A welded bracket on a machine that cycles 20 times per minute. It cracked at the weld toe after 6 months. The weld looked fine. The static strength was fine. It failed in fatigue. The…
I was asked to measure the deflection of a welded frame under load. I mounted a strain gauge on the frame, wired it to a signal conditioner, and read the output. The number bounced around…
A gear reducer on a conveyor. It was rated for 500 N·m output torque. The conveyor needed 200 N·m (40% load). After two hours of operation, the reducer housing was too hot to touch (85°C)….
A pneumatic cylinder that took 0.8 seconds to extend over 100 mm. The customer wanted 0.3 seconds. The cylinder was fine. The tube from the valve to the cylinder was 6 mm ID, 5 meters…
A servo motor coupled to a ball screw. The axis had 0.1 degrees of lost motion at the motor shaft. The customer thought the servo was missing steps. It wasn’t. The coupling was a jaw-type…
A compressed air system at a customer’s plant. The compressor cycled on every 3 minutes even though no machine was running. I put a ultrasonic leak detector on the lines. It found 12 leaks. The…
A vacuum gripper on a pick-and-place robot. It couldn’t hold a perforated cardboard box. The customer thought the vacuum pump was weak. It was a small venturi ejector. The box leaked. The ejector couldn’t pull…
A ball screw axis that vibrated violently above 2000 RPM. The customer thought the servo tuning was off. It wasn’t. The screw was approaching its critical speed — the natural frequency of the screw as…
A fixture that locates a part within ±0.1 mm. The parts were 0.3 mm off. I ran the tolerance stackup. The design had four dimensions in the chain, each with ±0.1 mm tolerance. Worst case:…
I’ve seen FEA models that show a stress concentration at a bolt hole. The engineer read the peak stress as 450 MPa and flagged the part for failure. But the peak was at the center…
A Ø50 cylinder, 500 mm stroke, pushing a 200 N load horizontally. It didn’t push — the rod bent. The customer thought the cylinder was weak. It wasn’t. At full extension, the rod was like…
A timing belt drive between a servo motor and a ball screw. The belt slipped under acceleration. The customer had installed a 2:1 reduction but the belt was the wrong width. The motor was 750W,…
A VFD (variable frequency drive) in a sealed electrical cabinet. It tripped on over-temperature every hot afternoon. The cabinet was 600×800×300 mm, sealed, with the VFD dissipating 120 W. The customer thought the VFD was…
I was reviewing a welded frame last week. The engineer had used a 50×50×3 mm square tube as a crossbeam spanning 1.5 m, carrying a 100 kg axis at center. He said “it’s square tubing,…
A servo axis that buzzed and oscillated at low speed. The motor was 400W, the load was a 20 kg slide on a ball screw. The drive tuned fine at high speed. At 10 mm/s…
