Mec-B4 — Integrated Manufacturing Systems
Production automation and the role of the computer in modern manufacturing systems via a comprehensive overview of applications of advanced technologies in manufacturing and their business impact on the competitive dimensions of cost, flexibility, quality and deliverability. Particular topics include: cellular and flexible manufacturing systems, fundamentals of automation, numerical control programming, material handling and storage, automatically-guided vehicles, manufacturing information systems, production planning and control, automatic identification and data collection, lean and agile manufacturing, computeraided process planning, quality control.
Subject outline
Mec-B4 Integrated Manufacturing Systems is a Mechanical Engineering technical exam (PEO National Examination 16-Mec-B4). Its official syllabus covers production automation and the role of the computer in manufacturing: cellular and flexible manufacturing systems, fundamentals of automation, numerical control programming, material handling and storage, automatically guided vehicles, manufacturing information systems, production planning and control, automatic identification and data collection, lean and agile manufacturing, computer-aided process planning and quality control. The two 2019 papers solved here examined the systems side of running a plant: inventory control and the economic order quantity; production planning and control; break-even analysis; statistical process control with x̄ and R charts; process capability; the reliability of series, parallel and redundant systems; forecasting; engineering economy — present and future worth and rates of return; automation, robot cells and cycle time; and job-shop scheduling by priority dispatch rules. This course is built on those two papers, so it does not teach NC part programming, AGV and storage-system sizing, flexible manufacturing systems, automatic identification and data collection, computer-aided process planning or lean and agile manufacturing.
The paper is 3 hours and open book; any non-communicating calculator is permitted. Each sitting sets seven questions, most of them in two parts — twenty-three parts in all across the two papers — and you answer any five: any five constitute a complete paper, only the first five as they appear in the answer book are marked, and all questions are of equal value. No mark value is printed anywhere on either paper. Some questions require an answer in essay format, so budget writing time as well as calculating time. Because the paper is open book, the formula sheet in this course is built to be checked against your own text and taken in.
What this course gives you
Worked solutions — all twenty-three question parts from May 2019 (seven questions, eleven parts) and December 2019 (seven questions, twelve parts), fully retypeset as live maths with the final answers pulled out ahead of the working and every data table set as a real table, and every published answer checked — with five corrections flagged at the exact step that goes wrong, and three further slips in the published working caught in notes. The five flagged corrections: the May Q1(a) published order size of 2,467.43 dollars of stock (half a week of supply) does not pass the EOQ check — at that quantity the two cost arms differ by a factor of a thousand, because the published route substitutes the average stock Q/2 for the per-unit holding cost and ends up solving an equation in Q to the power 3/2; balancing the two arms gives 86,667 dollars of stock, 17.3 weeks of supply, at 15,600 a year against 274,191, and that is the answer given here. May Q3(b): materials-handling labour is normally an indirect cost (factory overhead), not the direct cost the published answer claims. May Q6: the standard DAC relation gives an output of 7.03 V (10 × 45/64), not the 7.14 V the published solution gets by dividing by 2⁶ − 1. December Q4(b)(i): the question gives no tax rate, so the unadjusted rate of return is 44%, not the 35.2% the published solution reaches with an assumed 20% tax. And in December Q7, three of the five dispatch sequences the published solution lists (static slack, first-in-system-first-served and slack per remaining operation) do not follow from the priority values it computes itself, and its slack values mix time conventions; the sequences here are ranked straight off a recomputed priority table, and FCFS and SOT agree with the source exactly. The three notes: May Q2(b) labels the lower control limit (15.53 cm) as a second UCL; December Q2(a) evaluates the second capability term with 4 in place of the lower specification limit 4.4 — the smaller term still governs, so Cpk = 0.33 stands; and December Q5 writes a load-and-unload time of 0.1 + 2 × 0.1 + 0.1 as 0.6 min when it is 0.4, the value its own boxed cycle time of 10.1 min and production rate of 47.52 parts a day depend on (that model leaves out the robots' empty return moves; counting them gives 26.3 and 10.7 min, and the solution shows both). Where a published figure stands it is used; where it does not, the published value is quoted and a flagged correction of its own — headed, and set into the working at the step that fails — explains what went wrong and gives the value the same numbers actually give. Essay and discussion questions — the parts this paper sets in essay format are answered in full, not sketched: the benefits of planning a materials-handling system, whether its labour is a direct or an indirect cost, and why plant layout is decided at the same time (May Q3); the categories of forecasting techniques, and choosing a method for two years of monthly demand once it is plotted (December Q3); a statement of the true value of a measured part from the instrument's accuracy and precision (December Q2(b)); and which dispatch rule to prefer and why (December Q7). Study notes — ten condensed topics: inventory control and the EOQ; production planning and control; break-even analysis; statistical process control with x̄ and R charts; process capability; reliability of systems; forecasting; engineering economy — present and future worth; automation, robotics and cycle time; and scheduling and priority dispatch rules — each pointing back at the exam questions it answers. Formula sheet — two pages in five groups: inventory control; production planning and control; break-even and profit; control charts and capability; and reliability, economy and scheduling — 37 relations, every one the two papers actually use. This exam is open book, so print it, check it against your own text and take it in. Reference links — ten, each with a note on what it is good for: six to reading (techniques of inventory control, the steps of production planning and control, break-even analysis, statistical process control, present and future value, and a search of MIT OpenCourseWare for manufacturing-systems material) and four to YouTube, each opening a search for the topic it names — the economic order quantity, x̄ and R control charts, series and parallel reliability, and priority dispatch rules. Printable resources — four blank exam stationery templates: a ruled answer sheet matching the answer-book layout, dot-grid rough-work paper, graph paper and isometric paper — plus the formula sheet, all printing straight from the page. Practice papers — the two question papers on their own, unmarked, for a timed run: May 2019 (4 pages, questions 1 to 7) and December 2019 (5 pages, questions 1 to 7) — the same two sittings that are solved above.
Throughout, 90 figures were drawn for this pack — 54 in the solutions and 36 in the notes — so the cost curves, saw-tooth inventory plots, control charts, capability curves, reliability block diagrams, cash-flow diagrams, demand plots and robot-cell time strips are shown rather than described.