Automating a Stainless Longitudinal Seam: Payback and Risk
Your shop welds 2,400 ft of longitudinal seam per year on 3/16 in. stainless steel. Manual GTAW takes 0.9 hr/ft at $58/hr fully burdened, with 10 percent rework at $45/ft. A used seam tracker and automated GTAW setup costs $78,000 delivered, plus $12,000 installation and $6,000 training. It should run 0.35 hr/ft at $92/hr all-in, with 4 percent rework at $30/ft. Annual maintenance is $4,500. Floor space and power are available. The owner requires payback under 24 months and will not borrow. Production volume is stable, but the only two GTAW welders are near retirement. The shop has no automation experience, and one welder is openly skeptical. The owner asks for a recommendation with numbers, not enthusiasm.
1. Calculate annual cost, savings, and simple payback. Does the project meet the owner's hurdle?
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Manual annual cost: labor = 2,400 x 0.9 x $58 = $125,280; rework = 2,400 x 10 percent x $45 = $10,800; total = $136,080. Automated annual cost: labor = 2,400 x 0.35 x $92 = $77,280; rework = 2,400 x 4 percent x $30 = $2,880; maintenance = $4,500; total = $84,660. Annual savings = $136,080 - $84,660 = $51,420. Capital cost = $78,000 + $12,000 + $6,000 = $96,000. Simple payback = $96,000 / $51,420 = 1.87 years, or about 22.4 months. The project technically meets the under-24-month hurdle, but the cushion is only about 1.6 months. If startup scrap and downtime add $10,000, payback rises to about 24.7 months and fails. I would recommend proceeding only with a firm installation and startup budget and a customer volume commitment.
2. What non-financial risks could change the decision?
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Volume is the biggest assumption. A 10 percent drop in footage cuts savings to roughly $46,000 and pushes payback past 25 months. Retirement cuts both ways: losing the two GTAW welders is a reason to automate, but someone must still run, program, and maintain the machine. A single machine failure could stop the seam line, so spare parts and a service agreement matter. The skeptical welder is a real implementation risk; training may take longer than $6,000 suggests. Stainless quality depends on consistent fit-up, and automated GTAW can produce lack of fusion if the joint gap varies. The WPS and operator still need qualification. The $92/hr machine rate may omit floor space, power, and programming time. Also consider whether the customer will accept the automated weld without additional qualification or inspection.
3. If volume falls 30 percent, does the project still meet the owner's hurdle? Show the calculation.
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At 1,680 ft per year: manual labor = 1,680 x 0.9 x $58 = $87,696; rework = 1,680 x 10 percent x $45 = $7,560; total = $95,256. Automated labor = 1,680 x 0.35 x $92 = $54,096; rework = 1,680 x 4 percent x $30 = $2,016; maintenance = $4,500; total = $60,612. Savings = $34,644 per year. Payback = $96,000 / $34,644 = 2.77 years, or about 33 months. That fails the 24-month hurdle. The decision therefore depends on contracted volume, not hope. I would seek a three-year customer commitment, a lower-cost used machine, or a lease arrangement before committing. If the shop cannot secure volume, keep the manual process and cross-train a third welder to reduce retirement risk.