Torch Ring ONA-6391-3321 Suitable for Symons 4.25FT Cone Crusher Parts

Product Overview

The ONA-6391-3321 torch ring is a sacrificial consumable designed specifically for the mantle locking system of cone crushers suitable for Symons 4.25FT. Weighing 10 kg, this precision‑machined ring is installed directly between the main shaft nut and the top surface of the mantle. Its primary function is to safely absorb the high clamping preload that locks the mantle onto the main shaft. When the mantle becomes worn and needs replacement, the maintenance crew simply flame‑cuts the torch ring using an oxy‑acetylene torch. The cutting process instantly releases the preload without any force applied to the main shaft nut or the threads. This allows the nut to be unscrewed by hand, and the
old mantle can be removed easily. The torch ring thus acts as a protective barrier: it is sacrificed during each liner change, preventing heat damage, thread galling, or breakage of the much more expensive main shaft nut and the main shaft itself. ONA manufactures each torch ring to exact OEM specifications, ensuring proper fit, consistent thickness, and correct flatness. Every unit undergoes 100% dimensional inspection before shipment and is coated with anti‑rust oil for long‑term storage. By using the ONA-6391-3321 torch ring, crusher operators can significantly reduce maintenance risks, speed up liner change times, and extend the service life of their critical crusher components.



                                    

Key Features

Sacrificial Design

The torch ring is intentionally designed to be flame‑cut during mantle removal. It is a one‑time consumable that absorbs the stress and heat of cutting, thereby protecting the main shaft nut and shaft threads from damage. This sacrificial function saves costly repairs and extends the life of your crusher’s main components.

Precision Fit

Each ONA-6391-3321 torch ring is machined to exact OEM specifications. The inner and outer diameters, thickness, and flatness are precisely controlled to ensure proper seating between the main shaft nut and the mantle. A perfect fit guarantees even load distribution and reliable preload.

Easy Cutting

The torch ring is made from low‑carbon steel specifically chosen for its excellent response to oxy‑acetylene cutting. It produces a clean, narrow cut with minimal slag, allowing maintenance crews to work quickly and safely. No special cutting techniques or heavy equipment are required.

Light Weight

Weighing only 10 kg, the torch ring can be easily handled by a single technician. Its manageable weight simplifies logistics, reduces lifting risks, and shortens maintenance time. No overhead crane or extra manpower is needed for positioning.

Anti‑Rust Coated

Every torch ring is coated with a protective layer of anti‑rust oil before shipment. This prevents corrosion during long‑term storage in humid or harsh environments. The coating can be wiped off easily before installation.

100% Inspection

Each ONA-6391-3321 torch ring undergoes 100% dimensional inspection before leaving the factory. We check for cracks, warpage, surface defects, and critical measurements. Only parts that meet our strict quality standards are shipped to customers.

Applications
The ONA-6391-3321 torch ring is used exclusively during scheduled mantle replacement procedures on cone crushers suitable for Symons 4.25FT. These crushers operate in a wide range of industries, and the torch ring plays a vital role in each of them.

Hard rock mining
In iron, copper, and gold mines, the crusher runs continuously under extreme loads. Mantle change intervals are frequent. Using a fresh torch ring each time ensures that the main shaft nut and threads remain undamaged, avoiding costly downtime in remote mining locations.

Aggregate and sand production
Aggregate plants often have tight production schedules. The torch ring speeds up liner changes by eliminating the need to force off a tight nut. This means less downtime and more consistent output of road base, concrete, and asphalt materials.

Quarrying
Granite, basalt, and other hard stones cause heavy mantle wear. Regular replacement is standard. The torch ring protects the crusher’s expensive main shaft components from heat and stress during cutting, keeping the crusher in good condition year after year.

Construction waste recycling
When crushing concrete and asphalt rubble, tramp iron is common. Mantle changes occur more frequently. The torch ring’s quick‑release design helps recycling plants get back online faster, reducing operational delays.

Important note: The torch ring is a one‑time consumable. It must be replaced with a new ONA-6391-3321 every time the mantle is changed. Never reuse a cut torch ring, as it cannot provide the correct preload and may lead to mantle loosening or thread damage. ONA recommends keeping several torch rings in your spare parts inventory to avoid delays during scheduled or emergency maintenance.

Installation & Maintenance

1. Clean the main shaft threads and mantle bore.

2. Place the new torch ring flat on top of the mantle.

3. Install the main shaft nut and torque to crusher manual specification.

4. When the mantle is worn, cut the torch ring with an oxy‑acetylene torch.

5. Remove the mantle, clean threads, and repeat with a new torch ring.

Important: Never reuse a torch ring. Always use a new ONA torch ring for each mantle replacement.

FAQs

Is the ONA-6391-3321 torch ring compatible with both standard and short head Symons 4.25FT crushers?

Yes, it is suitable for both configurations. However, we recommend verifying your crusher model and original part number before ordering.

Why must I replace the torch ring every time I change the mantle?

The torch ring is designed to be flame‑cut during removal. Once cut, it cannot provide proper preload or sealing. Reusing an old ring can lead to mantle loosening, uneven wear, and potential damage to the main shaft nut.

What happens if I don't use a torch ring?

Without a torch ring, the main shaft nut would be torqued directly against the mantle. Removing it later would require extreme force, risking thread galling or breakage. The torch ring absorbs the cutting heat and stress, protecting expensive components.