Industries as varied as paper production, steelmaking and power generation rely on servo valves for precise motion control. A servo valve can last well above 1 billion cycles. But achieving that longevity only happens when selecting the right manufacturing techniques, mechanical designs and maintenance approach.
A Paper Chase
Paper mills, for example, use hydraulic pistons placed inside a roll to exert forces at each load zone to maintain a controlled profile across the complete width of the roll. The force exerted by each piston is controlled by a pQ (pressure and flow) servo valve that controls the position and pressure on these rolls as paper runs almost continuously through the machine shift after shift. If one spot on a roll causes a variation in pressure or position, the paper can slide or rip causing a stoppage that can shred the paper into confetti. We recently found the customized servo valves running a paper mill’s calendar rolls weren’t able to consistently control the pressure on its paper because routine repairs (by an un-authorized repair house) had not restored the valves to original condition.