11-CS-4 Engineering Law and Professional Liability · May 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2018 — 11-CS-4 Engineering Management. Closed book; no calculators. Any five questions constitute a complete paper; all questions are of equal value (20 marks each). Full worked answers to all seven questions are given below.
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.
Design for Manufacturability is the practice of designing a product so that it can be made easily, reliably, and economically, recognizing that the majority of a product's cost is committed at the design stage. The factors that must be considered include minimizing the number of parts, since every part carries tooling, assembly, and inventory cost and adds a potential failure point; standardizing components and materials so that common, off-the-shelf items replace custom ones; and designing for ease of assembly (Design for Assembly), for example by providing self-locating features, symmetry or clear asymmetry to prevent misorientation, and access for tools. Further factors are selecting appropriate materials and processes matched to the production volume, specifying realistic tolerances—tight tolerances raise cost sharply and should be relaxed wherever function permits—and designing for the chosen process (draft angles for moulding, adequate radii for casting, and avoidance of features that require secondary operations). Designers must also consider ease of inspection and testing, modularity to allow variety without complexity, and serviceability so the product can be maintained. Concurrent engineering, in which manufacturing and quality staff participate from the outset, is the organizational mechanism that makes DFM effective.
Lean manufacturing, derived from the Toyota Production System, is a philosophy of producing more value for customers while consuming fewer resources by relentlessly identifying and eliminating waste (muda)—any activity that consumes resources without adding value the customer would pay for. The classic seven wastes are overproduction, waiting, unnecessary transportation, over-processing, excess inventory, unnecessary motion, and defects. Lean pursues these objectives: to eliminate waste in all its forms; to reduce cost and lead time while improving quality; to establish continuous one-piece flow and pull production in which items are made only in response to actual demand (just-in-time) rather than pushed to forecast; to level and smooth production; and to foster continuous improvement (kaizen) through the involvement and respect of the workforce. Supporting techniques include value-stream mapping, 5S workplace organization, kanban signalling, quick changeover (SMED), and mistake-proofing (poka-yoke). The overarching aim is a responsive, low-inventory system that delivers exactly what the customer wants, when wanted, at the lowest sustainable cost.
(a) Total Quality Management (TQM) is an organization-wide philosophy whose objective is to embed quality into every process and every employee's responsibility, driven by customer satisfaction as the ultimate measure of success. Its objectives are continuous improvement (kaizen) of all processes, full employee involvement and empowerment, management by fact using data, strong supplier partnerships, and a culture in which quality is designed and built in rather than inspected after the fact. (b) Six Sigma is a rigorous, data-driven methodology whose objective is to reduce process variation and defects to an extremely low level—no more than 3.4 defects per million opportunities—thereby lowering cost and raising consistency. It pursues this through the structured DMAIC cycle (Define, Measure, Analyze, Improve, Control) applied by trained practitioners (Green and Black Belts) using statistical tools. Where TQM sets the broad cultural aim of universal quality, Six Sigma provides the disciplined statistical machinery to achieve near-perfect process performance; the two are complementary and are often combined as Lean Six Sigma.
An engineering team redesigning a pump housing would apply DFM by consolidating three bolted plates into a single casting with generous draft and relaxed non-critical tolerances, cutting part count and assembly time. On the shop floor, value-stream mapping would expose waiting and inventory waste between machining and assembly, and a kanban pull system would cut work-in-process. A Six Sigma DMAIC project would then attack the leak-test failure rate by measuring variation in the seal groove and controlling the machining process, while the TQM culture keeps every operator engaged in ongoing improvement.
