Worked example 03 · Machine shops & fabrication

Machines are busy.
Orders are still waiting.

More output upstream can make the delivery problem worse when the shared inspection resource is overloaded.

$28,512

Potential net savings / year
After recurring control costs.

Research-based composite. Business figures, savings and risk ratings are modeled assumptions. Proposed controls have not been validated with a business.

The bottleneck

Where the work gets stuck.

The scenario's proposed constraint is qualified inspection time, partly consumed by avoidable handling and missing information. Scheduling machines without reserving inspection capacity pushes work into a queue that cannot clear at the required rate. Inspection must be measured in minutes and qualification needs, not just pieces.

The proposed improvement

Change how the work moves.

Schedule qualified inspection capacity, release ready lots and control priority changes.

900 to 792Inspection demand minutes / day · modeled

840Available inspection minutes / day · modeled

Read the business situation

The shop releases work to keep machines busy. Lots visit inspection between operations, but inspection is loaded by piece count instead of required minutes. Hot jobs interrupt the queue. Inspectors repeatedly find drawings, fixtures or paperwork missing. Machining utilization looks healthy while finished orders wait and premium freight becomes routine.

42 employees, multiple machining routes and two qualified inspectors sharing a central inspection queue. All quantities are scenario assumptions.

Follow the work.

Proposed workflow: make the next action and responsibility explicit.

01Check full routingMinutes + skills + materials

02Reserve constraintInspectors + equipment

03Release ready lotsBound queue by hours

04Inspect to planProtect blocking checks

05Ship + learnReview actual minutes

What needs to change

Finite inspection loadingAdd planned minutes and qualification needs to routes. Separate first-article, in-process and final checks. Include gauge and CMM availability.

Ready-for-inspection gateRequire approved drawing, traveler, program, fixture and material trace before a lot enters the ready queue. Missing items stay on a visible hold list.

Controlled release and prioritiesInitially cap ready-queue load at one day of qualified inspection hours. Review actual variability before fixing a permanent limit. Authorize exceptions through one scheduler.

Remove handling waste, preserve checksReduce assumed handling/search time from 14 to 8 minutes per equivalent lot while retaining 36 minutes of technical inspection. No acceptance criterion or sampling requirement is relaxed.

How to verify the bottleneck

Hypothesis	Evidence to inspect	Proposed test
Inspection is truly overloaded	Measure arrivals, service time and available qualified minutes.	Ten days of lot-level receipt and release timestamps.
Priority churn consumes capacity	Record queue changes, interrupted checks and restart time.	Observe two inspection shifts with reason codes.
The constraint is elsewhere	Track programming, gauging, deburr and outside-process queues.	Compare queue growth and starvation across routes.
Paperwork creates hidden work	Separate actual inspection from search, handling and correction.	Time study 20 representative lots by inspection class.

The capacity calculation

Measure	Calculation	Modeled implication
Available qualified capacity	2 inspectors x 7 productive hours x 60	840 minutes/day
Baseline demand	18 equivalent lots x 50 minutes	900 minutes/day
Target demand	18 equivalent lots x 44 minutes	792 minutes/day
Capacity check	Baseline 107.1%; target 94.3% loaded	48 target minutes/day average buffer

Example: inspection dispatch queue

Lot / inspection class	Minutes + readiness	Scheduling action
L-241 / first article	60 min; gauge + drawing ready	Next qualified slot; blocks machining
L-242 / final inspection	40 min; pack ready	Reserve before Thursday ship cutoff
L-243 / in-process	55 min; program missing	HOLD; engineering resolves by noon

The implementation plan

Days 1-10Scheduler + quality

Time 20 lots; map qualification and equipment availability.

Evidence: Measured handling vs inspection minutes; true constraint confirmed.

Days 11-20Scheduler + shop lead

Pilot minute-based queue and ready-lot release on one route.

Evidence: No required quality checks removed; actual minutes captured.

Days 21-30Quality + operations

Trial backup coverage and exception priority review.

Evidence: Backup demonstrates agreed check scope; no hidden queue.

Days 31-60Analyst + scheduler

Compare queue age, freight, overtime and shipped output.

Evidence: At least four comparable pilot weeks and stable quality.

What to measure

Measure	Definition	Target	Owner / review
Inspection load	Planned required minutes / available qualified minutes	107.1% to 94.3% average	Scheduler / daily
Queue age	Median and 90th-percentile wait to qualified inspection	Reduce from measured baseline	Quality / daily
Overtime	Paid inspection overtime hours per week	14 to 6	Payroll / weekly
Quality guardrail	Required checks complete; first-pass and escape measures	No degradation	Quality / every release

How to validate the result

Verify the constraint with actual queue growth and qualified-minute demand before changing release rules. Compare equivalent inspection classes and mix. The 94.3% average load still leaves little variability buffer; size the buffer from measured peaks and keep service targets provisional.

Show the financial effect.

This models avoidable operating expenditure. Time released without a reduced payment is reported separately as capacity.

Financial line	USD
Overtime avoided	$24,192
Premium freight avoided	$6,720
Gross annual benefit	$30,912
Recurring annual scheduling cost	$2,400
Annual net run rate	$28,512
First-year net benefit	$14,760

What if the improvement is smaller?

Adjust the share of the modeled improvement achieved. Control and setup costs stay the same.

Modeled improvement achieved100%

ANNUAL NET ESTIMATE$28,512FIRST YEAR AFTER SETUP$14,760

First year: 10 benefit months, less the full setup allowance. Results are illustrative, not a guarantee.

Equivalent lots are a simplified capacity unit, not an assumption that every part takes the same time. The live plan must use actual inspection demand. Savings require maintained inspection quality and comparable shipped output.

Baseline inputs and calculations

These inputs describe the 100% modeled case. The slider changes the share of the proposed improvement achieved.

Illustrative assumption	Value	Units
Inspection overtime before	14	hours/week
Inspection overtime after	6	hours/week
Avoidable overtime cost	63	USD/hour
Operating weeks	48	weeks/year
Premium shipments before	8	per month
Premium shipments after	4	per month
Premium per shipment	140	USD/shipment
Calendar months	12	months/year
Recurring scheduling cost	200	USD/month
One-time implementation allowance	9,000	USD
Benefit months in first year	10	months

Overtime avoided: (14 - 6) x $63 x 48

Premium freight avoided: (8 - 4) x $140 x 12

Gross annual benefit: Payroll + freight premiums

Recurring annual scheduling cost: $200 x 12

Annual net run rate: Gross benefit less recurring cost

First-year net benefit: Annual net x 10/12 - $9,000

What is included and excluded

No avoided machine purchase, extra sales, fixed wage reduction or inventory release is included. The 108 inspection minutes/day released equal nine hours/week; only eight hours/week are assumed to replace paid overtime. The remaining hour is not monetized.

Some recovery costs may also appear in overtime and freight savings. Use this as a separate resilience illustration and do not combine it with annual operating benefits.

Make each risk actionable.

Eight modeled risks. Assessment horizon: one 12-week delivery program.

1Critical5High2Moderate0Low

Current ratings are scenario assumptions. Select a risk to see its mitigation, owner and response.

01CapacityInspection demand exceeds qualified minutes, increasing queues and late orders.20 · Critical

The risk: Inspection demand exceeds qualified minutes, increasing queues and late orders.

Existing control · assumed: Machine schedule has no inspection-minute load.

Proposed mitigation: Load work in inspection minutes; reserve qualified resources and control release.

Owner & timing: Production scheduler
Day 14 from pilot start.

Warning trigger: Three days of planned demand exceed available qualified minutes.

Contingency: Reprioritize committed work; evaluate qualified external capacity.

How to verify: Capacity load, actual queue age and release performance.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L5 × I4 = 20. Target: L3 × I4 = 12.

02Quality Specialist reviewPressure to clear the queue causes skipped checks or invalid sampling.10 · Moderate

The risk: Pressure to clear the queue causes skipped checks or invalid sampling.

Existing control · assumed: Quality procedure exists but schedule pressure is informal.

Proposed mitigation: Quality lead retains acceptance authority; protect required inspection scope.

Owner & timing: Quality manager
Before pilot.

Warning trigger: Any request to bypass a required check to ship.

Contingency: Hold affected lot; apply approved containment and escalation.

How to verify: Inspection record and independent quality release.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L2 × I5 = 10. Target: L1 × I5 = 5. Impact 5 requires specialist review regardless of total score.

03ContinuityInspector absence removes a critical qualification and blocks delivery.12 · High

The risk: Inspector absence removes a critical qualification and blocks delivery.

Existing control · assumed: Two inspectors with incomplete backup coverage.

Proposed mitigation: Qualify backup for defined checks; approve external lab route and lead time.

Owner & timing: Quality manager
Day 30 from pilot start.

Warning trigger: No qualified cover for a scheduled critical check.

Contingency: Resequence independent work and use approved inspection provider.

How to verify: Skills matrix, witnessed qualification and backup trial.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L3 × I4 = 12. Target: L3 × I3 = 9.

04MeasurementUnderstated inspection times create an infeasible plan.12 · High

The risk: Understated inspection times create an infeasible plan.

Existing control · assumed: Minutes estimated by piece count.

Proposed mitigation: Estimate by inspection class, features and sample needs; compare planned to actual.

Owner & timing: Manufacturing engineer
Day 14 from pilot start.

Warning trigger: Actual time exceeds planned time by over 20% on five lots.

Contingency: Revise standards and promise dates; retain variance evidence.

How to verify: Time study and route standard revisions.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L4 × I3 = 12. Target: L2 × I3 = 6.

05PrioritiesSales expedites continually override the queue and displace commitments.12 · High

The risk: Sales expedites continually override the queue and displace commitments.

Existing control · assumed: Any supervisor can label work urgent.

Proposed mitigation: One scheduler approves expedites with displaced-job and capacity effects shown.

Owner & timing: Operations manager
Day 10 from pilot start.

Warning trigger: More than two unplanned priority changes per day.

Contingency: Freeze nonessential releases; renegotiate affected priorities.

How to verify: Expedite log with reason and affected commitments.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L4 × I3 = 12. Target: L2 × I3 = 6.

06EquipmentA gauge or CMM outage eliminates the assumed inspection capacity.12 · High

The risk: A gauge or CMM outage eliminates the assumed inspection capacity.

Existing control · assumed: Calibration dates tracked apart from schedule.

Proposed mitigation: Link calibration and maintenance to available-capacity calendar; identify alternate equipment.

Owner & timing: Metrology lead
Day 21 from pilot start.

Warning trigger: Calibration or equipment outage conflicts with a reserved slot.

Contingency: Hold affected characteristic checks; use approved alternate resource.

How to verify: Capacity calendar and alternate-method approval.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L3 × I4 = 12. Target: L2 × I4 = 8.

07FlowLarge batches improve setup efficiency but delay urgent downstream assembly.9 · Moderate

The risk: Large batches improve setup efficiency but delay urgent downstream assembly.

Existing control · assumed: Lots grouped informally.

Proposed mitigation: Group only within due-date and assembly needs; define authorized transfer batches.

Owner & timing: Production scheduler
Day 21 from pilot start.

Warning trigger: Assembly is blocked while a large lot waits for full completion.

Contingency: Split approved transfer batch without losing traceability.

How to verify: Transfer-batch record and assembly-ready timestamp.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L3 × I3 = 9. Target: L2 × I3 = 6.

08AdoptionOperators start unreleased work to keep machines busy, flooding the queue.12 · High

The risk: Operators start unreleased work to keep machines busy, flooding the queue.

Existing control · assumed: Local utilization drives behavior.

Proposed mitigation: Show ready, held and released work; review total delivery and queue age.

Owner & timing: Shop supervisor
Day 14 from pilot start.

Warning trigger: Unreleased lot arrives or ready queue exceeds approved hour cap.

Contingency: Pause new releases; reconcile priorities with scheduler.

How to verify: Release authorization and queue-hour audit.

Review & status: Weekly during pilot.
Proposed; unvalidated.

Modeled current: L4 × I3 = 12. Target: L2 × I3 = 6.

View the risk map

Likelihood ↑

Impact increases →

Each number matches a risk in the register. Select an occupied cell to open a risk.

Higher likelihood and impact move a risk toward the top right. The Target view shows conditional ratings after the proposed controls.

Where several risks share a cell, it opens the first listed risk. All remain available in the register above.

What could one risk cost?

Inspection coverage is lost during a delivery-critical week.

Scenario	Probability × event loss	Expected loss
Before	25% × $40,000	$10,000
With proposed controls	25% × $16,000	$4,000
Expected-loss reduction	Before less after	$6,000
Separate mitigation cost	Over this risk horizon	$2,000
Net modeled risk benefit	Reduction less mitigation cost	$4,000

Absence likelihood is unchanged. Qualified backup and preapproved external inspection reduce assumed event impact from $40,000 to $16,000. Loss includes incremental recovery and customer concessions, not ordinary production payroll.

Some recovery costs may also appear in overtime and freight savings. Use this as a separate resilience illustration and do not combine it with annual operating benefits.

How the ratings work

Score = likelihood × impact, each rated from 1 to 5. Scores 1–5 are Low, 6–11 Moderate, 12–19 High and 20–25 Critical. These are scenario judgments over the stated assessment horizon.

Likelihood: 1 below 5%; 2 from 5% to below 20%; 3 from 20% to below 40%; 4 from 40% to below 70%; 5 at least 70%. Impact: 1 below $1,000; 2 below $5,000; 3 below $20,000; 4 below $75,000; 5 at least $75,000 or potentially severe safety consequences. Impact-5 safety or technical issues require specialist review regardless of score.

Research sources & assumptions

How do you do production planning/ scheduling in a job shop environment? ↗Reddit · r/Machinists contributorsIndexed post and comment excerpts. Different shops and job mixes; suggestions require local validation.
Production Scheduling: High Mix/Low Volume, Shared Resource Inspections ↗Reddit · r/manufacturing contributorsIndexed post and comment excerpts. Larger-shop account; our smaller-shop numbers are a separate composite model.
Don't Add a Machine, Fix Your Bottleneck ↗LinkedIn · Mike PaynePublic authored post opened. Practitioner opinion; third-party percentage claims in comments are excluded.
Dual-resource job-shop scheduling and sequence-dependent setups ↗LinkedIn · Sasan BarakPublic authored post opened. Summary of the author's research; this report does not reproduce its optimization results.

Public discussions informed the problem selection. LeanLine Advisory developed the composite scenario, diagnosis and proposed controls. All company profiles, financial inputs and risk ratings are illustrative assumptions. The sources do not establish an industry-wide ranking of these issues.

One bottleneck.
A measurable difference.

Find a problem that feels familiar.

The crew arrives.
The work is not ready.

The extra work is done.
The revenue is missing.