Have you ever wondered how traffic lights keep a consistent flow of traffic? How—if you’re not speeding—you always seem to hit green light after green light?
It’s not a coincidence when this happens. This kind of planning ensures maximum traffic flows with minimum disruptions (like sitting at a red light).
The same is true in factories, using a process called takt time planning. Already a well-known concept in manufacturing, here’s how it applies to industrialized, pre-fab, and modular construction.
Takt time vs. cycle time vs. lead time
A lot of manufacturing runs on cycle time: how long it takes to build one product, from start to finish. For instance, take a prefab single-family home. Let’s say it takes six weeks to build the structure in your factory, meaning your cycle time is six weeks for your standard home product
Lead time, on the other hand, is how long it takes to deliver a single product—including all pre-processing (think: shop drawings and ordering necessary material) and post-processing (think: final quality control and movement to the storage yard, or final delivery). If it takes two weeks to source material (pre-processing) and another two weeks to deliver and set the home on-site (post-processing), the end result is a 10-week lead time.
Takt time is a bit different. In manufacturing, it means how fast you need to build to meet customer demand. Instead of only considering how long it takes to complete something, it takes into account the interval between one unit beginning production and another. In the house example, it would be how much time elapses between starting to build the first house in your factory and starting to build the second house in your factory.
The goal of takt time planning
The goal of takt time is to make the most efficient use of resources, erring on the side of consistency rather than spurts of quick action. With that in mind, you base calculations on customer demand combined with available time to produce.
For instance, let’s say customer demand amounts to five houses per week in a new development. And your team works 40hours per week on average. In an ideal world, your takt time goal is to start production of a new house every eight hours. Assuming demand remains steady, you will always be able to meet the demand for five houses per week after your initial 10-week cycle time.
How to takt time plan
1. Set up your pre-requisites
Before you can begin takt time planning, you need to know four things:
Production processes: A step-by-step documentation for each thing you build.
Cycle times: How long each product takes to build, along with how long each step takes.
Parallel opportunities: What cycles can run concurrently to save overall time?
Crew hours: How many people do you have for each step vs how many people are required for each station or step?
Shifts: How many shifts do you have in a day and how long are each of these shifts?
2. Categorize production processes
Take every production process and group it into one of two categories:
● Tool time: Steps directly related to building your structure.
● Non-tool time: Indirect steps such as material restocking or equipment replacement.
3. Define your ideal takt time
Calculate your ideal takt by dividing your weekly shift hours by the estimated customer demand per week.
For example: Demand for five houses per week operating on a 40-hour week (8-hour day).
Calculation: 40 / 5 = 8
To meet demand, your ideal takt is starting one house per day. After the initial delay of your first cycle, you will always be able to meet demand on this cadence(assuming demand stays consistent).
4. Calculate target takt
Target takt is what happens when ideal takt time meets reality. To calculate it, you’ll need to reduce your available workhours by non-tool time and any other cycle limitations you have.
The simplest is to re-do the calculation from step three without non-tool time included to start. Carefully measure how long steps take and recalibrate to hone in on target takt.
For example: Demand for five houses per week with only 30hours of tool time per day (six hours of tool time per day).
Calculation: 30 / 5 = 6
With non-tool time in the mix, your takt cadence should actually be starting construction once every six hours. This will ensure not only that you meet demand after the initial delay but also takes into account the realities of your business so you aren’t artificially delayed by operations.
When calculating your actual target takt, always err on the side of realistic and reserved. Build in buffers and approach production with real data. You can always pump things up later if you’ve wildly underestimated things.
Slow down to speed up
A common criticism of takt time planning is capability—that if you can do more in a day, you should. The argument goes that this will help you wow customers with fast delivery times and gives you a leg up against the competition. The reality is that simply being able to do more doesn’t mean it’s possible to do more consistently.
The goal is smooth operations. When things run smoothly, you can produce more over time and you can more easily improve processes over time (leading—again—-to even higher production). Stop chasing fires and focus on steady, higher production over a long time period.
