The Bolt and Nut Galvanizing Drying Tunnel Oven is a continuous industrial heat treatment equipment specially designed for fasteners (such as bolts, nuts, washers, and other components) after processes including electro-galvanizing, hot-dip galvanizing, passivation, and other surface treatments. It is mainly used for continuous dehydration, drying, and hydrogen embrittlement relief treatment (hydrogen de-embrittlement baking) through controlled heating.

Applications

Drying After Surface Treatment

After galvanizing, passivation, and rinsing processes, the equipment quickly removes surface moisture from fasteners to prevent moisture retention and secondary corrosion.

Hydrogen De-Embrittlement Baking

High-strength bolts (such as Grade 8.8 and above) are prone to hydrogen embrittlement during acid pickling and electroplating processes. They require prolonged baking at approximately 200°C to promote the release of absorbed hydrogen atoms from the steel structure.

Coating Curing

Used for heat curing of fasteners with special coatings, such as Dacromet (zinc-chromium coating) and Magni coating.

Standards

The equipment manufacturing and process implementation generally comply with the following standards:

GB/T 3098.1 / ISO 898-1

Mechanical properties of fasteners — Specifies requirements for high-strength fasteners, including heat treatment requirements related to hydrogen embrittlement prevention.

JB/T 10214

Technical requirements for industrial continuous heat treatment mesh belt furnaces.

GB 5226.1

Electrical safety requirements for machinery — Electrical equipment of machines.

GB/T 13345

Specifications related to zinc-water separation and temperature control during metal surface heat treatment processes.

Features

Continuous Mesh Belt Conveying System

Uses high-temperature-resistant stainless steel mesh belts to achieve automatic loading and unloading of materials, making it suitable for high-volume continuous production lines.

Hot Air Circulation System

Equipped with powerful circulation fans and multiple independent temperature control zones to ensure uniform temperature distribution inside the furnace (usually within ±5°C).

High-Efficiency Energy-Saving Insulation

Adopts high-density aluminum silicate fiber insulation to reduce external surface temperature, minimize heat loss, and improve energy efficiency.

Intelligent Temperature Control

Equipped with PID intelligent temperature controllers or PLC systems with touch screens, allowing precise setting and control of multi-stage heating curves.

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