K-TIG Vs Laser Beam Welding

Process Comparison

What are K-TIG’s Advantages Over Laser Beam Welding (LBW)?

Laser Beam Welding (LBW) is a welding technique used to join a work piece through the use of a powerful laser. The beam provides a highly concentrated heat source, allowing for narrow, deep welds and high welding rates. High powered lasers capable of penetrating medium and heavy gauge materials are available, but their cost is prohibitive for most applications.

K-TIG is similar to laser welding only to the extent that both processes open a ‘keyhole’ through the full thickness of the joint. K-TIG achieves this at a small fraction of the cost of a laser welding system and requires no specialist skills to operate it or maintain it.

K-TIG is also much more tolerant of irregularities in fit-up, compared with Laser welding which has virtually zero tolerance to irregular fit-up.

The Benefits of Switching

How does K-TIG overcome the issues of LBW Welding?

 K-TIG overcomes the most common issues associated with LBW:

  • Equipment Cost: A K-TIG system costs $100,000 USD (approximately), a remarkably low cost for a complete welding system with all the benefits of high energy density welding that can be connected to any mechanised motion system. LBW is a relatively inconsistent process with very high equipment costs of $600,000 USD.  Laser power level has a large influence on overall equipment cost.
  • Penetration: K-TIG slightly outperforms LBW on single pass penetration, with K-TIG maxing out at 16mm (titanium) and LBW capable of performing single pass welds of up to 15mm. LBW’s performance is dependent on power level (e.g., 10 kW or 20 kW).
  • Weld Quality: Both processes use keyhole welding meaning they both allow vaporised impurities to leave the weld through the back of the keyhole instead of being trapped in the solidifying weld as porosity. A key difference is in K-TIG’s ability to maintain keyhole stability at higher thicknesses where LBW can suffer from focal shift and lens distortion.
  • Fit-Up Tolerance: The K-TIG process can maintain a stable keyhole even with joint gaps in excess of 1 mm, although a tight fit is better.  Mismatch in the joint of 20% or more is also handled with ease. The typical max joint gap permitted for LBW is 10% of thickness, not to exceed 0.1 mm.  The process can manage up to 20% mismatch.
  • Complexity: K-TIG is very simple to operate. The arc structure and keyhole develop spontaneously and are maintained automatically by the controller throughout the weld.  K-TIG weld parameters are basic and simple to adjust. Laser is widely regarded as a complex, beam welding process. There are more parameters to set than for arc welding, and the set-up and fit-up of joints are very critical.  Focus shift and lens degradation can cause process drift from established parameters and results.
  • Weld Appearance: If proper gas shielding protocol is followed on the face and root sides of the weld the K-TIG process will naturally create a smooth and uniform appearance, with no grinding or dressing required. If the travel speed outruns the gas in LBW the appearance can be affected. The root base of LBW is very rough, with some undercut and spatter, and requires dressing or grinding.
  • Keyhole Stability: There is no requirement to seek a balance between arc force (plasma column) and surface tension with K-TIG, due to the high travel speeds and surface tension in the weld pool. The keyhole inherently self-corrects and dynamically responds to fluctuations in the arc forces. Although laser is a high energy density process, it relies on photons of light being focused through a fixed lens to achieve its keyhole.  The lens can become contaminated during welding, and it can distort due to high heat in thick sections and create focal shift, which dramatically alters the welding results.
  • Keyhole Close-Out: The laser process is capable of a smooth and orderly slope out of the weld, including closing the keyhole and gradually reducing the penetration until the weld is terminated.  The high energy density can occasionally lead to "spiking" defects (voids) during the slope out. The high energy density arc and patented torch design mean no plasma gas or complex constricted arc are required, which makes the overlap and slope out of a circumferential weld extremely simple.
  • Process Consistency: The high energy density laser beam can produce a smooth and consistent keyhole through the joint, especially at low power levels.  For thick section welding, the thermal distortion and contamination of the lens cause significant drift in the process, especially if focal shift occurs. A large, long-lasting electrode, the simplicity of the process and a smooth, consistent keyhole make process drift, erosion and variation insignificant.
  • Maintenance Costs: Laser welding systems require frequent maintenance, including replacement of focusing lenses.  It is considered to be a very sensitive process to any form of contamination (such as a normal weld shop environment). K-TIG, on the other hand, incurs very low maintenance costs due to their simplicity. K-TIG systems have few consumable components, are robust and extremely reliable.
  • Skill of Operator: LBW requires extensive operator training due to its complexity and sensitivity to the many critical variables involved.  A skilled operator is required. Training times are typically 2 to 4 weeks. The sophistication of the K-TIG controller and the simplicity of the process mean that an operator is sufficient and training can be completed in 3 hours, with supervisor training only taking 1-2 days.

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I’m currently using Laser Beam Welding; can I switch to K-TIG?

Users of LBW can easily switch to LBW if they want to cut costs and increase productivity. The K-TIG system can just be incorporated into your LBW system. If you’re using an LBW system you’ll definitely have the scale of demand to reap all the benefits of a switch.


How Do I Change to K-TIG?

It really couldn’t be easier.

If you’re currently using laser beam welding, the upgrade process is simple. Your existing welding automation system can still be used.

Literally all you have to do is setup the K-TIG system, and integrate the controller into your existing automation system.

The K-TIG process tolerates at least twice the gap and mismatch of laser welding, and provides a much smoother root bead.
Attila Szabo, Principal Joining Engineer, GE

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