How to test leakage in hydraulic cylinder?

Introduction

In the hydraulic system, the hydraulic cylinder is the core actuator, and its sealing performance is directly related to the operating efficiency and reliability of the equipment. As a hydraulic cylinder manufacturer, we are well aware of the importance of internal leakage detection. Therefore, during the production process, we will use a series of rigorous and efficient testing methods to ensure that each hydraulic cylinder can achieve high standards of sealing performance.

1. Causes of leakage in hydraulic cylinder

Internal leakage of hydraulic cylinders mainly occurs between the piston and the inner wall of the cylinder, at the seal between the piston and the piston rod, and at the one-way valve on the piston. Under normal circumstances, the seal fills the fitting gap through its own elastic deformation to prevent the hydraulic oil from flowing from the high-pressure chamber to the low-pressure chamber. However, when the seal is aged, worn, or damaged, or the fitting gap increases due to manufacturing errors or long-term use, the hydraulic oil will bypass the seal and leak from the high-pressure chamber to the low-pressure chamber, forming an internal leakage.

2. Hydraulic cylinder internal leakage test method

(1) Static pressure test

The static pressure test is our first step in detecting leaks in hydraulic cylinders. We will install the hydraulic cylinder on a dedicated test bench to ensure that it is firmly fixed and accurately positioned. Then, we connect the two ends of the hydraulic cylinder to the pressure source and pressure sensor respectively. Before the test begins, we will release the pressure inside the hydraulic cylinder to zero to eliminate the effect of any initial pressure on the test.

Next, we will slowly inject the test medium into the hydraulic cylinder and gradually increase the pressure until the hydraulic cylinder reaches the designed working pressure. During this process, we will closely observe the changes in the readings of the pressure gauge to ensure that the pressure rises smoothly and evenly. When the pressure reaches the set value, we will turn off the pressure source and keep the hydraulic cylinder at this pressure for a period of time. During this time, we will carefully observe whether the reading of the pressure gauge has a downward trend. If the pressure drops by more than the specified allowable range, this may mean that there is an internal leak in the hydraulic cylinder.

(2) Dynamic test

Dynamic test simulates the movement state of the hydraulic cylinder in the actual working process to detect whether there is internal leakage during the movement. In the dynamic test, we will install the hydraulic cylinder on a test bench with a drive device, which can accurately control the extension and retraction speed and stroke of the hydraulic cylinder.

We will adjust the pressure of the hydraulic cylinder to its working pressure range and start the drive device to make the hydraulic cylinder reciprocate at a certain speed. During the movement, we will use flow sensors to monitor the flow changes at both ends of the hydraulic cylinder. If there is an internal leakage in the hydraulic cylinder, the leaking hydraulic oil will generate additional flow in the return oil pipeline during the movement. We will use the readings of the flow sensor to determine whether there is such abnormal flow. At the same time, we will also observe whether the movement of the hydraulic cylinder is smooth, whether there is any stuck or abnormal noise, etc., which may be indirect manifestations caused by internal leakage.ConclusionAs a hydraulic cylinder manufacturer, we always put product quality first. Through a strict internal leakage test process, we ensure that each hydraulic cylinder can demonstrate excellent sealing performance and reliability in actual applications. In the future, we will continue to work hard to continuously improve our testing technology and production process to make greater contributions to the development of the hydraulic industry.