[L1] 1 Cleaning [L2] 1) Definition [L4] - A series of work processes to remove unspecified foreign substances and other organic components from the surfaces of instruments, containers, equipment, etc. [L2] 2) Types of Cleaning [L2] 3) Types of Cleaning Agents [L3] ① Classification by Manufacturing Method [L4] - Soap, Synthetic Detergent [L3] ② Classification by Use [L4] - For Washing: Facial soap, liquid soap, shampoo, rinse [L4] - For Household: Kitchen detergent, laundry soap, laundry powder soap [L4] - For Industry: Scouring, cleaning, dyeing, etc. [L3] ③ Classification by Characteristics [L4] - Water-based Cleaner: Contains various components in water. [L4] - Semi-aqueous Cleaner: Contains water-soluble organic solvents. [L4] - Non-aqueous Cleaner: Contains insoluble organic solvents like hexane. [L3] ④ Classification of Cleaning Agents [L4] - Surfactants [L4] - Builders [L4] - Water Softeners [L4] - Alkaline Additives [L2] 4) Conditions for Cleaning Agents [L4] - Must mitigate contamination adhesion from the appearance of mechanical devices after cleaning. [L4] - Removal of contaminants must be easy. [L4] - Non-toxicity and ecological safety must be secured. [L4] - Rinsing power must be good and rinsing must be easy. [L4] - Must be economical and easy to supply/demand. [L2] 5) Principle of Cleaning [L3] ① Lowering the surface tension between the dirt attached to the object and the cleaning liquid. [L3] ② Separating dirt by the wetting and penetrating action of the cleaning liquid. [L3] ③ Dispersing and suspending into fine particles. [L5] cf. Suspension: A phenomenon where solid fine particles are dispersed in a liquid. [L1] 2 Rust Prevention (Anti-rust) [L2] 1) Definition of Rust Prevention Work [L4] - Collectively refers to the action of preventing rust generation on metal surfaces by creating a film on the metal surface to block contact with air or moisture. [L4] - Rust: A state where the surface becomes rough and coarse by changing from the iron surface in the atmosphere at room temperature. [L5] * Refers to corrosion products mainly composed of insoluble ferric oxide. [L5] * Substances forming a barrier of a strong adsorption film on the steel surface. [L2] 2) Rust Preventive Agents (Anti-rust Agents) [L4] - Prevents rust by applying to the metal surface to form a film, thereby blocking water and oxygen in the environment. [L4] - Anti-rust oil consists mainly of anti-rust additives which are corrosion inhibitors. It is made by adding petroleum-based solvents to this, varying the amount/type of additives as needed. [L2] 3) Required Specifications for Rust Preventive Agents [L4] - Rust Prevention (Corrosion Resistance): Must have good rust prevention performance considering the waiting period between processes. [L4] - Water Displacement: Must be able to cope with condensation due to humid environments (or rainy season) and daily temperature differences. [L4] - Degreasability: Must be easily removed in the degreasing line. [L4] - Cleanability: Foreign matter cleanability on the steel sheet surface must be good during leveling work. [L4] - Workability: Low viscosity with little change such as hardening. [L4] - Stability: Must be harmless to the human body (Odor, dermatitis, etc., should be benign). [L4] - Flash Point: Flash point must be high to be safe from fire. [L4] - Oil Stain Resistance: No oil stain should occur during on-site storage. [L2] 4) Application of Rust Preventive Agents [L4] - Immersion Application (Dipping): A method of forming a rust preventive film by immersing metal products in a bath of rust preventive agent. Tank capacity becomes large, and there is a risk. [L4] - Spray Method (Pump Spray, Can Spray): A method of applying by spraying using gas pressure or compressed air using aerosols or spray nozzles. Easy to harm the working environment. [L4] - Brush Application: Used for outdoor structures and special shaped products when dipping or spraying cannot be applied. Requires worker's skill.