increase the capacity of the bottleneck? Speed up? Speed up? Add more available time?Add more available time? Reduce setup time and other downtime?Reduce setup time and other downtime?

• Cut the constraint resource out of some Cut the constraint resource out of some processes?processes?

• Use alternate resources?Use alternate resources?• Improve the effectivenessImprove the effectiveness

Inspection prior to bottleneck?Inspection prior to bottleneck?• Can we break the constraint?Can we break the constraint?

If in the previous steps a constraint If in the previous steps a constraint has been broken, go back to step 1has been broken, go back to step 1

Once you break the critical / active Once you break the critical / active constraint there will be a new oneconstraint there will be a new one

Find the new one and repeat the Find the new one and repeat the processprocess



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300 600

50/50 Split

ID ConstraintsID ConstraintsExploitExploitSubordinateSubordinateElevateElevateBreak/RepeatBreak/Repeat

What if demand is = 275 per shift?

#’s are MaximumProduction RatesIn Units/Shift

Multiple Product FlowsMultiple Product Flows

300

300

300

400

500

200

300

250

250

250

250

250

What if demand is…150 per hour of A 150 per hour of B

Flow for AFlow for B

#’s are MaximumProduction RatesIn Units/Hour

Assembly Product FlowsAssembly Product Flows

75

350

300

150

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175

55

175

What if demand for assemblies is 150 per shift

Flow for AFlow for B

Assembly Station

Combines part Aand part B into one assembly which is sold as a complete

product

Capacity:75 assemblies per shift

100 Production RatesIn Units/Shift

Cycle Time ExampleCycle Time Example

1.5 min/unit of D

1.5 min/unit of C

1.5 min/unit of D

What if demand is 150 assemblies per shift and

One shift has 410 available production minutes?

Flow for CFlow for D

Assembly Station

Combines part Cand part D into one assembly which is sold as a complete

product

Standard Time:3 min per assembly

2 Min/unit of C

1 min/unit of D

3 Min/unit of C

Machine 1

Machine 2

Machine 3Machine 4

Machine 5

Example 1

Bobco makes a product consisting of these 9 parts which are

manually assembled.There are 8 plastic parts and one turned metal part. A process flow

diagram is on the next page

Process MapCustomer Service

Production Control

Marketing

ForecastsOrders

Final Assembly

Distribution

Matl HdlFinished Goods

Plastic Molding

Orders

WIP - Assy

PartsCNC Turning

Raw Material

1 Part/Assy

8 Parts/Assy

Cutoff Saw

Raw Matl

Matl Hdl

Production SchedulesWarehouse

Deflash/Inspect

Process Standard Time/Part # of Machines(min) (qty)

Cutoff Saw 1.6 1CNC Turning 1.5 4Deflash/Inspect 1.5 18Plastic Molding 0.25 3Final Assembly 3 2

Example – Can you find the bottleneck if all departments run 40 hrs/week? - Can you meet a forecasted demand for 2000 units per week?

Bobco

Process MapCustomer Service

Production Control

Marketing

ForecastsOrders

Final Assembly

Distribution


Plastic Molding

Orders

WIP - Assy

PartsCNC Turning

Raw Material

1 Part/Assy

8 Parts/Assy

Cutoff Saw

Raw Matl

Matl Hdl


Deflash/Inspect

Process Standard Time/Part # of Machines(min) (qty)

Cutoff Saw 1.6 1CNC Turning 1.5 4Deflash/Inspect 1.5 18Plastic Molding 0.25 3Final Assembly 3 2

Example – Can you find the bottleneck if all departments run 40 hrs/week? - Can you meet a forecasted demand for 2000 units per week?

Bobco

FIND THE CAPACITY OF THE SYSTEM

Samco Mini-Case ProblemSamco Mini-Case Problem Samco makes three products

• A B and C. • The Three are very similar..

A • two metal and three plastic components• assembled manually

B• two metal and three plastic components• assembled manually

C• two metal and three plastic components• assembled manually

The process map and details are shown on the following pages

Parts for Product A

Parts for Product B

Parts for Product C

Process Map-TOC Project

Customer Service

Production Control

Marketing

Forecasts

Orders

AssemblyDistribution


Plastic Molding

Orders

WIP - Assy

Parts

CNC Turning

Raw Material

2 Parts/Unit

3 Parts/Unit

Cutoff Saw

Raw Matl

Matl Hdl


Deflash/Inspect

Pad Print

Skip

A B CForecasted Demand/Week 3900 2200 3100

Standard TimesProduct A Product B Product C Shifts Machine Availability Qty of Machines

(min) (min) (min) (#/day) (hrs/week/machine) (#)Cutoff Saw 1.60 1.60 1.60 2.00 77 7CNC Turn 1.50 2.00 3.00 1.00 37 12Deflash/Inspect 1.50 1.50 1.50 2.00 77 9Plastic Molding 0.25 0.25 0.25 2.00 77 9Pad Print 1.00 - 1.00 1.00 37 8Final Assembly 3.00 3.50 3.00 2.00 77 12

Samco

The production system is having problems. WIP is piling up all over the factory. Orders are going out late. Departments are requesting overtime to catch up, but even when overtime is authorized for all departments the situation does not improve. When overtime is authorized the backlogged orders are filled, but WIP seems to grow, adding to the confusion and congestion on the floor, which seems to generate additional request for overtime to catch up and clear out WIP and new late orders.

What can be done? The company has no money for capital investments (new equipment) but is willing to consider implementing recommendations that do not involve capital spending.


Customer Service

Production Control

Marketing

Forecasts

Orders



Plastic Molding

Orders

WIP - Assy

Parts

CNC Turning

Raw Material

2 Parts/Unit

3 Parts/Unit

Cutoff Saw

Raw Matl

Matl Hdl


Deflash/Inspect

Pad Print

Skip





Customer Service

Production Control

Marketing

Forecasts

Orders



Plastic Molding

Orders

WIP - Assy

Parts

CNC Turning

Raw Material

2 Parts/Unit

3 Parts/Unit

Cutoff Saw

Raw Matl

Matl Hdl


Deflash/Inspect

Pad Print

Skip




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