Author: Site Editor Publish Time: 2025-10-16 Origin: Site
What Is a Threaded Rod? A Complete Guide to Selection, Materials, and Applications – Master Key Points of Threaded Rod Selection in One Article
1. What Is a Threaded Rod? Its Core Functions and Application Scenarios
A threaded rod, also known as a "threaded bar" or "lead screw rod," is a mechanical component with continuous helical threads on its outer surface. It is usually used with a nut to primarily realize the conversion of rotational motion into linear motion (or vice versa), while also providing positioning, fixing, and transmission functions.
Its application scenarios cover almost all industrial fields, with core uses including:
Mechanical transmission: e.g., sliding tables of machine tools, translation mechanisms in automated production lines;
Equipment fixing: e.g., anchor fixing of large equipment, connection of pipe supports;
Adjustment functions: e.g., height adjustment of lifting platforms, tightness control of fixtures;
Precision positioning: e.g., assembly of 3C electronic equipment, precision displacement mechanisms in medical devices.
2. How to Choose Threaded Rod Materials? Comparison of 3 Common Materials (with Table)
The material of a threaded rod directly determines its load-bearing capacity, corrosion resistance, and service life. Different scenarios require matching materials. Below is a comparison of the 3 most commonly used threaded rod materials in the industrial sector:
Material Type
Core Characteristics
Applicable Scenarios
Reference Hardness (HRC)
Stainless Steel Rod
Corrosion-resistant, easy to clean, stable performance at low temperatures
Food machinery, medical devices, outdoor equipment, humid environments
20-30
Carbon Steel Rod (45#)
High strength, strong load-bearing capacity, cost-effective
General machinery, heavy-duty equipment, fixed structures, non-corrosive environments
35-45
Alloy Steel Rod (40Cr)
High hardness, excellent wear resistance, good impact resistance
3. Core Specifications of Threaded Rods: Understand These 3 Points to Avoid Mistakes in Selection
The specifications of threaded rods are key to selection. Focus on the following 3 core indicators to prevent equipment failures caused by mismatched parameters:
1. Pitch (P)
Pitch refers to the distance between two adjacent threads along the axial direction, which directly affects transmission efficiency and precision.
Large pitch (e.g., P=5mm, P=10mm): Fast transmission speed but low precision, suitable for scenarios requiring quick adjustment;
Small pitch (e.g., P=1mm, P=2mm): High transmission precision but slow speed, suitable for precision positioning scenarios.
2. Nominal Diameter (d)
The nominal diameter is the outer diameter of the threaded rod, which determines its load-bearing capacity.
Smaller diameter (e.g., d=6mm, d=10mm): High flexibility, suitable for light-load and small-space scenarios.
3. Precision Grade
Threaded rod precision is usually classified according to the GB/T 5796 standard, with common grades being C7, C8, and C9 (precision decreases from high to low).
Grade C7: Precision grade, used in scenarios requiring high precision such as machine tools and automated equipment;
Grade C8: General grade, used in conventional scenarios such as general machinery and fixed structures;
Grade C9: Rough grade, used in scenarios such as temporary fixing and low-precision adjustment.
4. 4-Step Guide to Threaded Rod Selection: A Complete Process from Demand to Implementation
Many people rely on experience for selection, leading to problems such as "insufficient load-bearing" or "inadequate precision" later. Follow these 4 steps to ensure accurate selection:
Clarify the application scenario: First, determine whether the threaded rod is used for "transmission," "fixing," or "adjustment." At the same time, specify the load weight (e.g., 50kg, 500kg) and operating speed (e.g., 0.1m/s, 1m/s);
Match the material: Select stainless steel, carbon steel, or alloy steel based on whether the environment is corrosive (e.g., humid, acidic/alkaline) and the temperature range;
Determine specifications and parameters: Choose the diameter based on the load (larger load requires a larger diameter), and select the pitch and precision grade based on precision requirements;
Confirm supporting components: Threaded rods need to be used with nuts and bearing blocks. Ensure the nut model (e.g., T-slot nut, trapezoidal nut) matches the threaded rod, and the load-bearing capacity of the bearing block is not lower than that of the rod.
5. Key Points for Threaded Rod Installation and Maintenance: 3 Tips to Extend Service Life
After selecting the right threaded rod, proper installation and maintenance can extend its service life by more than 30%. The core points are as follows:
Pre-installation inspection: Ensure the rod surface is free of scratches and deformation, and the threads are undamaged. During installation, keep the rod parallel to the guide rail to avoid jamming or wear caused by tilting;
Regular lubrication: Add grease (e.g., lithium-based grease) every 1-3 months according to usage frequency to reduce friction between threads;
Daily cleaning: Regularly clean dust and iron chips from the rod surface, especially in scenarios with high impurities (such as machine tools and processing equipment), to prevent impurities from entering thread gaps and causing wear.
6. Frequently Asked Questions (FAQ) About Threaded Rods
Q1: Is there a difference between a threaded rod and a lead screw?
Yes, there is a difference. A threaded rod usually refers to a "trapezoidal threaded rod," which focuses on general transmission and fixing. A lead screw (e.g., ball screw) integrates balls into the rod structure, offering higher transmission efficiency (up to over 90%) and precision, but it also costs more and is mostly used in precision equipment.
Q2: What causes "abnormal noise" from a threaded rod?
It is most likely an installation or maintenance issue. Common causes include: 1. Excessive parallelism deviation between the rod and the nut; 2. Insufficient lubrication leading to dry friction; 3. Impurities (e.g., iron chips, dust) mixed in the threads. You can first check the parallelism, then clean the rod and add grease.
Q3: Which material is the most durable for threaded rods used outdoors?
Prioritize 304 or 316 stainless steel rods. 304 stainless steel is suitable for general outdoor humid environments, while 316 stainless steel has stronger acid and alkali resistance, making it ideal for highly corrosive scenarios such as coastal areas and chemical industries.
Q4: Can the length of a threaded rod be customized?
Yes. The conventional length of threaded rods on the market is 1m or 2m. If a longer length (e.g., 3m, 5m) or shorter length (e.g., 0.5m) is needed, you can contact the manufacturer for customization. Note that longer rods require additional bearing blocks to prevent bending during operation.
Conclusion
Although small in size, threaded rods are "key components" for mechanical transmission and fixing. Selection requires comprehensive consideration of scenarios, materials, and specifications to avoid minor errors leading to major losses. Mastering the selection methods and maintenance points in this article can effectively improve the operational stability of equipment and reduce the risk of subsequent failures.
