Takt time and line balancing
Takt time is the pace a line must keep to meet demand. Line balancing divides the work between stations so that none of them takes longer than takt. Together they decide how many stations a line needs.
What takt time is
Takt time is the available production time divided by the number of units customers need in that time:
Takt time = available time ÷ demand
A shift of 8 hours with 30 minutes of breaks has 7.5 hours, or 27,000 seconds, of available time. If customers need 225 units per shift, the takt time is 27,000 ÷ 225 = 120 seconds. One finished unit must leave the line every 120 seconds.
Takt time comes from demand, not from the equipment. Cycle time is how long a station actually takes. A line meets demand when every station's cycle time is at or below takt.
Takt time calculator
From takt time to stations
Divide the total work content of one unit by the takt time and round up. That is the least number of stations any balance can reach:
Minimum stations = ⌈ total work content ÷ takt time ⌉
Take an e-bike with seven work steps at a takt of 120 seconds:
| Station | Work steps | Time | Of takt |
|---|---|---|---|
| 1 | Mount frame 80 s, Fit fork 35 s | 115 s | 96% |
| 2 | Mount wheels 40 s | 40 s | 33% |
| 3 | Fit drivetrain 90 s, Install battery 30 s | 120 s | 100% |
| 4 | Route cables 45 s, Final check 55 s | 100 s | 83% |
The work content is 375 seconds, so at least ⌈375 ÷ 120⌉ = 4 stations are needed, and this balance reaches that. Its efficiency is the work content over stations × takt: 375 ÷ (4 × 120) = 78%. Station 2 waits two thirds of every cycle, and station 3 has no margin at all.
Real balancing has more rules than the times. Some steps must come before others. Some need a particular machine, a side of the product facing up, or a station big enough for the part. A step longer than takt needs parallel stations. Finding the fewest stations under all of these rules is the simple assembly line balancing problem (SALBP-1), and it is hard to solve by hand once a product has more than a few dozen steps.
What takt time does not tell you
A balance on paper assumes every step takes exactly its time and every part arrives when needed. On the floor, times vary, machines break down, operators are shared and units travel between stations. A station at 100% of takt, like station 3 above, falls behind as soon as anything varies. That is why a balanced line is checked with a discrete-event simulation of the actual layout before anyone buys equipment.
How Machsizer uses takt time
In Machsizer you set the takt time or the demand. It balances the work across stations, respecting precedence, orientation and which machine can do what, lays the stations out on the floor and simulates the line, so you see whether the design meets takt with variation, breakdowns and transport included. Change the takt and the line is rebuilt. Its balancer reaches the published optimum on the open line balancing benchmarks; see Validation.