One of the tenets of lean manufacturing is that goods should flow like water through production. That flow is smoothed by determining the takt time and configuring manufacturing to achieve it.
This blog explains takt time in manufacturing. It covers the formula used, how to interpret what it reveals, and why it should matter to the maintenance function.
What is Takt time?
Picture one of the ancient ships powered by two rows of oarsmen. Their strokes had to be perfectly synchronized, otherwise there would be chaos and confusion. That synchronization was achieved, at least allegedly, by a rhythmic drumbeat.
Takt time is the drumbeat of a production line. It’s the rate at which goods move forward through the process, and eventually on to the customer. What distinguishes takt time from cycle time is that it’s set by the customer and not the process. In this sense, takt time creates the “pull” that characterizes lean manufacturing.
Takt time is the time to produce a single unit, if those units are made at the rate the customer wants them. If goods are made faster than the customer wants them, the result is to build inventory, which is a form of waste in lean. Conversely, make them at a slower rate than the customer desires and the result is a shortage and an unsatisfied customer.
Unusually for lean manufacturing, “takt” is a German, rather than Japanese, word. It translates as time, cycle or cadence, and originates from efforts made to maximize use in weapons production.
Takt time formula
A simple equation provides the takt time in a manufacturing process. It’s given as:
Takt Time = Available Production Time/Customer Demand
Some explanations and an example will make this clear. First, the calculation is done for a fixed time, which could be a week, month or even year. The number of minutes available in this period is divided by the number of units the customer wants in the same period, which gives the number of minutes per unit.
For example, if there are 40 hours available in week, and the customer wants 240 units per week, the takt time is (40 x 60)/240 = 10 minutes per unit. This is the rate at which the factory needs to produce to satisfy customer demand without building inventory.
How to calculate production Takt time
1. Select the line or process for which the takt time will be calculated. (Takt time cannot be determined in any meaningful sense for different products made on different lines.)
2. Determine the time over which takt will be calculated. For products where demand is relatively stable, this is usually done over a short period, such as a week. If demand is seasonal, it may make sense to use a longer period, but there is the risk of building inventory, leaving the customer waiting, or a combination of the two.
3. Determine how many units the customer wanted in this period.
4. Calculate the available production time in the same period. Time when the line is not planned to run is deducted from the total hours available. Examples of this non-productive time are lunch breaks or planned maintenance. Note that any breakdown maintenance needed is performed during the available production time.
5. Divide the available time by the quantity demanded by the customer to arrive at the takt time.
How to interpret Takt time to make decisions
There are five main ways in which manufacturers make use of takt time:
1. When setting up a new production line: The cycle time of the bottleneck operation must be at least equal to the takt time.
2. When scheduling production of a particular product: Knowing the rate at which customers will pull product from the factory lets schedulers make decisions about how fast to produce, how much inventory to build, and even when to have material delivered.
3. For planning maintenance activities: Preventive maintenance should be focused on the bottleneck operation to avoid breakdowns eating into available time. However, the available time calculation also depends on how much time is needed for preventive maintenance and when this will be performed. For other operations within the line with cycle times shorter than the takt time, these have the potential to catch up on lost production and can make time available for maintenance.
4. As a target for output measurement: Takt time determines the output required per shift and per hour, which can form the basis of production targets. With modern data collection tools, it’s possible to display performance against plan as a means of motivation. This provides a metric that’s easier for production workers to relate to than overall equipment effectiveness (OEE). That’s of more value to management as a measure of machine, line or factory productivity.
5. To guide efficiency improvement efforts: Takt time helps improve operational efficiency by directing attention toward the bottleneck. Increasing the number of hours available here, or increasing the speed at which the bottleneck can run, can reduce takt time or increase capacity.
Benefits of Takt time calculation
Calculating the takt time for a line or product, and then implementing it as a drumbeat for the line to run at, yields takt production. This has many benefits for manufacturing and maintenance:
- Supports one piece flow: Once a rate is established, each operation can pass a single part or workpiece onto the next operation.
- Space savings: With one piece flow, there’s less work-in-progress inventory, and production equipment can be positioned closer.
- Extends machinery life: Operations upstream and downstream of the bottleneck can run at less than their full speed, reducing wear and fatigue.
- Raises bottleneck visibility: Takt time highlights the slowest step in the process, so maintenance and operations management attention can be focused appropriately.
- Makes more time available for PM: Outside of the bottleneck operation, it’s possible to incorporate some preventive maintenance work without disrupting production.
- Supports standard work: Another component of lean manufacturing, standard work reduces variability in how jobs are done and enables better work balancing, in turn, helping improve product quality.
- Improves delivery performance: The stability created by the drumbeat of takt time enables better schedule adherence, which means easier and more reliable forecasting of shipment dates.
Improving equipment reliability and availability
Takt time enables synchronization of sequential operations, which creates flow through a production line. Flow is important for reducing inventory, saving space and driving out waste, but it also has implications for equipment maintenance.
By highlighting bottleneck operations, takt time shows maintenance where attention must be focused to avoid lost output. Breakdowns at the bottleneck are especially impactful, but taking too much time away from production for preventive maintenance results in a shorter takt time being needed to meet customer demand.
Therefore, the goal at this machine is to improve reliability without affecting availability. Elsewhere, takt time can create some “slack” that permits preventive maintenance work without costing output.
As a leader in industrial maintenance, ATS understands the challenge of performing maintenance work in a lean environment. Our specialists work with manufacturers in many industries to develop strategies that deliver higher reliability and availability while simultaneously managing costs effectively. Contact us to learn more.
