A fabrication shop is a different beast than a machine shop. Where CNC monitoring tracks spindle loads and tool wear, fab monitoring tracks weld quality, press alignment, and consumable usage. The failure modes are different, the costs are different, and the monitoring approach needs to match.
A bad weld in structural steel is not a scrap part — it is a liability. A misaligned press does not just ruin a part — it ruins a die that costs $50,000 to replace. And arc-on time is the single metric that separates a profitable welder from one that is costing you money. This guide covers what to monitor in a fab shop and why the metrics are different from everything else in manufacturing.
Weld Quality: The Metric Nobody Tracks
Most fab shops inspect welds after the fact — visual inspection, dye penetrant, or X-ray on critical joints. The problem is that inspection catches defects, not drift. By the time you find a bad weld, the welder has been running with degraded gas flow or wrong wire feed speed for the entire shift.
Real-time weld monitoring tracks the parameters that predict quality:
- Voltage and amperage stability: Consistent arc voltage produces consistent penetration. Spikes indicate contact tip wear, gas coverage issues, or wire feed problems.
- Gas flow rate: Shielding gas flow below spec causes porosity. Above spec wastes gas at $0.50-$1.00 per cubic foot. Either way, it costs money.
- Wire feed speed: Deviation from programmed feed speed indicates drive roll wear, liner contamination, or incorrect tension.
- Travel speed: Too fast creates cold laps. Too slow causes burn-through on thin material. Monitoring travel speed identifies technique drift between operators.
Press Health: Protect the Die
A stamping or forming press applies hundreds of tons of force thousands of times per shift. When alignment drifts — even by thousandths of an inch — the die wears unevenly, parts go out of spec, and eventually the die cracks. Replacing a production die costs $20,000-$100,000 and takes weeks.
What to monitor on presses:
- Tonnage per stroke: Consistent force means consistent forming. Rising tonnage suggests die wear, material hardness variation, or lubrication issues.
- Vibration signature: A healthy press has a repeatable vibration profile. Changes in the signature indicate bearing wear, gibb looseness, or foundation issues — all precursors to misalignment.
- Cycle time consistency: Like injection molding, cycle time drift in pressing signals mechanical or hydraulic degradation.
Arc-On Time: The Productivity Metric for Welding
Arc-on time is the percentage of a welder's shift spent actually welding (arc struck, metal being deposited). Industry benchmarks show that most manual welders have 20-30% arc-on time. Robotic welding cells run 60-80%.
The remaining 70-80% of a manual welder's time goes to: fitup, part handling, grinding, inspecting, walking to get materials, waiting for crane time, and breaks. You cannot improve what you do not measure. Monitoring arc-on time per welder, per shift, per job type reveals exactly where time is lost.
Improving arc-on time by even 5 percentage points (25% to 30%) increases welding output by 20% — without hiring another welder.
Getting Started in Fabrication
Start with arc-on time tracking on your busiest welding stations and vibration monitoring on your highest-tonnage press. These two investments cover the highest-value failure modes in a fab shop.
Flowstate supports welders, presses, and fabrication equipment as part of 22 equipment types. Arc-on time, tonnage, vibration, and machine state data flow through the same Sparkplug B pipeline — no special integration required.
