Mfg-B6 — Metrology
The language and systems of measurement. Standards and measuring units system. Calibration and traceability and Optical, pneumatic, electronic and mechanical measuring instruments and related methods. Coordinate metrology and mathematical concepts of dimensional metrology. Measuring errors analysis, their sources and propagation. Uncertainty in physical measurements. Precision and surface engineering. Applications of computers in metrological work and the interfacing of digital measuring equipment.
Subject outline
Mfg-B6 Metrology is a Manufacturing Engineering technical exam (PEO National Examination 08-Mfg-B6) on dimensional metrology — the measurement side of manufacturing: measurement fundamentals (accuracy against precision, resolution, repeatability against reproducibility, and uncertainty), standards, calibration, traceability and the ten-to-one rule, geometric dimensioning and tolerancing to ASME Y14.5, scales, verniers and micrometers, gage blocks and wringing, mechanical, pneumatic and electronic comparators, surface plates, flatness and angular measurement with the sine bar, light, interferometry and optical measurement, surface roughness, and coordinate measuring machines.
This paper is unlike the other Manufacturing papers, and the pack is shaped accordingly. It is 3 hours and open book — note 2 on the front page of both sittings reads, in capitals, "This is an OPEN BOOK EXAM" — and it is examined almost entirely by multiple choice. Any non-communicating calculator is permitted, provided you write its name and model on the first inside left-hand sheet of the exam workbook. The paper has three parts. Part A is mandatory: sixty multiple-choice questions at one mark each (60 marks). Part B is mandatory: a single coordinate-measuring-machine measurement sequence for a drawn part (20 marks in December 2020, 25 in December 2012). Part C is a set of short essays at 5 marks each — three of which any two are marked in December 2020 (10 marks), four of which any three are marked in December 2012 (15 marks). So the two sittings total 90 and 100 marks respectively, and the pack states both wherever a mark count appears. The papers also contradict themselves, and the pack says so: the December 2020 front page claims Part A has 70 questions while its own Part A header says 60 (there are 60), and both front pages say the Part C essays "of your choice" will be marked while the Part C headers say only the first two (2020) or first three (2012) answers on the answer sheet will be.
What this course gives you
Worked solutions — all 120 multiple-choice questions from December 2020 and December 2012, grouped by topic rather than in exam order, each with the keyed answer and an explanation written for this pack: the published solutions mark the answer and say nothing else, so every one of the 120 explanations — why the keyed option is right and why the one you were probably tempted by is not — is new. Both Part B CMM measurement sequences are answered in full, as a complete, ordered, generic command sequence with the alignment established before anything is measured, and every Part C essay is written out — seven in all. Where the published Part B and Part C model answers go wrong, the original is quoted and a flagged correction, set into the working at the exact step that goes wrong, explains what went wrong and gives the answer that earns the marks — ten such corrections across the two sittings: the 2020 model answer probes a bolt-hole pitch circle that is not a surface, aligns the part before it has measured anything to align to, and never measures the dimensions the rubric asks for; the 2012 model answer clamps an unspecified material on magnetic V-blocks and is three PC-DMIS commands long when the rubric demands generic ones; and the essays describe calibration as adjustment, put NIST rather than the NRC at the head of a Canadian traceability chain, never mention uncertainty in a traceability answer, never state the mechanism or give a number for probe compensation, and organise the uncertainty essay around the pre-GUM systematic/random split that the GUM replaced. The two official keys disagree — and the pack carries both. 54 of the 60 questions recur between the sittings with the same stem and the same options, but on fifteen of them the two official keys give a different answer (a sixteenth merely moved letter when a fifth option was inserted). The pack lists the fifteen, dissects each one in the topic that owns it, and says which answer the standard references support — so there is no such thing as "the" Metrology key, and you learn the concept rather than the letter. Study notes — eleven condensed topics written as definitions and distinctions, because that is how this paper is examined: how this paper works (including the per-sitting key comparison); measurement fundamentals; standards, calibration and the ten-to-one rule; GD&T and ASME Y14.5; scales, verniers and micrometers; gage blocks; comparators; surface plates, flatness and angle; light, interferometry and optical measurement; surface roughness; and coordinate measuring machines — each pointing back at the exam questions it answers. Practice & case studies — ten fresh multiple-choice questions and five longer problems, none of them from the 120 above: a gage-block stack with its thermal error and wringing film; a vernier, a micrometer and the uncertainty budget behind them; the two-wire method for a screw-thread pitch diameter — including the slip in the study material supplied with this subject, whose worked example drops the wire-diameter term and prints 32.172 mm where the correct route gives 31.017 mm; a sine bar set to 27° 30′; and a complete inspection plan for a machined plate — all with worked answers. Formula sheet — two pages: the few real formulae this paper uses (vernier least count, the micrometer screw, the two-wire method, the sine bar, Ra, thermal expansion, the ten-to-one rule) alongside the definitional contrasts the questions actually turn on. This exam is open book, so it goes in with you. Printable resources — ten cards, including a table of every distinction the paper tests with the letter each sitting actually marks, and a seven-step CMM method card worth 20–25 marks on its own, plus four blank exam stationery templates. All of it may be carried into the exam. Practice papers — two question papers on their own, unmarked, for a timed run: December 2020, which is solved above, and May 2013, a sitting this pack does not solve — though most of its Part A questions and its Part B drawing also appear in the solved sittings, so treat it as a timed dress rehearsal rather than unseen material, and use it last.
Throughout, 82 figures were drawn for this pack — 43 in the solutions and 39 in the notes — so the vernier with its coinciding line, the micrometer barrel, the gage-block stack, the sine bar, the two-wire triangle, the tolerance zones, the fringes under an optical flat, the roughness profile, the 3-2-1 alignment and the probe-compensation vector are shown rather than described.