Improving Deposition Rate With Hot Wire GTAW

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Example of Hot Wire GTAW

It is generally accepted that TIG welding, or GTAW, produces higher quality welds. And weld consistency, which contributes to weld strength, is often cited as an indicator of TIG welding quality. TIG welding not only produces high-quality welds, though, it is also a versatile process applied across a wide range of applications that include sanitary tube and pressure vessel welding. 

GTAW does have its disadvantages, though. In addition to being the most difficult process to master, GTAW can be slow and meticulous when compared to GMAW or MIG welding. However, for some projects, particularly high-spec applications, the cost savings generated by high-quality GTAW can mitigate most other concerns. This is especially true when the welder chooses hot wire GTAW and optimizes the deposition rate. Let’s explore this important quality parameter for TIG welding. 

Understanding Welding Deposition

The welding deposition rate can be defined as follows:

  • Welding deposition rate refers to the amount of filler material that actually is converted and deposited for a given current and 100% operating factor. 
  • Note: This rate assumes a continuous welding process.

This is an important parameter. When pricing a project, this parameter helps determine filler material requirements, as well as job length. To determine the deposition rate, take the following steps:

Welding Deposition Calculation Steps:

  1. Determine the cross-sectional area of the filler metal
  2. Multiply the result of 1 by the density of the filler material metal
  3. Multiply the result of 2 by the wire feed rate (in per min)
  4. Multiply the result of 3 by 60
  5. Multiply the result of 4 by the electrode efficiency

Obviously, the types of electrodes used will significantly affect the deposition rate. In the table below, a number of welding process parameters are compared—including deposition rates.

Deposition Rate vs Weld Quality

As previously stated, GTAW delivers high quality welds that are required for some applications, especially systems that employ narrow groove welding and/or where corrosion may be a concern and cladding or overlay is necessary. However, GTAW is relatively slow when compared to other processes; such as GMAW or MIG welding. Therefore, in some cases, it may be faster to opt for an alternative method even though additional time may be required to do repairs and cost may be higher due to extra materials and man-hours. 

For projects where quality is at a premium, the speed deficiency of TIG welding can be improved by using hot wire feeding. GTAW may be performed both with cold wire and hot wire feeding. Cold wire, where the filler wire is not heated prior to being applied to the weld puddle, produces high-quality welds. The rate of deposition, in this case, is controlled by the main power supply that determines the wire feed rate. However, higher deposition rates are obtainable with hot wire TIG, which makes this process particularly suitable for extreme environment usage. In fact, hot wire GTAW can achieve up to four times the cold wire TIG deposition rate and compares favorably with other processes, as shown in the table below [1].

Comparison of popular welding techniques

GTAW has one of the highest deposition rates among the welding processes listed above. Now, let’s see how we can maximize the deposition rate for TIG welding. 

Optimizing GTAW Hot Wire Deposition Rate

Undoubtedly, a much higher deposition rate can be achieved with hot wire GTAW, as opposed to cold wire. Nevertheless, TIG welding is still comparatively slow and meticulous–which is actually a strength that lends itself to the creation of consistent welds. However, the process can be optimized such that the advantage of high quality is preserved, while also maintaining the improved deposition rate. To achieve these goals, automation should be utilized—such as with the orbital process shown below.

Orbital GTAW of thick-walled pipe

As illustrated in the figure, welding thick-walled pipe is an application where maximizing the deposition rate is important. This is also true for piping that requires cladding; for example when the Inconel cladding process is implemented, to prevent corrosion due to the environment in which the piping system is installed. By employing an automated orbital welding system you can obtain precise, consistent welds and leverage the improved deposition rate gained by hot wire GTAW.  

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Arc Machines, Inc. is an industry leader in advanced technology welding, providing high-tech welding equipment, expert consultation, and superior support. This includes orbital welding machines and weld heads for hot wire GTAW that enable you to achieve the best deposition rates for your project. For inquiries regarding products, contact sales@arcmachines.com. For service inquiries, contact service@arcmachines.com. Arc Machines welcomes the opportunity to discuss your specific needs. Contact us to arrange a meeting.