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Welding Automation: Arc Motion vs Work Motion

08 August, 22 2:16 am · Leave a comment · Red-D-Arc
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Welding Automation: Arc Motion vs. Work Motion

Arc Motion vs Work Motion Welding Automation

The welding world consists of a broad spectrum of technologies suitable for a wide range of use cases, budgets, and levels of complexity. Between the two extremes of entirely manual and entirely automated processes is welding mechanization. Mechanization can be accomplished using devices that move the workpiece, move the arc, or both simultaneously. Regardless of the mechanical device used, the goals are the same: to make a welding operator’s work easier and more productive.

An Introduction to Welding Positions

To better understand the target applications of these devices, a quick refresher on welding positions can be helpful. Both the American Welding Society (AWS) and the International Standards Organization (ISO) use terms and designators to communicate the position of the axis of welding relative to the vertical and horizontal planes for both plate and pipe. The four fundamental welding positions for plate are:

 

  • Flat (aka 1G/1F depending on if the weld joint is a Groove or Fillet weld, respectively)
  • Horizontal (aka 2G/2F)
  • Vertical (aka 3G/3F)
  • Overhead (aka 4G/4F)

 

The four fundamental welding positions for pipe are:

  • 1GR (rolled horizontally oriented pipe)
  • 2G (vertically oriented pipe/horizontal welding axis)
  • 5G (horizontally oriented pipe, vertical welding axis)
  • 6G (~45° inclined pipe)

Welding in the flat and horizontal positions provides the greatest opportunity for the use of high-productivity welding parameters since the influence of gravity on the weld pool is not (or at least less) detrimental. Conversely, welding in the vertical and overhead positions often requires comparatively low amperages and wire feeds to fight gravitational influence, even if an all-position welding electrode or wire is used.

 

In-position welds are also favorable from an ergonomic perspective; out-of-position welding can be physically taxing, and the ability to mechanize an application provides an opportunity to locate the operator away from the welding arc in a more favorable location.

 

Welding Positioners

In a perfect world, every weld could be performed in the flat or horizontal welding positions and, in the case of a pipe, rotated during welding. “Work motion” devices allow the workpiece to be repositioned during or between welds and are also known as “positioners.”

 

Weld Rotator

  •  Weld rotators have a rotating platen that the workpiece can be mounted to using a chuck or fixturing. Often, the platen is designed to tilt approximately 90 degrees so that a workpiece oriented vertically is reoriented horizontally. These positioners are available in sizes ranging from benchtop to multi-ton heavy-duty units. Note that these positioners typically leave the workpiece cantilevered, which may constrain the maximum weight that can be placed on the unit before reaching rated capacity. These positioners are popular for applying flanges to process piping. In some applications, the welding cell can be designed to use a welding rotator to permit welding on one assembly while another is being welded.

Headstock & Tailstock

  • Like weld rotators, headstock and tailstock positioners have one powered rotatable platen that allows the workpiece to be rotated about the horizontal axis. However, the workpiece bridges from the powered headstock to the idle tailstock so that the workpiece is supported and not cantilevered. These positioners are excellent for large, unwieldy weldments such as large boom assemblies or even entire railcars. With proper fixturing, the workpieces need not be cylindrical.

Turning Rolls

  • Turning rolls also provide the rotational movement of a workpiece. Unlike weld rotators and headstock/tailstock positioners, the workpiece is not fixtured to turning rolls, it is simply cradled by them. These positioners are popular for performing circumferential welds on very large cylinders or pipes found in the oil, gas, and power generation industries

 

Arc-Motion Devices

While work-motion devices such as welding rotators help make welding easier by placing the weld in the ideal position, arc-motion devices serve to make welding easier by mechanizing the actions of the welding operator. Some common arc-motion devices are:

Welding Manipulators

  • These devices consist of a vertical mast mounted to a horizontal boom. Typically, the vertical movement of the boom up and down the mast is powered using an electric motor. If the horizontal movement of the boom is powered as well, the device can be used to perform longitudinal welds. However, some manipulators do not have mechanized boom travel and exist primarily to hold the torch at a fixed point in space above a welding positioner. Small manipulators may be mounted to a base having castors or lift points that permit ease in moving the device to the workpiece.

Track Torches:

  • These devices are typically portable and consist of a track and carriage. The welding torch is mounted to the carriage, and the track is typically affixed to the workpiece using magnets, permitting both in- or out-of-position welding. Specially designed track torches can be affixed to pipes for circumferential welding.

Seam Welders/Seamers

  • Seamers are specialized side-beam that has integrated workpiece clamps. The workpiece clamps are cantilevered over the equipment’s base, which allows loading and unloading from a single side. Seamers are especially popular for performing longitudinal welds on smaller-diameter tanks and pipes.

Welding Oscillators

  • Oscillators are an important accessory for many of the arc-motion devices described above. These devices can be affixed to a carriage or boom and permit the mounting of a welding torch. The oscillator is then able to finely manipulate the position of the torch—back and forth—similarly to how a welder would perform wide weave weld passes.

Conclusion

The adage “work smarter, not harder” can certainly be applied to the use of welding positioners and arc-motion devices. And because there is such a wide range of equipment types and capacities, finding a device that fits within your budget is not a complex task.

 Furthermore, these devices can be rented, allowing you to invest in the best technology for the job when you need it. Sometimes, the best solution may be to integrate both a work-motion and arc-motion device into a single weld cell. Red-D-Arc Welder Rentals has automation specialists who are able to help you identify the best devices for your application.

Automating the Pipe Welding Process

03 August, 22 9:48 pm · Leave a comment · Red-D-Arc
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“Welding Pipe” encompasses many applications ranging from small-diameter sanitary tubing to large-diameter pressure vessels. Some applications are more accessible to automate than others, but many difficult-to-automate applications can still be assisted by some degree of mechanical integration into the pipe welding process (mechanization).

 

Why Automate?

But automation adds complexity to the welding process. Successful automation requires additional equipment, fixturing, and control of manufacturing processes (for example: part geometry and fit-up). In short, automation is not without cost—tangible and intangible.

 So why automate? 

Automation:

  • Helps improve productivity. Machines can achieve a higher operator factor (more time spent welding versus time spent not welding) and handle higher deposition rates than even a dedicated welder using a handheld semi-automatic welding process.
  • Helps improve quality. Mechanization controls the fine motor skills required to produce high-quality welds. This means that fatigue does not become a detractor to weld quality. This also means that newer operators may be able to produce high-productivity high-quality welds.

Both general and specialized methods of mechanization and automation can respond to the challenges of the pipe welding industry with respect to the upfront cost and process control that can be afforded.

 

Welding Roll Out

Rolling out pipe is one of the first methods commonly employed to help automate the welding process, and doing so can significantly maximize welding productivity. Typical methods of rolling pipe place the pipe “in position ” As with welding plates, welding in position allows the use of high productivity welding parameters since the adverse influences of gravity are minimized.

 While evaluating your application, look at pipe-to-flange, pipe-to-elbow, or straight pipe-to-pipe connections, which can be accomplished as subassemblies. Once you have identified these sub-assemblies, consider the following equipment:

 

  • Pipe Stands: The equivalent of jack stands for small-to-medium pipe weldments. Most pipe stands are approximately waist high with adjustments up and down. The stand includes a set of rolls whose distance apart can be adjusted to accommodate pipes of different sizes. Some pipe stands integrate a powered roll into the stand so that a separate welding positioner is not required.
  • Pipe Rollers: These are typically used for rolling larger-diameter and heavier pipe assemblies. Much like pipe stands, a single pipe roller features a set of wheels with an adjustable wheelbase. Two or more pipe rollers—at least one of which is powered—are required to cradle the assembly low to the ground.

 

Achieving the Weave

Oscillation—also known as weaving—is a commonly employed welding technique to achieve wider weld bead width to span a joint, deposit additional weld metal per pass, or combine both. However, weaving properly requires skill to maintain good bead contour and consistency. But even skilled operators can experience fatigue when attempting to maximize welding productivity. Therefore, to recreate the technique of a professional welder, a precision device is required to implement oscillation.

The Process Pipe Cell is a near-turnkey solution for some pipe weldments that implements both work-motion and arc-motion to facilitate welding in-position but with manual welding. Work motion is provided by a welding drop-tilt welding turntable. Arc-motion is provided by an oscillator specially designed for welding. The mechanism of the oscillator is mounted to a welding manipulator so that the torch is supported as it traverses side-to-side across the weld joint. Oscillator, manipulator, and power source controls are mounted at a single location on the welding manipulator away from the weld joint to allow the welding operator to perform many adjustments during and between weld passes without having to leave the control station.

 

The Small Stuff: Orbital Welding

Orbital welding is true welding automation; with the push of a switch, an operator can fuse two small-diameter pieces of tubing to a level of quality suitable for pressurized and sanitary applications. In addition, automation is attractive for reducing the risk of rework when encountering small diameter pipe/tube since welding becomes increasingly difficult as pipe/tube diameter decreases.

 

One type of orbital welding system consists of a specialized GTAW/TIG power source and an unconventional welding torch that clamps around the weld joint. After clamping around the joint, a welding head inside the torch performs a full out-of-position revolution around the weld joint to produce a high-quality autogenous weld in an inert atmosphere (note that an internal shielding gas purge may still be required in some applications). The specialized power source simplifies developing a high-quality welding procedure by coming preloaded with parameters (amperage, travel speed, etc.) that can be selected respective to the diameter and thickness being welded.

 

The Big Stuff: Cladding

The use of welding processes is not limited to simply joining two workpieces. For example, cladding often uses conventional arc welding processes to deposit stainless steel or nickel alloy onto the surface of lower-cost base material to improve the component’s overall performance in corrosive and/or high-temperature environments.

Some systems implement GMAW, SAW, or GTAW. Regardless of the process used, the cladding operation requires making many overlapping passes, sometimes across several weld layers. Low dilution processes and parameters are ideal for minimizing the number of weld layers that may be required. Red-D-Arc supplies a variety of turnkey cladding systems that couple automation with hot-wire TIG. These systems allow the use of high cladding travel speeds, reasonable deposition rates, and low dilution.

 

Conclusion

While not all applications can be easily automated or mechanized, the variety of equipment available makes it viable for many use-cases in the world of pipe welding. Some options provide great flexibility in how they can be implemented, such as pipe stands and rollers that can accommodate a wide range of pipe diameters. 

 

Other systems are turnkey, such as the Process Pipe Cell. Although more complex, turnkey solutions can automate a more significant portion of the welding process “out of the box.” Contact Us Today to speak with Red-D-Arc’s automation experts. This specialized team is available to assess the needs of your welding application and help you better understand potential solutions for your application.

 

Tools that Improve Pipe Welding Efficiency

03 August, 22 9:35 pm · Leave a comment · Red-D-Arc
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Tools that Improve Pipe Welding Efficiency

Pipe Welding Efficiency

Discovering new equipment is an excellent step in improving operational efficiency. However, the first step of any improvement is changing your thinking about the existing process. 

What isn’t working about the “old way” of doing things? How does new equipment address those deficiencies? This article aims to share not just tools used to improve pipe welding efficiency but considerations to make about the welding process before researching equipment.

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