Why Do Long Screws Bend? How to Fix It | Professional Bolt Straightening Services
Long screw bending is a common issue during manufacturing, especially for fasteners longer than 10 times their diameter. This problem often occurs after heat treatment, leading to straightness deviations that fail to meet international standards.
If your bolts or screws are bent, they can compromise assembly accuracy, machinery performance, and product aesthetics. In this article, we’ll explain why long screws bend, how to fix bent screws, and the professional straightening services we provide to ensure perfect alignment.
Why Do Long Screws Bend During Production?
Long screws go through several manufacturing stages—cold forming, threading, and heat treatment. Each process introduces internal stress. When the screw is exposed to high temperatures during heat treatment, these stresses release unevenly, causing warping or bending.
Key factors include:
Length-to-diameter ratio: Screws like M8 × 85mm or longer are highly susceptible.
Material composition: Alloy steel and stainless steel respond differently to heat.
Cooling rate: Improper quenching can induce distortion.
Problems Caused by Bent Screws
Bent or warped screws can:
Fail to meet ISO 4759-1 or IFI 138 straightness standards.
Cause misalignment during assembly.
Affect machinery safety and performance.
Increase rework and rejection rates, raising production costs.
How to Fix Bent Screws? Professional Straightening Process
Our bolt and screw straightening services restore your fasteners to precise straightness, ensuring they pass international quality standards.
Our Process Includes:
Precision straightening machines designed for long screws and bolts.
ISO 4759-1 compliance for metric screws.
IFI 138 compliance for inch screws.
SKD-11 inspection tubes for high-accuracy measurement.
100% manual inspection for critical applications.
After straightening, screws undergo:
Surface finishing (plating or coating)
Sorting and packaging
Final quality control checks
