Understanding the personality of a Constant Current (CC) DC welding machine can make the difference between a successful or unsuccessful weld test or between a student who pursues a career in welding and one who may quit in frustration.
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A true story: A young journeyman (well call him Joe) was testing to qualify for a Stick pipe job using unfamiliar equipment. Joe failed several tests in a row, something that had never happened before. Was it Joes fault? Did he not practice enough? No, Joe had the right stuff but the wrong machine. An instructor saw Joe struggling, put him on a different welding machine, and his next weld was flawless.
What Joe and many others dont understand is that CC welders have two different personalities. You can learn a lot about a welders personality by looking at its volt/amp curve, the birth certificate of a welder:
1. Stick welders that can TIG weld. An example of this type of welder would be a DC generator, an 8 pack magnetic amplifier-type unit or traditional welder with a big mechanical rheostat for amperage control. Older welders call these machines droopers because of the shape of their volt/amp curve (see Fig. 1).
Fig. 1The drooping volt/amp of a traditional Stick unit (which can also TIG weld) enables the operator to control heat input and the shape of the weld bead by manipulating the electrode.
2. TIG welders that can Stick weld, which have more of a vertical constant current output (see Fig. 2). An example of this type of welder would be a conventional TIG machine (this is the type of welder that gave Joe fits with an E rod).
Fig. 2Notice how the TIG volt/amp curve on this modern TIG welder is nearly vertical. Amperage will remain constant even if the operator varies voltage (arc length).
There are also welders that Stick and TIG weld equally well, which often use inverter or chopper technology (Joe used an inverter to pass his weld test). Welders with multiple personalities may be able to produce both diagonal and vertical volt/amp curves (Fig. 3).
Fig. 3The CC volt/amp curve of an inverter changes personalities when switched from Stick to TIG modes. Also, notice how the percentages for arc force control increase amperage as voltage drops.
To interpret a volt/amp curve, you must understand the relationship between arc length and voltage. A basic fact of the arc welding process is that as arc length increases, voltage goes up; as arc length decreases, voltage goes down.
Manufacturers design Stick welders in such a way that as the operator changes arc length, the amperage does the opposite of voltage. If the operator decreases arc length (lowers voltage), amperage increases. If the operator increases arc length (increases voltage), amperage decreases. In conjunction with this information, another basic fact that operators need to remember is that voltage is electrical pressure. Pressure (voltage) controls the height and width of the weld bead, while amperage controls penetration.
Armed with this knowledge, reexamine Fig. 1. Experienced Stick welders know that pulling a long arc (increasing voltage while lowering amperage) enables them to create a flat, wide bead with shallow penetration. Long arcing also causes the weld puddle to freeze faster because it lowers the total amount of energy available. Conversely, pushing the rod closer to the joint (increasing amperage while lowering voltage) creates a narrower weld bead, deeper penetration and a more fluid (hotter) weld puddle.
Thus, Stick welders with drooper characteristics allow the operator to control weld bead quality and appearance by manipulating the electrode. However, this same welder, while ideal for Stick, is less than ideal TIG. Image youre welding an outside corner on 18-gauge stainless steel. If for whatever reason you shorten the arc length (lower voltage), a Stick welder that can TIG weld will attempt to maintain total output power (watts) by increasing amperageand that extra amperage (penetration) could blow a hole right through thin material.
For this reason and others, manufacturers design conventional TIG welders so that variations in voltage dont affect amperage. As the volt/amp curve in Fig. 2 shows, such a welder provides more of a vertical CC output. It holds the current constant regardless of voltage (arc length) changesand thats what frustrated Joe during his Stick weld test. Joe could have been the worlds best welder, but a TIG machine that can Stick weld simply couldnt react correctly to Joes manipulation of the Stick electrode.
Manufacturers of conventional TIG/Stick welders have overcome some of these performance limitations by adding an arc force control function to the welder (more on arc force later). However, many training facilities have older TIG equipment without this function or, if they have modern equipment, may not understand how to use arc force. Either way, students are at a disadvantage when learning how to Stick weld. Further, TIG-specific welders also tend to have more complicated controls, which could confuse beginners. Finally, while many welders work very well, they simply cant beat the benefit and performance of new technology.
Inverter technology enables manufacturers to create welding machines with multiple personalities, as the volt/amp curve in Fig. 3 indicates. Basically, because the welding output is controlled through microprocessors and high-speed current switching devices, an inverter can create just about any welding output imagined. In short, inverters can perform all welding processes equally well.
For many facilities, a CC/CV DC inverter with an output of 350 amps at 60 percent duty cycle meets most of their welding needs. This type of unit (Millers XMT® 350 CC/CV inverter is an example) enables training students on Stick welding and DC TIG welding in a broad variety of applications, as well as training students on the MIG and flux cored processes. Note that for TIG-specific training and AC TIG welding on non-ferrous metals, an AC/DC TIG inverter like the Dynasty® 350 will offer the most flexibility.
To help instructors choose the best unit for their facility, Miller offers recommendations for classroom packages on its welding instructors Web page, MillerWelds.com/instructors.
Miller generally recommends inverters because they offer schools several advantages:
To provide operators with additional Stick arc control, advanced CC welders offer arc force or dig control. This function enables operators to tailor the shape of the volt/amp curve to better suit different joint configurations and electrode types, and it can create an arc that experienced operators describe as soft and buttery or stiff and driving.
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Fig. 4Increasing arc force (dig) makes it easier for this pipe welder to achieve good penetration on an open root pass with an E electrode.
Under normal arc length conditions, a Stick electrode operates at about 20 volts. However, some welding situations demand shorter arc lengths, such as when the operator has to push the rod into a tight corner or into a deep bevel of an open root joint. In these situations, Stick electrodes are notoriously prone to living up to their namesake and sticking the rod (e.g., the voltage drops so low that the arc extinguishes itself). Arc force control overcomes this problem by increasing current when the voltage levels drop below about 20 volts (see Fig. 3). The boost of current increases total power, keeps the weld puddle molten, prevents the rod from sticking and eliminates a lot of operator frustration.
It helps to remember that inverters can adjust the welding output thousands of times per second. Thus, the speed of the human hand pushing an electrode closer to the joint is nothing compared to the speed of a microprocessor! Working with todays newest state-of-the-art welders is the difference between giving an account an abacus or a computer.
For schools and training centers that want to teach Stick, TIG and MIG* welding, choosing the right machine can mean the difference between helping students become successful as fast as possible or quitting the welding program in frustration. As a whole, the industry desperately needs to add more skilled welding operators to its ranks. We owe it to students and trainees to provide them with the tools that will help them succeed.
*Dont forget about multiprocess CC/CV welders, which provide outputs for Stick, TIG, MIG, flux cored and air carbon arc gouging.
Fig. 5About the Author. After leaving the U.S. Navy where he worked on a submarine tender, Neal Borchert joined Miller Electric Mfg. Co. in and spent 12 years as an instructor. Today, as business development manager, he works extensively with schools and training facilities.
Individual operators have their own ideas about where to set arc control, which is adjusted by a knob on the machines front panel. Some general recommendations are as follows:
Welding machines are a piece of essential machinery that has Revolutionizing metalworking and fabrication industries, thus knowing the suitable welding machine to use for an excellent welding experience could be a challenge for most welders because there are different types of welding machines available in the market to make it easier, we have a put together some essential guides that you should consider before buying either a TIG MIG or stick welding machine used mainly by welders. One of the steps every welder should know when selecting a suitable welding machine is to remember the three major elements used for metalworking: carbon steel, stainless steel, and aluminum. Carbon steel is the most commonly used as it is compatible with a majority of welding machines and also can handle any excess heat that might be applied to the metal. If you are using stainless steel, it is compatible with TIG or MIG welding machines and does not need much strength to operate as carbon steel. If you are using aluminum, it requires more complex welding machines, like the MIG machine. You can also use a high-end TIG machine for the aluminum weld. As all the elements have a different nature of work, it would be best to access the metal you wish to conjoin before selecting a welding machine.
The benefit of knowing the suitable welding machine to use would not just save cost for your welding process but also save time because instead of using a month tig welding a trailer, you can MIG it in a couple of days; each welding has advantages and disadvantages learning each one will allow you to be a better welder." This underscores the importance of selecting the best welding machine for your application, thus helping you become a more efficient and effective welder. Also, keep in mind that there are versatile welding machines with the ability to weld multiple welding processes, and there are engine-driven (fuel-powered) welders for work off the electrical grid. (These more complex welders will be covered in different articles.) This article will focus on the basic MIG, TIG, and stick welding machines. If you need to familiarize yourself with their welding processes, check out the Understanding TIG vs. MIG welding machines: A comprehensive guide here.
This article starts with the basics of choosing a machine. After that, we will show you how to compare key features in a welding machine and a guide to consider when using compressed gas for welding.
In the realm of industrial applications, welding serves as the cornerstone of fabricating structures, machinery, and products that define various sectors. To select the right welding machine for these demanding settings, it's imperative to delve into the diverse welding processes, the scope of projects, and the range of materials commonly encountered.
The TIG welding machine
Understanding the scope of industrial projects is pivotal in selecting the appropriate welding machine. Projects can range from small-scale, intricate fabrications to large, heavy-duty constructions. Factors like project size, complexity, and desired weld quality influence the choice of welding process and machine.
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Compressed gases play a crucial role in various welding processes, as they provide the necessary shielding or reactive atmosphere to achieve successful welds. Identifying the appropriate compressed gas requirements is essential to ensure optimal welding performance. Oxygen, argon, and carbon dioxide are among the commonly used compressed gases across different welding techniques. It is imperative to assess your specific compressed-gas needs before selecting a welding machine, as the type of gas used can significantly impact the welding outcome.
Diverse gases, such as carbon dioxide (CO2), argon, oxygen, and mixtures thereof, are employed in distinct welding processes. When considering MIG welding, factors including the welding procedure, base metal, welding position, and environmental conditions collectively determine the suitable gas or gas mixture. Some common gases and mixtures used are argon, CO2, helium, oxygen, and nitrogen. For instance, a blend of argon and CO2 is often utilized for certain MIG welds. In the case of oxyfuel welding, only fuel gas and oxygen are required to facilitate the process.
Pure argon is the typical choice for TIG welding, providing the necessary shielding gas. However, in specific applications that demand unique properties, helium might be added to the gas mixture. Understanding the distinct gas requirements for different welding techniques ensures that you select the appropriate welding machine equipped to accommodate the specific gases needed for your projects. For a more comprehensive understanding, you can refer to information on welding gases and their respective purposes to make informed decisions about your compressed gas selection.
Choosing the right welding machine for industrial applications requires a comprehensive evaluation of various factors that directly influence performance, efficiency, and safety. These considerations encompass power supply, welding process compatibility, duty cycle, welding thickness, portability, safety features, budget constraints, and more. In this section, we delve extensively into each of these pivotal aspects.
Duty cycle indicates the amount of time a welding machine can operate within a 10-minute period before needing to cool down. For industrial applications requiring prolonged welding sessions, choosing a machine with a higher duty cycle ensures uninterrupted operation and increased productivity.
Consider the range of welding thicknesses you'll be working with. A welding machine's amperage range determines its suitability for various thicknesses. Ensure the machine can handle the thickest and thinnest materials you'll encounter.
Portability is crucial, especially if your industrial projects demand mobility. Choose a welding machine that's easy to transport and offers options for using it in diverse workspaces. Features like wheels, handles, and lightweight design enhance maneuverability.
Evaluate the availability of essential accessories such as torches, cables, gas regulators, and wire feed systems. Additionally, consider features like adjustable settings, digital displays, and customizable parameters, as these contribute to the machine's versatility and user-friendliness.
Prioritize welding machines with comprehensive safety features, including thermal overload protection, voltage fluctuation safeguards, and proper grounding options. Ensuring the machine complies with industry safety standards is vital for operator well-being and compliance.
Balance your budget with the long-term value offered by the welding machine. While cost is a factor, investing in a high-quality machine that meets your industrial demands ensures optimal performance, reduced downtime, and longer lifespan.
A MIG welding machine
Understanding the basic processes of using welding machines is important for a new or aspiring welder. Your prospects for employment increase dramatically if you understand the features and benefits associated with the various types of welding machines. The guidelines mentioned above will be very helpful in buying a welding machine. If you are looking for quality welding machines or a wide range of exclusive portable welding machines online, then you can visit gz-supplies.com and get the best one.
We at GZ Industrial supplies offer a wide selection of welding machines that are best suited for all your requirements. You can get a full range of welding machines like TIG, MIG, and Stick welding machines, welding accessories, etc. Contact us for the best price.
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