Tài liệu Wts_4_stopwatch_time_study

Stopwatch Time Study Work and Time Studies Vietnamese German University Dr.-Ing. Marlene Helfert 2016 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 1 Stopwatch time study Contents Stopwatch time study Description Advantages Disadvantages REFA stopwatch time study REFA standard program stopwatch time study Preparation of the stopwatch time study Implementation of the stopwatch time study Evaluation of the stopwatch time study Introduction and application of the results Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 2 Stopwatch time study REFA 1997 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 3 Stopwatch time study Description Work measurement technique for recording the times and rates of working Method for analyzing the data so as to obtain the time necessary for carrying out a job at a defined level of performance Only valid for the elements of a specified job carried out under specified conditions The objective of stopwatch time study is to determine reliable time standards for all work, both direct and indirect, including allowances and recovery times. Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 4 Stopwatch time study Advantages Enables analysts to observe the complete cycle, providing an opportunity to suggest and initiate methods improvement The only method that actually measures and records the actual time taken by an operator Provides also coverage of process elements that occur less than once per cycle Quickly provides accurate values for machine-controlled elements Relatively simple to learn and explain Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 5 Stopwatch time study Disadvantages Requires the performance rating of a worker’s skill and effort Requires continuous observation of the worker over repeated work cycles May not provide accurate evaluation of noncyclic elements Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 6 REFA standard program stopwatch time study REFA stopwatch time study Method for systematic observation, determination and recording of work flows 1. Preparation of the stopwatch time study Aims on the determination of work flows within and in between companies and work systems 2. Implementation of the stopwatch time study 3. Evaluation of the stopwatch time study 4. Introduction and application of the results The REFA stopwatch time study includes several sophisticated tasks, which are presented in specific standard programs and embedded in the REFA standard program stopwatch time study:  Performance rating  Evaluation of time studies  Statistical evaluation of time studies REFA 2013 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 7 Preparation of the stopwatch time study 1. Preparation of the stopwatch time study 2. Implementation of the stopwatch time study 3. Evaluation of the stopwatch time study 4. Introduction and application of the results  Determination of the aim of the study and use of the data  Information of stakeholders  Description of the work system  Break down of the workflow into process sections  Specification of measurement points  Specification of a time measurement method  Recording of reference quantities and influences  Setting the scope of the study  Timing of the study period  Selection of operator(s)  Selection of a time measurement device  Preparation of data documentation REFA 2013 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 8 Preparation of the stopwatch time study Determination of the aim of the study and use of the data Content, process and effort of the study as well as the timing and the amount of examiners, depend on its purpose, so this must be clearly defined. Depending on the work situation to be recorded, the simultaneous study of several examiners might be necessary, e.g. in group work. The time data collected can be used for process, job, or work planning, for cost accounting, etc. REFA 2013 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 9 Preparation of the stopwatch time study Determination of the aim of the study and use of the data Occasions for analyzing a particular job A new not previously carried out job (new product, component, operation, or set of activities) or a change in material or work method requires a new time standard A complaint has been received from a worker or worker’s representative about the time standard for an operation A particular operation appears to be a bottleneck holding up subsequent operations Standard times are required before an incentive plan is introduced A piece of equipment appears to be idle for an excessive time or its output is low, and it therefore becomes necessary to investigate the method of its use Need of a preliminary study to make a methods study or to compare the efficiency of two proposed methods The cost of a particular job appears to be excessive Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 10 Preparation of the stopwatch time study Areas of application Purpose of time data Work planning To select suitable processes, means and methods Pre-calculation To determine estimated piece prices, budgets Scheduling To minimize delays, to calculate and monitor delivery deadlines Workplace and machine occupation To optimize the exploitation of capacity, to design workplaces and machines Material delivery To optimize the availability of materials and to plan the stock Personnel planning To plan employee capacity, work schedules and production programs Cost accounting To calculate the manufacturing costs and sell prices, to balance projects, departments etc. Payment To determine piece-per-hour production rate, to set the wage per unit and bonuses Schlick 2005 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 11 Preparation of the stopwatch time study Possible focusses of the study Production facilities: Utilization and interruption of utilization Do the machines operate at full capacity? How long do the distinct processing steps take? How large are fault and idle times? Working person: Activities and interruption of activities Do the workers operate at full capacity? How long do the distinct activities done by the workers take? How large are allowance and waiting time of the working persons? Workpiece: Processing and interruption of processing How much time do the distinct processing steps of the workpiece take? How large are waiting and storage times? How large are typical processing times (time actually worked on the work piece) and throughput times (time it takes to produce it)? Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 12 Requirements for effective stopwatch time study Information of stakeholders Because of many human interests associated with the stopwatch time study technique, a full understanding among the supervisor, employee, union steward, and stopwatch time study analyst is essential. Time standards directly affect both the employee and company financially, so stopwatch time study results must be completely dependable and accurate. To achieve and maintain good human relations the stopwatch time study analyst should conduct himself or herself in a manner that will gain and hold the respect and confidence of both labor and management What kind of information should you give to the workers? Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 13 Preparation of the stopwatch time study Information of stakeholders The employees need to be informed about the study and its purpose at an early stage Questions need to be clarified factually The observers should avoid tense situations by seeking conversations with employees immediately prior to the stopwatch time study The tariff and, if applicable in-plant regulations concerning the information of supervisors and others (e.g. work council) must be observed REFA 2013 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 14 Preparation of the stopwatch time study Description of the work system The reproducibility of the results - regardless of the examiner – can only be ensured, if the work situation and the work systems are described in sufficient detail, e.g. by using the work system documentation. If the work situation could be improved, appropriate measures should be implemented in advance of data collection: Then shortcomings do not become status quo. The stopwatch time study does not have to be repeated after the change. E.g. items must be picked up or deposited several meters away from their use in the workflow again. This causes non-value added time, possibly by wearing loads, and could be avoided by improved supply and conveyance of parts. REFA 2013 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 15 Preparation of the stopwatch time study Breakdown of the workflow into elements An element is a distinct part of a specified job. It is a division of work that can be easily measured with a stopwatch and that has readily identifiable breakpoints. Elements should be chosen so that they represent naturally unified and recognizably distinct segments of the operation. E.g., reaching for a tool can be detailed as reaching, grasping, moving, and positioning. This can be better treated as a whole and described as ‘‘obtaining and positioning of wrench.’’ Elements should be easily identifiable (with clear start and break-off points) so that once established, they can be repeatedly recognized. Sounds (such as machine motor starts and stops) and change in motion of hand (putting down tool, reaching for material) are good breakpoints. Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 16 Preparation of the stopwatch time study REFA 1997 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 17 Preparation of the stopwatch time study Breakdown of the workflow into elements To divide the operation into individual elements, the analyst should carefully observe the operator over several cycles. A work cycle is the sequence of elements that are required to perform a job or yield a unit of production. The sequence may include elements that do not occur every cycle. Workflows are usually defined in work plans and procedures. Always check whether this workflow is actually executed. If there is no adequate information on the planned workflow, the actual flow will be determined and recorded. REFA 2013 Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 18 Preparation of the stopwatch time study Breakdown of the workflow into elements Additional or unscheduled process sections are also recorded in the stopwatch time study. To which extend they will effect the results, e.g. the standard times, will be clarified in the evaluation. Ascertain that all elements being performed are necessary. If some are unnecessary and the objective is to come up with a standard time, the stopwatch time study should be paused and a method study should be conducted. REFA 2013 Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 19 Preparation of the stopwatch time study Breakdown of the workflow into elements Criteria for the delimitation of the elements Change of the factor, that influences the time needed for the element: In element 1 this might be for example the weight, and in element 2 the surface Change of the working method: If an surface is first ground, then cleaned and then painted, three elements can be clearly distinguished Completion of a process section, for example, with the installation of a module Workflow sections that can be fully, partially or not influenced by the employees need to be delimited:  Machine-paced elements should be separated from operator-controlled elements; the division helps recognize true delays REFA 2013 Salvendy 2001 Dr.-Ing. Marlene Helfert | Work and Time Studies | 2016 | 20