23-Ind-A4 Production Management · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Technical Examinations — December 2019 — 17-Ind-A4 Production Management. Three-hour, closed-book exam; Casio or Sharp approved calculators only. Format: seven questions, each worth 20 marks (sub-part weights per the front-page marking scheme); candidates do two questions from Section A and three from Section B, and only the first five questions appearing in the answer book are marked. All seven are solved below for completeness. The paper asks for point-form answers wherever possible; the solutions below use full working for clarity.
Reference texts: Liker, The Toyota Way, and Shingo, A Revolution in Manufacturing: The SMED System — JIT, 5S/andon/poka-yoke/SMED/TPM and lean root-cause analysis; Niebel & Freivalds, Methods, Standards, and Work Design — process charting and methods analysis; Nahmias & Olsen, Production and Operations Analysis (7th ed., Waveland/McGraw-Hill) — forecasting, lot sizing (Wagner–Whitin) and aggregate planning; Hillier & Lieberman, Introduction to Operations Research (11th ed.) — project scheduling (CPM/PERT); Pinedo, Scheduling: Theory, Algorithms, and Systems (5th ed.) — parallel-machine scheduling and days-off workforce scheduling.
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.
Given. A three-stage build for one custom order: kitting (pick components → place in "internals" bin), case customization (create custom case → retrieve case/power supply/cooling → print custom graphics), assembly (retrieve "internals" bin → assemble and install into case).
Find. (a) A process chart of the described sequence; (b) a revised, improved process chart, with the wastes it removes explained.
The chart above lays out the described sequence as seven steps: 1 pick components (Operation), 2 place them in the "internals" bin (Operation, followed implicitly by Storage/Transport of the bin while case work proceeds — a Delay), 3 create the custom case (Operation), 4 retrieve the case, power supply and cooling system (Operation), 5 print custom graphics on the case (Operation), 6 retrieve the "internals" bin from storage (Transport), and 7 assemble and install the components into the case (Operation). As drawn, the two work streams — kitting and case customization — are sequential rather than parallel, so the internals bin, once filled at step 2, sits idle (a delay, the classic process-chart symbol for waiting work-in-process) for the entire duration of steps 3–5 before it is finally retrieved at step 6.
The revision releases both work streams from the order at the same instant instead of sequentially: 1 pick components (Operation, parallel) and 2 create the custom case (Operation, parallel) start together, 3 the two outputs are brought together the moment both are ready (a single combined transport/inspection point, no storage in between), 4 retrieve the power supply and cooling system and print the case graphics (Operation), and 5 assemble and install (Operation). This collapses the original seven steps to five and removes the separate step-6 "retrieve internals bin" transport entirely, since the bin never goes into storage in the first place.
This reduces waste in two concrete ways. First, it eliminates the waiting/delay waste identified in part (a): the internals bin no longer sits idle in storage for the whole duration of case customization — a real cost in a build-to-order shop, since that WIP ties up floor space and picked components (which may be needed elsewhere) for no value-adding reason. Second, it eliminates the excess transport/motion waste of a separate retrieval step (the original step 6): synchronizing the two streams so they meet exactly once, rather than storing and re-fetching the bin, removes a non-value-added handling step and its associated risk of misplacing or damaging a picked kit. The remaining process time is unchanged (the same work is still done), but total flow time for a customer's order shortens by however long the bin previously waited in storage, and one handling touch is removed from every order.
Beyond the two wastes already named in part (b), the revised process reduces waste along three further dimensions recognized in lean manufacturing's seven-wastes framework (muda). Overproduction/excess inventory waste is reduced because the internals bin, under the original sequence, effectively became a small work-in-process inventory buffer sized to the duration of case customization; running the two streams in parallel removes the need to hold that buffer at all, so less capital and floor space sit tied up in partially-completed orders at any instant, which matters directly in a build-to-order shop where every order is unique and cannot be sold to a different customer if left incomplete. Motion waste is reduced at the point where the two streams converge: instead of a technician having to locate, retrieve and physically carry a bin that has been sitting in a storage area (and potentially searching for it if storage is disorganized), the bin is handed directly from kitting to assembly the moment both streams are ready, removing unnecessary walking and searching motion. Finally, defect waste is reduced indirectly: a kit that sits in storage for an extended, variable period is more exposed to being misplaced, damaged, or having a component pulled for a different rush order by mistake — risks that shrink to nearly zero once the window between kitting and use is compressed from "the whole case-customization stage" to "the instant both streams finish." Taken together, the revised process does not change how much work each step performs, but it removes every unit of time and handling that this specific order's parts previously spent waiting, moving, or at risk while idle — the classic lean result of exposing and removing waste through re-sequencing alone, with no new equipment or added labour.
