Connect processes: flow, bounded FIFO or supermarket

Connect processes: flow, bounded FIFO or supermarket

Connect adjacent work directly when the process can safely support it. When that is not feasible, make the waiting mechanism explicit. A bounded FIFO lane preserves arrival sequence and creates a clear response when full. A supermarket holds defined quantities of repeat items and replenishes what is consumed. Neither is a license for unlimited stock. Consider product variety, required sequence, replenishment reliability and quality status before choosing. In custom administrative work, a finite sequenced queue may be more useful than pretending every possible request can be stocked. Review end-to-end delay after the connection changes.

Follow the method

1. Can work flow directly?
2. Direct flow
3. If not, choose a connection
4. Bounded FIFO
5. Supermarket

Choose a connection from the handoff evidence

Fictional mixed-products workshop: planner Omar reviews adjacent assembly and test, a custom-nameplate queue before curing, and repeat fasteners supplied to several benches. Management proposes putting every item into the same open storage rack.

Follow the method

1. Assembly/test
2. Custom nameplates
3. Repeat fasteners
4. Generic overflow rack

Three handoffs need three different controls

Select a provisional connection between processes from identity, sequence and replenishment evidence, and specify what happens when the connection is full or blocked.

Fictional mixed-products workshop: planner Omar reviews adjacent assembly and test, a custom-nameplate queue before curing, and repeat fasteners supplied to several benches. Management proposes putting every item into the same open storage rack.

Role: Material-flow designer with operators from both sides of each handoff.

Normal condition

The connection preserves identity, appropriate sequence and response to demand without uncontrolled accumulation.

The gap

A generic rack does not say which item moves next, how much may wait or what authorizes replenishment.

• Direct flow requires feasible process, safety and quality conditions.
• A bounded FIFO preserves its agreed sequence; a supermarket uses controlled stock and replenishment, not unlimited storage.

1. Check direct flow first

   Omar asks whether assembly can hand one eligible unit directly to a ready test position while preserving the approved method. He checks both process timing and safe access.

   Why: Direct connection removes a separate waiting location only when the work can genuinely move. Proximity alone is insufficient.

   Evidence: Provisional assembly/test choice: direct flow, subject to verified feasibility.

2. Use sequence where identity matters

   For custom nameplates, he proposes a four-position FIFO lane with visible oldest-to-newest order and traceable customer identity. The exact limit is an illustrative local trial setting.

   Why: Making stock for unknown custom orders would not create useful availability. A bounded sequence makes both age and excess release visible.

   Evidence: Custom lane: four defined positions; downstream takes the next eligible ordered item.

3. Define replenishment for repeat items

   For repeat fasteners, he records each item’s location, eligible stock boundary and consumption signal before proposing a supermarket. Quantity parameters require separate usage and lead-time evidence.

   Why: A supermarket is a controlled connection for replenishment. Calling any shelf a supermarket does not supply its missing authorization rules.

   Evidence: Repeat-item proposal names identity, location, replenishment signal and parameter owner.

4. Write the full or blocked response

   When all four FIFO positions are occupied, upstream does not put a fifth item beside the lane. The owner checks downstream blockage and follows an explicit release/exception rule. A held item retains its quality status.

   Why: The limit loses meaning if overflow is hidden. Sequence and eligibility are separate; a local rule must govern any held item rather than silently bypassing it.

   Evidence: Full-lane record names the blocked handoff, owner and next review time.

5. Test the selected connection

   Observe demand, WIP, waiting age, stockouts and quality after a limited trial. Keep alternative connection choices open if product variety or process constraints change.

   Why: The diagram is a design decision based on observed conditions, not a permanent label attached to a department.

   Evidence: Connection review links the choice and limit to actual operating evidence.

A FIFO item is on quality hold

The first custom nameplate becomes held while the other three positions remain occupied.

Retain identity and hold status, notify the owner and apply the approved hold/sequence rule; do not assume moving it away opens an ordinary release slot.

Physical movement, eligibility and commitment are different facts. The response must preserve all three.

Hold disposition and any authorized resequencing are traceable.

Run a practice session

Materials

• Three route cards, four queue tokens and a blank decision tree
• An optional quality-hold card

1. Identify the handoff differences · 4 minutes

   Which fact makes a custom item different from a repeat fastener?

2. Choose three controls · 8 minutes

   What must be known before calling a shelf a supermarket?

3. Introduce the full/held lane · 8 minutes

   Who may change sequence or release?

4. Apply to repair · 5 minutes

   Which observation would reverse your provisional choice?

Debrief

• Accept reasoned alternatives when their rules and conditions are explicit.
• Reject solutions that simply move overflow out of view.

Draw one evidence-to-choice branch for each route and audit the exception before opening the answer.

Transfer into the work

Owner: End-to-end material-flow owner

Record: Connection decision, declared limits and full/hold exception log

Review: After the limited trial and whenever mix or process constraints change

Evidence: Controlled WIP, preserved identity, reliable replenishment and known queue age

Revisit feasibility and parameters with both process owners; remove untracked overflow paths.