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Arc Welding and CD Welding: What’s the Difference?

Written by Jason Godbout on . Posted in Uncategorized

If you’ve read our previous blog, you know that stud welding comes in handy for a variety of situations. Whether you plan to build a boat, an apartment complex, or a bridge, stud welding strengthens your application.

But did you know that you can use multiple techniques to weld studs?

The two most common methods are arc stud welding and capacitor discharge (CD) stud welding. Though both methods involve fastening studs to base metals, they each offer their own benefits for different projects.

What Is Arc Welding?

Arc welding relies on either an AC or DC electrical current to create an arc. The current melts the metals at the welding point, and then the gun pushes the metals together. When the metals have cooled, they form a solid seam.

Arc welding breaks down into three different techniques:

  • Drawn arc stud welding. In this technique, you load the stud into your welding gun and place a ferrule (disposable ceramic shield) at the end. From there, you set the gun against the base metal and press the trigger. The electrical current energizes the gun’s lift mechanism and creates a
    pilot arc. The pilot arc paves the way for the welding current, which then heats the metal. When the lifting mechanism discharges, the stud plunges into the melted metal and solidifies. You can then discard the ferrule.
  • Gas arc stud welding. With gas arc welding, you use an inert shielding gas rather than placing a ferrule at the end of the welding gun. You load the stun into the gun and position the gun for welding. When you pull the trigger, shielding gas pours into the welding area. As the stud lifts, an electrical current creates the arc, which heats the stud and base metal. The gun then pushes the stud into the melted metal, and more gas blows onto the welding area to quickly cool the metals.
  • Short arc stud welding. Short arc welding is similar to drawn arc welding, but it doesn’t require a ferrule. It has a higher current and shorter weld time than drawn arc, though it also produces a more porous weld.

Though timing varies between techniques, all three arc welding methods offer similar benefits.

What Benefits Does Arc Welding Offer?

Arc stud welding methods allow you to quickly fasten almost any shape or size of metal. It offers maximum penetration and reliability, making it especially useful for thicker, rougher base metals. You can create a strong, one-sided weld in less than 0.06 seconds.

In general, arc stud welding enables you to create a bond stronger than either the stud or the surrounding base metal. The bond resists vibrations and breaking, so you don’t have to worry about your project loosening or weakening.

What Applications Work Best?

Some of the most common arc welding applications include:

  • Automotive (power steering, dashboards, insulation, and exhaust systems)
  • Farm equipment (cabs, spreaders, thresher teeth, and wiring)
  • Shipbuilding (insulation, hatch covers, and wire management)
  • Construction (piping, bridges, and buildings)

However, arc studs work well with most aluminum, stainless steel, and mild steel projects.

What Is CD Welding?

Capacitor discharge welding involves principles similar to arc welding. But rather than an AC or DC power supply, CD welding uses a capacitor storage system to create its electrical discharge. The discharge heats and melts the metals, and the gun then pushes the two pieces together. When the metal cools, you have a highintegrity weld.

As with arc welding, CD welding breaks down into multiple techniques:

  • Contact welding. With this technique, you load the stud with a specialized ignition tip into the gun and position the gun against the base metal. As energy discharges from the capacitors, the ignition tip vaporizes and creates a gap. The current then flows through the gap, melting the stud and the base metal. The gun forces the pieces together until they cool and harden.
  • Gap welding. Like contact welding, you load a stud with an ignition tip into the gun. But rather than placing the stud against the base metal or workpiece, you hold the gun above it. The stud accelerates toward the metal at the same time as an open-circuit shoots through the gap. The ignition tip vaporizes, the two pieces melt, and the weld forms as the metals cool.

Both techniques offer similar benefits, depending on the project you have in mind.

What Benefits Does CD Welding Offer?

CD stud welding allows you to join small studs to thinner, lightweight base metals, including materials as thin as 0.02 inches. You can typically complete a weld cycle in 0.01 seconds with minimal discoloration or distortion.

Furthermore, the process creates a one-sided weld, so the reverse side won’t show any dimples or rivets.
You can paint the reverse side before welding without worrying about damage to the finish.

What Applications Work Best?

If you have a project where cosmetic appearance is a top priority, choose CD welding over arc welding. Some popular applications include:

  • Jewelry (earrings, pins, and pendants)
  • Cookware (pots, pans, and utensils)
  • Electronics (motors, terminals, and pumps)
  • Doors (escutcheon plates, insulation, and commercial doors)

In general, CD studs work well with thin sheet metals as well as with projects where you weld two dissimilar metals.

Still Confused?

This simple guide will help you decide which welding technique will work best for your project. But, of course, the listed ideas are far from comprehensive. If you need additional help deciding whether to use arc studs or CD studs, meet with a professional welder to discuss your ideas.  

5 Significant Structures That Required Welding in Their Construction

Written by Jason Godbout on . Posted in Uncategorized

Rising 630 feet above the Mississippi River, St. Louis’s Gateway Arch stands as a modern structure that memorializes the city’s place in American history. The arch symbolizes two important aspects of the American spirit: the adventurous bravery evident in the numerous travelers who headed West through St. Louis and the technical prowess of designers, builders, and welders who constructed the monument.

The iconic Gateway Arch is just one structure that would not exist without the invention and evolution of modern welding techniques. In this blog, we’ll examine five significant structures made possible by welding.

1. The Gateway Arch in St. Louis

Workers used numerous welding techniques to construct this geometric structure. The arch’s legs consist of small triangle-shaped sections that were assembled individually in Pennsylvania.

Each triangular section below 300 feet high has two walls: an outer stainless steel wall and an inner carbon steel wall. Welders used butt welding techniques on both walls. Builders also used MIG, or metal inert gas, welding to join the polished stainless steel that forms the arch’s exterior walls. These stainless steel plates also had long rows of studs welded to them.

To attach the inner and outer walls, welders chose spot welding. This nearly heatless welding method ensured that the steel would not warp and become misshapen. The assembled triangular sections were welded to train gondola cars so they would stay in place during the trip to St. Louis. Finally, the individual sections were welded together to form the historic arch.

2. Yankee Stadium

The new 2009 Yankee Stadium sits just one block north of the where the original Yankee Stadium was located. The updated version currently holds the top spot on the list of most expensive sports arenas ever built. More than 53,000 baseball fans can gather to watch games inside this huge structure.

To please Yankee fans, designers of the new stadium incorporated elements from its predecessor. One such element, the white frieze surrounding the roof, consists of zinc-coated steel sections. Welders joined these sections together. The frieze provides structural support for the upper decks and stadium lights. Consequently, steel beams do not block fans’ views of the field below.

3. Liberty Ships

During World War II, the United States needed to quickly build inexpensive ships for cargo transport. American military forces adapted a British design to create Liberty ships. These boats lack aesthetic beauty and earned insulting nicknames such as “Ugly Duckling,” but they served their purpose and helped move goods safely from the USA to Europe.

More than 2,700 Liberty ships were built during the war. A crew could assemble an entire Liberty ship in around 42 days once the process was streamlined. The secret to the quick construction was submerged arc welding. Earlier similar ship models mainly used rivets, which take longer to install.

Some Liberty ships experienced cracks in their hulls or decks. But those cracks occurred because of the brittle steel used to make them, not poor quality welding. In fact, the welded hulls actually allowed the cargo-loaded ships to travel farther than riveted ships could have.

4. The Grand Canyon Skywalk

Before 2007, visitors to the Grand Canyon had to observe its grandeur from observation decks on the edge of its rims or descend into the canyon itself. But today’s visitors can look down into the canyon if they dare to venture onto the Grand Canyon Skywalk. (The bridge is safe but might be scary for people with a fear of heights.) This horseshoe-shaped bridge has a transparent floor and extends 70 feet over the canyon’s rim.

To construct this wonder of modern engineering, crews welded together more than a million pounds of steel. The main technique used was an efficient submerged arc welding method that employed both alternating and direct currents. These welds make the structure extremely strong. It can withstand earthquakes up to an 8.0 magnitude and hold 70 million pounds of weight.

5. The Detroit-Windsor Tunnel

The last landmark on our list is also the oldest. Built in 1930, the Detroit-Windsor Tunnel runs below the
Detroit River and into nearby Windsor, Ontario, Canada. Workers first attempted to build the tunnel in the
1870s, but obstacles such as sulfur gas and limestone made the project expensive and dangerous.

Luckily, by the 1920s, new techniques, including arc welding, made the tunnel possible. The Detroit-
Windsor Tunnel is just under one mile in length (5,160 feet), but it contains around 65 miles of arc welding. Today, this tunnel serves as the second-busiest border crossing between the United States and Canada.

 

The five structures listed above show that welding has played a significant role in the creation of modern engineering feats. If you need to build structures that will stand the test of time, incorporate welding into your building process. Your designs may not become iconic like those listed here, but the final structure will be firmly fastened together and ready to withstand strong forces.

A Basic Guide to Stud Welding

Written by Jason Godbout on . Posted in Uncategorized

As a commercial contractor, you want your projects to stay sound, stable, and secure despite the heavy loads they bear.

Consequently, you have to rely on a variety of techniques to mount, attach, and support each piece of equipment or hardware.

Although you could turn to any number of welding methods to finish your next project, consider adding stud welding to your arsenal of essential tools and methods.

What Is Stud Welding?

Stud welding, or drawn arc stud welding, joins a stud with another piece of metal. You use an arc to heat both pieces, and when you push them together, they create a permanent, high-strength bond.

Unlike other welding types, stud welding does not need packing metal.

What Benefits Does Stud Welding Offer?

When performed correctly, stud welding offers numerous benefits for commercial and industrial applications, including the following:

1. Greater Strength

Stud welds lend strength to the parent material as well as the stud. Whereas bolts with a peripheral weld or “clinch” fastener press into place, stud welds allow for complete cross-sectional welds. This characteristic enables the weld to outlast the rest of the product and function well in leak-proof projects.

2. Cost Efficiency

You likely already know that welding metal doesn’t come cheap-especially when your project consists of expensive metals and materials. But when you opt for stud welding, you don’t have to use as many fasteners to achieve great support and strength. And because of this weld’s enhanced durability, you won’t have to worry about maintenance costs over the years.

Better still, stud welding only requires one skilled worker to install rather than several people working together. On average, stud welding times range between 0.006 and 1.25 seconds depending on the fastener’s size. Since labor costs often represent a large percentage of your project’s budget, any cut in assembly time will save you a significant amount of money.

3. Increased Safety

Many welding techniques involve spatter, or droplets of molten material generated near the welding arc. Though generally considered a nuisance, spatter can present numerous safety hazards when it sticks to clothing or skin. Additionally, spatter results in loss of material from the weld and requires excessive effort to clean and remove.

Stud welding, however, keeps spatter to a minimum if you use a ceramic shield near the arc and weld zone. When to Use Stud Welding

Stud welding works well in a variety of applications, from cosmetic elevator buttons to tamper-proof ATM machines.

Some of the most common industrial projects that require stud welding include:

Ships

Liners, cargo carriers, warships, and submarines all rely on stud welding to hold equipment in place. After all, stud welding does not require holes drilled into the vessel, and it creates a waterproof seal between joints.

Bridges

Large highway bridges often feature a metal expansion joint. This metal plate allows the bridge to expand and contract with temperature changes, rather than buckling in inclement weather. On the back of this metal plate, you’ll find large weld studs set with concrete to hold the joint in place.

Food Service Equipment

Stainless steel ovens, worktops, and microwaves often rely on weld studs to hold them together. The weld studs grips the stainless steel finish without the need for screws or bolt heads. And without the additional fasteners, the appliances will have fewer rough surfaces to collect food particles and debris.

Have a Project in Mind?

As you can see, stud welding has a lot to offer. If you have a commercial or industrial project in mind that requires stud welding, or if you have more questions about the process, talk to a stud welder professional.