THE CRITERIA IN HYDRAULIC CYLINDERS DESIGN

 Designing hydraulic cylinders requires many factors involved in the process. Ignoring any of these critical steps in the design process could increase the possibility of a design mistake. Hydraulic cylinders have many different working conditions, and that affects the design criteria. For example, the cylinders used in the mining & construction machines versus forestry have other design criteria in terms of materials used. 

There are a few main variables that should be taken into account while designing a hydraulic cylinder. What to consider when specifying hydraulic cylinders?

WORKING CONDITIONS

In general, it’s essential to consider the working conditions – where and what – the hydraulic cylinder is designed to do and what kind of load it has to endure. For example, challenging working conditions could be a corrosive environment, falling rocks in the mining industry, or high working cycles causing welding fatigue and shortening seal life span. For example, the requirements are different if the cylinder is mounted on the driving machine’s base, where stones and stumps may hit the cylinder compared to a cylinder mounted on a shelter inside the boom. If the cylinder is working underwater conditions, how to prevent the water from entering the cylinder fluid? These are examples that the designer needs to take into account when designing a hydraulic cylinder.

STROKING DISTANCE REQUIREMENTS

It is essential to consider the system pressure when choosing suitable design elements and cylinder parts. The stroke length can be a problem even at distances shorter than 3m. The thickness of the cylinder shaft is usually not determined by the impact but by force required. Long-stroke lengths may require choosing a larger cylinder size class than what the pressure levels would evaluate. 

TEMPERATURE

Considering the working conditions in terms of temperature – high temperatures like desert conditions or icy weather conditions with more than – 30 Celsius Degrees affects the fluid choices used in the system. Hydraulic cylinder systems using standard components can meet application temperatures over 200°C and under -50°C degrees. These temperatures affect both the “hard” and “soft” design components of cylinders. Applications working in extreme temperature spectrum conditions require individual components’ best performance in short- and long-term expectations. 

CYLINDER BORE SIZE

The amount of push or pull force required is one of the variables what determines the cylinder bore size needed. Bore size is then related to operating pressure. 

SPEED

When the designer chooses suitable cylinder parts, he needs to consider the system sliding speed. The definition of – excessive speed – can vary from one design engineer to another. As a good rule of thumb, standard hydraulic cylinder seals can easily handle rates up to 0,5 meters per second. For higher speed applications, a standard low-friction seal is the better choice. 

CAPACITY

Some applications, such as mining and construction machines and automotive manufacturing, require heavy-duty systems. Our cylinders typically have a working pressure of 200 to 350 bars. Testable pressure limits for our production are typically 420 bars, in special cases up to 700 bars.