REFA Time Study
REFA - Time determination through time study
REFA developed a standard program with the following main steps for the determination of default times.
Determine the purpose of the time recording. The intended use decisively determines the care and accuracy to be used in the subsequent study.
Description of the work to be measured: A description of the work system is made that is so precise that a trained work organizer could restore comparable working conditions. The work task to be carried out, the working method and the working method used must be specified precisely using the structure outlined above. It is also determined which activities belong to the work and in which work steps the process can be broken down.
Carry out time recording: Divide the process into process sections and describe them. Define measuring points that indicate the beginning and end of the process sections. Record reference quantities and influencing factors. The measured actual times are documented in the REFA time recording sheet in the form of a log and then evaluated.
Performance level assessment: Even during the recording, the measured performance is compared to a reference performance, the so-called REFA normal performance. This is characterized by the fact that it can be performed by every trained and fully trained employee over the long term and as an average performance of a shift time, and serves to determine the target time for a job.
Statistical evaluation of the determined times for validity. Since the times measured in a time recording always scatter, the extent of the scatter is determined. If it exceeds a specified value, more times either have to be taken or a workflow that is more stable has to be achieved through work design.
Calculation of the target times for the process sections and summation to the base time for the workflow of a unit.
If necessary: determination of recovery times.
Determining the distribution times: Since the duration of the distribution times depends on personal needs or machine malfunctions, they are determined using a distribution time recording or statistical methods, such as multi-moment recordings, are estimated. Many collective agreements contain flat-rate values for personal and factual distribution times to be applied. In such cases, they are negotiated.
Determination of any other time supplements that may be necessary.
Calculation of the default time as time per unit: The basic, recovery and distribution times related to a unit are added.