Introduction to GB/T 6403.3-2008 Standard
This standard specifies types and dimensions for knurling on cylindrical surfaces for general purposes, focusing on straight knurling and net knurling. It ensures consistent surface texturing for improved grip, aesthetics, or functional assembly in mechanical components.
Scope
GB/T 6403.3-2008 applies to knurling processes on cylindrical surfaces, defining parameters for straight (linear) and net (cross-hatched) patterns. It is essential for manufacturing parts requiring enhanced friction or decorative finishes, such as handles, knobs, and shafts. Compliance guarantees interoperability and quality in engineering applications.
- Primarily for general-purpose knurling, not specialized high-precision uses.
- Covers modulus values from 0.2 to 0.5 mm.
- Integrates with related standards for material and tolerance specifications.
Types of Knurling
Knurling creates raised patterns on surfaces via rolling or pressing. This standard addresses two main types: straight knurling (parallel grooves) and net knurling (intersecting patterns forming diamonds or meshes). Straight knurling provides linear grip, while net knurling offers omnidirectional friction resistance.
- Straight Knurling (Type RAA/RBL): Grooves parallel or helical to the axis, suitable for simple anti-slip needs.
- Net Knurling: Crossed patterns for enhanced holding power in rotational applications.
Select type based on functional requirements, such as torque transmission or user interface.
Dimensions and Parameters
Key parameters include modulus (m), tooth height (h), radius (r), and pitch (P). These ensure uniform knurl formation. The formula for height is h = 0.785m – 0.414r. Dimensions are in mm, optimized for standard tooling.
| Parameter | Modulus m | |||
|---|---|---|---|---|
| 0.2 | 0.3 | 0.4 | 0.5 | |
| h | 0.132 | 0.198 | 0.264 | 0.326 |
| r | 0.06 | 0.09 | 0.12 | 0.16 |
| P (Pitch) | 0.628 | 0.942 | 1.257 | 1.571 |
Post-knurling diameter increases by Δ ≈ (0.8~1.6)m, enhancing fit without excessive material displacement.
Technical Requirements
Surface preparation is critical: pre-knurl roughness Ra ≤ 12.5 μm ensures clean patterns. Post-knurl, verify diameter expansion and pattern uniformity to avoid defects like undercutting or cracking. Use appropriate pressure to prevent workpiece deformation.
- Material suitability: Prefer ductile metals like steel or aluminum.
- Tooling: Match knurl wheels to modulus for precision.
- Inspection: Measure pitch and height with calipers or profilometers.
Sovellukset ja parhaat käytännöt
Knurling improves handling in tools, fasteners, and instruments. For straight patterns, apply in low-vibration settings; net for high-torque needs. Best practices include pilot testing on samples and adjusting feed rates for optimal finish.
Usein kysytyt kysymykset
What is the difference between straight and net knurling?
Straight knurling creates parallel grooves for linear grip, while net knurling forms a cross-hatched pattern for multi-directional friction, ideal for rotational components.
How to calculate knurl height h?
Use h = 0.785m – 0.414r, where m is modulus and r is radius, ensuring precise pattern depth for functional performance.
Why control pre-knurl surface roughness?
Ra ≤ 12.5 μm prevents irregularities that could distort the knurl, maintaining uniformity and strength.
What causes diameter increase after knurling?
Material displacement during rolling; expect Δ ≈ (0.8~1.6)m to avoid interference in assemblies.
Is this standard suitable for all materials?
Primarily for metals; test on non-ferrous or hardened materials to ensure no cracking or tool wear.
How to select modulus m?
Choose based on part size and grip needs; smaller m for fine patterns, larger for coarse.
