Cleaning refers to the process of removing liquid and solid contaminants from the surface of fasteners, aiming to achieve a certain level of cleanliness. It is an essential intermediate step in the production of fasteners that should not be overlooked. If contaminants on the fastener surface enter the heat treatment furnace or are released into the workshop through volatilization or burning, they can lead to environmental pollution. Therefore, cleaning is considered part of the cleaner production process. The cleaning process involves interactions between the cleaning medium, contaminants, and the fastener surface, making it a complex physical and chemical operation.
1. Cleaning Methods and Techniques
1.1 Types of Cleaning
In the fastener industry, there are two primary cleaning steps: one before heat treatment, which focuses on removing residual oil, coolant, and anti-rust agents from previous processes; and another after heat treatment, mainly for eliminating quenching oil left behind. Based on the method and principle used, cleaning can be categorized into physical cleaning, chemical cleaning, and others.
Physical cleaning involves using mechanical forces and energy to break down and remove contaminants from the object's surface. Common techniques include spraying, high-pressure water jets, agitation, and ultrasonic cleaning.
Chemical cleaning, on the other hand, uses chemical agents or aqueous solutions to chemically react with and dissolve contaminants. This includes methods such as alkaline water cleaning and solvent cleaning.
1.2 Common Cleaning Techniques
1. Immersion cleaning involves submerging the fastener in a cleaning solution. However, this method has limited washing power and requires longer time.
2. Jet cleaning uses a nozzle to spray the cleaning liquid onto the fastener at pressures exceeding 2 MPa.
3. Liquid-phase jet cleaning employs the stirring force of the cleaning solution to enhance the cleaning effect, offering better performance than immersion.
4. Spray cleaning applies the cleaning liquid at lower pressures (less than 0.2 MPa) to the surface of the fastener.
5. Decompression cleaning creates a vacuum in the tank, allowing the cleaning agent to penetrate deeply into small gaps. When combined with ultrasonic waves, the effect is significantly improved.
6. Gas-phase spray cleaning uses a spray tube to apply the cleaning agent under pressure (typically 0.2–2 MPa).
1.3 Residual Oil Removal
Residual oil cleaning targets oils attached to the fastener surface during cold heading or cutting, as well as oil remaining after heat treatment.
1. Alkaline water cleaning is a simple and cost-effective method using sodium carbonate or sodium hydroxide solutions. It is commonly used for intermediate cleaning before tempering.
2. Metal cleaning agents offer better performance but are more expensive and may have a strong odor and corrosive effects.
3. Organic solvents like trichloroethane provide excellent cleaning results but can pollute the environment if not properly managed. A closed vacuum system helps recover solvents and reduce emissions.
4. Combustion degreasing involves heating the fastener to burn off oils, suitable for light oils but ineffective for heavy quenching oils.
2. Cleaning Technology Overview
For high-quality fasteners such as aerospace bolts or automotive engine connecting rod bolts, advanced technologies like vacuum or ultrasonic cleaning are now preferred over traditional chlorinated hydrocarbons due to their environmental benefits. These methods ensure efficient and eco-friendly cleaning.
2.1 Vacuum Solvent Cleaning
This technique uses hydrocarbon solvents to effectively remove oils and coolants. It includes pre-washing, steam cleaning, and vacuum drying. The process is energy-efficient, environmentally friendly, and ensures thorough cleaning.
2.1.1 Vacuum Water-Based Cleaning
This method combines vacuum technology with water-based solvents to lower boiling points, enabling efficient cleaning of deep or blind-hole fasteners. It also allows for quick drying without leaving residues.
2.1.2 Vacuum Water-Based Process
It starts with pre-cleaning using micro-jets and air bubbles, followed by vacuum cleaning and drying. This reduces water usage and improves overall efficiency.
2.2 Ultrasonic Cleaning
Ultrasonic cleaning uses sound waves to create cavitation, breaking down dirt and improving cleaning effectiveness. It is widely used for precision components and offers faster results compared to traditional methods.
2.2.1 Ultrasonic Cleaning Mechanism
Ultrasonic waves generate tiny bubbles that collapse and release energy, dislodging contaminants from the fastener surface. This method works well with both chemical and water-based cleaning agents.
2.2.2 Key Parameters
Factors such as frequency, power density, temperature, and cleaning medium significantly affect the efficiency and quality of ultrasonic cleaning.
2.2.3 Applications
Ultrasonic cleaning is now widely adopted in industries where high cleanliness is required, offering speed, efficiency, and reduced environmental impact.
3. Types of Cleaning Agents
Choosing the right cleaning agent depends on the type of contamination and the cleaning process. Common options include water-soluble, organic solvent-based, and hydrocarbon cleaning agents.
3.1 Water-Soluble Cleaners
Alkaline and synthetic cleaners are widely used for their low cost and good performance in removing oils and coolants.
3.2 High-Efficiency and Eco-Friendly Cleaners
Water-based and vacuum oil-based cleaners offer strong cleaning power with minimal environmental impact. Hydrocarbon solvents are also gaining popularity for their safety, recyclability, and effectiveness.
Safety valve lobe pumps: Built-in safety valve is the most important way to protect the pump. This is a special sanitary safety valve designed and developed by our company, with sensitive response, compact structure, beautiful appearance and so on.
Safety valve lobe pumps, Safety valve Rotary pumps, Safety valve Rotary lobe pumps, Safety valve Rotor pump, Safety valve Stainless Steel Rotor pump
NINGBO DURREX PUMPS CO.,LTD , https://www.durrexlobepump.com