19What is interpass temperature

Interpass temperature refers to the temperature of the steel just prior to the depositing of an additional weld pass. It is identical to preheat, except that preheating is performed prior to any welding. When a minimum interpass temperature is specified, welding should not be performed when the base plate is below this temperature. The steel must be heated back up before welding continues. A maximum interpass temperature may be specified to prevent deterioration of the weld metal and heat...

How to Select the Right Engine Driven Welder for the

Engine-driven welders are generally used when electric power is not available for arc welding. Usually these are outdoor applications. However, engine-drive welders are often used for indoor applications when it is not convenient to supply power to electric plug-in arc welders. These indoor situations include everything from minor repair jobs to major plant shutdowns. When operating engine-driven welders indoors, vent the exhaust outside if at all possible, or use in large spaces with good...

Related Articles

How to Strike and Establish an Arc Creating High Quality Stick Welds A User's Guide Arc Welding Fundamentals Stick Weldirectory This project has been published to show how individuals used their ingenuity for their own needs, convenience and enjoyment. Only limited details are available and the projects have NOT been engineered by the Lincoln Electric Company. Therefore, when you use the ideas for projects of your own, you must develop your own details and plans and the safety and performance...

2Why is hydrogen a concern in welding

Hydrogen contributes to delayed weld and or heat affected zone cracking. Hydrogen combined with high residual stresses and crack-sensitive steel may result in cracking hours or days after the welding has been completed. High strength steels, thick sections, and heavily restrained parts are more susceptible to hydrogen cracking. On these materials, we recommend using a low hydrogen process and consumable, and following proper preheat, interpass, and postheat procedures. Also, it is important to...

How To Successfully Weld Aluminum with a Compact MIG Welder

By Jim Harris , Product Manager, The Lincoln Electric Company and Frank Armao, Group Leader, Non Ferrous Applications, The Lincoln Electric Company When it comes to welding aluminum items around the home or garage, there are a few misconceptions we hope to clear up 1) That you need to invest in a 4,000 welding machine and be highly skilled to have success 2) With no practice you can make excellent welds the first time the wire feed welder is taken out of the box and 3) You need an expensive...

Common Problems and Remedies for GMAW

Reprinted with permission from the September October, 1997 issue of Practical Welding Today magazine, copyright 1997 by The Croydon Group, Ltd., Rockford, IL In much the same way that the automatic transmission has simplified the process of driving, Gas Metal Arc Welding (GMAW) has simplified the process of welding. Of all welding methods, GMAW is said to be one of the easiest to learn and perform. The main reason is because the power source does virtually all the work as it adjusts welding...

MIG Welding Stainless Steel

Source Adapted from The Procedure Handbook of Arc Welding. The Lincoln Electric Company, 1994. Although welding stainless steel may not be as difficult as welding aluminum, the metal does have its specific properties that vary from your more common steels. When MIG welding on stainless, you usually have three choices of transfer depending on your equipment spray-arc, short-circuiting, or pulsed-arc transfer.

4 What input power is available

Another key question to ask yourself is what input power do you have available. For instance, if you will be doing most of your welding in your home or garage, you may only have access to a 115v input power source -- this will limit your selection to a 115v-wire welder. If you have access to 230v power in your home due to special wiring or a job shop, you may look to a machine that has higher voltage capabilities (230v is usually readily accessible in an industrial setting).

5 Whats your budget

There are a number of technology features that set one compact wire feed welder apart from another. For instance with both a 115v and 230v machine, you can purchase either a tapped or continuous control model. Tapped control basically offers you four or five discrete voltage settings. With continuous control, you have a continuous range of settings that can provide for fine adjustments and heat control. The continuous control is a nice feature, especially when working with thin materials where...

11Look for Safety Features

Look for a machine that offers a true Nozzle-in-Place safety sensor. With such a feature, the plasma cutter will not start an arc unless the nozzle is in place. Some safety systems can be fooled into thinking the nozzle is in place (i.e. shield cup sensing), even when it is not. If the output is turned on, the operator will be exposed to 300 VDC, a very unsafe condition. This cannot happen with the Lincoln Nozzle-in-Place safety sensor. Look for a machine that provides a pre-flow sequence. This...

How to Strike and Establish an

Source adapted from New Lessons in Arc Welding, The Lincoln Electric Company, 1990 A welding arc is maintained when the welding current is forced across a gap between the electrode tip and the base metal. A welder must be able to strike and establish the correct arc easily and quickly. There are two general methods of striking the arc The scratching method is easier for beginners and when using an AC machine. The electrode is moved across the plate inclined at an angle, as you would strike a...

What are the limitations to Plasma Cutting Where is Oxyfuel preferred

The plasma cutting machines are typically more expensive than oxyacetylene, and also, oxyacetylene does not require access to electrical power or compressed air which may make it a more convenient method for some users. Oxyfuel can cut thicker sections (> 1 inch) of steel more quickly than plasma. What to Look for When Purchasing a Plasma Cutting Machine Once you have determined plasma cutting is the right process for you, look at the following factors when making a buying decision.

MIG Wire

Like a stick electrode, MIG wire completes the electrical circuit creating the arc, but it is continually fed through a welding gun from a spool or drum. MIG wire is a solid, non-coated wire and receives shielding from a mixture of gases. (Process is also known as GMAW, or Gas Metal Arc Welding.) Common Problems and Remedies for GMAW 20 Frequently Asked Questions Frequently Asked MIG welding Questions MIG vs. Flux-Cored Which Welding Process is Right for You

Really User Friendly

Wire-feed welders are self-contained, portable units that are great for repairing metal fences and railings, shop equipment and even trailer bumpers We don't recommend making structural repairs, such as frame work on a car or trailer. Take those jobs to an experienced welder. Most units are either 115-volt or 240-volt. The 115-volt unit (the type you rent) works off standard household electric current. The 240-volt requires a 240-volt receptacle. Both are DC arc welders that use an electric arc...

3Can the Machine Offer an Alternative to High Frequency Starting

Most plasma cutters have a pilot arc that utilizes high frequency to conduct electricity through the air. However, high frequency can interfere with computers or office equipment that may be in use in the area. Thus, starting methods that eliminate the potential problems associated with high frequency starting circuits may be advantageous. The lift arc method features a DC+ nozzle with a DC- electrode inside. Initially, the nozzle and the electrode physically touch. When the trigger is pulled,...

How Does Plasma Cutting Compare to Oxyfuel cutting

Plasma cutting can be performed on any type of conductive metal - mild steel, aluminum and stainless are some examples. With mild steel, operators will experience faster, thicker cuts than with alloys. Oxyfuel cuts by burning, or oxidizing, the metal it is severing. It is therefore limited to steel and other ferrous metals which support the oxidizing process. Metals like aluminum and stainless steel form an oxide that inhibits further oxidization, making conventional oxyfuel cutting impossible....

Selfshielded Flux Cored Arc Welding process

(FCAW per the American Welding Society), or flux-cored for short, is different in that it uses a wire which contains materials in its core that, when burned by the heat of the arc, produce shielding gases and fluxing agents to help produce a sound weld, without need for the external shielding gas. We achieve a sound weld, but in a very different way. We have internal shielding instead of external shielding. The shielding is very positive and can endure a strong breeze. The arc is forceful, but...

Arc Welding Fundamentals

Arc welding is one of several fusion processes for joining metals. By applying intense heat, metal at the joint between two parts is melted and caused to intermix - directly, or more commonly, with an intermediate molten filler metal. Upon cooling and solidification, a metallurgical bond is created. Since the joining is an intermixture of metals, the final weldment potentially has the same strength properties as the metal of the parts. This is in sharp contrast to non-fusion processes of...

Fumes and Gases Are Silent Hazards

The fumes and gases that result from the welding process can cause acute or chronic health effects if proper precautions are ignored. The fume plume contains solid particles from the consumables (electrodes), base metal, base metal coating and gases formed in the process, which include oxides of nitrogen and ozone The gases used for shielding (argon, helium, and carbon dioxide) are non-toxic, but as they are released, they displace oxygen in breathing air. This can cause dizziness,...

6 Pilot to Cut and Cut to Pilot Transfers

The transfer from pilot arc to cutting arc occurs when the pilot arc is brought close to the work piece. A voltage potential from nozzle to work is mechanism for this transfer. Traditionally, a large resistor in the pilot arc current path created this voltage potential. This voltage potential directly affects the height at which the arc can transfer. After the pilot arc transfers to work a switch (relay or transistor) is used to open the current path. Look for a machine that provides a quick,...

Build Your Own Texas Grill

If you are a traditional barbecue connoisseur like me, then this is your grill. Don't you love that smooth smoky flavor charcoal lends to all your grilled foods To make sure you have a grill that can handle the heavy season of barbecue parties and get-togethers you're planning, let's talk a little bit about pulling this project together. This is a do-it-yourself welding project that won't cost a fortune to build. And, with the right equipment this project requires only one person with little to...

9Determine the Ruggedness of the Machine

For today's hard job site environments, look for a machine that offers durability and has protected controls. For example, fittings and torch connections that are protected will wear better than those that aren't. Some machines offer a protective cage around the air filter and other integral parts of the machine. These filters are an important feature since they ensure oil is removed from the compressed air. Oil can cause arcing and reducing cutting performance. Protection of these filters is...

Disadvantages

It is not recommended for very thin materials (less than 20 gauge). When flux-cored welding, machine settings need to be precise. A slight change in a knob position can make a big difference in the arc. In addition, the gun position is more critical in that it must be held consistently, and at the proper angle, to create a good weld. This process creates spatter and slag that may need to be cleaned for painting or finishing. It should be noted that the same machine can be used to weld with...