This Blog contribution is from James Bertram. He is a continuous improvement engineer for Starkey Hearing Technologies, a global leader in hearing aid technology. Jim splits his time providing support between Starkey’s Global Headquarters, located in Eden Prairie and its facility located in Glencoe, MN. His role includes everything from working directly with the team members on the shop floor to developing training for the entire Starkey Organization. Prior to joining Starkey, Jim worked in the Lean Departments of both Pella Corporation and Larson Manufacturing.
When not at work, Jim enjoys chasing his two kids around, hiking, reading, or just taking off on a drive and seeing what is around the next bend in the road.
This posting reminds us to run the business based on customer demand and not let the business (the beast in this case) run you. Enjoy it!
Takt time is one of the fundamental concepts of the Toyota Production system. I also believe it is one of the most misunderstood. In many lean organizations, if I were to ask, “What is takt time?” The typical answer I get back is something like, “How long it takes someone to complete their standard work.”
Unfortunately, that answer isn’t correct, that answer is actually cycle time. So in our years of lean implementation, we have lost touch with one of the key principles of Lean and lost a technique that helps drive improvement in our organizations.
So what is takt time? Takt time is a calculated number that tells us the rate of production that is required to satisfy customer demand. The formula itself is…
For an example. Company A has a daily demand of 300 units. The company runs 8 hours (480 minutes), with two 15-minute paid breaks during the day. Putting the numbers into the equation we get:
So for the company to meet the demands of their customer, they need to produce a unit every 90 sec. Now that we understand the takt time, we can put the cycle time of each work station into context. Often we do that using a tool called a “Load Chart” or “Cycle Time/Takt Time Chart”, which usually looks something like this.
In this chart each bar represents the cycle time of the individual workstation (or operator). That information is typically gathered by conducting time observations. The Red Line represents the takt time of our process. In this this example Station 2’s cycle time is greater than takt, which means in its current state, the process is incapable of hitting our production targets.
At this point, possible solutions are to rebalance the work between the stations, possibly moving activity to station 3 or performing improvement activity at station 2 to reduce the cycle time.
The above discussion is a fairly straight forward, Lean 101 activity. In the above scenario you could theoretically pick any number to substitute for takt time. If I have a machine that has an 85 second cycle time, you could substitute that for takt and start from there.
However, I would argue if you take that approach, if you allow an internal process to pace your organization, you are missing an opportunity to drive improvement.
The market (takt time) isn’t influenced by your existing processes, takt time has no preconceived notions about your organization. Since the market is an external force, when the market changes, you will be forced to re-evaluate your work, which will force you to improve it.
Let’s investigate that a bit further.
Let’s say a fictional company called Joe’s Sprocket follows the philosophy I mentioned earlier. They have an expensive machine that has an 85 sec. cycle time. Joe’s management group has done some good work; they have created a work cell that includes the machine. The management team has decided to “feed the beast” so they have balanced all their workers to run at 85 sec. as opposed to calculating a takt time based on customer demand. The team sets up the cell, and it runs that way… forever… There are certainly opportunities for improvement, but what would drive them? The demand is set at 85 seconds and the cell runs well. There is no challenge to the team, their process is subjugated to the machine, it’s a monument. Additionally, we may not even need a sprocket every 85 sec, but it runs really well.
A second company, Bob’s Widgets, runs using takt time as their true north. They are dedicated to passing one good part at takt time through their value stream. Bob ‘s orders are increasing, his takt time needs to drop from 95 sec. to 90 sec. His team builds the cycle time vs. takt time chart from above, they see that Station #2 isn’t capable. The team now has a meaningful and achievable challenge to lower that station’s work content by 4 sec. In 6 months, maybe it changes again, it goes from 90 sec. to 85 sec. Again the team goes out, evaluates the flow, and performs additional improvement activity, and drives incremental improvements to their process.
I have seen very few organizations that run like Bob’s widgets. Many run like Joe’s Sprockets, where their goal is to feed the monument and keep it fed. Often they have multiple monuments or processes in their value stream and different areas run at different speeds. Other places define takt as “as fast as possible”, which usually causes confusion through the entire value stream. All of these organizations have lost sight of the meaning of takt time. It not only provides a “true north” with regards to pacing an entire value stream, but it also provides an outside push that challenges us to re-evaluate how we do things within our organization.