Yes, TIG welding is suitable for thick metal. It offers precision, quality, and versatility, making it ideal for welding various types of metals. However, TIG welding requires higher skill levels and can be slower and more costly compared to other welding methods such as MIG or flux-cored welding.
TIG Welding and Metal Thickness
Understanding Metal Thickness in Welding
In welding, metal thickness plays a crucial role. For example, thin metals, usually around 0.3mm to 1mm, require a delicate approach to avoid burning through. Conversely, thicker metals (greater than 3mm) need a higher power welder capable of providing a deep and strong weld. The thickness of the metal directly affects the time, cost, and quality of the weld.
Regarding TIG (Tungsten Inert Gas) welding, it is typically employed for thinner metals, yet its usage for thick metals is feasible but demanding. A Miller Multimatic 220 TIG welder, for instance, allows for a wide amperage range of 20-210 A, enabling welding of metal thickness up to 6.4mm. However, it costs around $3,000, implying a substantial financial investment.
The Role of TIG Welding in Thick Metal Welding
TIG welding’s effectiveness on thick metal depends largely on the power of the welding machine, the skill level of the welder, and the welding technique applied. For welding thick metals with TIG, the welder must sustain a high amperage to ensure proper penetration and strength of the weld.
For instance, welding 6mm thick stainless steel requires a power setting around 150-180A. This process, albeit slow, results in high-quality, precise welds suitable for critical applications like pressure vessels. The slower speed of TIG (compared to techniques like MIG) could mean a higher labor cost over time, especially on large projects.
As for equipment lifespan, a well-maintained TIG welder like the Lincoln Electric Square Wave TIG 200 can last for over 10 years with regular use, offering excellent value for its price, which is roughly $1,700.
TIG welding also excels in controlling heat input, essential for welding thick metals. For example, the temperature at the weld can reach up to 3,500°C, making thermal insulation a concern. Proper control of the welding arc during TIG welding can minimize deformation and improve the quality of the weld, even when dealing with thicker metals.
Advantages of TIG Welding for Thick Metal
Quality and Precision
One of the primary advantages of TIG welding is the superior quality and precision it offers. Unlike other welding methods such as MIG or stick welding, TIG welding provides more control over the weld, leading to cleaner and more precise results.
A prime example of this would be the Airbus A380, where TIG welding was used extensively in the aircraft’s construction due to the need for high-quality, precise welds. Using a high-end TIG welder like the Miller Dynasty 350, which has an output range from 3A to 350A and costs around $6,500, welders can control the amperage precisely, allowing for better control and higher quality welds, even on thicker materials.
TIG welding is exceptionally versatile, capable of welding more types of metals and alloys compared to other methods.
In the case of the automobile industry, TIG welding is often used to create custom exhaust systems. A popular machine for this application is the Lincoln Electric Precision TIG 375 due to its ability to weld a wide range of metal thicknesses, from 0.012 inch (0.3 mm) to over 1/2 inch (12.7 mm) in a single pass. This unit costs around $5,600 but offers extensive functionality and versatility for the price.
Strength and Durability of Welds
When it comes to the strength and durability of welds, TIG welding stands out due to the high-quality, full penetration welds it produces. For example, in pipeline welding — a field where weld strength is paramount due to the high pressures involved — TIG welding is commonly used.
Consider the case of underwater pipelines used in oil extraction. These pipelines, often made from thick metal, need welds capable of withstanding enormous pressures. A machine like the Miller PipeWorx 400 Welding System is often used. This system, costing around $7,000, can deliver up to 400A, providing the power necessary for creating strong, durable welds in such demanding environments.
Challenges and Limitations of TIG Welding for Thick Metal
The level of control and coordination required to manage the electrode, filler rod, and welding torch simultaneously can pose a significant challenge to beginners.
For example, when welding thick sections of aluminum, a material commonly used in shipbuilding, achieving proper heat control to prevent warping or burn-through can be challenging. Equipment like the Hobart EZ-TIG 165i offers an easy-to-use interface to aid beginners. Priced around $1,460, it’s a beginner-friendly model, yet the mastery of TIG welding still requires considerable time and practice.
Time and Speed
When working on thick metals, the process can be even slower as the welder needs to ensure complete penetration of the weld, which demands maintaining a slower, steadier pace.
For instance, TIG welding a 6mm thick stainless steel plate can take twice as long as using MIG or FCAW. This time factor can lead to increased labor costs, particularly in large-scale industrial applications.
Equipment and Power Requirements
TIG welding thick metals requires powerful and often expensive equipment. Welding machines need to be capable of high amperage output to ensure full penetration in thick metal pieces.
The ESAB Rebel EMP 205ic AC/DC, for instance, is a powerful TIG welder that provides an output up to 300A. However, this machine costs around $3,300, which can be a significant investment for small businesses or individual users.
In terms of power supply, TIG welders often require access to a 220V outlet, which may not always be readily available, especially in residential settings. This can limit the usability of TIG welding for thick metals in certain situations.
Comparison with Other Welding Techniques
TIG Welding vs. MIG Welding
MIG welding generally operates at a faster rate compared to TIG. For example, MIG welding a 6mm stainless steel plate can be up to twice as fast as TIG welding the same piece. This can lead to lower labor costs and faster project completion times.
However, MIG welders, such as the Millermatic 252 (around $2,800), may not offer the same level of control and precision as TIG welders. For projects requiring high-quality, precise welds, TIG welding often proves superior.
TIG Welding vs. Stick Welding
Stick welding, or Shielded Metal Arc Welding (SMAW), is an older welding process, known for its simplicity and low equipment cost. A basic stick welder like the Hobart Stickmate 210i can cost as low as $700.
However, when welding thick metals, stick welding often results in less clean welds, requiring more cleanup and finishing work. In contrast, TIG welding provides cleaner welds and requires less post-weld cleanup, reducing the overall time spent on a project.
TIG Welding vs. Flux-Cored Welding
Flux-cored welding is another method that’s typically faster than TIG welding. However, it tends to create more spatter and requires more cleanup afterward.
A popular flux-cored welder, the Lincoln Electric Power MIG 210 MP (around $1,300), offers higher speed but may compromise the quality and precision that TIG welding offers.