Running hot
Running hot turns up in 2 fields: tribology, thermal spray. Here is what it means to the people in each one.
Running hot in tribology
Shop phrase for a bearing, gearbox or motor operating above its normal temperature.
Shop shorthand for equipment running well above its usual temperature, checked with an infrared gun, thermal camera or a temperature sticker. Common lubrication causes are overgreasing, the wrong viscosity, low oil level, a fouled cooler and contamination. A rise of about 10 C over baseline is a common trigger to investigate, and by the Arrhenius rule of thumb every 10 C of extra heat roughly halves oil life.
"Fan bearing's running hot, 88 C on the gun against 60 last week, and somebody greased it yesterday."
Running hot in thermal spray
Booth talk for parameters that are overheating the particles or part; running cold is the opposite.
Said of a gun whose settings put too much heat into the particles or substrate: high power, extra hydrogen, short standoff or slow traverse. Running hot raises oxide content, decarburizes carbides, vaporizes fines and overheats parts. Running cold, with low power or long standoff, gives unmelts, low deposition efficiency and higher porosity, and a good parameter set sits between the two.
"Carbide's coming out brittle and the W2C peak is up on XRD, we're running hot, back the oxygen off."