Precision screws are prone to residual oil stains during production and processing. Specialized cleaners with different properties can be selected according to oil types and workpiece materials. Demulsifying cleaners are mainly used to remove anti-rust floating oil; alkaline cleaners eliminate oxidized dirt and processing contaminants. For heat-treated screws, residual quenching oil must be thoroughly cleaned to avoid defects in subsequent electroplating, assembly and service performance. Two professional cleaning methods are widely adopted to solve oil residue problems in the production of non-standard precision screws.
1. Professional Degreasing and Cleaning Processes for Precision Screws
1.1 Soluble Demulsifying Cleaner
Demulsifying cleaners are formulated with organic solvents, emulsifiers, detergents, desulfurizers and a small amount of pure water without granular impurities. Water promotes uniform dissolution of emulsifiers, enabling the cleaner to decompose and strip various oil contaminants on precision screw surfaces. A thin temporary anti-rust film forms on the workpiece after cleaning for short-term protection. Emulsifiers and cleaning additives encapsulate grease particles thoroughly and disperse suspended oil into the cleaning solution to achieve effective oil-water separation. The original cleaner is a transparent oily liquid and turns milky white after dilution. It is suitable for removing residual anti-rust oil and mechanical lubricating oil.
1.2 Synthetic Cleaner
Different from traditional alkaline cleaners, synthetic cleaners are mainly composed of amine-based organic compounds without strong corrosive alkaline ingredients. They effectively remove alkaline residues, oxidized stains and stubborn anti-rust oil through single-step integrated cleaning. Without damaging screw substrates, they deliver residue-free surface cleaning and are applicable to both stainless steel and carbon steel precision screws.
2. Common Surface Treatment Processes for Stainless Steel Precision Screws
Stainless steel screws feature smooth surfaces and excellent inherent rust resistance, requiring no additional surface treatment under normal working conditions. Custom surface treatments can be applied according to project requirements to further enhance corrosion resistance, wear resistance, assembly compatibility and appearance quality, meeting standard engineering specifications. The mainstream surface treatment processes for stainless steel and carbon steel precision screws are listed as follows:
2.1 Electroplating
Screw workpieces are immersed in electrolyte containing metal complex compounds. Under electrification, metal ions precipitate and deposit uniformly on the screw surface to form a dense protective coating. Common electroplating technologies include zinc plating, copper plating, nickel plating, chromium plating and copper-nickel alloy plating. Featuring uniform and high-precision coatings, electroplating is widely used for miniature and precision screws.
2.2 Hot-Dip Galvanizing
Mainly applied to carbon steel fasteners, this process immerses steel workpieces in molten zinc at approximately 510°C. Metallurgical reactions occur on the steel surface to form an iron-zinc alloy layer and an outer pure zinc passivation layer. Hot-dip aluminizing follows a similar principle. With thick and highly anti-corrosive coatings, these processes adapt to heavy-duty outdoor and high-corrosion environments.
2.3 Mechanical Plating
Through high-speed mechanical impact, metal coating particles cold-weld and deposit on workpiece surfaces to form uniform protective layers. This process causes no high-temperature damage and avoids hydrogen embrittlement or deformation of fasteners.
Standard precision screws generally adopt electroplating. Hot-dip galvanizing is preferred for outdoor facilities requiring superior corrosion resistance, such as power equipment and highway structures. Mechanical plating is commonly used for large non-standard fasteners.
Proper combination of cleaning and surface treatment processes completely eliminates surface oil stains and contaminants on precision screws, effectively improving surface quality, corrosion resistance and overall service performance to meet diverse engineering assembly requirements.
