Pit Type Spheroidizing Annealing Furnace

2. Product Overview

Our Pit Type Spheroidizing Annealing Furnaces are engineered to transform the microstructure of high-carbon steel, alloy tool steel, and bearing steel into a perfectly spheroidized state. This process is critical for improving cold-heading properties and machinability. By utilizing a high-purity Nitrogen ($N_2$) or protective atmosphere, our furnaces ensure that wire coils and bar stocks are processed without oxidation or decarburization, meeting the strictest quality standards for the fastener and bearing industries.

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3. Key Features & Benefits

• Optimized Spheroidizing Quality: Advanced cooling rate control (slow cooling phase) ensures a high degree of spheroidization, resulting in uniform hardness and excellent cold-forming performance.

• Oxidation & Decarburization Control: Vacuum-purge technology combined with precision nitrogen atmosphere management guarantees a bright, scale-free surface and zero carbon loss.

• Superior Temperature Uniformity: Equipped with high-power convection fans and a multi-zone heating system to ensure that large-diameter wire coils are heated evenly from the core to the outer layers.

• Energy-Efficient Design: Features high-density ceramic fiber lining and a precision-sealed furnace lid to minimize heat loss and reduce electricity/gas consumption.

• Highly Automated Cycles: PLC-based control systems manage the entire multi-stage process: heating, soaking, controlled slow cooling, and rapid cooling.

• High Loading Capacity: Deep pit design allows for the stacking of multiple wire coils, maximizing throughput in a compact floor footprint.

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4. Technical Specifications

Data structured for technical buyers.

Feature	Specification
Max Operating Temperature	850°C – 950°C
Atmosphere Protection	High-Purity Nitrogen ($N_2$) / Protective Gas
Temperature Uniformity	$\leq \pm 3$°C (During Soaking)
Cooling Rate Control	5°C/hr – 50°C/hr (Adjustable)
Loading Capacity	2 Tons – 40 Tons per batch
Process Control	Intelligent PLC with multi-program memory

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5. Typical Applications

This furnace is the industry benchmark for:

• Fastener Industry: Spheroidizing of CHQ (Cold Heading Quality) steel wire for bolts and screws.

• Bearing Industry: Heat treatment of GCr15 and other bearing steel rods and wires.

• Tool & Die Steel: Softening of high-alloy tool steels for better machinability.

• Automotive Parts: Precision annealing of steel components for cold extrusion.

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6. Engineering Excellence

• Vacuum-Sealed Lid: Proprietary vacuum-tight seals prevent any oxygen ingress, which is vital for maintaining the surface chemistry of high-carbon materials.

• Heavy-Duty Loading Baskets: We provide customized heat-resistant alloy baskets designed for easy loading/unloading by overhead crane.

• Safety Monitoring: Integrated gas pressure sensors and over-temperature alarms for 24/7 safe, unmanned operation.

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7. FAQ

Q: Why is a Pit Furnace better for spheroidizing wire coils?

A: The Pit Type configuration allows for vertical stacking of wire coils, which promotes better airflow through the center of the coils compared to horizontal loading. This leads to much better temperature uniformity, which is critical for achieving a consistent spheroidized structure throughout the entire batch.

Q: How do you prevent decarburization during the long annealing cycle?

A: We use a Vacuum Purge at the beginning of the cycle to remove all air and moisture. During the heating and soaking stages, the furnace is kept under a slight positive pressure of high-purity Nitrogen, ensuring no oxygen can react with the carbon on the steel surface.