Work Design and Methods Engineering
Methods engineering is the systematic study of how work is structured so that it can be improved before it is measured. Candidates must know the classic problem-solving sequence (define the problem, analyze the present method, develop the improved method, install it, and maintain it) and the charting tools used at each step: operation process charts, flow process charts, flow diagrams, string diagrams, and the two-handed (left-hand/right-hand) process chart. The primary-questioning technique and the secondary (why/what/where/when/who/how) questioning approach drive method improvement; the ECRS framework (Eliminate, Combine, Rearrange, Simplify) is the practical ordering for redesign.
Motion economy is heavily tested. Know the principles of motion economy grouped by use of the human body, arrangement of the workplace, and design of tools and equipment. Distinguish therbligs (Gilbreth's basic motion elements) as effective versus ineffective. Traps: candidates confuse therbligs with elements; confuse a flow diagram (plan view with travel paths) with a string diagram (measures distance traveled); and misapply ECRS order by jumping to Simplify before Eliminate. Another trap: assuming automation always improves a method-questions reward eliminating unnecessary work first.
Worked rule of thumb: when evaluating a proposed method change, compute the annual labor savings as (time saved per unit × units per year × labor rate), then subtract added capital cost amortized over the payback life. If payback exceeds the firm's hurdle, the method is not justified even if it looks elegant.
For the two-handed chart, apply the rule that both hands should begin and end their motions simultaneously and should not be idle at the same time except during rest.
Worked example
A task takes 0.80 min/unit, 12,000 units/yr, labor at $30/hr. A fixture costing $9,000 cuts time to 0.65 min. Savings = 0.15 min × 12,000 = 1,800 min = 30 hr × $30 = $900/yr. Payback = 10 years-reject unless the fixture yields other benefits.