For a long time, the rust prevention technology in the fastener industry has generally used high-grade gasoline to clean screws and nuts, which fails to meet environmental protection requirements and poses safety risks.
As the state will gradually restrict and eventually phase out ozone-depleting substances (ODS) cleaning agents, and prohibit or limit the use of toxic and hazardous chemicals such as dichloromethane, dichloroethylene, and gasoline, some enterprises have attempted to use water solutions and alcohol as cleaning agents, but these have shortcomings in terms of rust prevention effect, safety, and environmental protection. Therefore, it is necessary to consider adopting new process methods.
Cleaning Process Technology of Fasteners
1. Defects of the original cleaning agent process
During the process of cleaning fasteners with gasoline, gasoline evaporation occurs. The impurities in the exhaust gas are rust preventive oil vapor and volatile gasoline. After gasoline vaporizes into vapor, its volume expands to several dozen times its original size.
When the gasoline vapor in the air reaches 2% to 7%, it will explode upon encountering a spark. Benzene, which is contained in gasoline, is a carcinogen. In the production environment, gasoline is absorbed through the respiratory tract in vapor form, and it can also penetrate the human skin and enter the body, posing a significant threat to human health.
Mild acute poisoning is accompanied by severe headache, nausea, palpitations, blurred vision, etc. Severe acute poisoning may result in convulsions, coma, and extremely high concentrations can cause sudden loss of consciousness. Moreover, the original process used manual cleaning, which could not solve the problem of cleaning and drying blind holes and crevices due to the presence of air.
2. Selection of Cleaning Agents
Currently, high-purity hydrocarbon cleaning agents are widely used in Europe, America and the Asia-Pacific region to clean fasteners. Such substances comply with the EU WEEE/RoHS environmental protection directives and are an excellent alternative to ODS as cleaning agents.
Hydrocarbon cleaning agents are superior to water-based cleaning agents and halogenated hydrocarbons in cleaning fasteners. They have extremely low oral toxicity, inhalation toxicity and skin contact toxicity, and do not contain carcinogens or corrosive substances such as chlorine and sulfur. They do not cause oxidation or corrosion of metal materials.
They can completely evaporate at room temperature and when heated, leaving no residue. The boiling point at room temperature is higher than 150℃. The loss caused by evaporation during the cleaning process is smaller than that of halogenated hydrocarbons with a boiling point of 40 to 80℃.
The flash point of most hydrocarbon cleaning agents is around 50℃, which belongs to the third category of flammable substances. Their safety is higher than that of high-grade gasoline. Through natural degradation, the waste liquid of hydrocarbon cleaning agents after cleaning is mainly composed of water and CO2 when burned, causing no pollution to the air.
3. Comparative Verification of Cleaning Agents
The original process employed manual cleaning methods, where bolts and nuts were soaked in high-grade gasoline and scrubbed with clean brushes, followed by natural or mechanical ventilation for drying. This process failed to address the cleaning of tiny blind holes and crevices, and the drying process involved the emission of organic waste gases, which was restricted by environmental protection policies.
Some enterprises adopted ultrasonic methods to enhance the cleaning effect, but due to the presence of air in blind holes and crevices during the cleaning and drying process, the cleaning effect was weakened.
To ensure representative coverage of the bolts and nuts requiring oil seals, MML35, 35CrMo, and 20MnTiB steel bolts were selected, with C10H22 hydrocarbon cleaning agent as the cleaning agent.
The comparison results of the cleaning tests show that the products cleaned with C10H22 cleaning agent have a clean appearance with no oil residue, and can effectively remove surface dirt, with the cleaning effect being consistent with that of high-grade gasoline. After immersion in C10H22 cleaning agent, the cross-sections of the samples showed no change compared to before immersion, indicating that the cleaning agent has no corrosive effect.
No adverse phenomena such as oxidation layer peeling or damage were found on the samples, and the surface condition was good, without any impact on the product dimensions.
C10H22 hydrocarbon cleaning agent can be used as a substitute for high-grade gasoline for cleaning purposes. For important fasteners, ultrasonic and vacuum high-temperature vapor phase cleaning technologies can be adopted to enhance the cleaning effect. This can fully meet the requirements of cleaning quality, safety and environmental protection.
If you are looking for quality fasteners, please visit us here https://hktl-fastener.com/.
