Release time：2020-01-16 18:44 Browse：
The straightness or verticality of a long screw refers to the deviation of the screw’s axis from being perpendicular to the reference surface under the screw head. This becomes especially important for screws longer than 200mm.
V-Block + Dial Indicator Method (Laboratory or QC use)
Place the screw in a V-block.
Use a dial indicator to measure deviation as the screw is rotated.
Record any fluctuations to assess verticality.
Fixture + Laser or Optical Sensor Method (Mass production)
Fix the screw in a custom fixture.
Use laser sensors or an optical grid to detect deviation along the screw's length.
Suitable for automatic or semi-automatic production lines.
Ruler + Visual Inspection (Manual pre-shipment check)
Stand the screw on a flat glass surface.
Use a ruler or angle gauge to check for obvious bending or tilting.
A quick method for general-quality inspection.
| Application | Verticality Requirement | Reason |
|---|---|---|
| Steel structures, solar mounts | High | Precise drilling and alignment required |
| Curtain walls, aluminum cladding | Very High | Affects visual alignment and structural integrity |
| Timber frames, wooden sheds | Medium | Wood allows for some installation tolerance |
| Decorative panels, roofing sheets | Low | Installation tolerances are relatively large |
| Precision machinery assemblies | Very High | Must align perfectly with mechanical components |
Longer screws are more prone to bending or vertical deviation, especially after thread rolling.
Use cold heading process instead of hot forging to reduce deviation.
For high-precision projects, verticality tolerance can be defined as:
≤300mm length: deviation ≤0.5mm
>300mm length: deviation ≤1.0mm
