Cast Steel Gear Lubricating Oil Pump

I. Classification and Characteristics of Cast Steel Materials

(1) Carbon Cast Steel (ZG)

Characteristics: Carbon content 0.15%~0.60%, tensile strength 400~700MPa, compressive strength 500~850MPa. It has good castability and weldability, can withstand impact and vibration under medium loads, and exhibits stable mechanical properties at room temperature.

Applications: Suitable for manufacturing non-high-pressure key components such as gear pump housings and gears, commonly used in general industrial lubricating oil circulation systems (e.g., machine tool lubrication, small mechanical gearboxes).

(2) Low-Alloy Cast Steel

Characteristics: Added with alloy elements such as manganese, silicon, and chromium, the tensile strength is increased to 500~900MPa, and the yield strength is 20%~30% higher than that of carbon cast steel. The wear resistance and fatigue resistance are significantly enhanced, and it can work stably under higher pressure (≤3MPa).

Applications: Used for components such as gears and bearing seats of high-pressure lubricating oil pumps, commonly found in lubrication systems of construction machinery and heavy machinery (e.g., excavator gearboxes, rolling mill bearing lubrication).

(3) High-Alloy Cast Steel

Characteristics: Contains elements such as nickel, chromium, and molybdenum, with excellent corrosion resistance and heat resistance. It can maintain mechanical properties in high-temperature environments above 200℃, has good tolerance to lubricating oils containing extreme pressure additives, and outstanding anti-seizing performance.

Applications: Suitable for special working conditions, such as lubrication of high-temperature equipment in the metallurgical industry (blast furnace gearboxes) and transportation of lubricating oils containing corrosive media in the chemical industry, requiring resistance to oil oxidation or medium erosion.

II. Technical Advantages and Limitations of Cast Steel Gear Lubricating Oil Pumps

(1) Core Advantages

1. High Strength and Wear Resistance

The anti-deformation ability of low-alloy cast steel gears under high load (gear meshing pressure ≤4MPa) is 40% higher than that of carbon cast steel, and the wear rate is only 0.015mm per thousand hours (when the medium contains impurities ≤0.3%), with a service life exceeding 20,000 hours.

After quenching treatment, the hardness of cast steel gear teeth can reach HRC45~55, effectively resisting wear from particulate impurities in lubricating oil, suitable for heavy-load mechanical lubrication.

2. Good High-Temperature Resistance and Stability

High-alloy cast steel pump bodies can operate in high-temperature lubricating oil environments of 300℃, with a thermal deformation rate below 0.5%, suitable for circulating lubrication systems of metallurgical and heat treatment equipment, avoiding pump body deformation and leakage caused by increased oil temperature.

Cast steel gears have high meshing accuracy, with an operation vibration amplitude ≤0.05mm and noise below 75dB, ensuring stable oil supply for the lubrication system.

3. Balance of Cost and Reliability

The cost of cast steel materials is 1/2~2/3 of that of stainless steel, and the single-piece production cost is 30% lower than that of forged alloy steel. The casting process is mature, suitable for mass production.

The gear pump has a simple structure, and manual maintenance (such as replacing seals and cleaning filters) costs 50% less than screw pumps, suitable for industrial scenarios requiring long-term continuous operation.

(2) Main Disadvantages

1. Weight and Installation Limitations

Cast steel has a density of 7.8g/cm³, 3 times higher than aluminum alloy. For example, a 2-inch diameter gear pump weighs about 25kg, with poor portability. Fixed brackets are required for installation, increasing infrastructure costs.

The pump body and motor need precise alignment; otherwise, bearing wear is likely to occur due to weight offloading, with installation accuracy requirements higher than plastic pumps.

2. Corrosion Resistance Limitations

Carbon cast steel is prone to electrochemical corrosion in lubricating oils containing extreme pressure additives (such as sulfur and phosphorus compounds), relying on coating protection (such as galvanizing or epoxy resin spraying), increasing costs by 15%~20%.

Although high-alloy cast steel is resistant to oil corrosion, it still requires additional anti-corrosion treatment in strongly acidic (pH＜3) or strongly alkaline (pH＞12) media; otherwise, the service life is shortened to less than 5,000 hours.

3. Energy Efficiency and Environmental Challenges

The hydraulic efficiency of cast steel gear pumps is 8%~10% lower than that of stainless steel pumps. In large-flow lubrication systems (such as ≥100L/min), the annual energy consumption cost increases by about 5,000 RMB.

Carbon emissions from casting are 40% higher than aluminum alloy, facing the pressure of green manufacturing transformation under the "dual-carbon" policy, requiring optimization of the heat treatment process to reduce energy consumption.