Double-Thread Screw
Products Description
Double-thread screws are cylindrical fasteners with external threads at both ends and a smooth middle section. Made of carbon steel and galvanized, they are primarily used for pipe and valve flange connections, mechanical equipment base fixing, and blind flange installation on pressure vessels. This product solves the problem of through bolts being unsuitable for blind hole connections. By permanently fixing the screw-in end to the base and locking the connected parts with the nut end, a detachable rigid connection between the two components is achieved.
Manufacturing Advantages
Multi-station cold heading
Utilizing a 4-6 station cold heading machine, wire is formed into a double-ended diameter blank in one step. The diameters at Double-Ended Threaded are pre-reduced to the thread root diameter, achieving a material utilization rate of over 90%, far exceeding that of bar turning processes.
Precision thread rolling process
Simultaneous or step-by-step thread rolling is used at Two-Ended Screw, achieving thread accuracy up to 6g/6h grade, with a go/no-go gauge pass rate of over 99.5%. The thread surface after thread rolling develops a work-hardened layer, increasing hardness by approximately 20% and improving fatigue resistance.
Controlled atmosphere heat treatment
Carbon steel parts undergo tempering treatment (quenching + high-temperature tempering) in a mesh belt furnace to achieve the target strength grade (4.8/8.8/10.9/12.9), with hardness uniformity controlled within ±2HRC for Two-End Stud.
Zinc plating surface treatment
Barrel plating or rack plating processes are used, with a zinc layer thickness of 5-15μm. It is available in a variety of passivation colors such as yellow zinc, blue-white zinc, and black zinc, and has a neutral salt spray tolerance time of 48-240 hours.
Detailed Specifications
Thread Finish and Shaft Transition
The thread end of Threaded Rod should smoothly transition to the shank, free of burrs and missing teeth, ensuring the nut can be smoothly screwed onto the shoulder.
Center Hole or Reference Outer Diameter Quality
As a manufacturing and inspection benchmark, Both-Ended Screw must be regularly shaped and highly precise.
Shaft Roller Hardening Texture
The roller-hardened shank surface should have a uniform work-hardened texture, free of folds or cracks for M6 Double Ended Dowel Screw.
Coating Uniformity and Appearance
The zinc coating should have a uniform color (blue-white, multicolored), free of defects such as incomplete plating, blistering, and yellowing, especially at the thread root and ends.
Frequently Asked Questions
Q: Are galvanized carbon steel Double-Ended Threaded suitable for high-temperature and high-pressure environments?
A: Yes. High-strength carbon steel, after proper heat treatment, possesses excellent resistance to heat creep. Combined with a high-quality galvanized layer, it can maintain stable sealing preload in conventional high-temperature and high-pressure piping systems.
Q: How to avoid thread seizing or stripping during installation for Two-Ended Screw?
A: The key is to ensure the cleanliness and correct alignment of the threaded parts. It is recommended to apply an appropriate amount of anti-seizing lubricant before assembly and use a calibrated torque wrench to tighten step by step strictly according to the specified torque value. Avoid forceful operation.
Q: What are the advantages of galvanized carbon steel Two-End Stud compared to ordinary stainless steel studs?
A: For the same diameter, high-strength galvanized carbon steel typically has higher tensile strength and yield strength, and exhibits superior fatigue fracture resistance under strong vibration conditions, while also offering excellent cost-effectiveness.
contact us
If you are looking for a double-thread screw suitable for connecting piping systems, mechanical equipment, or industrial structures, please contact us for more specifications, sample support, and customized fastening solutions.
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