Question 2 of 7: Motion Economy, Savings from Methods Engineering, and Macroscopic Workplace Improvement

Question 2: Motion Economy, Savings from Methods Engineering, and Macroscopic Workplace Improvement (20 marks)

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.

(i) Basic Principles of Motion Economy — Use of the Human Body

The classical Gilbreth/Barnes principles governing how the body itself should move fall into one connected group: (1) both hands should begin and complete their motions at the same time, so neither hand waits idle on the other; (2) both hands should not be idle at the same time except during a genuine rest pause; (3) motions of the arms should be made in opposite and symmetrical directions, simultaneously, since this is more natural to the body’s musculature and easier to coordinate than mismatched motions; (4) hand motions should be confined to the lowest classification with which the work can be performed satisfactorily — the same lowest-classification principle developed in Question 1(i); (5) momentum should be employed to assist the worker wherever it helps carry a motion, and minimized (or absorbed by a jig, not the operator’s muscles) wherever it must be overcome; (6) smooth, continuous, curved motions are preferable to straight-line motions with sudden sharp changes in direction, because a direction reversal requires the moving mass to stop and re-accelerate; (7) ballistic (free-swinging) movements are faster, easier and more accurate than restricted or “controlled” movements, since a controlled movement fights antagonistic muscles throughout its path; (8) work should be arranged to permit an easy and natural rhythm, since a rhythmic cycle is both faster and less fatiguing than one with irregular pauses; and (9) eye fixations should be as few, and as close together, as possible, since each new eye fixation interrupts the motion pattern and adds time. Applied together, these principles are the reason a well-designed two-handed assembly cycle looks and feels different from an ad hoc one long before any stopwatch is involved.

(ii) Savings from Methods Engineering and Work Measurement

Methods engineering (eliminating, combining, rearranging and simplifying unnecessary work, per the operations-analysis approach of Question 1(ii)) generates savings directly: shorter cycles reduce direct labor cost per unit, reduced motion and travel reduce fatigue and non-productive time, improved tooling and workplace layout reduce scrap and rework, and a simplified method is easier to train, which shortens the learning curve for new operators and reduces the cost of labor turnover.

Work measurement, applied after the method is fixed, converts the improved method into a defensible time standard, and the standard itself is the source of a second, independent layer of savings: it enables accurate cost estimating and quoting, realistic production scheduling and capacity planning (because planners know how long each job actually takes), a fair basis for wage-incentive pay (Question 7(iii)) that motivates output beyond the guaranteed rate, objective performance appraisal and line-balancing, and a quantitative baseline against which future method changes can be judged to prove they were genuine improvements rather than just different.

(iii) Macroscopic Approaches to Workplace Improvement

Where micromotion study analyzes individual therbligs and motion classifications one at a time, the macroscopic (whole-workplace) approaches improve the station as a system: (1) workplace layout — arranging tools, materials and controls within the normal working area on both sides of the operator, in the sequence they are used, rather than optimizing one motion in isolation; (2) simultaneous, symmetrical two-handed work — designing the job so both hands work productively (and, where possible, in mirror-image motion) rather than one hand working while the other holds or waits; (3) mechanization of heavy, repetitive or hazardous elements — power feeds, conveyors, foot-operated clamps and fixtures that remove load from the hands entirely rather than merely shortening a manual motion; (4) workstation height, seating and posture design matched to the specific task and to anthropometric data, so the whole body — not just the hands — works efficiently; (5) environmental control — illumination, temperature, ventilation and noise, since these affect the whole workstation’s output rather than any single motion; and (6) work-rest scheduling and job rotation, spreading fatigue and monotony across the shift rather than trying to eliminate them motion by motion. These approaches are “macroscopic” precisely because they redesign the station as a whole rather than re-classifying one reach or move at a time, and they are normally applied first, with fine motion-economy analysis reserved for the specific elements that remain a bottleneck afterward.