MOST

Introduction

The Mynard Operation Sequence Tecnique is a well known methodology in the field of processing times estimation, based on the object to be moved rather than on the movement itself, since each motion and action considered is always directly linked to the object at issue. It is very well structured, since the tables are defined in a univocal way with well defined sections, so that many aspects of the movements can be taken into account. On the other hand it is also very fast in the application (faster than MTM-UAS) and flexible, since it is easy to modify when a change in the working cycle or in an activity occurs. The Basic MOST is based to a division in three main sections, corresponding to three tables, named General Move sequence model, for the activities done moving freely in the space, Tool Use sequence model, for those actions accomplished with the aid of a tool, and Controlled Move sequence model, for the activities done with a contact with other surfaces. Each of them are characterized by a predefined sequence of letters, each of which requires an index to be assaigned by looking at the tables. This brings to the main advantage that this methodology has, compared to the MTM-UAS: here subactivities are taken into account, since for each activity inserted, depending on the section, many letters are available to specify which sub-parts of the macro action contributes to the total time required. The final sum of all the indexes in the tables will give an indication of the processessing time of the working cycle at issue. Following the main objective of this project, that is to give back a toolkit of digital instruments to be used in order to ease the implementation of some methodologies for the measurement of the work, in this specific package for the Basic MOST the main elements are:
  • a general excel input file, to be filled in by the operator by
    following some specific instructions;
  • a python code, that takes the table in the Excel input file and uses its values to compute the required processing time;
  • one example related to one of the layouts considered for the manual operations in the Catenaccio case, on which the project is based, so to give the possibility to the user to have a practical interface for a complete understanding of the methodology.

Limitations

As already said, the MOST is a very widely used methodology in the industrial environment, very fast and flexible in the application, but it presents also some limitations:
  • despite the presence of many subactivities to specify the details of the lines inserted by the assessor, this can also represent a disadvantage, in fact in this way it is very easy to fall in redundancy, by overestimating the time values for example by inserting indexes related to the same situation in more than one cell, also related to different macro-activities. This will be further exaplained in the next chapter;
  • the tables, as will be seen later, are not so rigorous in the way of assaigning a value instead of another, in fact the descriptions leave space to a certain arbitrariness in the judgement;
  • the choosen version, the Basic MOST, is the most general one and the most widely used since it includes the majority of the industrial situations to deal with; anyway in cases with very low distances and cycle times or on the contrary very high distances with very big loads to handle, this methodology is not so adapted, and the Mini MOST and Maxi MOST respectively would be a better choice for a good analysis.
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