In their book Lean Thinking, James Womack and Daniel Jones talk about Lean Management as a system based on 5 pillars:
- Identify value for customers
- Analyze the flow of value
- Create flow in operations
- Work with Pull Flow systems
- Apply Continuous Improvement
Every single pillar is, more or less, customer oriented. Therefore, the question to be addressed is clear; what does it mean to focus a process on the customer and how will we know if we are really customer-oriented?
To answer these questions, we must understand and even delve deeper into both a concept and a metric: the ‘Takt Time’.
What is Takt Time?
Takt Time is a concept used to refer to the rhythm that a production process should perform in order to satisfy the rhythm of demand set by the customer.
The word ‘Takt’ is German and means ‘cadence’, ‘rhythm’ or ‘beat’. And it suggests that, to achieve a fully customer-oriented process, we have to define a production process. Furthermore, it has to be capable of manufacturing at the pace that the customer is demanding.
A nice example is the ice cream shop that serves a customer every 30 seconds, this means their ice cream production process has to take less than 30 seconds.
Here is the formula to calculate Takt Time:
Thus, calculating the Takt Time of a process requires to know two variables:
Opening time: period of time in which a production process will be in operation to meet a customer’s demand.
Customer demand: units needed to be produced:
The result of the preceding calculation sets the pace for the production process.
Let’s take as an example a production process that has a demand (D) of 400 pieces with exactly 8 hours to produce them; that is, the opening time (O) is 8 hours. In this case, the Takt Time is:
In this case, the production process must be capable of producing one piece every 1, 2 minutes, otherwise the process will not keep pace with the customer’ s demand.
If a process does not follow the pace set by Takt Time, there are going to be problems facing us with two different scenarios.
First, the production process falls below Takt Time or second, the process exceeds Takt Time.
In the first of these two scenarios, when the production process is faster than the takt, or in other words, when the Cycle Time is less than the Takt Time, the company is generating stock. In this case, the process delivers at a faster rate than the customer has demanded and, therefore, finally manufactured units are accumulated on stock.
Lean Manufacturing and Customer Satisfaction
Returning to our ice cream store, if it is capable of producing ice cream in less than 30 seconds, this generates, on the one hand, idle time for the store employees. And on the other hand, a stock caused by the misalignment between the speed of the production process and the consumption.
In the second scenario, when the production process exceeds Takt Time – that is, when the Cycle Time is higher than the Takt Time – the process will not able to keep up with the pace demanded by the customer.
In this case, and recovering the ice cream shop, if to produce an ice cream requires a time of one minute and we receive a client every 30 seconds, it is easy to see that there will be a long queue of customers growing, which could generate dissatisfaction and possibly, loss of some of them.
Takt Time in administrative processes
While the concept of Takt Time is quite widespread in production environments, it is not that usual to talk about Takt Time in administrative processes. For example, a team is expected to be able to manage 30 customer requests (demand) in 4 hours (opening time).
It sounds rather bizarre to talk about Takt Time in a healthcare environment, where a general practitioner must be able to attend to 60 patients in 8 hours, with Takt Time being 8 minutes per patient.
It´s easy to determine the necessary resources in the process once the Takt Time and the necessary time of manufacture (Cycle Time) are known. In this example, the number of doctors needed if we consider that the average time of assistance of a doctor requires 15 minutes to attend a patient, 2 doctors are needed:
And finally, when do we speak of Lead Time?
In any process, apart from Takt Time and Cycle Time, we can use another essential metric: the Lead Time. Unlike Takt Time, Lead Time is a metric measured in time units that determines the time for a product unit to be produced.
Meaning; while Takt Time tells us that the medical practice should attend to a patient every 8 minutes. Lead Time would reflect the time from the patient´s arrival at the ambulatory until he or she leaves, taking fully into account the time to arrive at the practice, the waiting time, the time of attention and the time to leave the ambulatory…
Knowing the Takt Time of a process is the first step to Continuous Improvement. When we have detected a process being unable to follow the ‘rhythm’ marked by the customer, or ‘Takt’, we have to analyze all operations involved in the process to identify those that do not add value.
By streamlining operations and balancing workloads, we will be able to make a process follow the ‘takt’ rhythm set by the customer.