The core of a corrugated production line lies in the corrugating roll, which operates for extended periods under high temperatures, heavy loads, and in a humid environment. To ensure the long-term operation of the equipment, it is crucial to use appropriate lubricating grease for the corrugated machine to provide lubrication and corrosion protection. However, despite many lubricating greases on the market boasting high dropping points and claiming to withstand temperatures of up to 300°C or higher, various issues frequently arise in practical applications. Therefore, when selecting lubricating grease, it is necessary to consider multiple indicators comprehensively to ensure its long-term reliability in actual operations.
1. Customer Pain Points
Our customers primarily engage in the production of corrugated paper products, with production line equipment including BHS, J.S.Machine, and Guangdong Wanlian, among others.
Corrugated paper production line
Although the production equipment varies among different customers, they face similar problems:
1. Lubricating grease exudation, known as the “oil flow” phenomenon.
2. Lubricating grease carbonization, causing the “coking” issue.
3. Insufficient lubrication of the grease, leading to equipment wear and damage.
These problems, whether minor or severe, may require frequent grease addition, increasing labor costs. In more critical situations, they can lead to bearing seizure, escalating maintenance costs and resulting in a loss rather than gain.
2. Principles of Corrugated Product Manufacturing
During the normal operation of corrugating rolls, the operating temperature at critical locations often exceeds 180°C, reaching instantaneous temperatures of over 230°C.
Therefore, the lubricating grease at the corrugating roll not only operates for extended periods at high temperatures but is also subjected to shear forces, often exhibiting a tendency for viscosity reduction and susceptibility to coking.
Corrugated paper production process
Principle of production of single tile machine
3. Analysis of Problem Causes
3.1 Grease Exudation – Oil Flow
Manifestation: The viscosity of the lubricating grease becomes thinner, flowing out from the bearing.
Cause: The lubricating grease cannot withstand prolonged exposure to high temperatures and shear environments. The soap base structure in the grease is disrupted, leading to the separation of oil and soap, resulting in softening and loss.
3.2 Grease Carbonization – Coking
Manifestation: Severe bearing wear or seizure, resembling dry friction. Upon opening the bearing, it is observed that the lubricating grease is no longer in a semi-fluid state but has transformed into black carbonized material.
Cause: The oil components in the lubricating grease undergo chemical changes, such as oxidation, at high temperatures. Long-chain molecules break down into short-chain molecules, ultimately forming carbides.
3.3 Insufficient Lubrication Capability – Wear and Seizure
Manifestation: During regular maintenance, there is a semi-fluid lubricating grease on the bearing, but the bearing is severely worn.
Cause: The lubricating grease lacks sufficient lubrication capability, and there is no formation of boundary lubrication or extreme pressure lubrication between the friction pairs. This is equivalent to the lubricating grease either not providing lubrication or offering limited effectiveness, resulting in direct friction between the bearings.
Given the working characteristics of corrugating rolls in high-temperature, high-load, and humid environments, the selected lubricating grease must meet the following requirements to ensure long-term operation and reduce downtime:
• High-Temperature Resistance: Capable of working for extended periods at temperatures of at least 200°C without loss.
• Oxidation Resistance: Possesses excellent oxidation stability, meaning it does not rapidly oxidize or generate oxides even when exposed to air in high-temperature environments, avoiding the formation of carbides.
• Water Vapor Resistance: The lubricating grease does not undergo emulsification or hydrolysis when in contact with water.
• Shear Stability: In mechanical operations, lubricating grease is subjected to prolonged shear forces, causing the separation of soap fibers and resulting in flow.Therefore, an ideal lubricating grease exhibits minimal viscosity change after shear, providing a longer service life.
Important Points to Note:
It is worth noting that many lubricating greases in the market emphasize high dropping points in their advertising, claiming temperature resistance of up to 300°C or even higher. However, the dropping point merely indicates the lowest temperature at which the lubricating grease begins to melt and drip, serving as an important but not exclusive indicator of the actual operating temperature of the grease. For example, clay-thickened greases may not have a dropping point, yet their practical use temperature generally does not exceed 200°C, and their anti-wear performance is typically moderate, making them unsuitable for use in high-speed rolling bearings. In practical applications, it is essential to comprehensively consider various performance indicators of lubricating grease, such as high-temperature stability, volatility, shear stability, and more.
5. Product Recommendations
Based on the lubrication requirements and corrugated machine equipment, we recommend the following solution for our customers.
|Products||Overview||Product Substitution||Grease Change Cycle||Grease Adding Cycle||Application Equipment|
|CMG 555 Corrugator Grease||PTFE & PFPE||BHS PERFLU V250; Krytox GLP 226/227; Kluber AR 555; LUBCON LP 2502; NYE Corr 140||500 hours or 12 months||3 months||BHS; AGNATI; SIMON; MITSUBISHl; ISOWAUCM; UCM; LANGSTON; FOSBER|
|CMG 648 Corrugator Grease||Synthetic hydrocarbons & Polyurea||Kluber HB74-401/GH 461/GH 462; J.S. Machine tile line grease 1#||1000 hours or 3 months||1 month||J.S.Machine; MarquipWardUnited; HSIEH HSU; WANLIAN; Shandong Mingwei; YUELI Machinety; TAIWAN XIEYANG; HANKUK PACKAGE|
|CMG 645 Corrugator Grease||Synthetic hydrocarbons & Polyurea||Mobil SHC 100/460; BRUGAROLAS KOMPLEX HT-2/G||300 hours or 1 month||15 days||Various Low- Speed Production Lines|
6. Application Scenario
Some customers originally used lubricating greases advertised as having high dropping points, often experiencing various issues, as seen in the pictures taken at the customer’s site.
The lubricating grease did not withstand shear, and after six months of use, its viscosity became thinner.
The lubricating grease did not withstand high temperatures, and after six months of use, carbides appeared.
After replacing the recommended product based on the customer’s operating conditions, the corrugated rolls are operating normally according to the regular lubrication and replacement cycles.