Equipment lubrication management serves as an "invisible defense line" in industrial production. According to statistics, approximately 80% of rotating equipment failures are directly related to poor lubrication. However, in actual operation and maintenance, problems such as improper selection of lubricating grease, arbitrary filling cycles, and non-standard operations are widespread. These issues, at the very least, increase energy consumption and wear out components; at worst, they can lead to serious accidents such as fires and explosions.

I. Scientific Selection of Equipment Lubricating Grease: There is no best, only the most suitable

The selection of lubricating grease is the cornerstone of the healthy operation of equipment. Incorrect selection often leads to lubrication failure and accelerates equipment failure. The selection should follow the following basic principles:

Tailor to the working conditions

- Load size: The greater the load, the greater the pressure that the lubricating oil film bears. For heavy-duty or equipment with impact loads (such as steel rolling mills and compressors), lubricating oils/greases with higher viscosity or containing extreme pressure additives must be selected to prevent oil film rupture. However, for light-load equipment, high-viscosity oil will instead increase movement resistance, resulting in energy waste.

- Relative speed: For high-speed rotating components (such as high-speed motor bearings), lubricating oil is required to have good fluidity to quickly enter the friction surfaces. Therefore, low-viscosity oil or grease with a higher penetration should be selected. High-viscosity oil is required in low-speed and heavy-load applications.

- Temperature range: In high-temperature environments (such as above 100℃), lubricating oil is required to have a high viscosity index, high flash point and good oxidation stability. Synthetic oil is often a better choice. In low-temperature environments, oil products with low freezing points and low viscosity should be selected to ensure sufficient lubrication during cold starts.

- Environmental humidity: In damp or water-rich environments (such as water pumps, paper machines), the lubricating oil must have excellent anti-emulsification and anti-rust properties. At this time, sodium-based grease that is prone to emulsification when exposed to water should be avoided, and lithium-based or complex aluminum-based grease should be selected instead.

2. Match the equipment according to its characteristics

- Lubrication parts: Industrial gear oil is usually selected for gearboxes; Hydraulic oil is selected for the hydraulic system. Rolling bearings are mostly lubricated with grease. Even if they are both bearings, the requirements for pump grease and motor grease are different.

- Precision and clearance: If the friction surface is rough or the fit clearance is large, it is advisable to use oil with a higher viscosity to fill the surface unevenness and reduce impact. The precisely fitted components require low-viscosity oil to ensure penetration.

3. Pay attention to the core performance indicators of oil products

Viscosity is the core reference basis for oil selection. In addition, for equipment with heavy loads or impact loads, it is necessary to confirm whether extreme pressure and anti-wear agents have been added to the oil. For damp environments, anti-emulsification and anti-rust properties are of vital importance.

Ii. Determination of Fueling Cycle and Fueling Volume: Excess is as bad as deficiency

After determining the correct type of grease, how to decide how much to add and when to add it becomes the core challenge in daily management.

1. Dosage: Emphasize the "golden ratio";

Grease is not the more the better. Excessive addition is a common operational mistake, which can lead to increased stirring resistance, a sharp rise in temperature, accelerated oxidation and deterioration of the grease, and even damage to the seal.

- Inside the bearing: It is generally recommended that the filling amount be 1/3 to 1/2 of the free space inside the bearing and the cavity. At low speeds, the amount can be appropriately increased, but at high speeds, it must be strictly controlled to prevent excessive temperature rise.

Empirical formula: For the deep groove ball bearings commonly used in pumps and motors, the single grease replenishment amount can be referred to the formula G=0.005×D×B (G is the weight, D is the outer diameter of the bearing in mm, and B is the width of the bearing in mm). This is a practical estimation method to avoid overloading.

- Operation verification: In actual operation, slowly inject until a small amount of old grease is squeezed out from the oil outlet and then stop. This not only ensures that the new grease is fully filled but also removes the old grease and impurities.

2. Fueling cycle: Dynamically adjusted rather than fixed

Changing the oil at a fixed time (such as "every three months") may seem convenient, but in fact, it is not scientific. The determination of the filling cycle needs to take into account the type of equipment, working conditions and environment comprehensively.

- General Reference Standard:

For new equipment or after major overhauls: Within 10 to 15 days of the first operation, check and replenish the grease to remove air and excess impurities during the assembly process and ensure that the initial lubrication is in place.

- Normal operation period: It is generally recommended to replenish once every 1,600 hours or every 3 months. For ordinary motors, two-pole motors (high-speed) are usually refilled once every six months, while four-pole and above motors can be refilled once a year.

Linear guide rails: Generally, they should be replenished every six months. For long-stroke reciprocating motion, it is recommended to shorten the replenishment to three months.

- Environmental correction coefficient: Working conditions are the key variable for periodic adjustment.

- Temperature influence: Bearing temperature is the "killer" of grease lifespan. When the bearing temperature exceeds 70℃, for every 15℃ increase, the interval for adding grease should be halved.

- Harsh environment: For equipment operating under conditions of high temperature, high humidity, much dust or continuous heavy load, the grease replenishment cycle must be shortened (such as monthly or every 800 hours).

Iii. Root Cause Analysis and Prevention Strategies of Lubrication Faults

Even if the right oil is selected and added periodically, problems with equipment lubrication may still occur. The key lies in identifying early signs and establishing a systematic prevention system.

1. Common lubrication faults and causes

- High temperature and overheating: Besides issues with the cooling system, lubrication reasons include excessively high viscosity of the oil, excessive greasing (stirring heat), and deterioration of the oil leading to a decline in heat dissipation performance.

- Abnormal wear and pitting: When pitting, adhesion or severe wear occurs on the friction surface, 80% of the cases are related to poor lubrication. The possible reasons could be that the viscosity of the oil is too low to form an effective oil film, insufficient extreme pressure performance (lack of additives), or hard particle impurities are mixed into the oil.

- Oil leakage and emulsification: Seal failure is often accompanied by oil emulsification. For equipment such as water pumps, if the oil has poor anti-emulsification properties, water entering will damage the oil film, leading to rust and wear of the equipment.

2. Establish a standardized defense line of "five determinations and three filters";

To prevent malfunctions, lubrication management must be transformed from a "guerrilla force" to a "regular army". The "Five Fixed Points" (fixed points, fixed quality, fixed quantity, fixed time, and fixed person) clearly define the person responsible for each lubrication point, the type of oil, the quantity used, and the time. The "three filters" (inbound filtration, distribution filtration, and refueling filtration) are the "three gatekeepers"; to prevent contaminants from entering the equipment. For instance, when new oil is stored in the warehouse, it passes through a 60-mesh filter screen; when it is released, it passes through an 80-mesh filter screen; and when it is added to the equipment, it passes through a 100-mesh filter screen to ensure the cleanliness of the oil.

3. Abandon common operational misunderstandings

Misconception 1: Only looking at the oil level, not the oil quality: A normal oil level does not necessarily mean the oil is healthy. Lubricating oil will oxidize, its viscosity will change and additives will be consumed during use. If the oil is only replenished but not changed for a long time, the grinding debris and gum in the old oil will continue to circulate, accelerating wear. "Oil change based on quality" should be gradually implemented. The timing of oil change should be determined through regular testing (such as moisture content >0.1% or viscosity change ±15%).

Misconception 2: Mixing oils of different brands at will: Base oils and additives of different formulas may undergo chemical reactions, leading to a decrease in the strength of the lubricating film or the formation of sediment. Before switching to a new brand, be sure to thoroughly remove the old fat.

4. Technological development trends

The current lubrication management is undergoing a transformation towards intelligence. By using Internet of Things (iot) sensors to monitor the temperature, viscosity, moisture content and particulate matter of oil products in real time, the system can automatically analyze the data and issue early warnings when abnormalities occur. In addition, the application of new materials such as nano-lubrication technology and green degradable lubricating oil has also provided new possibilities for the long service life and environmentally friendly operation of equipment.

Equipment lubrication is by no means a simple task of "adding oil", but a systematic project involving tribology, materials science and management. Correct selection is the prerequisite, precise cycle and quantification are the means, and establishing a comprehensive fault prevention system is the guarantee. Only by transforming lubrication management from passive "fire-fighting" to proactive "fire prevention" can the service life of equipment be truly prolonged, production safety be guaranteed, and hidden economic benefits be created for enterprises.