23-Ind-A2 Analysis and Design of Work · May 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2015 — 98-Ind-A2 Analysis and Design of Work. Three-hour, closed-book exam (approved Casio/Sharp calculator only); any five of the seven questions constitute a complete paper and only the first five answered in the answer book are marked — all seven are solved below for completeness. The source’s marking-scheme line for Question 3 mislabels its final sub-part “(ii)” a second time instead of “(iii)”; it is answered here in the natural (i)/(ii)/(iii) order that matches the question text itself, 5/5/10 marks.
Reference texts: Niebel & Freivalds, Niebel’s Methods, Standards, and Work Design (13th ed.) — operations analysis, workplace/tool design and motion economy, stopwatch time study, performance rating and allowances, predetermined time systems (MTM/MOST), work sampling, wage-incentive and job-evaluation systems.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Methods-Time Measurement is a predetermined motion-time system (PMTS): rather than timing a specific operator performing a specific job with a stopwatch, MTM analyzes any manual task into its constituent basic motions — reach, move, turn, grasp, position, disengage, release, plus body, leg and eye motions — and assigns each a standard time value drawn from tables built once, in advance, from careful study of experienced operators. A normal time for a new job is then synthesized by identifying the sequence of basic motions the job requires and summing their table values; no stopwatch and no subjective performance rating is needed for jobs the system covers, because the rating is already built into the table values.
MTM was developed by H.B. Maynard, G.J. Stegemerten and J.L. Schwab, published in 1948, from frame-by-frame analysis of motion-picture film of skilled operators performing a wide range of industrial tasks. Each frame was timed to a fraction of a second, motions were classified by type, distance and difficulty, and the resulting times were tabulated in units of TMU (Time Measurement Unit, $1\text{ TMU}=0.00001\text{ hr}=0.0006\text{ min}=0.036\text{ s}$), giving a common, analyst-independent time base usable across any plant or industry.
Both Reach (moving the empty hand to a destination) and Move (transporting an object with the hand) times are governed primarily by two factors: the distance travelled, and the case, which describes how much control and visual attention the motion requires.
For Reach, the case depends on the certainty of the destination location: Case A (to a fixed location, another hand, or an object the other hand rests on) is fastest; Case B (to a single object whose location varies slightly cycle to cycle) is somewhat slower; Case C (to an object jumbled with other objects, requiring search and select) is slower still; Case D (to a very small object requiring precise fingertip grasp) is slowest; Case E (an indefinite reach for balance or to position the hand for the next motion) has its own time class. For Move, the governing factors are distance, the weight or resistance of the object moved (a dynamic factor for the first few pounds plus a static constant beyond that), and the case: Case A (move to the other hand or against a stop) is fastest, Case B (to an approximate or indefinite location) is intermediate, and Case C (to an exact location requiring care, e.g. fitting or positioning) is slowest, because more of the motion time is spent decelerating and correcting rather than transporting.
Maynard Operation Sequence Technique (MOST) is a higher-level PMTS, developed from MTM data, that trades a small amount of precision for a very large gain in analysis speed. Instead of classifying every individual basic motion as MTM-1 does, MOST recognizes that almost all manual work fits one of a small number of standardized activity sequence models: the General Move sequence (Action distance – Body motion – Gain control – Placement, “ABG”) for moving an object freely through the air; the Controlled Move sequence for moving an object along a controlled path or surface (e.g. operating a lever or sliding a part along a guide); and the Tool Use sequence for the sub-activities of using a hand tool (fasten, loosen, cut, gauge, etc.).
For each occurrence, the analyst assigns an index value from a small fixed table to each parameter of the applicable sequence model (rather than time-classifying every discrete motion), sums the indices, and multiplies the sum by 10 to obtain the time in TMU. Because whole activity patterns, not individual motions, are the unit of analysis, a MOST study can be completed several times faster than an equivalent MTM-1 study at only a modest loss of precision, which makes it well suited to setting standards on the longer, more repetitive cycles typical of production and material-handling work rather than the very short, high-precision cycles MTM-1 was built for.
