Hybrid Laser Welding: The Real Hybrid on Manufacturers’ Minds

Experts delve into the latest uses for this process

By Kelly Wanamaker, head of sales development, TRUMPF Inc. Laser Technology Center, Plymouth, Mich.

Hybrid workplaces, hybrid vehicles, and even hybrid animals. The word hybrid is often used to describe something that is “two different things that are mixed into one.” The worlds of laser technology and manufacturing come together as a hybrid model, too — hybrid laser welding. Hybrid laser welding is the combination of laser welding and another welding process or method. Processes compatible with laser welding include gas metal arc welding (GMAW), flux cored arc welding (FCAW), gas tungsten arc welding (GTAW), and plasma welding (Ref. 1).

One industry that has seen the success hybrid welding can achieve is shipbuilding — Fig. 1. Shipbuilders must weld large steel plates, often up to 30 m (1181.1 in.) long and 15 mm (0.59 in.) thick. These large pieces can create larger joint clearances between the plates, making it too big for a laser beam to bridge by itself. So how is it done? A promising solution combines laser welding with GMAW.  At high welding speeds, the laser provides the high-power densities needed for such deep welds while reducing any distortion and heat input. Meanwhile, the GMAW gun bridges the large joint clearance between plates, using a filler wire to close the joints. In this application, combining traditional laser welding with GMAW offers a technique that’s much faster than just GMAW and has the added benefit of parts that are less distorted (Ref. 1).

Experts Discuss Trends in Hybrid Welding

Two industry experts possessing firsthand experience with hybrid welding in the manufacturing world recently sat down to discuss the trends they are seeing.

Travis Stempky is head of laser technology applications at TRUMPF Inc.’s Laser Technology Center in Plymouth, Mich., and Santa Clara, Calif., where he helps to develop various multiaxis cutting, welding, marking, cleaning, and micromachining applications.

Yama Fedai is key account and industry manager at TRUMPF Inc., Milton, Ontario, Canada. He has more than 15 years of experience related to welding and other manufacturing technologies.

What type of companies or industries do you see using hybrid welding today, and why?

Hybrid welding is being used mainly by companies within the automotive industries, for example [original equipment manufacturers] OEMs and Tier 1 (modules and systems) and Tier 2 (component manufacturers) suppliers. The reason I see primarily automotive-related companies using hybrid welding is because the reduced heat input minimizes impact on dimensional deformity typically seen with GMAW. Battery structures in electric vehicles require hermetically sealed welds, making hybrid welding one of the main candidates to use there. Shipyards could also continue to benefit from hybrid welding since this process can help with fusion depth on thicker materials while maintaining a faster speed than GMAW. Larger joint clearances in fitup are common with higher-gauge metal, and hybrid welding can help close these gaps. — Yama Fedai

How are industries currently using hybrid welding?  Are there certain methods or processes you see commonly used?

I often see hybrid laser arc welding (HLAW) used to help bridge joint clearances, increase process speeds compared to GMAW, and supply filler metal addition for crack-sensitive materials. Hybrid welding provides added process stability when filler material is required and allows for higher mixing of the filler and base material in deeper fusion depth welding. In joint clearance bridging, laser beam welding uses light to interact with the base material. When there is a joint clearance, the light travels through the joint clearance and this energy is lost during the melting process. With hybrid welding, the arc welding process creates a weld pool and bridges the joint clearance allowing for the laser light to interact with the already established weld pool. The laser process helps drive the weld pool deeper and allows for higher travel speeds. — Travis Stempky

Are there any current or future trends that you see in hybrid welding? 

Hybrid welding is a popular topic for aluminum structural welding of 6061. With 6061, the aluminum requires filler material in almost all instances, and this welding method provides higher processing speeds than GMAW or laser beam welding (LBW) with cold wire addition. Another application is in defense or shipbuilding with thicker-plate welding (¼- to 1-in.-thick plates). These applications require fusion depth, but part fitup that meets LBW requirements is difficult with these thicker plates. The GMAW process helps bridge the joint clearances that are difficult to close due to the thicker plates. Hybrid welding also has much less heat input than traditional arc welding because you can weld with a single pass without creating a V-groove. I can see an increase in industries with similar manufacturing needs looking into utilizing hybrid welding more in the future. — Stempky

Any tips or suggestions for someone interested in starting a hybrid welding process, perhaps from an applications or industry point of view?

Recent trials have shown that lasers that promote less spatter when welding have enhanced the performance of hybrid welding systems. Improvements can be seen in successfully welding larger joint clearances, higher speeds, and spatter control. — Fedai

Hybrid welding is a more complex process than GMAW or LBW, so it is really important to not complicate the process if you don’t need to. Hybrid welding adds the complexity of understanding GMAW and LBW parameters and how these processes interact with each other. The spacing between the systems is critical to get a true hybrid process with both processes interacting with the same weld pool. If the process zones are too far apart, you will have two separate processes occurring. If the processes are too close together, the laser beam can affect the GMAW process by premelting the wire before the arc can be established. A benefit of using hybrid welding vs. cold wire feed welding for crack-sensitive materials is that you can get more efficient mixing. In traditional LBW, keyhole mixing dynamics tend to separate into three mixing zones at deeper fusion depths (> 6 mm [0.236 in.]). There is a high-speed zone on top, a slow-movement zone in the middle, and a high-speed mixing zone at the bottom. This makes it difficult to get proper dilution of the base material with only cold wire addition. By adding GMAW, the arc welding process helps drive the filler material down into the weld zone to help the mixing occur deeper into the joint. Another benefit of hybrid welding vs. cold wire LBW is joint clearance bridging capabilities. With LBW, the laser light needs to interact with the filler material and base material. Typically, we are welding with 300- to 1000-m spot size. Therefore, the joint clearances need to typically be less than 50% of your spot size. With HLAW, the GMAW process allows for larger bridging capabilities. GMAW does a good job of bridging the joint clearance and allows for the laser light to interact with the weld pool from the arc welding process. You still don’t want too large of a joint clearance because the laser light will only interact with its spot size. Usually this is limited to a maximum of ~0.035- to 0.040-in. joint clearance. — Stempky

Conclusion

There are many benefits that come from a hybrid laser welding process. As illustrated by industry experts, hybrid welding is an efficient and effective welding method and can be useful for applications in many industries.  WJ 

References

1. TRUMPF. 2023. Hybrid welding. Retrieved October 27, 2023, from trumpf.com.

2. TRUMPF. 2023. Low-spatter welding with beam formation technology. Retrieved October 27, 2023, from trumpf.com.

Fig. 1 — Laser welding combined with GMAW is a hybrid welding process often used in shipbuilding. (Photo courtesy of TRUMPF.)