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Keep the assembly line ready for the next frame

Part readiness + synchronized flow + yamazumi. Follow the visual, practise a decision, then check your thinking.

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Fictional teaching examples and AI-generated illustrations. Proposed changes and goals are not achieved results. Use the written instructions and check local conditions before applying a method.

Teaching view 1 of 2

Refill the right component for the next frame

Material travels to an assembly point while refill information returns upstream; identity and finite storage remain visible. — AI-generated teaching illustration. Follow the steps below, then try the practice question. View full size ↗

The current case measures component search: twenty observations, 3.4-minute median, 1.5-minute goal. A replenishment loop connects consumption to the right refill and preserves identity. Make the signal, pack quantity, responsible person and full-lane response explicit. Level release to agreed customer demand and mix; do not schedule every upstream point independently. Search-time improvement alone cannot establish synchronized flow or line balance.

Follow the method

Use verified component
Expose replenishment signal
Send item + quantity information
Refill verified material
Confirm next-frame readiness

Read the example carefully

Retained component-search sample: 20 observations, median 3.4 minutes; proposed goal 1.5 minutes. It is separate from the new flow and balance exercise.

Material travels toward the using process; replenishment information returns upstream. Preserve part and lot identity and define the finite-lane response.

A refill signal specifies item, quantity and responsible role. Synchronized flow requires an agreed demand and release rule, not independent pushing at every step.

Try it before revealing the answer

Which arrow carries the request to replenish, and which carries the parts?

Reveal the answer and reasoning

Information travels back from consumption; replenished material travels toward the using process.

Teaching view 2 of 2

Balance work to demand using a yamazumi

Observers record window-assembly tasks, arrange work-element cards, compare work with takt and propose transferring one tote-return task between operators. — AI-generated teaching illustration. Follow the steps below, then try the practice question. View full size ↗

Yamazumi makes work elements and uneven loading visible. This new exercise is separate from the photo case. An 85-second station exceeds the 80-second demand rhythm; equal averages would hide it. Moving one transferable 10-second element gives a theoretical 75/75/60 balance, but precedence, skill, walking, ergonomics, variability and machine time must be checked. A theoretical balance does not demonstrate a stable method. Test the method with the team; do not turn the chart into a headcount target.

Follow the method

Define net time + demand
Observe repeatable work elements
Stack element times
Compare with takt
Trial a safe redistribution

Read the example carefully

New fictional balance exercise: 400 net minutes × 60 / 300 units = 80-second takt. Human work content is 85, 65 and 60 seconds across three operators.

E4, Return empty tote, is a provisionally transferable 10-second element. Moving it from operator 1 to operator 2 gives 75, 75 and 60 seconds; total work remains 210 seconds.

These are human work-content bars, not measured machine cycle times. Actual precedence, walking, competence, ergonomics, quality, variation and machine overlap still need validation.

Work through the numbers

new fictional exercise, not window case measurements

400 available minutes × 60 ÷ 300 units = 80 seconds takt.

Each work element keeps its identity and duration.
Element	Seconds	Current operator	Proposed operator
E1 · Position frame	30	1	1
E2 · Prepare corner kit	25	1	1
E3 · Confirm fixings	20	1	1
E4 · Return empty tote	10	1	2
E5 · Prepare seal kit	25	2	2
E6 · Check component identity	20	2	2
E7 · Record job reference	20	2	2
E8 · Check frame readiness	30	3	3
E9 · Confirm kit identity	20	3	3
E10 · Acknowledge handoff	10	3	3

Current loads: 85 / 65 / 60 seconds. Proposed loads: 75 / 75 / 60 seconds. Total work: 210 seconds.

E4 is provisionally transferable; actual precedence, walking, safe access, competence, variability and machine overlap must be validated. Chart is human work content, not measured cycle time.

Try it before revealing the answer

What remains to be checked after the bars fit below the takt line?

Reveal the answer and reasoning

Safe feasible sequence, task transfer, variability, machine overlap, quality and actual end-to-end performance.

Build on reliable methods

Sources and further reading

Toyota Motor Corporation — Toyota Production System ↗
Just-in-Time coordinates processes to provide the needed item, timing and quantity. Downstream withdrawal prompts replenishment; minimum necessary parts support the flow.
Lean Enterprise Institute — First In, First Out (FIFO) ↗
FIFO preserves arrival sequence through a finite lane. When the lane fills, the supplying process stops adding production until the consuming process releases capacity.
NIST — Lean Manufacturing: Don’t Leave Home Without It! ↗
Visual minimum and maximum inventory controls support material management. The proposal’s numerical sizing is an authored training policy, not a universal formula prescribed by this source.
Lean Enterprise Institute — Operator Balance Chart ↗
A yamazumi stacks timed work elements by operator against takt to expose uneven loading and explore redistribution. Feasible sequence, skills, ergonomics and machine overlap still require validation.
Lean Enterprise Institute — Takt Time ↗
Takt equals available production time divided by customer demand for the same period. It expresses the demand interval, distinct from measured cycle time and end-to-end lead time.
Lean Enterprise Institute — Heijunka ↗
Heijunka levels production quantity and mix over a chosen period while responding to customer need. Feasible changeovers, process capability and appropriate buffers support smaller repeated sequences.
Lean Enterprise Institute — Pull Production ↗
Downstream need authorizes upstream production or replenishment. Supermarket, sequential and mixed pull serve different conditions; a shelf or card alone does not establish an effective pull rule.
Lean Enterprise Institute — Heijunka Box ↗
A heijunka box distributes production instructions by product and time interval. Pitch equals takt multiplied by pack-out quantity, linking the release rhythm to a defined amount of work.

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