It is a consensus to say that it is necessary to control processes in order to try to maximize the performance of its assets. These performance maximization mechanisms, in practice, work as a competitive differential for companies in the market.
At the end of the last century, for example, the concept of OEE (Overall Equipment Effectiveness), attributed to the Japanese Seiichi Nakajima, founder of TPM (Total Productive Maintenance). The OEE would be an instrument used to indicate underutilization of a production system, so that industries can outline actions to reduce/eliminate losses involved in the production process, thus reducing their unit costs.
The concept of OEE is very simple, it is about mapping and categorizing the events that reduce the productive output into three groups: Availability, Performance e Quality, so that later there can be action plans on them.
Figure 1 - What impacts OEE
Source: ILOS
To calculate the Availability it is necessary to evaluate how long the equipment was effectively operating in relation to a standard time that it, theoretically, should be operating. Although some production indicators use calendar time as a theoretical time, 24 hours a day and 7 days a week, this is not the case for OEE. For the OEE, this theoretical time can be constructed by decomposition: let's think of the total time available (or calendar time), of this time, there is a portion of time that there is no load, that there is no schedule, either because there are no groups hired for operation , either because there is no demand, or even due to legal restrictions such as lunch hours, inspections, etc. all this time without load must be disregarded from the theoretical time. Once these discounts have been made, we can call the remaining time with charge “Programmed Time”. Note that the focus of the indicator is to evaluate the execution and not issues of sizing the production park.
So what can cause unavailability? Several factors such as, for example, Setups, breaks, failures and unscheduled stops. Thus, we can define the availability indicator as the time the machine was effectively operating versus the time it was loaded with production scheduling (Time Producing/Time Scheduled).
To evaluate the Performance it is necessary to compare what was actually produced in relation to what should have been produced in the Scheduled Time. We know that in day-to-day operations, machines often operate below nominal capacity, due to minor stops or a reduction in speed. Thus, the so-called Real Production Time would be the (theoretical) time needed to produce what was actually produced, if the machine was running at its nominal capacity (Produced Volume/Nominal Capacity). In this way, the performance indicator is calculated through the quotient of how much it should take to produce what was produced, versus the time that was available for production (Real Production Time/Producing Time).
From the point of view of Quality, the definition is more intuitive, referring to the percentage of conforming products in relation to the total produced, that is, of the total produced, rejects are slaughtered. We calculate the quality indicator, therefore, as the division of production approved by quality over the total volume produced (Compliant Production Time/Actual Production Time).
Figure 2 - Composition of OEE Calculation
Source: ILOS
Reflecting and making a parallel of this concept of Production to Logistics, let us consider the case of a vehicle, for example. What would be the availability? Well, we could consider the days that the vehicle theoretically should be in operation against how many it actually ran, an indicator of vehicle use, for example. What would the performance be? Well, it is known that the vehicle has a nominal transport capacity, its performance can be measured by the volume it transported versus how much it should have transported in the same trips if it operated at nominal capacity, an indicator of vehicle occupancy. And the quality? If the vehicle's mission is to properly deliver all of its cargo, the amount of rejected or non-compliant cargo may be associated with the quality of the delivery itself. Therefore, the indicator of returns ou transport losses. In the end, OEE would be the combination of utilization, occupancy and non-attendance.
And do you also believe that OEE concepts for manufacturing can also be transposed and applied to logistical assets?
References
COSTA RS and JARDIM EGM: The five dimensions of operational diagnosis, NET, Rio de Janeiro, 2010.
HANSEN, RC Overall Equipment Efficiency. 1.ed. Bookman Editora LTDA, 2008. 264p.
HAYES, R.; PISANO, G.; UPTON, D.; WHEELWRIGHT, S.: Operations, strategy, and technology – pursuing the competitive edge. Hoboken: Wiley & Sons, 2004.
NAKAJIMA, S. Introduction to TPM: Total Productive Maintenance. 1.ed. Productivity Press, 1988. 129p.
