Why does the ultra long stroke hydraulic cylinder barrel adopt the scraping and rolling boring process? The first recommended phenolic cloth guide ring can avoid noise and vibration?

2025,09,17

In the production and manufacturing of hydraulic cylinders with ultra long stroke (>8 meters), it is common to encounter cylinder shaking and noise. Through extensive data analysis, it was found that after excluding other factors, the following typical problems were identified:

1. The probability of shaking and making noise in the cylinder tube processed by scraping and rolling boring technology using POM guide rings is high, while replacing them with phenolic cloth guide rings can mostly eliminate shaking and making noise;

2. The probability of shaking and making noise when using POM support rings for cylinder barrels processed by internal hole honing and scraping rolling boring technology is very low.

The close integration of Hydraulic Cylinder manufacturing technology, material tribology, and practical applications is fundamentally due to the surface microstructure of the cylinder inner wall and its compatibility with different guide ring materials friction pairs.

Let's analyze and explore the reasons together:

一、 The core reason is that the micro surface morphology of the cylinder barrel processed by internal honing and scraping and rolling boring is completely different from that of the inner wall.

1. Scraping and rolling boring process · Surface features: Scraping and rolling is a one-time composite process (boring, rolling). Rolling tools use tremendous pressure to flatten and compact the protruding parts of the metal surface, creating plastic flow and filling the depressions, thus forming a very smooth, mirror like surface.

·Advantages: Extremely low surface roughness (usually up to Ra0.2-0.4 μ m or even lower), good sealing performance, and wear resistance.

·Disadvantage: Poor surface oil storage capacity. Because the surface is too smooth and lacks micro pits (oil valleys) for storing lubricating oil. Friction pairs find it difficult to form a stable and continuous lubricating oil film during relative motion.

2. Internal honing process · Surface features: Honing is achieved by low-speed rotation and reciprocating motion of an oil stone embedded in the honing head, which performs cross cutting on the inner wall.

·Advantages: It will form a typical "cross mesh" structure. These mesh patterns are composed of countless tiny, uniformly deep grooves, forming an ideal oil storage tank.

·Disadvantages: The surface roughness is relatively high (but controllable, usually Ra0.4-0.8 μ m is suitable for hydraulic cylinders). Precision honing can reach within 0.2 μ m

二、 Material characteristics of guide ring: POM vs. phenolic sandwich fabric.

1. POM (polyoxymethylene) guide ring

Advantages: 1) Extremely high mechanical strength and stiffness: POM is one of the materials with the highest strength and stiffness in engineering plastics, capable of withstanding large radial loads and resistance to compression, preventing direct contact between the piston rod or piston and the cylinder, and providing excellent support. 2）. Low friction and self-lubricating properties: POM has a very smooth surface and natural lubricity, with a low coefficient of friction with metal surfaces. This can reduce starting resistance, improve the overall efficiency of the hydraulic cylinder, and reduce wear and energy consumption. 3）. Excellent wear resistance: POM has excellent wear resistance and a long service life under clean oil and good working conditions. 4）. Good dimensional stability: POM has low water absorption and is not easy to expand in oil, maintaining good dimensional stability and ensuring stable sealing gaps. 5）. Good economy: Compared to phenolic sandwich support rings, POM material has lower cost and simpler processing (usually injection molding), so the product price is usually more advantageous. 6）. Oil and chemical resistance: It has good resistance to hydraulic oil, lubricating oil, and most solvents.

Disadvantages: 1) Poor high temperature resistance: This is the biggest weakness of POM. Its continuous operating temperature generally does not exceed 90 ° C (194 ° F), and the short-term peak value is also preferably below 100 ° C. At high temperatures, it will soften, and its strength and stiffness will sharply decrease, leading to deformation and failure. 2）. Not resistant to strong acids and alkalis: may be corroded in certain special chemical media. 3）. Gap sensitivity: For designs with sharp corner gaps, stress cracking may occur under impact loads. 4）. Dry running performance is average: although it has good self-lubricating properties, it has a strong dependence on lubrication conditions. In the absence of a continuous lubricating oil film, its friction coefficient will significantly increase and it is prone to "stick slip" phenomenon, leading to shaking and abnormal noise. Its material texture is relatively uniform.

2. Phenolic sandwich cloth guide ring

Advantage 1) Extremely excellent high temperature resistance: This is the most prominent advantage of phenolic sandwich support rings. It can work stably for a long time in high temperature environments above 120 ° C, even 150 ° C-200 ° C, without significant performance degradation. A hydraulic cylinder that is very suitable for high-temperature working conditions. 2）. Excellent resistance to compression and load-bearing capacity: The laminated fiber cloth structure endows it with extremely high mechanical strength and impact load resistance, capable of withstanding extreme instantaneous impact pressure without rupture or permanent deformation. 3）. Excellent dry running and boundary lubrication performance: Even under harsh conditions such as damage to the lubricating oil film or extreme oil shortage, its fiber structure can provide a certain degree of lubrication and oil storage, providing relatively stable friction performance and avoiding severe stick slip phenomena. The fracture and wear of fibers themselves can also play a role in solid lubrication to a certain extent. Prevent locking and severe wear, with extremely high reliability. 4）. Good embeddedness: Its material is relatively soft, allowing small hard contaminants to be embedded in the material instead of scratching the metal surface that matches it, thereby protecting expensive piston rods and cylinder barrels. 5）. Flexible size specifications: usually made by turning bar or pipe materials, especially suitable for customization of large sizes, small batches, or non-standard sizes.

Disadvantages: 1) High cost: The cost of raw materials and processing (lamination+turning) is higher than that of POM rings formed by injection molding. 2. Water absorption and expansion: Phenolic sandwich fabric materials have a certain degree of water absorption, and attention should be paid during storage and installation as slight size changes may occur after moisture absorption. But it tends to stabilize after long-term immersion in oil. 3. Relatively high friction coefficient: Under normal operating conditions, its friction coefficient is usually higher than POM, which may cause slightly greater starting resistance of the hydraulic cylinder. 4. High cleanliness requirements: Small fiber debris may be generated during the wear process, and systems with strict requirements for oil cleanliness need to be carefully considered (but this issue is no longer significant with high-quality phenolic sandwich materials).

Comprehensive analysis: Why must the process and materials be matched? Now let's combine the surface of the cylinder with the support ring material to see:

Scenario 1: Scratching and rolling boring (mirror surface)+POM support ring=prone to noise and shaking

The mirror cylinder produced by scraping and rolling boring has extremely poor oil storage capacity.

When the long hydraulic cylinder (over 8 meters) of the crane extends and retracts, the stroke is long, the speed may be uneven, and the lubricating oil film is easily damaged or unable to form.

POM material directly contacts with smooth metal surface under lean oil condition, the friction coefficient increases sharply, and the "stick slip" phenomenon is very easy to occur.

Sticky ": The static friction force is high, and a large force is required for the piston rod to start instantly.

Sliding: Once activated, the dynamic friction force suddenly decreases and the piston rod slides suddenly.

This' one card, one card 'movement pattern results in noticeable shaking and abnormal noise.

The weight and deflection deformation of the long cylinder will exacerbate this uneven motion.

Scenario 2: Scraping and rolling boring (mirror surface)+cloth clamping support ring=smooth operation

Under the same poor oil conditions, the fiber structure of the clamping support ring can better cope with poor lubrication.

Its material is softer and has better toughness, which can absorb and dampen small vibrations generated by the "stick slip" trend, avoiding them from developing into severe shaking.

Therefore, even on smooth surfaces of scraping and rolling processes, the clamping support ring can ensure smooth operation.

Scenario 3: Internal honing (mesh surface)+POM support ring=smooth operation

The cross mesh pattern generated by internal honing is a natural micro oil reservoir that can continuously provide lubricating oil for the friction pair.

The excellent self-lubricating properties of POM are highly dependent on good lubrication. With sufficient oil film, the friction coefficient between POM and metal surfaces can be maintained at a very low and stable level.

A stable oil film avoids the occurrence of "stick slip phenomenon", resulting in smooth, quiet, and vibration free operation.

Under these ideal lubrication conditions, the advantages of POM wear resistance and low friction are fully utilized, and its performance is usually superior to that of the clamping support ring.

To sum up, the fundamental reason lies in the guarantee of lubrication conditions:

Scraping and rolling boring process: unable to provide good lubrication conditions on its own, belonging to a "poor oil" friction environment. Therefore, it is necessary to use a clamping support ring that is insensitive to lubrication and has good anti shake properties to compensate.

Internal honing process: Its cross mesh structure can actively create and maintain good lubrication conditions. Therefore, it can perfectly match POM support rings that require good lubrication but have better friction performance. For hydraulic cylinders with ultra long stroke (over 8 meters), the flatness and self weight deformation of the cylinder barrel have a greater impact, and the stability requirements for the friction pair are also higher. Therefore, the matching selection of this process and materials is crucial.

Of course, the actual working conditions are complex and intricate, requiring specific analysis based on factors such as working conditions and processing technology to select the guiding ring reasonably. This article is for reference only.

Author:

Ms. Melody

E-mail:

sale@gyhydraulic.com

Phone/WhatsApp:

+86 15852701381