Archive for the ‘Uncategorized’ Category

The significance of constant voltage in MIG welders

Thursday, August 12th, 2010

In MIG welding, what should be constant? Is it welding voltage or current? This is a question that bewilders most of the welders. The answer is that the MIG welding actually requires constant voltage-type power supplies. This is exactly in contrast to TIG and stick welding which use power supplies that comes from the constant current. Constant voltage is actually crucial in MIG welding since it ensures a stable arc gap size, resulting in stable arc operation and smooth metal transfer from the wire tip.

The main difference noted on voltage and current is on the way they respond to varying electrical resistance in the arc. The greater the resistance would be if the arc is longer. Keep in mind that increasing the arc gap size causes a drop in current in constant voltage. Therefore it causes a decrease in the power and heat input of the arc. This can be substantiated by the Joule’s law. If it is a constant current machine, the voltage increases as the arc gap is increased thereby causing the heat input to increase. So altogether, the longer arc gap would be colder in a Constant Voltage machine. And on the other hand in constant current machine, the longer arc gap would be hotter. Here the heat is a lot less focused as a bigger arc has greater surface area to wade off the heat.

On the whole, the constant voltage is important in MIG welder in order to balance the melting off rate and heat input as well as the arc length.

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Uses and purpose of Metal Insert Gas welding:

Tuesday, June 8th, 2010

Generally welding machines are used for merging two or more materials together. The categories of welding machines are Arc welding, Mig welding, Spot welding, Tig welding and many more which are utilized for different aim. While welding you need lot of concentration and is a very hard job.

Mig welding is famous as feed welding. The full form of mig is metal insert gas. These are less expensive and consumes less time. Other welding machines consume lot of time and are more expensive than mig welding. The main reasons for using mig welding are:

• It is simple and gives high performance.
• The welding work is done in lesser time than other welding machines.
• It is capable of working with all kind of metals. For example aluminum and steel are commonly used.
• It is also known as gas metal arc welding because it can utilize any shielding gas for obtaining smooth finish.

The Mig welding are utilized by farmers, metal fabricator and house mechanics. Almost all farmers use this because it is affordable and saves time. The fabricators use this because they need to work on all metal.

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welding hoods

Friday, May 28th, 2010

There are two main types of welding hoods, the stationary filter lens welding hood and the flip-front filter lens welding hood.

The stationary filter lens welding helmet has a fixed lens housing with the shaded lens held in by a spring retainer from where a lens can be slipped out and replaced as welding requires. It is important to change a welding hood lens when it becomes scratched or dirty in order to prevent the wearer from accidents such as tripping and falling.

The flip-front filter lens welding hood has a lens housing with a front side that can be flipped up so that it leaves a clear-glass lens that permits the hood to be worn while chipping.

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Posted in Spare Parts, Uncategorized, Welder Accessories, Welding Helmet | 1 Comment »

Welding Certification

Thursday, May 27th, 2010

The first step toward getting a welding certification is to learn proper welding techniques. Short programs in welding  are available from community and career colleges. Introductory, intermediate, and advanced welding  classes are typically eight to 12 weeks in length. These courses are a combination of theoretical training and hands-on practice with welding equipment.

There is no formal training or experience requirement to get welding certification in the United States. Candidates apply to the American Welding  Society® (AWS®) to complete the Certified Welder test. The candidate is required to provide a sound weld for inspection by an AWS® Certified Welding Inspector. This test must be completed at an AWS® accredited testing facility. The weld is evaluated against the welding procedure specification, which includes the fit-up, assembly, and position.

Upon successful completion of the welding certification, candidates are able to work as welders. It is important to note that all certified welders are required to submit a certificate maintenance form every six months. This form must be signed by the employer, confirming that the welder is performing only the welds that he or she is certified for. Candidates who let this certification  lapse must repeat the examination.

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Pipe Welding:

Wednesday, May 26th, 2010

When working for Silico Products, Naddir Patel noticed that despite the SAW process being highly efficient in depositing weld metal, some of his customers were experiencing significant downtime between processes. They also were getting burn-through defects because welders were not proactively measuring the inter-pass temperatures.

Selecting a different high-deposition power source, such as twin wire, tandem wire, or power wave source was not a viable option simply from a capital cost standpoint. Retraining welders and requalifying weld procedures also would increase a project’s capital cost. This high capital investment still would have limited versatility in a typical multitasking shop that makes circumferential welds on 6-in. to 42- in. diameters in various plate thicknesses.

A published survey indicated that increasing electrode extension would seem to be the ideal remedy for increasing production rates and decreasing the heat input.

Whereas earlier attempts to increase electrode stickout (extension) were not very successful or consistent, Patel found a company that produced ceramic nozzles that could be screwed onto the contact tip of the welding head to guide the hot wire without jamming it.

This simple ceramic nozzle allows electrode extensions of 3 in. or more without wire straying. It eliminated arc wandering, provided adequate weld penetration, and produced quality welds. As welding parameters were not changed (except for a very small voltage increase), there was no need to requalify weld procedures.

The electrode extension was increased in increments to yield deposition rate improvements of 45 percent without any radiographic testing (RT) defects occurring.

As the heat-affected zone (HAZ) was narrower, narrower grooves were designed for greater efficiencies and less distortion.

Tests found that a 3/32-in. electrode with a 2 ¼-in. extension could be used for normal welds on various material thicknesses. Heavy-walled welds were completed with a 5/32-in. dia. electrode.

Tests were conducted at various customer locations and on a variety of groove welding applications for both mild steel and stainless steel in a 350- to 650-amp range.

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