Edited by Alan L. Hitchcox, editor
|Hydraulic integrated circuits consist of a manifold and multiple cartridge and/or subplate mounted valves contained in a single assembly that can drastically reduce the number of fittings and lengths of hose and tubing otherwise required for circuits using line-mounted components. |
Even though the effects of hydraulic integrated circuits (HICs) are not as dramatic as those in the world of electronics, they still can substantially reduce the size, complexity, and overall cost of hydraulic systems. Furthermore, HICs exhibit additional advantages that go beyond these benefits.
An HIC consists of a manifold containing multiple pressure-, directional-, and even proportional-control valves. In extreme cases, an HIC may even contain pumps, filters, actuators, or any combination of these to form a completely self-contained hydraulic system. Most HICs, however, consist of a manifold containing inlet and outlet ports, cartridge and subplate mounted valves (or both), and a network of internal passages that route hydraulic fluid through branch circuits of the hydraulic system.
Sizing up the benefits
Conventional hydraulic systems use hose and metal tubing to route hydraulic fluid from a hydraulic power unit (HPU) to a variety of valves and actuators, and back to the HPU. With an HIC, hose and tubing still routes fluid from the HPU to a variety of valves, but most of these valves may be contained within a single manifold tucked away in an available space on a machine.
With a conventional system, the line-mounted valves take up more space than cartridge valves, so they may end up being installed at many different locations throughout a machine. This complicates troubleshooting and maintenance and can require installing hoses in locations where they could be struck by foreign objects or otherwise damaged by ambient conditions.
Although the time to design the HIC and machine the manifold are additional expenses for the initial system, Dick Simoni, vice president, R. L. Miller Inc., Pittsburgh, says this cost usually is more than offset by the lower cost of cartridge valves, reduction in the cost of required hose, tubing, and fittings, and the much lower cost of assembly and installation. This means benefits like a lighter, more compact system and easier maintenance come at no additional cost.
Simoni adds that troubleshooting can be easier with an HIC because multiple valves, switches, and test points may all be located within close proximity to each other, instead of being located throughout a machine. Furthermore, he says eliminating hose and tubing assemblies and fittings reduces the potential for leakage and component failure, so less maintenance is required and reliability is improved.
Beyond breaking even
However, Simoni explains that you shouldn’t expect to integrate all in-line valves into HICs. “The break-even point must be considered when making a switch to integrated circuits. The financial advantage to using HICs depends on quantity — but not in the usual sense that unit cost decreases as the number of units increases.
“From the aspect of quantity,” continues Simoni, “mine equipment, for example, would not seem to be a viable application because only a few complete units of a particular model machine are manufactured annually. But HICs are effective here because one machine — such as a roof bolter — contains so many components that can be incorporated, integrated, or eliminated.
“We may provide a specific HIC only two or three times a year, so there’s no way a custom-made block will be more economical than off-the-shelf components. However, the installed cost of the block with the many cartridge valves can be much less than the numerous individual valves, fittings, hose, and the cost to install them would’ve been. What’s more, the HIC adds even greater value throughout the life of the machine because a cartridge valve can be replaced at a fraction of the cost of its in-line counterpart — and without even having to disconnect a single hose!”
Moreover, Simoni says, “Real estate on mining equipment has become a real focus with original equipment manufacturers because of ever-increasing options offered on equipment.That makes HICs and their benefits even more attractive to the OEM’s design engineers. Couple that with the movement to standardization for global design and this creates a plethora of opportunity for the HIC concept to the point where the majority of HIC applications I deal with are now mining equipment related.