The idea
Every station on a line takes a different time. The slowest station sets the pace, the others wait, and the total waiting is lost capacity. Line balancing redistributes the steps so the times are even and all sit just under takt.
How to balance a line
- Calculate takt time: available time ÷ demand.
- List every work element with its time, from observation, not estimates.
- Note the precedence: which elements must follow which.
- Calculate the minimum stations: total work content ÷ takt, rounded up.
- Assign elements to stations in sequence so each station's total is at or just below takt, respecting precedence.
- Draw the balance chart: a bar per station against the takt line. Rebalance until the bars are even.
- Standardise the new station work and train it.
A worked example
Takt time is 60 seconds. Work content across the line is 270 seconds in nine elements. Minimum stations: 270 ÷ 60 = 4.5, so five. Elements are grouped into five stations at 55, 58, 52, 57 and 48 seconds. The old layout had six stations with one at 75 seconds (over takt) and two at 30 (waiting half the cycle).
Line balancing and improvement
Balancing exposes the longest elements, which become targets for waste removal. Removing 15 seconds from one station may let the line run on four stations instead of five. Rebalancing is repeated whenever demand (takt) or the work content changes.
Common mistakes
- Balancing to a target output instead of real takt.
- Using estimated times rather than observed ones.
- Ignoring variation: a station balanced to the average will fall behind on the hard units.
- Balancing once and never revisiting as products and demand change.