Batch Production of Acrylic Desk Organizers
A technology education class has agreed to produce 120 desktop organizers for a community event. Each organizer is a 150 mm by 100 mm acrylic base with two 30 mm slots and a laser-etched logo. The class has a 60 W laser cutter that cuts one base in 9 minutes, a 3D printer that makes one organizer in 6 hours, and a manual drill press. Acrylic sheet costs $18 for a 600 mm by 400 mm sheet; each sheet yields six bases with layout nesting. The laser kerf is 0.15 mm. The event is in four weeks, and the class meets five 50-minute periods per week. The teacher wants students to learn production planning, not just operate machines. A local business offers to donate injection-molded organizers, but the teacher wants student work. One student suggests skipping a prototype and cutting all parts immediately.
1. Determine whether the laser cutter alone can meet the deadline on class time and calculate the acrylic material cost. State your assumptions.
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Material: 120 organizers divided by 6 bases per sheet equals 20 sheets. At $18 per sheet, the acrylic cost is 20 times $18, or $360, before scrap and replacement. If the nesting wastes a sheet or a sheet is cracked, add at least $18 per extra sheet.
Time: 120 bases times 9 minutes equals 1,080 minutes, or 18 hours of cutting. Available class time is 4 weeks times 5 periods times 50 minutes, or 1,000 minutes, about 16.7 hours. That assumes every minute is available for cutting, which is unrealistic because of setup, instruction, cleanup, etching, and maintenance. So the laser alone does not fit comfortably in class time. The 3D printer is not viable: 120 times 6 hours equals 720 hours. The class needs roughly 2 or more additional hours, a reduced order, or an outside cutting session. A 100-unit order would require 900 minutes, about 15 hours, and would fit only with tight scheduling.
2. Outline a production plan that teaches planning and quality control. Include kerf and first-article inspection.
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Start with one prototype base cut from scrap or a partial sheet. Measure the slot width and base dimensions, check fit with the intended card or tablet, and adjust the CAD file for kerf. The 0.15 mm kerf matters because a slot cut without compensation can come out undersized or oversized depending on how the cutter offsets the path. The first article is the reference, not the drawing alone.
Then nest six bases per sheet, schedule 20 sheets across the available sessions, and assign roles: CAD/nesting, machine operator, measurement, etching, cleanup, and inventory. Cut one sheet, inspect the first part and one random part, and only then continue. Record scrap and dimensional checks every 10 parts. Keep a labeled reject bin and a replacement sheet reserve. The teacher should sign off on the first article before batch production. This teaches the difference between making a part and controlling a process, and it prevents a small CAD or focus error from being repeated 120 times.
3. The student wants to skip the prototype. Explain why that is a poor decision here, using cost, time, and quality reasoning.
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Skipping the prototype saves at most one 9-minute cut and a small piece of acrylic, but it exposes the whole batch to a single unverified setup. If the kerf compensation is wrong, the slots may not fit; if the nesting is wrong, a sheet may yield only five bases; if the etch is misaligned, 120 parts may be marked incorrectly. A rejected sheet costs $18 and 54 minutes of cutting, plus the time to recut and reschedule.
The prototype also supports the learning goal. Students should see that production planning includes first-article inspection, not just running the machine. A controlled first article gives them data: measured slot width, edge quality, and fit. Those data justify any CAD change before committing the remaining 19 or more sheets. The correct decision is to prototype one or two bases and inspect them, not to cut all 120 immediately.