Parts at the line, every day: three shortages eliminated

The plant

Large, configured units built to customer order on paced assembly lines, fed by a supplier pipe programme, an internal sheet-metal area and a laser cell. A unit can only move when every part for the next station is there, so a shortage from any of the three stops the line.

Loop 1: pipe from the supplier

Free-cooling units need a long list of pipe parts, and every one has to be at the line when the unit reaches that station.

The problem

• Pipe for the free-cooling units ran short several times a week.
• Each shortage stopped the line and cost many hours of downtime.
• Orders to the supplier followed forecasts and lead times, not what the line was actually building.

What we did

1. Tied supply to the build schedule. The supplier delivers pipe to the line’s build sequence, a set time ahead, instead of to forecast.
2. Supplier-held stock as a buffer. A set level of pipe is held for the line and topped up as it is used.
3. A real-time visual signal. The line’s use triggers replenishment, visible to the plant and the supplier at a glance.
4. A daily check. Anything at risk is flagged before it can reach the line.

The result

• Pipe shortages on the free-cooling line: from several a week to none.
• Within a week of go-live.
• Many hours of line downtime no longer lost to missing pipe.

Loop 2: sheet metal to assembly

A sheet-metal area cutting and forming parts for several assembly lines, with a mix of common parts and parts specific to each unit.

The problem

• Sheet-metal parts were missing at assembly every day.
• At the same time, the area carried large piles of parts nobody needed yet, taking work in process and floor space.
• The area worked to its own list, not to what assembly was using.

What we did

1. Kanban for common parts. Assembly’s use signals the sheet-metal area to make the next set, so common parts are replaced as they are consumed.
2. Sequenced kits for unit-specific parts. Parts specific to a unit are made as a kit, in the build sequence, a set time ahead.
3. A closed loop. Every signal comes back to the sheet-metal area; nothing is made without one.
4. Visual control on the floor. Anyone can see what is due, what is ready and what is late.

The result

• Sheet-metal parts missing at assembly: from every day to none.
• Less work in process in the sheet-metal area.
• Less floor space taken by parts waiting.

Loop 3: the laser cell

One laser cell cutting parts for several assembly lines. Every hour the laser stands still is an hour of parts that assembly will miss later.

The problem

• Laser-cut parts were short at assembly every day.
• The laser lost time at the start of the day swapping gas, and waiting for steel.
• Jobs were released without everything they needed, then stalled half-finished.

What we did

1. Moved the gas swap off the clock. Maintenance now does a 30-minute gas exchange before the day shift starts.
2. Took steel waits out. The steel supplier pre-cuts the two highest-volume items.
3. Full kit before release. A material-flow supervisor checks each job is complete before it reaches the laser.
4. Red/green on the floor. Visual management of the laser’s flow, tracked every day.

The result

• Laser-cut parts short at assembly: from every day to none.
• Within a month of the changes.
• No new equipment: the same laser, with its losses and waits removed.

More results: all case studies · How we work: lean and Theory of Constraints implementation.