Wear-resistant seal ring

Category:

Thermal Spray Equipment Accessories (Wear Parts)

Key words:

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Product Description

Wear-resistant seal ring

The sealing ring of the plasma torch is a critical component that maintains the equipment’s seal and ensures the stability of the plasma arc. Its performance directly affects the equipment’s reliability and service life. The following will discuss... Core functions, key materials, causes of wear and tear, fault diagnosis, maintenance, and replacement Analyze across five dimensions.

I. Core Functions and Typical Locations

(1) Core Features

Sealed gas and liquid
1. Isolate the high-pressure gases (such as argon or nitrogen) and cooling water inside the plasma torch to prevent leaks that could cause instability in the plasma arc or damage to the equipment.
2. For example, failure of the sealing ring at the connection between the nozzle and the gun body can lead to gas leakage, causing the arc column to spread and the cutting kerf to widen.

Buffering and Shock Absorption
1. Reduce mechanical friction and vibration between components to prevent loosening of connections caused by high-frequency vibrations (e.g., the piston chamber seal can cushion the impact of the reciprocating motion of the piston rod).

Pressure compensation
1. Under high-pressure conditions, the sealing ring compensates for the gap through elastic deformation, ensuring reliable sealing performance—for example, the piston chamber seal automatically presses tightly against the inner wall when the air pressure rises.

(2) Typical Installation Locations

Water needle connection part
1. Installed within the annular groove of the cutting gun, adjacent to the main body of the water needle. O O-ring seal to prevent coolant leakage.

Piston chamber sealing structure
1. The sealing ring (such as one made of fluororubber) between the piston’s outer circumference and the chamber wall is used to isolate the compressed gas and prevent pressure loss.

The connection between the gun body and the gun tip
1. The gun head and gun body are sealed with a gasket to achieve an airtight connection, preventing gas leakage from affecting the stability of the plasma arc.

Electrode and piston rod interface
1. Prevent high-voltage electricity from leaking through the piston rod while simultaneously sealing the cooling water flow.

II. Key Materials and Selection Criteria

(1) Comparison of Mainstream Materials and Their Performance

Material	Temperature resistance range ( Celsius )	Core Advantages	Typical application scenarios
Fluororubber ( FKM )	-20~210	High temperature resistance, chemical corrosion resistance, oil resistance	High-temperature cutting (e.g., stainless steel, aluminum), high-pressure spraying
Silicone rubber ( VMQ )	-55~250	Good resistance to high and low temperatures and excellent insulation properties, but poor oil resistance.	Sealing in low-temperature environments and with non-oily media
Ethylene propylene diene monomer rubber (EPDM) EPDM )	-30~150	Resistant to steam, weak acids and bases, and ozone.	Humid environment, sealed cooling water piping
Perfluoroether rubber ( FFKM )	-20~320	Extremely temperature-resistant and highly resistant to strong corrosives (such as strong acids and ketones).	Semiconductor manufacturing, ultra-high-temperature spraying

(2) Key Factors in Selection

Temperature matching
1. High-temperature conditions (such as cutting) ≥20mm Carbon steel) Select FKM or FFKM , low-temperature environments (such as - 20℃ The following) select VMQ 。

Chemical compatibility
1. Select for exposure to corrosive gases (such as fluorine gas, chlorine gas). FFKM , choose when in contact with steam EPDM 。

Pressure rating
1. High pressure (> 10MPa ) The scene requires selecting highly elastic materials (such as... FKM ), and is reinforced with a metal framework for added support.

Installation method
1. For dynamic seals (such as reciprocating motion of piston rods), choose lip-type seals; for static seals (such as water needle connections), choose... O O-ring.

III. Vulnerable Core Causes and Typical Failure Modes

(1) Vulnerability Mechanisms and Scenarios

Failure Type	Core reason	Typical Scenarios and Representations
High-temperature aging	Prolonged high temperatures cause rubber to harden and become brittle.	Continuous cutting > 30 Minutes later, cracks appeared on the surface of the sealing ring.
Chemical corrosion	Metal vapor (such as Cr 、 You ) or impurities in the protective gas reacting with the rubber	When cutting stainless steel, the surface of the sealing ring turns black and flakes off.
Mechanical wear	Frequent loading and unloading or component friction can cause the sealing ring to deform.	The reciprocating motion of the piston rod causes wear on the lip, resulting in gas leakage.
Thermal Shock Damage	Sudden temperature changes (such as interrupted cooling) can cause rubber to crack.	After the cooling water pipe becomes blocked, the sealing ring develops radial cracks.
Improper installation	Too tight—fracturing, or too loose—leaking.	Hand installation can cause deformation of the sealing ring, or failure to use specialized tools can scratch the surface.

(2) Typical Failure Modes

O O-ring failure
1. Performance: Sectional flattening, surface scratches, loss of elasticity.
2. Reason: The installation was not lubricated (e.g., no petroleum jelly was applied) or the groove dimensions did not match.

Lip seal failure
- Appearance: Wear on the lip, flaring, and poor sealing surface contact.
- Reason: The surface roughness of the piston rod exceeds the specified tolerance. Ra > 0.8 μm ) or moving too fast.

Combined seal failure
1. Performance: The metal frame has separated from the rubber, and the sealing gasket is torn.
2. Cause: Excessive pressure fluctuations or mismatched thermal expansion coefficients of the materials.

IV. Fault Diagnosis and Detection Methods

(1) Visual Inspection

Visual Diagnosis
1. Observe the surface of the sealing ring for cracks, notches, or discoloration (such as... FFKM May turn dark brown after prolonged use.
2. Check the installation groove for wear, deformation, or embedded metal debris.

Elastic testing
1. Press the sealing ring with your finger. If it lacks elasticity—meaning it doesn’t spring back when pressed—it’s aged and needs to be replaced.

(2) Performance Testing

Sealing Test
1. Pressure test: Inflated 0.5 MPa Compressed air, immerse in water and observe the bubbles (leakage amount > 5 Bubble / Needs to be replaced every minute.

1. Hydraulic pressure test: Pressurize the cooling water circuit to... 1.5 Double the working pressure, maintain pressure. 5 No pressure drop in minutes.