Carbon steel, aluminum, copper, and stainless steel electrophoresis black M3, M4, M5, M6, and M8 1/4-20 straight-grain, thin-head knurled thumb screws are a type of manually installed knurled screw that combines various materials, specifications, and surface treatments. Below is a detailed description of their custom requirements, balancing comprehensiveness with key highlights.
1. Material Selection and Characteristics
Carbon steel: Low cost and high strength, requires an electrophoresis black coating for rust prevention.
304/316 stainless steel: Naturally rust-resistant, electrophoresis black is for cosmetic purposes, and coating adhesion must be verified.
Aluminum alloy: Preferred for lightweighting, requires special pretreatment before electrophoresis.
Copper: For conductive or decorative purposes, electrophoresis may affect conductivity, so the intended use must be clearly defined.
Key Points: The electrophoresis process must be compatible with the material, and stainless steel and copper require pre-testing with test specimens.
2. Thread Specifications and Standards
Metric threads: M3, M4, M5, M6, and M8, with coarse threads as the default.
Imperial Thread: 1/4-20 UNC (American Standard Unified Coarse Thread).
Special Requests: Fine or non-standard threads may be requested.
Note: Imperial and metric thread sizes cannot be mixed in the same order; production must be done in separate batches.
3. Head Design
Thin Head: Head height ≤ 1/2 the thread diameter.
Straight Knurl: Diamond pattern, 0.5-1mm pitch, anti-slip force ≥ 5 N·m.
Slotless Design: Hand-tighten, no tools required.
Key Parameters: Specific dimensional tolerances for head diameter and height are provided.
4. Surface Treatment
Electrophoretic Black: Film thickness 15-25μm, salt spray test ≥ 500 hours.
Alternative: PVD black can be applied to stainless steel, which offers improved wear resistance but at a higher cost.
Required Inspection Items: Color difference (ΔE ≤ 1.5), no exposed base of the coating.
5. Performance and Testing
Mechanical Properties:
Carbon Steel: Grade 8.8 or Grade 12.9 (please specify).
Stainless Steel: A2-70/A4-80.
Aluminum Alloy: Hardness ≥ 80 HB.
Torque Test: Hand-tightening torque for M5 screws ≥ 3 N·m (reference value).
6. Packaging and Labeling
Packaging: 1000 pieces/carton (divided into 10 small bags), or as per the customer's requirements.
Labeling: Laser marking of material/batch.
7. Delivery Time and MOQ
Prototype Lead Time: 7-10 days (3-5 materials available).
Mass Production Lead Time: 15-30 days (depending on quantity).
MOQ: 500 pieces/specification (mixed and matched quantities are possible, total quantity ≥ 5000 pieces).
8. Key Confirmation Items
Prioritize the material and thread combination. Is ROHS/REACH certification required?
Providing drawings or samples can significantly reduce communication costs (focusing on noting the knurl and head dimensions).
Through the combination of materials, specifications, and surface treatment, this type of screw strikes a balance between functionality, aesthetics, and adaptability, making it an ideal choice for quick-release and fine-tuning applications.
