What are the common methods for surface treatment of roller chains?

What are the common methods for surface treatment of roller chains?

Introduction
As a common mechanical transmission element, roller chains are widely used in industrial and agricultural machinery. In order to improve the performance and service life of roller chains, surface treatment technology plays a vital role. This article will introduce the common surface treatment methods of roller chains in detail, including heat treatment, surface coating, lubrication treatment, etc., and explore the process characteristics, applicable environment and advantages and disadvantages of each method.

1. Heat treatment method
1.1 Quenching and tempering
Quenching is a common heat treatment process used to improve the hardness and strength of roller chains. The specific steps are as follows:
Heating: Heat the roller chain to an appropriate temperature so that the material reaches the quenching temperature range.
Insulation: After reaching the quenching temperature, maintain a certain insulation time to make the internal temperature of the chain uniform.
Quenching: The chain is quickly immersed in a quenching medium, such as cold water, oil or brine, and quickly cooled to form a hardened structure.
Tempering: In order to reduce the internal stress generated during the quenching process and increase the toughness of the chain, tempering treatment is usually performed. Heat the quenched chain to an appropriate temperature, keep it for a certain period of time, and then cool it down.
1.2 Carburizing and nitriding
Carburizing and nitriding are two common surface hardening processes used to improve the surface hardness and wear resistance of roller chains.
Carburizing: Heat the chain to the liquid carburizing temperature, immerse it in a carburizing medium, such as sodium cyanide solution, and carburize it for a certain period of time. After carburizing, quench and temper it to solidify the carburized layer and increase the hardness.
Nitriding: Improve the hardness and wear resistance by improving the internal structure of the chain. The specific steps include heating, heat preservation and cooling to form a fine grain structure.
1.3 Carbonitriding
Carbonitriding is a process for improving the surface hardness and wear resistance of the chain, which is mainly used for special materials such as stainless steel chains. The specific steps are as follows:
Heating: Heat the chain and the carbon and nitrogen source together to the co-carburizing temperature and keep it for a certain period of time.
Quenching: The chain after the carburized layer is formed is quickly immersed in the quenching medium and quickly cooled to solidify the carburized layer and increase the hardness.
Tempering: Tempering is usually performed to reduce the internal stress generated during quenching and increase the toughness of the chain.

2. Surface coating technology

2.1 Galvanizing
Galvanizing is a common surface treatment method. By electroplating or hot-dip galvanizing, a zinc layer is formed on the surface of the roller chain to improve its corrosion resistance. Galvanizing is suitable for use in outdoor rain erosion and other occasions, but it cannot prevent corrosion from concentrated chemical liquids.

2.2 Nickel plating
Nickel plating forms a nickel layer on the surface of the roller chain by electroplating. It has a beautiful appearance and mild corrosion resistance, and is suitable for use in outdoor rain erosion and other occasions.

2.3 Dacromet coating
Dacromet coating is a special surface treatment method with super corrosion resistance and high heat resistance. It is suitable for high temperature, high humidity or long-term water environment. Dacromet coating can resist high temperature corrosion, and the heat resistance temperature can reach above 300℃.
2.4 Bluing treatment
Bluing treatment forms a dense oxide film on the surface of the roller chain through chemical reaction, improving its corrosion resistance and aesthetics. The chain after bluing treatment usually has a dark blue or black appearance.

3. Lubrication treatment
3.1 Hot oil immersion
Hot oil immersion is to immerse the roller chain in hot oil so that its surface can fully absorb the lubricating oil and improve the lubrication effect of the chain. This method is suitable for occasions that require long-term lubrication.
3.2 Surface spraying
Surface spraying is to spray lubricant on the surface of the roller chain to form a protective film to reduce friction and wear. This method is suitable for occasions that require rapid lubrication.

4. Other surface treatment methods
4.1 Shot blasting
Shot blasting removes oxide scale and impurities on the surface of the roller chain by spraying steel or glass shots at high speed, improves surface roughness, and provides a good foundation for subsequent surface treatment.
4.2 Special coating treatment
Special coating treatment improves the wear resistance and corrosion resistance of roller chains by applying special coatings, such as polytetrafluoroethylene (PTFE) coating, on the surface of roller chains. This method is suitable for occasions that require high wear resistance and low friction coefficient.

5. Comparison and selection of surface treatment methods
5.1 Method comparison
Surface treatment method Advantages Disadvantages Applicable environment
Quenching and tempering Improve hardness and strength May produce internal stress High strength requirements
Carburizing and nitriding Improve surface hardness and wear resistance Complex process High wear resistance requirements
Galvanizing Good corrosion resistance Cannot prevent corrosion from concentrated chemical liquids Outdoor rain erosion
Nickel plating Beautiful appearance, mild corrosion resistance Slightly lower strength than steel chain Outdoor rain erosion
Dacromet coating Super corrosion resistance, high heat resistance High cost High temperature and humidity or long-term water environment
Bluing Beautiful appearance, certain corrosion resistance Poor corrosion resistance High decorative requirements
Hot oil immersion Good lubrication effect Requires regular maintenance Long-term lubrication requirements
Surface spraying Fast lubrication, reduced friction Lubricating film is easy to wear Fast lubrication requirements
Shot blasting Improve surface roughness and remove impurities Only as pretreatment Pretreatment before surface treatment
Special coating treatment High wear resistance, low friction coefficient High cost Occasions requiring high wear resistance and low friction coefficient
5.2 Selection recommendations
Choose the appropriate surface treatment method according to the specific use environment and performance requirements of the roller chain. For example:
In situations where high strength and high wear resistance are required, choose quenching and tempering or carburizing.
In situations where corrosion resistance is required, choose galvanizing, nickel plating or Dacromet coating.
In environments with high temperature, high humidity or long-term water, choose Dacromet coating.
In situations where decorative requirements are high, choose bluing.

6. Conclusion
There are many different surface treatment methods for roller chains, each of which has its own unique advantages and applicable environment. By reasonably selecting and applying these surface treatment methods, the performance and service life of the roller chain can be significantly improved. In practical applications, the most suitable surface treatment method should be selected according to the specific use requirements and environmental conditions to ensure the stable operation and good performance of the roller chain under various working conditions.

7. Case Analysis
7.1 Case 1: Application of galvanized roller chain in agricultural machinery
In agricultural machinery, roller chains are often exposed to rain and humid environments and are susceptible to corrosion. Through galvanizing, the corrosion resistance of roller chains has been significantly improved, extending their service life. User feedback shows that galvanized roller chains perform well in farmland operations, reducing maintenance costs and downtime.
7.2 Case 2: Application of Dacromet-coated roller chains in the food industry
In the food industry, roller chains need to work in high temperature, high humidity and water environments, and are required to be pollution-free. Dacromet-coated roller chains are widely used in food processing equipment due to their super corrosion resistance and environmental protection characteristics. User feedback shows that Dacromet-coated roller chains perform well in high temperature and high humidity environments and meet the hygiene standards of the food industry.
VIII. Future Development Trends
With the continuous advancement of technology, the surface treatment methods of roller chains are also constantly innovating. Future development trends include:
High efficiency and energy saving: Develop more efficient and energy-saving surface treatment processes to reduce energy consumption and environmental pollution.
Environmentally friendly and harmless: Use environmentally friendly surface treatment materials and processes to reduce pollution to the environment.
Versatility: Develop surface treatment technologies with multiple functions (such as corrosion resistance, wear resistance, self-lubrication, etc.) to meet the needs of different industries.

8. Summary
The surface treatment technology of roller chains is of great significance for improving their performance and service life. By reasonably selecting and applying different surface treatment methods, the performance of roller chains under various working conditions can be significantly improved. In the future, with the continuous innovation and development of technology, the surface treatment methods of roller chains will be more diversified and efficient, providing more reliable transmission solutions for the development of various industries.