by Prabir Jana
02-November-2014 | 26 mins read
With increasing competition at domestic and global fronts, apparel producers in manufacturing destinations have slowly but steadily started adopting PMTS based work measurement approaches which are more logical in nature and have minimal subjectivity but are still not as popular as Time Study. India and Bangladesh are way behind other countries like Sri Lanka and Thailand in adopting PMTS as a key work measurement tool in apparel manufacturing. Dr. Prabir Jana, Professor, NIFT Delhi and Manoj Tiwari, Associate Professor, NIFT Jodhpur discuss various aspects of PMTS right from its genesis, key characteristics, practical know-how and challenges to PMTS in Indian apparel manufacturing sector.
Pre-determined Motion and Time Systems (PMTS) are an alternate to Time Study and used for work measurement. As the name implies, motions are pre-determined hence work analysis is done before it actually takes place on the floor. The Work Study practitioner visualizes the hand and body motions and other elements required to perform a particular operation and then with the help of PMTS (a data base, in soft or hard form) time values (which are pre-determined) are assigned to each motion. The standard time required to perform the operation is calculated by adding necessary allowances to such time values.
The concept of PMTS is to analyze a job into its fundamental human activities, apply basic times for these from tables and synthesize them into a basic time for the complete job. The times for basic motions are adjusted for other factors which take into account such variables as distances moved (in inches or centimetres) and difficulty in performing the actions such as avoiding obstacles during moves, closeness of fit during assembling, weight of the object, all of which increase the time to carry out the basic actions. The unit for measuring the basic time is Time Measurement Units (TMU), wherein 1 TMU is 100,000th part of an hour and equals to 0.036 second.
PMTS vs. Time Study
PMTS offers a number of advantages over stop-watch Time Study. With PMT Systems one time is indicated for a given motion, irrespective of where such a motion is performed. Some of the key advantages of PMTS over Time Study are:
1. Work measurement using Time Study by direct observation and rating may lead to inconsistency and an added subjectivity.
2. Work measurement using Time Study requires more manpower which may be costlier in long term.
3. Since the time for the various operations can be derived from standard tables (PMTS database), it is possible to define the standard time for a given operation even before the production begins, and often while the process is still at the design stage.
4. Based on the results from PMTS analysis, the layout and design of the workplace may be arranged in advance in such a way that the optimum production time is achieved.
5. Estimation of the cost of production which is useful for estimating and tendering purposes or for budgeting.
It is true that Time Study techniques of work measurement are quite popular and practiced by IE across the globe but it involves a good amount of time, money and efforts. On top of that, Time Study techniques are prone to errors, (Time standards established by different IE on the same job may be different), are subjective in nature and have a limited scope for method improvement. Further, while initially work measurement by Time Study may appear as an economical option with low investment, but in the long term, it’s not that economical as we have to devote a number of valuable IE hours in Time Study.
On the other side, “Pre-determined Motion Time System” (PMTS) seems costly (may be due to initial investment in license and training etc.), but it proves to be economical in the long term as it saves a considerable amount of time, manpower and over processing. Accurate planning and precise costing are the few other added advantages. On top of all, one worth mentioning quality of PMTS is its standardization which is irrespective of the operator and just focused on the Right Way of doing an operation. Hence time values derived from PMTS are fair to all operators (provided it is practiced by genuine PMTS experts). Adopting PMTS over Time Study for work measurement is a strategic decision and should be respected and followed religiously to get the best results, after all an investment in success is much more important than the cost of failure.
Types of PMTS
MTM is the most detailed and elementary system, having maximum number of codes for actions, hence difficult to imply. MTM-2 is the second level system developed in 1965, in fact it is a simplified version of MTM, achieved usually by the four methods of combining, statistically averaging, substituting and/or eliminating certain basic motions. MTM-2 reduces the 350 codes (from 10 categories) of MTM-1 codes to 39 codes (from 9 categories). MTM – 3, a further simplification, was developed in 1970. MTM- 3 is more useful for long-cycle operations and consists of only four categories (Handle, Transport, Step & Foot Motion and Bend & Arise) with only 10 time values. The original MTM system is now commonly referred to as MTM-1.
|MTM-2 Code (GET and PUT)|
MTM-2 is the most accepted and applicable PMTS which contains fewer codes as compared to earlier versions, hence it is easier to understand and implement. The motions and their codes are shown in Table 1 and Table 2. GET (G) is termed to the actions of reaching and grasping an object to secure sufficient control over it, while PUT (P) is referred to the actions required to move and position an object. Further, GET and PUT are divided into 3 categories – A, B and C (from easy to difficult) – depending on the difficulty level in grasping in case on GET and accuracy required (from approximate to precise), while move & position in case of PUT.
|MTM-2 Code (Body Motions)|
|Bend and Arise||B||61|
Difficulty level can be explained with an example; grasping a scissor will be less difficult than grasping a piece of wash care level from a tray. Similarly, putting the scissor back to its position (approximate location is fine in this case) is easier than putting the wash care level to a pre-decided position on the seam (precise position in this case). Deciding which case will have what level of difficulty is gained by training and experience.
Initially industrial engineers employed in any industry used MTM-2 data to visualize and analyze an operation and thus decide upon the work content. For doing the same, industrial engineers required to be professionally trained (duration in years) and gradually used to memorize the motions patterns used in a specific industry and thus the relevant codes and specialize in any specific industry segment. For example an industrial engineer working for automobile factory would remember the sequence of get-put codes of MTM-2 table by heart for tightening a screw. However, when the same industrial engineer is employed with an apparel manufacturing plant, he/she may not find similar motions being performed by sewing workers and needs to acclimatize with the motions being performed by sewing operators, search for those codes in MTM table and arrive at work content and memorize for future visualization. As the exhaustive list of codes in MTM table were too many, only professional industrial engineers were able to use the same.
Subsequently, some entrepreneurial experts have segregated the relevant codes for different industries from original MTM code, made macro codes using frequently used micro codes, created user-friendly interface and commercialized the solution bundled with short duration training, and GSD (General Sewing Data) was born. All the PMTS used in the garment industry be it GSD, Pro-SMV, SewEasy, MODAPTS or SPD are derived from the same MTM database.
Every PMTS system for sewn products industry has two components: the codes for handling elements and sewing formulae for machine elements. Sewing time values in TMU may also be calculated considering a number of factors such as length of the stitch, level of difficulty and precision level required while stopping the stitching. Sewing is further divided into 5 categories from simple to difficult. In the same way, precision level required while stopping the stitching is also divided into 3 categories from approximate stop to a precise stop of stitching.
Challenges to PMTS in India
In India, usage of PMTS is limited and factories generally follow work measurement which is Time Study based. The reasons of such scenario may be lack of awareness and availability of trained professionals. Moreover, factory managements are hesitant in investing in such systems, the reason is “when Time Study is satisfying the requirement, why to invest in PMTS? And why not invest this additional money in buying few more sewing machines?” It seems that in India, PMTS has failed to overemphazise the software’s interface and put less emphasis on training. Post training PMTS practitioner should spend at least one year on the sewing floor continuously watching the hand movements of sewing operators and co-relating the PMTS codes along with it. The PMTS solution providers should provide refresher training at least every quarter during the first year of training. Once the PMTS practitioner masters the visualising of motions, he/she will be able to calculate the work content of an operation sitting at desk itself. In India, after an organization implements PMTS, the practitioner tends to spend too much time understanding the software and the crucial learning is lost due to non-familiarity with shop-floor. Another important point to remember is PMTS practitioner should have familiarity with sewing operations; preferably he/she should sew him/herself. Basic knowledge of sewing will help the practitioner in visualising the motions later while selecting the right codes.
Pre-determined Motion Time Systems (PMTS) seems costly but it proves to be economical in the long term as it saves a considerable amount of time, manpower and over processing. Accurate planning and precise costing are few other added advantages.
Many apparel manufacturers consider usage of PMTS as a marketing tool to attract reputed buyers. They claim that they are using PMTS but may not be having the trained professional and licensed database. In such organizations, Time Standards are inspired (may be unauthorised copy) and getting used in a distorted or tampered manner which is many a times termed as ‘Customized’ by them. In true sense it’s nothing but the infringement of Intellectual Property Rights.
Many of the manufacturers treat such PMTS databases as software and they feel that such systems can automatically suggest the time values for a given garment style. This is indeed wrong, any software works only on what we feed (the term automatic should not be misused). In fact the basic information, like which code will apply where, has to be decided by the Work Study practitioner and the PMTS is going to work accordingly, following instructions from practitioner. Of course, time required can be derived from PMTS but the Work Study practitioner has to define the method (which may not be possible without proper training). If method is not correct, result (in time values) will also be wrong. It’s very important to understand that a PMTS is merely a tool that helps IE in decisions making which are based on practitioner’s visualization for a particular operation and a PMTS can’t think on its own.
Many other manufacturers treat PMTS with suspicion and feel that such PMTS are not for Indian conditions. In practical environment also, we witness a visible difference between Time Study standards and PMTS standards. Most of the time, PMTS based time standards are tough to achieve, this increases unrest in work force and production personnel. Such situation arises more frequently when there is scarcity of genuine PMTS practitioners; however blame goes to PMTS, that particular XYZ system failed in ABC organization. The key problem is that many of the IEs fail to visualize well how an operation is going to be performed, hence they are unable to decide on set of body motions required to perform the operation. This leads to a wrong time value from the PMTS. It is very important to understand that there is nothing wrong with a particular system (as all such PMTS’s are rooted from same MTM) but it is the way we use such systems.
It’s observed that IE gets the time values based on their visualization in their office only and set targets. The production personnel are forced to follow the method visualized by IE. This may result into failures and people blame PMTS for the failure.
Pre-cautions while practicing PMTS
The PMTS should be practiced with utmost care without which any PMTS may turn into a fancy tool with no practical applications.
Many a times, it’s observed that IE gets the time values based on their visualization in their office only and set targets. The production personnel are forced to follow the method visualized by IE. This may result into failures and people blame PMTS for the failure. Rather, it should be done in a manner where IE sets the line and trains the people on correct method. This will justify the targets set and help in confidence building among IE, production personnel and PMTS.
As stated earlier, any PMTS is fully dependent on the commands a practitioner gives. Based on the elemental breakdown, one may get the time required for the operation and missing out elements may result in wrong times, however there is no fault from PMTS. One must be very careful in elemental breakdown and ensure (by checking and re-checking) that no element is left out. To make it robust, IE are recommended to go to floor, observe the operators working carefully and work out the best methods. Later time values may be derived using PMTS; this will make the time values more realistic and valid.
A common doubt often raised by PMTS users in apparel industry is how any PMTS database differentiates the time required for handling different fabrics. For example pick-up and place time for a skirt panel of chiffon fabric and denim fabric will be different and how PMTS code will handle that? Here comes in the training and experience of PMTS user, there are no different ‘get’ and ‘put’ codes for different fabrics, but visualising (or by doing it himself/herself) the difficulty of pick-up, the engineer should use the right get-put sequence. While placing the fabric panel on the table, the denim fabric may lie automatically flat (due to fabric stiffness), but chiffon fabric may require multiple hand motions of flattening out and thus required number of additional codes to be put in.
In many of the factories in India and abroad, IE applies PMTS only for sewing operations and avoids using PMTS in other processes such as cutting and finishing & packing. Conventional branded PMT Systems are generally available for sewing operations. However, industrial engineers can use MTM data for estimating time for pre-sewing and post-sewing activities, which works as a constraint to achieve standardization while work measurement across the garment manufacturing processes. It is important to understand that PMTS are equally applicable to all the processes.
General Knowledge: PMTS
The BS 3138, Glossary of Terms Used in Work Study reads PMTS as “Tables of time data at defined rates of working for classified human movements and mental activities.” Such systems have been developed after an extensive study and analysis of human performance through continuous measurements, evaluation and validation. A predetermined time standard is a work measurement technique whereby times established for basic human motions (classified according to the nature of the motion and the conditions under which it is made) are used to build up the time for a job at a defined level of performance.
The principle of analysing work in to basic actions was first published by F. Gilbreth in 1920, as his Therbligs. The first commercial and internationally recognized PMT system was Methods-Time Measurement (MTM) devised in the 1930’s. MTM is a generic term for a family of Pre-Determined Motion Time Systems (PMTS).
|Key PMTS Database in Apparel Manufacturing|
|Name||Key features||Form of the database||Product name||Developed by|
|GSD||Developed from MTMMost popular and globally accepted.Specializes in solutions for Time Cost Benchmarking, Productivity Improvement and Work Measurement.||Soft form (Using Software)||GSD Enterprise and GSD QUEST||GSD Limited, UK|
|SewEasy||Developed from MTM and specializes in Lean Manufacturing. MTM based Quick Garment Sewing Data for transparent labour costing.||Soft form (Using Software)||SewEasy||SewEasy, Sri Lanka|
|MODAPTS||Focuses on the body part doing the moving rather than the distance covered by the body part of the object being handled.||Soft form (Using Software)||MODSEW||Byte Software, LLC of Mauldin, South Carolina|
|Pro-SMV||Developed from MTM-2 and has 36 codes 7 categories.||Soft form (using software)||Pro-SMV||Methods Workshop Ltd., South Africa|
|SPD||A total of 144 motion sequences are spread over 13 easy to apply tables, covering sewing elements and time values in TMU.||Book form||SPD Book||D G Stohlman|
|SSD||Developed from MTM and suits to all sewing rooms from light to heavy sewing works. SSD-5 can also be used in cutting, sewing, finishing and packing, etc.||Soft form (using software)||SSD (for Sewing operations), SWD (for manual or tool assisted operations), SFD (for finishing)||AJ-Consultants, Finland|
In 1948, Maynard, Stegemerten and Schwab published the book “Methods-Time Measurement” giving full details of the development of the MTM system and its application rules. The use of MTM spread, firstly in the USA and then to other industrialised countries. In 1951, the USA/Canada MTM Association of standards and research was formed by MTM Users. The system originators then assigned the MTM copyrights to the MTM Association.
|PMTS Chronology at a Glance|
|System||Year of the first application||Source of data in the system||Developed by|
|Motion Time Analysis||1924||Motion pictures, micro motion analysis||A. B. Segur|
|Body Member Movements||1938||Not known||W.G. Holmes|
|Motion Time Data for Assembly Work||1938||Time Study, motion pictures of factory operations and laboratory studies||Horald Engstrom and H.C. Geppinger|
|The Work Factor System||1938||Time Study, motion pictures of factory operations and stroboscopic (continuous motion is represented by a series of short or instantaneous samples) light picture||J.H. Quick, W. J. Shea and R.E. Koehler|
|Elemental Time Standard for Basic Manual Work||1942||Kymograph (time space plot), motion pictures of industrial operations and electric time recorder studies||Western Electric Co.|
|Methods Time Measurement (MTM)||1948||Time Study, motion pictures of factory operations||H.B. Maynard, G.J. Stegemerten and J.L. Schwab|
|Basic Motion Time Study (BMT)||1950||Laboratory studies||Ralph Presgrave, G.B. Bailey, J.A. Lowden|
|Dimensional Motion Times (DMT)||1952||Time Study, motion pictures and Laboratory studies||H.C. Geppinger|
|Pre-determined Human Work Times||1952||Motion pictures of factory operations||Irwin P. Lazarus|
Time Measurement by Maynard, Stegemerten and Schwab reads, “Methods-Time Measurement is a procedure which analyses any manual operation or method into the basic motions required to perform it and assigns to each motion a pre-determined time standard which is determined by the nature of the motion and the conditions under which it is made.”