Stainless steel 316 rust-proof plum blossom belt with pad K series plastic special self-tapping screws are a kind of fasteners specially designed for plastic (plastic) assembly. Its core features are reflected in the material, structure, rust resistance, and applicable scenarios.
Material and rust resistance
316 stainless steel: contains the molybdenum element, and its corrosion resistance is better than that of 304 stainless steel. It is especially suitable for humid and chemical environments, such as outdoor equipment and medical equipment. The surface maintains its original color without electroplating to avoid contamination of plastic,c and no additional rust prevention treatment is required.
The K value specification represents the screw diameter. The larger the K value, the higher the tensile strength. It needs to match the thickness of the plastic part: Thin-walled plastic (<2mm): Select K1.8~K2.2, because the thin diameter reduces the risk of cracking.
Thick-walled or high-load parts: Select K2.5~K4, because the thick diameter increases the bite force.
Structural design advantages
Plum blossom slot (cross slot): compatible with general screwdrivers, good anti-slip performance, suitable for high torque installation
Built-in media or washers: integrated design, avoid adding additional gaskets
Mesons (flat washers): disperse pressure to prevent plastic surface crushing.
Spring washers: Some models contain internal spring washers to prevent vibration loosening.
Triangular tooth type: extruding plastic to form internal threads instead of cutting, reducing debris and a stronger bonding force, especially suitable for plastics with good ductility, such as polypropylene and nylon.
Installation steps and key technologies
Preliminary preparation
Aperture design: Hard plastics need to be slightly enlarged (+0.1mm), and soft plastics can be slightly reduced.
Hole depth requirements: 1~2mm greater than the screw length to avoid bottom cracking of plastic.
Key operation: must be vertical in the initial stage; if the tilt is greater than 3°, it may cause slipping.
Speed control: Hand drills are recommended to be ≤ 800 rpm, and excessive friction and heat will soften the plastic.
Lubrication and cooling: For hard plastics (such as POM) or high-density parts, silicone lubricants can be applied to the screw threads to reduce the resistance to penetration. Oily grease is prohibited to avoid corroding plastics.
Common problems and solutions
Repair of slipped threads: Use self-tapping screw sleeves to embed into the original hole, re-form the thread, and select screw sleeves with outer diameters matching the K value.
Head slippage: Replace the high-precision plum cutter head and clean the residual glue in the groove.
Screw breakage: Mostly caused by tilting and tightening, nitric acid is required to corrode the broken body (only 316 stainless steel material) to avoid damage to the workpiece by expanding the hole.
Recommended application scenarios
K1.8~K2.2: Electronic product housings (routers, remote controls), thin-walled toys.
K2.5~K4: Automobile plastic brackets, home appliance structural parts (washing machine panels, air conditioner housings).
By accurately matching the K value with plastic properties and strictly controlling the installation verticality and torque, the screw can significantly increase the connection life. When repairing slipped threads, self-tapping screw sleeves are preferred rather than expanding the hole to retain the original design strength.
