23-Ind-A3 Facilities Planning · December 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2015 — 98-Ind-A3 Facilities Design. Three-hour, closed-book exam (Casio or Sharp approved calculator only); any five of the seven questions constitute a complete paper and only the first five answered in the answer book are marked — all seven are solved below for completeness.
Reference texts: Tompkins, White, Bozer & Tanchoco, Facilities Planning (4th ed., Wiley) — the facilities-planning hierarchy, the facilities planning process, facility location and plant-site selection, manufacturing cells, machine space and line-balancing models, computerized layout algorithms (CRAFT/CORELAP), and material handling equipment/systems; Niebel & Freivalds, Methods, Standards, and Work Design (13th ed.) — assembly-line balancing (Ranked Positional Weight technique), balance delay, and production-quantity planning with scrap/rework.
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 manufacturing cell has a recognizable set of characteristics that distinguish it from both pure process (functional) layout and pure product (line) layout: (1) it groups dissimilar machines and processes that would otherwise sit in separate functional departments, physically together in one area; (2) it is dedicated to a part family — parts with similar processing requirements, identified through group-technology classification and coding, rather than to a single product; (3) material flow within the cell is largely one-directional (often arranged U-shaped or circular) rather than the crossing, backtracking flow typical of process layout; (4) it is operated by a small, dedicated, cross-trained team responsible for the whole part family’s processing, not a single narrow operation; (5) it carries low work-in-process inventory and short throughput time relative to process layout, because parts move directly from machine to machine within the cell; (6) equipment is typically right-sized and sometimes duplicated across cells (a cell owns the machines it needs, rather than sharing a centralized machine pool); and (7) it supports visual management and self-inspection, since the small team can see the whole flow for its part family. Together these characteristics place the cell in the middle ground between process layout (maximum flexibility, poor flow efficiency) and product layout (excellent flow efficiency, poor flexibility).
Advantages: (1) reduced material handling distance and cost, since the part family’s processing is concentrated in one area instead of spread across functional departments; (2) reduced work-in-process inventory and shorter manufacturing lead time, from the near-continuous flow within the cell; (3) improved quality, because a defect is caught within one or two stations of where it occurred rather than discovered downstream; (4) simplified production planning and control for the part family, since the cell is scheduled as a single unit rather than as many independent department routings; (5) improved space utilization relative to process layout, because in-process storage and queuing between departments is largely eliminated; and (6) greater job enrichment and operator ownership, since a small cross-trained team is responsible for a complete part family rather than one repetitive operation.
Disadvantages: (1) potential duplication of equipment across multiple cells (each cell owns machines that a centralized process department could otherwise share/pool), raising capital cost and lowering individual-machine utilization; (2) lower flexibility to product changes outside the part family that defines the cell — a genuinely new product family may not fit any existing cell’s equipment set; (3) cell workload can be imbalanced if the part family’s demand mix shifts, since the cell’s fixed equipment set is sized to an assumed mix; (4) requires a cross-trained, more highly skilled workforce, raising training cost and making staffing more constrained than for narrow, single-task process-layout jobs; and (5) the upfront group-technology classification and coding effort needed to identify valid part families is itself a significant planning investment before any cell can be designed.
Cellular manufacturing is a physical/layout enabler; JIT, TQM and TEI are management philosophies that each depend on exactly the conditions a cell creates, so each is applied to the cell in a specific, identifiable manner:
Through Just-in-Time (JIT). The benefit is enhanced by running the cell on small-lot, pull (kanban) production: because the cell’s flow path is already short and compact, setup times can be driven down (SMED-style reduction) enough to make small lots economical, and visual kanban signals between adjacent stations — straightforward in a cell, far harder across a scattered process layout — replace push scheduling. This converts the cell’s inherent short-flow advantage into an actual reduction in WIP and lead time, rather than leaving it as unrealized potential.
Through Total Quality Management (TQM). The benefit is enhanced by empowering cell operators to perform source inspection and stop-the-line quality checks at each station, since in a cell every operator can see the immediately preceding and following operation. This converts the cell’s short feedback distance into an actual reduction in defect propagation (a defect is caught within one or two stations, not at final inspection after many additional units have been built), and supports continuous-improvement (kaizen) activity because the same small team owns the whole part-family process.
Through Total Employee Involvement (TEI). The benefit is enhanced by giving the cell’s small, stable, cross-trained team genuine authority over process improvement, scheduling within the cell, and problem-solving — not just broader task assignment. Because the team already owns the entire part-family process (rather than one operation repeated in isolation), team members develop the broad process understanding TEI needs to be meaningful, and management must supply the corresponding authority for that understanding to translate into actual improvement.
In each case the mechanism is the same: the cell supplies a physical/organizational precondition (short flow, short feedback, whole-process ownership) that the JIT/TQM/TEI initiative then converts into a measurable benefit (lower WIP, fewer defects, more improvement activity) — the cell alone only creates the potential, and the three programs are what actually realize it.
