23-Ind-B2 Manufacturing Processes · December 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Examinations, December 2019 — 17-Ind-B2 Manufacturing Processes. 3-hour closed-book exam; candidates may use a Casio or Sharp approved calculator. Any five questions constitute a complete paper (only the first five as they appear are marked officially); all seven are answered below as a full study resource.
Reference texts. Groover, Fundamentals of Modern Manufacturing: Materials, Processes, and Systems, 6th ed. (primary text for this subject — material selection, casting, polymer processing, machining, and composites).
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.
A progressive die carries several individual stamping operations — typically a sequence such as piercing, notching, bending, and finally blanking (part cut-off) — laid out as separate stations within one continuous die set. A coil or strip of sheet stock is fed automatically through the die, one station-pitch per press stroke; each stroke simultaneously performs one operation at every station, so the strip carries a part in progress that is a little further along at each successive station, and a finished part drops out of the last station on every stroke once the die is running at steady state.
This is recommended over performing the same operations as a sequence of separate single-operation dies (each in its own press) for several compounding reasons. First, production rate is far higher: one press stroke on one machine completes an entire part (once steady state is reached), instead of requiring the part to be individually handled, positioned, and struck in several separate presses. Second, labour and material-handling cost drop sharply, because the strip is fed and indexed automatically from station to station — there is no manual transfer of individual blanks between machines, and no risk of a part being mishandled or dropped between operations. Third, dimensional accuracy and part-to-part consistency improve, because the part-in-progress stays registered to the same strip (usually via pilot holes punched at an early station and used to precisely locate the strip at every later station) all the way through the die, rather than being re-clamped and potentially misaligned each time it moves to a different machine. Fourth, a single progressive die consolidates the tooling, floor space, and capital equipment that several separate single-station dies and presses would otherwise require, lowering both the piece-part cost and the plant footprint for high-volume sheet-metal production.
