303 stainless steel American thread automatic lathe straight knurled hand screw is a specific type of manual fastener. The following is a detailed technical solution for its customization, which takes into account both professionalism and practicality.
1. Core parameter specifications
Material standard: 303 stainless steel, tensile strength ≥500MPa, hardness HRB 70-90.
Surface treatment: default natural color passivation, optional electrolytic polishing or nickel plating, please indicate.
Thread specifications
American unified thread (UN series): such as #4-40, #6-32, #8-32, etc. (specific UNF/UNC code is required)
Tolerance grade: 2B (default) or 3B (when high precision is needed)
Thread length: full thread or segmented
Knurling requirements
Type: straight knurling (parallel to the axis)
Standard: DIN 82 or ANSI B94.6
Module: 0.5mm/0.8mm/1.0mm
Effective width: ≥1.2 times the diameter of the screw head
Head design
Head type: round head/flat head/cylindrical head (with diagram)
Slot type: slot/cross slot/hexagonal hole
Head diameter and height ratio: according to ASME B18.6.3 Adjustment
II. Key points of processing technology
Automatic lathe processing
Equipment: Swiss-type automatic lathe (accuracy ±0.01mm)
Tools:
Thread: Carbide extrusion tap (OSG EXOTAP recommended)
Knurling: Double-wheel knurling tool (HSS for coarse thread, tungsten steel for fine thread)
Cutting parameters
Speed: 1500-2500rpm
Feed rate: 0.05mm/rev
Knurling process control
Pre-pressing method: First, turn the outer diameter of the knurling area to the middle difference size
Pressure: 300-500N (avoid material accumulation)
Cooling: Fully synthetic cutting fluid (concentration 8%-10%)
Deburring requirements: A 45° chamfer needs to be added at the thread outlet, and the knurling edge is polished by magnetic polishing to remove sharp edges.
3. Quality control standards
Size: Go/no-go gauge to detect threads, three-dimensional measurement of key dimensions
Knurling: visual inspection of texture uniformity, projector to verify pitch
Material: spectrometer to verify S content (to ensure machinability)
Defective rate control: batch AQL 1.0, slight knife marks are allowed in the knurling area.
4. Packaging and delivery
Inner packaging: PVC blister + anti-rust paper
Outer packaging: carton (1000pcs per box, gross weight ≤15kg)
Marking: laser marking batch number + material marking
Delivery cycle: 15-20 days (3 days for samples, with test report)
5. Solutions to common problems
Thread rot → Check tap wear, replace every 5000 times, or use a spiral groove tap instead.
Knurling burrs are large → adjust the pre-knurling margin to 0.8-1.2 times the modulus.
Surface scratches → Use nylon grippers or add conveyor track bushings.
A complete 2D drawing or 3D STEP file is required, and key dimensions must be marked separately. Special requirements require additional tooling costs.
Through the design and process control described above, it can be seen that the screw strikes a balance between functionality, production efficiency, and reliability, and is suitable for medium and high intensity use requirements.
