Materials advancements and the use of multi-axis CNC controlled machines have given designers more options when designing HIC solutions. Manifolds once made almost exclusively from cut bar stock or extruded aluminum are now manufactured from advanced steels and aircraft quality alloys. Availability of lower cost tooling has made complex cast shapes economical in volumes much lower than in days past. The use of extruded steel shapes has provided designers a more economical starting ground for systems that exceed 3000 psi (206 bar). The improved quality of aluminum alloys is allowing properly designed aluminum HICs to operate in excess of 3600 psi (250 bar) in many cases.

Cast shapes in iron and aluminum provide packaging advantages in some machines. Integration of circuits into cylinders, pump housings and machine elements can take advantage of valuable machine real estate and reduce potential leak paths. Long term cost advantages can be real-ized, due to reduced machining costs of cavities and flow paths. Castings allow valves to be packaged in many different planes with complex geometries in the inner coring.

Advancements in CNC machining and CAD packages have opened up additional opportunities in system packaging. Multi-axis CNC centers can machine flow paths at odd angles and provide precision cavities for inserted elements. CAD packages with cavity libraries allow designers to place valves and populate manifolds with flow paths automatically. Error checking algorithms allow the designers to ensure that oil is delivered where it is required with minimal pressure drops. CAM packages help manufacturers move these designs from the CAD workstation to the machine with automatically generated CNC programs allowing rapid prototyping and seamless transitions into production.

System advantages of HICs

Hydraulic integrated circuits offer significant advantages over individually plumbed components in many important areas.

Packaging — Light weight and compact size are the genesis of the cartridge valve industry. HICs are frequently 1 /4 to 1 /3 the size and weight of individually plumbed valve packages. Extensive use of lightweight materials can save up to an additional third in weight reduction over traditional valve solutions. These weight and packaging advantages can increase vehicle efficiency and offer manufacturers additional vehicle capacity.

Performance — Elimination of hoses, fittings, and external plumbing can reduce system pressure drops, eliminate leak points, and optimize vehicle performance. Components are closely packaged and runs between control elements, a source of heat generation, are reduced providing more usable power to the application. Proportional control valves are provided with optimal flow conditions, making the full performance range of the valve available. Additionally, HICs are routinely used at pressures up to 6000 psi (415 bar) — often double that of traditional cast iron valves.

Costs — Incorporating many of a machine's control features in a single HIC can eliminate multiple hose runs, interconnections between components and the associated assembly times. An HIC solution incorporates pilot lines, load sense, drains, and other features that would otherwise be plumbed on a machine. The elimination of connections and external plumbing can often result in savings of 40 to 50% over traditional solutions. Efficiencies in manufacturing and compact packages can offer additional savings while offering a custom fit control solution.

Reliability — HICs can offer increased reliability to an manufacturer. The previously mentioned plumbing improvements make the machine less susceptible to vibration-related downtime. Additionally, fatigue is less of a factor due to lighter weight and improved mounting configurations. HICs that are integrated into other machine components can further increase machine reliability with their optimized mounting configurations.

Serviceability — Increased machine life-cycles requires that servicing of components be easy and risk free. The inherent ease of application of cartridge valves makes for convenient servicing and repair. End users can make repairs in the field without breaking hydraulic hose connections which can potentially lead to spilled oil, contamination, and improper hose routings. The manufacturer can be assured that a used piece of equipment repaired in the field will operate properly and be up and running in a minimal amount of time. Additional benefits can be derived from clear labeling of valves in the manifold, as shown at right. A repair technician can refer to call outs that will not fall off or become illegible over time.

Manufacturability — HICs can be custom configured to route hoses and fittings for ease of assembly. Many manufacturers will have the HIC designed to place all of the hydraulic connections on a common face, allowing easy access to both valves and fittings. Because of their compact nature, HIC manufacturers can use innovative mounting options allowing control packages to be mounted to doors or access panels. The panels may swing out, allowing the assembler (and re-pair technician) easy access to the hydraulics. Integration of HICs with cylinders, motors, and pumps may allow manufacturers to reduce the number of components to be assembled into a machine further reducing assembly times as well as shaving transactional costs.