Introduction
Determining time standards for repetitive tasks is crucial in many industries, from manufacturing to services. There are various approaches to measuring work, with one of the simplest being the use of historical time data from past work. Although often overlooked, this technique presents interesting benefits as well as challenges that should be considered. In this article, we will analyze the use of historical times to establish standards, their advantages and disadvantages, and provide recommendations on their application in different contexts.
Foundation and Method
The historical times method is based on using data from time required in similar previous jobs to determine the standard time for a current task. Instead of timing the work each time, the actual times that workers take to complete the work under normal conditions are recorded. These times are then compared with previous historical measurements and used to calculate a representative average.
The typical formula for calculating standard time from historical times is:
Normal Time = [To + (4 * Tm) + Tp)] / 6
Where:
- To is the optimistic time,
- Tm is the modal or most common time, and
- Tp is the pessimistic time.
For example, if for an assembly task previous measurements gave 2 minutes (To), 4 minutes most times (Tm), and 7 minutes in the worst case (Tp), the standard time would be:
(2 + 44 + 7) / 6 = 4.16 minutes*
Advantages of Using Historical Times
Using historical data presents some advantages compared to repeated timing of tasks:
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It is simple and does not require special measuring equipment. Times are recorded during normal work.
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It allows flexibility in the methods of experienced workers, promoting innovation.
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It can integrate well with incentive systems based on continuous improvement of historical times.
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It is useful when methods are standardized and there is little variability in work from one period to another.
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It requires fewer resources than timing everything all the time.
Disadvantages and Precautions
However, it also presents some drawbacks and requires certain precautions:
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It depends on workers recording times correctly and consistently.
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It does not allow analyzing and improving methods like time study does. Standards are based solely on current work.
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Standards can become obsolete if methods or technology change. It requires continuous updating.
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There can be great variation between different workers, making it difficult to define a precise standard.
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It is not suitable when the nature of work changes frequently.
Application in Different Contexts
Given its pros and cons, historical times are more suitable in some environments than others:
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Highly standardized and repetitive manufacturing, with little variation in the product. For example, assembly lines.
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Services with predictable and standardized tasks such as telephone service in call centers.
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Artisanal work or construction where each case is unique. Standards should be determined in another way.
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Jobs with high variation between workers. It is better to time specific workers.
Conclusion
In conclusion, the use of historical time data from similar previous jobs is a simple but useful approach to determining manufacturing times, applicable in highly standardized environments. It presents advantages of flexibility and resource use, but requires consistency in methods and needs continuous updating.
Its application is recommended by carefully analyzing the characteristics of variability and standardization of the work in question.
References
J. A. Cruelles (2012). Improvement of Manufacturing Methods and Times. Spain: MARCOMBO.
G. Kanawaty. (1996). Introduction to Work Study, 4th Edition. Geneva, International Labour Office.
Stevenson, W. (2018). Operations management (13th ed.). New York, NY: McGraw-Hill Education.