Takt Time - The pace set by the customer

At the Lean Coordinators Meeting held on March 16 at the Fresenius Medical Care plant in Jaguariúna – S.P., we had the opportunity to reflect on takt time (TT).

Why and what is all this for?

Let's see:
If I were asked to give a simple, short and direct one-word answer to what the most important thing in the lean philosophy is, I would without the slightest doubt answer that it is takt. For me, takt, or rather TT, synthesizes and characterizes the lean philosophy. Without it, there is no way to structure the lean philosophy, let alone talk about TPS (Toyota Production System), from which the lean philosophy we know originated (remember that the lean philosophy aims to reduce costs by eliminating waste!!!).

In our methodology (that of Lean Institute Brasil) for disseminating the concepts of the lean philosophy, the first mention of TT is made in the Workshop on Value Stream Mapping (VSM). When establishing the Future State, one needs to know the pull rhythm of demand, that is, at what rhythm the customer is demanding the product. It is the most important determination in VSM. All subsequent actions are developed based on the value of this tiny but very important element called TT.

Although it is of utmost importance, experience has shown and indicated to me that it is not taken as seriously as it should be by the vast majority of people who are implementing the lean philosophy in their companies. As a consequence, it has caused very great damage throughout the entire business chain, from the supplier, through manufacturing, all the way to the end customers, making it difficult to sustain the initiative. All this is mainly due to the lack of predictability of what needs to be done, which causes instability in the systemic chain. This instability (see my article on Stability, already published) jeopardizes the best of intentions, whatever the production system.

Once TT has been determined, be faithful, loyal and fully committed to it, because it is on its basis that all the actions needed in the business chain to satisfy the customer's needs are established.

TT in a lean company is determined when the annual budget is prepared. At Toyota this is a reality. Demand data are projected, as accurately as possible, based on marketing and sales research and strategic planning (every now and then, discrepancies in the research are observed - Toyota is not perfect!!! In these cases, opportunities are lost). The annual calendar, of how the company will operate during the year, is prepared by PPC (Production Planning and Control) and endorsed by top management. Once the annual calendar and the annual demand volume are known, takt time is the result of the ratio of that time to that demand. All members of the board know and understand that the common denominator, when it comes to the company's business, is this TT.

The annual budget is grounded, structured and prepared based on it (TT) and passed on to the company's Hoshin in order to be disseminated at all levels of the company. The success or failure of the company depends directly on meeting and fulfilling what is established in the budget. Hoshin Kanri plays a fundamental role in monitoring and controlling the company's activities.

We have seen that at the level of business strategy, the language and common denominator in the understandings of the company's leadership when it comes to the production business is TT. Let's now see what happens with TT at the shop floor level: it sets the pace of manufacturing. It is one of the essential elements of Standardized Work (SW), together with the worker's operation sequence and the standard in-process stock. It is TT that stabilizes the operator's rhythm of activity, protecting them from overburden at work (muri) and from variation in cadence and movement (mura), avoiding and summarily eliminating waste (muda) during the execution of their work. It is through SW that the operator's safety at work is stabilized, as well as the quality of the work and consequently of the product.

At Toyota, when a work accident or quality problems occur, the first thing to be checked and analyzed is whether the operator was performing the task according to the SW. In most cases it turns out that the operator was not following the SW. Nevertheless, there are cases in which the SW does not ensure what was mentioned above, thus requiring revision and improvement; in this situation one can see that the SW serves as a reference for implementing kaizen. Without SW there is no kaizen, as they usually say at Toyota. When developing the SW, the objective is to make the operator's work well defined, predictable, measurable, transferable from one operator to another in its work elements, and to make maximum use of this resource.

Another tool of utmost importance in sizing the workforce on the shop floor is the OBC (Operator Balance Chart). This tool is also based on TT. Once it is known, the workforce is distributed across the workstations. Work elements are assigned to each employee until the sum of the execution times of these work elements completely fills the TT. Proceeding in this way, all employees end up with a uniformly distributed and balanced workload, avoiding any discomfort and/or misunderstanding among them. In addition, it is good practice to promote job rotation across workstations (develop multiskilled employees)

Let's now look at the importance of TT in relation to the production capacity of machines and equipment (M&E). In the companies I have visited, practically all of them are very concerned with making maximum use of M&E resources without giving due importance to TT, causing great disruption in the production system. The operation cycle time (CT) should be slightly shorter (around 5%) than TT (I would point out that this is also, nonetheless, waste). M&E and processes whose CT is much shorter than TT are a source of waste, because by making maximum use of these resources, more is produced than necessary. Therefore, having resources beyond what is needed is a great waste. When acquiring M&E or establishing processes, always be guided by TT and always produce what is necessary as dictated by TT. (use the Balance Chart for M&E, similar to the OBC) And when CT is greater than TT, this characterizes a bottleneck that must be resolved by seeking to eliminate it through the implementation of kaizen and/or resizing and acquisition of M&E.

Before closing, let's look at the importance of TT with regard to suppliers. Remember that in the systemic view of the business, the supplier is connected to and part of your production chain. Treat the supplier as a business partner and as an extension of your activities. In this way, suppliers should operate at the same TT as the plant, obviously for the related items, and apply the JIT concept in both external and internal logistics using the “milk round” concept, thus avoiding the build-up of material (raw material) inventories at the plant.

In the next article we will deal in more detail with Standardized Work – a fundamental tool on the shop floor for sustaining the lean philosophy; stabilizing safety at work, quality and productivity; motivating and training employees and managing leadership, in addition to being a reference for implementing kaizen.