The primary function of the hydraulic cylinders is to convert pressure and fluid flow into force and linear motion. Hydraulic and pneumatic seals are used in various fields and industries. Many engineers are careful to overly complicate cylinder specifications — a precautionary habit with continually improving hydraulic cylinder technologies. Other engineers copy the previous design of the equipment, not combining the factors that were included in the original design and the achievements achieved since then. Recycling old designs for a similar function can save time. Still, it ignores technological advances that increase the efficiency of hydraulic cylinders or allow them to move and support more weight.
Hydraulics vs. Pneumatics
The choice between hydraulic and pneumatic seals primarily depends on the required force intensity. Although pneumatic devices are, in some respects, simpler, they are generally not able to withstand high loads and give great effort. Pneumatics can create a force of 15 tons or more, but, as a rule, it is more economical to use hydraulics for forces over 2.5 tons. Hydraulic cylinders also create a smoother, more controlled movement. As an added benefit, hydraulics can perform auxiliary tasks such as lubrication and cooling.
Nevertheless, since the availability of force and medium is a non-negotiable factor in the design of hydraulic power, it should be noted that properly designed and sized pneumatics can provide higher performance if a compact area is not required.
Key factors to consider when choosing hydraulic and Pneumatic cylinders include Cylinder capacity
Medium-duty hydraulics take into account most industrial applications and are usually designed for a pressure of 7 MPa. Heavy-duty hydraulics are widely used in hydraulic presses, the automotive industry, and other industrial applications. Standard heavy hydraulic cylinders withstand pressures up to 20 MPa. The capacity in these heavy machines depends on the area of the piston subjected to gauge pressure. Engineers can achieve a greater load without sacrificing other indicators, using tandem cylinder designs rather than larger diameter cylinders or non-standard high-pressure cylinders.
Although the non-standard stroke of the hydraulic cylinder can exceed 3.05 m, nominal pressure can be a problem. Engineers must determine if the rods should be thicker to withstand the load with a long stroke. If necessary, the nominal pressure at the load in the push mode should be indicated. Rod deflection in horizontal applications with a long stroke can lead to premature wear of the hydraulic guide rails. Weighing each positive effect with potential negative effects is essential for optimizing the operation of hydraulic equipment.
Each engineer has his definition of “excessive speed.” The tolerance threshold for standard seals is approximately two-thirds of this speed. Often, a standard low friction seal is the best choice for high-speed applications.
Hydraulic cylinder piston seals using standard components can operate at temperatures from 260 ° C to −54 ° C. But temperatures affect the design of cylinder components. For example, when used outdoors in the far north, seals and metal parts are compressed due to extreme temperatures.