Laser-Welded vs Non-Welded

When using spring-energized seals, the energizer spring can be a critical factor in sealing reliability and longevity. A well-executed weld — especially laser welding — can significantly improve load distribution, sealing consistency, and reduce the risk of seal failure. However, non-welded or traditionally joined springs remain attractive for their simplicity and flexibility. This article compares laser-welded and non-welded / spot-welded spring energizers, evaluates their pros and cons, and suggests guidelines to help you choose the right configuration for your application.

Why Spring-Energized Seals?

Spring-energized seals combine a polymer seal lip (e.g. PTFE, PEEK) with a metal spring energizer, providing constant radial load to ensure tight sealing even under pressure, temperature, or wear changes. This design offers wide chemical compatibility, excellent temperature range, low friction, and durability — making it preferable over conventional elastomeric O-rings in many demanding applications.

What is a Welded Spring Energizer?

A welded spring energizer means the ends of the spring (or energizer coil) are permanently joined — typically by welding — to form a continuous ring. In modern manufacturing, laser welding has become an advanced method for this task. Compared to spot-welding or mechanical joints, laser welding delivers a precise, even, low-distortion weld, preserving the spring’s mechanical properties and ensuring uniform load distribution.

Benefits of Laser-Welded Spring Energizers

• Uniform load distribution: A continuous welded ring prevents “end-gap” or weak points — ensuring the seal lip exerts even force all around.
• No stress risers or “high-points”: Proper laser welding avoids protrusions or weld tabs that might abrade the seal lip or create leak paths.
• Consistent quality for mass production: Laser welding provides repeatable, precise welds — ideal for high-volume manufacturing.
• Better long-term sealing reliability: Less risk of spring ends separating under pressure or vibration, reducing leakage risk over life cycles.
• Compact and clean geometry: No bulky weld tabs or mechanical joints — useful in space-constrained or high-precision assemblies.

Potential Drawbacks of Welding (Including Laser Welding)

• Heat-Affected Zone (HAZ) and residual stress: Welding alters microstructure around the weld — for spring steel this can reduce fatigue life or cause brittleness if not properly stress-relieved.
• Need for skilled welding & inspection: High-precision process, often requiring non-destructive testing to ensure weld integrity (no cracks, voids, or inclusions).
• Less flexibility for modification: Once welded, the spring ring is permanent — cannot easily be resized or reworked.
• Cost and equipment requirements: Specialized laser welding machines, fixturing, and QA increase upfront cost compared to non-welded/spot-welded parts.

Non-Welded or Spot-Welded Spring Energizers — Why They Remain Popular

Non-welded designs (e.g. crimped, mechanically joined ends, or simple spot weld) are still commonly used — especially in prototypes, small batches, or where flexibility is desired. Their advantages: lower cost, simpler manufacturing, easier modifications, and no HAZ concerns. However, they may suffer from uneven load distribution, potential end-gap leakage, and reduced reliability under high pressure or vibration.

Which Should You Choose — Welding or Not?

Consider welding if your application involves:

• High pressure / high vacuum / cryogenic or wide temperature range
• Critical sealing performance required long-term (e.g. aerospace, oil & gas, medical, vacuum chambers)
• High cycle count, vibration or dynamic loads
• Compact or precision geometry where uniform load and clean profile matter

Consider non-welded / spot-welded if:

• You require low-cost, small-batch or prototype springs
• Ease of rework or modification is important
• Application is low-pressure, non-critical or cost-sensitive

Best Practices for Laser-Welded Spring Energizers

• Use qualified laser welding setups with minimal heat input to reduce HAZ and maintain spring temper.
• Perform post-weld stress relief or tempering when required (especially for high-carbon or high-alloy spring steels).
• Conduct non-destructive inspection (NDT) — e.g. dye-penetrant / ultrasonic — to ensure weld integrity.
• Ensure welded ring is flattened and concentric to avoid lip misalignment and uneven sealing load.
• Select appropriate jacket/lip material (PTFE, PEEK, etc.) compatible with media, temperature and wear requirements.

Conclusion

Laser-welded spring energizers offer a high-reliability, low-leakage sealing solution — ideal for critical, high-pressure, high-vacuum, or cryogenic applications where uniform load and long-term performance matter. Non-welded or spot-welded variants remain useful for lower-cost, flexible, or low-stress applications. The choice depends on your application’s demands: for mission-critical sealing, welding (especially laser welding) is often worth the investment; for prototyping or benign conditions, simpler methods may suffice.

Need custom welded energizer springs or technical consultation? Contact Handa Springs today for quotes, drawings, and application support.