23-Ind-A2 Analysis and Design of Work · December 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 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 prints Question 3's second and third sub-parts both labelled “(iii)” in the question text (and the marking-scheme line repeats “(ii)” for the same slot) — a typesetting slip; they are answered here in the marking-scheme order (i)/(ii)/(iii), 8/6/6 marks.
Reference texts: Niebel & Freivalds, Niebel’s Methods, Standards, and Work Design (13th ed.) — operations analysis and process/flow charting, motion economy, multiple-machine assignment, stopwatch time study, performance rating and allowances, predetermined time systems (MTM/MOST), work sampling, and 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.
Operations (or “operation”) analysis is the critical-examination stage of the classical methods-engineering procedure — select the job, record the present method, then question every recorded detail before a new method is developed and installed. Design of parts and choice of materials are two of the standard lines of questioning applied at this stage, and both act as upstream levers: a change made here removes cost before a single operation, transport or inspection step is ever performed, whereas method changes downstream of a fixed part/material design can only rearrange or speed up work that the design itself has already made necessary.
(a) Design of parts. Every dimension, tolerance and feature specified on a drawing drives a corresponding operation, fixture, inspection step and scrap allowance on the shop floor. Operations analysis asks whether each specified tolerance, surface finish, hole, boss or feature is actually required by the part’s function and assembly fit, or whether it exists only by convention or over-caution. Loosening an unnecessarily tight tolerance can eliminate a finishing operation and its inspection step outright; combining two features that were designed as separate details (e.g., two bosses machined in one setup instead of two) removes a whole transport-and-refixture cycle. Because the part design is fixed before methods engineering typically becomes involved, catching an unnecessary feature or tolerance at the design-review stage is the single highest-leverage opportunity in the whole operations-analysis checklist — it prevents cost from ever entering the process, rather than trimming cost already committed.
(b) Materials. The material specified governs which processes are even available (castable vs. only machinable stock), the cycle time and tool wear of every operation performed on it, and the scrap/yield loss at each step. Operations analysis questions whether a cheaper, more workable, or more readily available material substitute would meet the same functional requirement (strength, corrosion resistance, appearance); whether purchasing stock closer to finished shape (near-net-shape casting or forging instead of bar stock requiring heavy material removal) would eliminate whole roughing operations; and whether standard, catalogue material sizes are used in place of special-order stock that adds lead time and cost with no functional benefit. As with part design, a material substitution decided early removes downstream operations and inspection steps entirely rather than merely making them faster, which is why both design of parts and materials are treated as primary — not secondary — approaches within operations analysis.
A flow process chart records every step a part, material, or worker goes through — not just the productive operations — using five standard ASME symbols: a circle for an operation (a step that changes the part’s form, adds a component, or otherwise adds value), an arrow for a transportation (the part or worker is moved from one place to another), a square for an inspection (the part is checked for quality/quantity without being changed), a large “D” for a delay (the part waits before the next step, uncontrolled by the process itself), and an inverted triangle for a storage (the part is held under authorization, as opposed to an unplanned delay). Each symbol is entered on its own numbered row, connected top-to-bottom by a vertical line showing the sequence, with the distance moved (for each transportation) and the time or quantity recorded alongside.
The summary form heads or foots the chart with a tally of how many steps of each type occurred, the total distance moved, and the total (or estimated) time consumed by each category — here, 2 operations, 2 transportations (55 ft total), 1 inspection, 1 delay and 2 storages.
| Symbol | Activity | Count | Distance |
|---|---|---|---|
| ○ | Operation | 2 | — |
| ⇒ | Transportation | 2 | 55 ft |
| □ | Inspection | 1 | — |
| D | Delay | 1 | — |
| ▽ | Storage | 2 | — |
The summary form is what turns the chart from a record into an analysis tool: because only operations add value, every count in the Transportation, Inspection, Delay and Storage rows is a candidate for elimination or reduction, and the summary lets the analyst see at a glance which category dominates the process before redesigning it.
(a) Flow process chart. Because it itemizes every step, not only the value-adding operations, the flow process chart is the primary tool for identifying and quantifying non-productive activity: it exposes how much of a part’s total cycle time is spent moving, waiting or being inspected rather than being worked on, and gives a distance and time total for each category that becomes the baseline against which an improved method is measured. It is used to compare an existing method against a proposed one side by side (before/after charts), to justify combining or eliminating steps (e.g., moving an inspection into an operation so the two collapse into one symbol), to support plant-layout and material-handling decisions by quantifying how much travel a re-arrangement would remove, and to standardize and document an approved method once installed so it can be audited later.
(b) Flow diagram. The flow diagram plots the same symbol sequence directly onto a scaled floor plan of the work area, connecting each symbol with the actual physical path travelled. Where the flow process chart gives the numbers (how many steps, how far), the flow diagram gives the geometry (where the backtracking, crossing paths and congestion actually occur), so the two are normally prepared together. It is used to spot backtracking and crossed traffic patterns that a purely tabular chart cannot reveal, to plan a physical re-layout of machines, benches and storage points that shortens the plotted path, to identify safety and congestion problems where paths of different workers or material streams cross, and to communicate a proposed new layout to floor supervisors and workers in a form that is immediately intuitive without reading a table.
