In an effort to boost the popularity of fluid power components, makers of hydraulic and pneumatic devices are banding together to create reliability standards.
The proposed benchmarks, which are expected to reach initial draft form this fall, will provide users of cylinders, valves, pumps, and other components with ways to obtain hard data, and therefore simplify the purchase process.
Test Curve: Using standardized tests,
reliability of fluid power products could be represented by a so-called
Wiebull graph. A sample Wiebull plot shows that, on average, 10% of a
certain cylinder population will fail by 12.2 million cycles.
"A standard would help get all the suppliers on a level playing field," says Larry Horning, technical maintenance manager for Waste Management, Inc. (Crestline, OH). "Right now, there's no standardized way to evaluate those products."
Board members of the National Fluid Power Association (NFPA), which is authoring the standards, plan to publish sections on hydraulic and pneumatic components.
NFPA officials say that the initiative was spurred by the auto industry, which needed a way of identifying the reliability of manufacturing machinery. NFPA members seized on the idea, noting that it could also benefit them in their head-to-head battle with electromechanical technologies, particularly in arenas where electric motors have gained ground.
"There used to be a lot of hydraulic robots, but now most robots are electromechanical," says Leonard Bensch, vice president of Pall Corp., a maker of hydraulic filters. "Some injection molding machines have also moved to electromechanical technology."
Manufacturers of hydraulic and pneumatic components feel that reliability standards would help them provide hard evidence to prove that fluid power components are at least equal to, and possibly better than, electromechanical competitors. NFPA officials say that the new reliability document may define reliability as the probability that a component can perform continuously without failure for a prescribed time. The first step is to introduce standard reliability test methods, then the association's members will look at the possibility of product certifications.
NFPA is also developing a plan for educating potential customers on how to use the standard. Ultimately, its directors say they want to take the concept beyond the component level and into the system reliability arena.
This spring, the association hopes to meet in Detroit with representatives of the Big Three automakers to get their input. Automakers, particularly in the U.S., have reportedly recommended that the NFPA launch such an initiative because it dovetails well with automakers' parallel efforts to boost manufacturing quality. During the past decade, carmakers such as Saturn have promoted manufacturing quality by calling for parts warranties from suppliers and by demanding that vendors go through qualification processes.
"The automakers' goal is to improve the uptime of their operations," said John Berninger, an NFPA member and a retired global engineering manager for Parker Hannifin's Pneumatics Products Division. "They'd like to improve the reliability of their machines, so that they don't have to spend so much time repairing and replacing components. For them, uptime means money."
Equally important, Berninger contends that reliability ratings would help some manufacturers save money by enabling them to shop for products that offer the appropriate combination of reliability and cost. Some manufacturers, he says, don't need high cycle life, and would benefit by being able to identify the level of reliability that's appropriate for them.
Reliability ratings could also help address issues away from the factory floor. Waste Management, for example, attributes 57% of its maintenance costs to the replacement of hydraulic cylinders on its fleet of more than 30,000 garbage trucks.
The company's engineers say that maintenance savings could be enormous with better product data. "Right now, all of our product evaluations are subjective," Horning concludes.