23-Ind-A2 Analysis and Design of Work · December 2017
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2017 — 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 front-page marking scheme prints Question 3's third entry as “(ii) 6”, a typesetting slip for “(iii) 6”; Question 3 as printed carries sub-parts (i) and (ii)(a)/(b), which are answered here against the 7/7/6 split.
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 analysts use a family of standardized charts, each matched to a different scope of the work being studied. At the plant/process level, the flow process chart records every operation, transportation, inspection, delay and storage a material or worker experiences, in sequence, using the ASME symbols (circle, arrow, square, triangle, D); the companion flow diagram plots that same sequence as a scaled route on the actual floor layout, exposing backtracking and excessive travel that a symbol list alone hides. At the workstation level, the operation process chart summarizes only the operations and inspections across an entire assembly (with a Gozinto-style tree of component parts), giving a one-page overview before detailed study begins. For a single workstation with two or more interacting resources, the right-hand/left-hand (operator) chart records each hand's motions side by side against a common time scale to spot idle-hand time and motion imbalance, while the human-machine (multiple-activity or man-machine) chart, detailed in part (ii), does the same for an operator working with one or more machines. Finally, micromotion study (a filmed or video record analyzed frame-by-frame into Therblig-level elemental motions) is used when the cycle is very short and high-volume enough to justify motion-level detail beyond what any chart can show directly.
A human-machine chart (also called a multiple-activity or man-machine chart) records, on a common vertical time scale, what the operator is doing in one column and what each machine is doing in an adjacent column, so the two activity streams can be read against each other at every instant of the cycle. Each column is divided into blocks representing continuous periods of working (operator loading/unloading/servicing, or machine running automatically) versus idle time, drawn to scale so that the length of a block is proportional to its duration.
The chart's summary form is a small table appended below (or beside) the chart itself, totalling for each resource the working time, the idle time, and the resulting percentage utilization (working time ÷ total cycle time × 100) over one full cycle — for the illustrative cycle above, the operator works 8 of 24 min (33% utilized) while the machine works 12 of 24 min (50% utilized). This numeric summary is what makes the chart actionable: a chart with no summary shows the pattern but not the magnitude of the opportunity.
The main uses of a human-machine chart are: (1) identifying and quantifying idle time on the more costly resource (operator or machine) so that a re-balancing of the work — assigning the operator additional machines, or overlapping a second operator's cycle — can be evaluated before it is implemented; (2) supporting the multiple-machine assignment calculation, where the chart's idle-time pattern is exactly what determines whether the operator or the machines are the limiting resource; (3) comparing proposed method changes on a like-for-like basis, since a "before" and "after" chart pair makes any reduction in idle time immediately visible; and (4) documenting the interaction for training, standard-setting, and layout/staffing decisions where several machines share one operator.
Operations analysis is a systematic questioning of every element of a job — purpose, design, tolerances, material, sequence of operations, setup, working conditions, material handling — conducted before any detailed motion or time study, because changes made at this stage typically yield far larger savings than any amount of subsequent motion refinement of an unchanged job.
(a) Design of parts. The part's own design (dimensions, tolerances, material specification, finish, and the number of separate parts an assembly is broken into) fixes a large share of the manufacturing cost before a single operation is planned: unnecessarily tight tolerances demand slower machines, more inspection and higher scrap; more separate parts than functionally necessary multiply handling, fastening and inspection operations; and a shape poorly suited to the intended process (e.g., a casting design that requires extensive secondary machining) locks in cost that no amount of downstream methods improvement can remove. Reviewing design for manufacturability — simplifying shapes, relaxing non-critical tolerances, combining parts, substituting easier-to-process materials where function permits — is therefore one of the highest-leverage steps in operations analysis, because it is applied once, upstream, rather than being fought against on every cycle thereafter.
(b) Process of manufacture. For a given part design, the choice of process (e.g., casting vs. machining from bar stock, stamping vs. welding a sheet-metal assembly, manual vs. automated assembly) and the sequence and grouping of operations within that process determine cycle time, tooling cost, quality consistency and volume flexibility. Operations analysis asks whether the current process is still the right one for today's volume and equipment (a process selected for low volume may be badly suited once demand has grown, and vice versa), whether operations could be combined or eliminated (e.g., machining two features in one setup instead of two), and whether a different sequence would reduce handling or setup time. Because process choice interacts directly with part design (a design decision can make one process feasible and another impractical), the two must be reviewed together rather than in isolation — a good process cannot fully compensate for a design that fights it, and a good design is wasted on a mismatched process.
