Tiempo de estudio

Source: MAYNARD’S INDUSTRIAL ENGINEERING HANDBOOK

CHAPTER 17.2

STOPWATCH TIME STUDY
Clifford N. Sellie
Standards International, Inc. Northbrook, Illinois

Time study is used to determine time standards (targets) for planning, costing, scheduling, hiring, productivity evaluation, pay plans, and the like. Time standards may be determined by a number of different time study techniques: (1)They can be based on historical records of time taken in the past to perform the task. These calculations of historical times can be based on straight arithmetic averages or sophisticated statistical analyses. (2) Another technique (sometimes called reasonable expectancies) is use of estimates by an individual knowledgeable of the time that it would take a qualified operator working at anacceptable performance level to do the job. (3) A third technique is predetermined times. Here the tasks are analyzed as to the work content and then predetermined times for the work segments are summed up to get the total time for the task. (4) The fourth and most often used technique is stopwatch time study. Stopwatch time study is the most popular method of work measurement. It was first developed byFrederick W.Taylor before the turn of the twentieth century. It is now used worldwide to determine the time required to do work. This chapter will discuss the basic principles and practices for setting fair, consistent stopwatch standards.

TIME STUDY
Time study may be defined as follows: Time study is a procedure used to measure the time required by a qualified operator working at the normalperformance level to perform a given task in accordance with a specified method [1]. In practice, time study usually includes methods study. The industrial engineer (time study analyst) has to observe the methods while making a time study. The definition of time study states that the task measured is performed with a specified method. It is desirable, while the time study is being conducted, forthe analyst to also look for opportunities for methods improvement. Many companies use the term methods/standards analyst to encourage the time study person to look for methods improvements while observing the methods for time study purposes. This chapter reviews the principles and techniques in using stopwatch time studies to establish allowed times. Section 3 of this handbook reviews principlesand techniques of methods analyses. Figure 17.2.1 presents a graphic analysis of the steps involved in establishing a stopwatch time standard. The first step is methods study and the second step time study. Methods study is shown first to emphasize the fact that the method should always be studied, improved, and standardized before the time study is begun. Time study begins with the category“selection of operator.”
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STOPWATCH TIME STUDY 17.22
TOOLS, TECHNIQUES, AND SYSTEMS

STOPWATCH TIME STUDY TOOLS
The stopwatch equipment used to make a time study varieswidely. It has often been said, and sometimes proved, that a good time study technician can make a usable time study with only the back of an envelope, a wristwatch, and a stubby pencil. This is a boast that has been responsible for many poor quality standards and the failure of many time study analysts. It is desirable that the time study be accurate, understandable, and verifiable. The time studytools used can help or hinder the analyst in meeting these requirements. A few of the essential tools that are needed by the time study analyst to make a good time study include 1. Time study watch—digital display (electronic) or sweep hand (mechanical). 2. Clipboard with bracket—to hold the time study forms. 3. Time study form(s)—(repetitive and nonrepetitive) that provide for the written...