who want to learn welding and have their work look and perform like a professional’s. Some skilled weldors don’t believe they need any more than their manual ability. Exceptional manual skills are great to have, and some weldors are on par with the best artists. However, understanding some of the reasons for certain weld problems and why defects occur is also needed. Some welding science is covered, which helps you resolve welding problems.
Modern Arc Welders
Recent advances in welding machines make it easier to produce quality welds. Welding is an art as well as a science and requires skill. However, depositing a stack-of-dimes weld is much easier with the new microprocessor-inverter–based TIG welders; you just preset two current levels: low and high. After the welding current has been on the high setting for a few seconds, filler metal is easier to add. When the current switches to the low setting, moving the torch forward avoids burn-through. Then you set the pulse rate and it switches between the two levels automatically. The current rise and fall times are very quick, providing a very stable arc. When TIG welding with AC power, there is no longer a need for continuous high frequency.
This book about advanced welding is not just for the skilled weldor. Understanding why welds behave as they do, and some welding science, assists in solving welding problems. Recent advances in welding machines make it easier to produce quality welds. Setting the welding machine to achieve optimum performance has been made much easier with the new microprocessor-inverter-based TIG and MIG welders. (Figure adapted from ESAB’s Oxyacetylene Handbook with sketch by Walter Hood)
By simply setting the correct plate thickness, the microprocessors in MIG welders automatically set all of the proper parameters. For MIG welding automotive sheet metal, the short-circuiting mode is used to avoid excess heat. In the past, you had to manually adjust voltage, slope, and inductance to optimize MIG short-arc weld performance; for those who were able to set them properly and possessed good manual skills a quality weld resulted.
Today, the microprocessor monitors the arc and sets the proper electrical characteristics to achieve the optimum short-circuiting conditions. Details of equipment features are presented in the book.
Modern Cutting Process
Oxyacetylene cutting produces a very hot flame temperature of 5,720 degrees F. A pure stream of oxygen oxidizes the iron, which generates heat to maintain the cutting process. This produces quality cuts in steel, but it relies on the oxidation of iron to maintain the cut, and therefore it cannot be used on other materials, such as stainless steel and aluminum. However, plasma cutting forces a 30,000 degree F arc and heated air stream through a very small hole to cut through the thickest and strongest material. The arc intensity is so high it quickly melts the metal and cuts thin steel sections much faster than oxyfuel. In fact, plasma cutting melts and severs any metal.
Welding Safety
Welding is safe if you take proper precautions and follow published instructions for the use of equipment and filler metals. The following is an overview of some important safety issues and where to find more safety information.
Material Safety Data Sheets
Before welding, read the safety information from the welding equipment manufacturer. This information includes, but is not limited to, warning labels on the packaging of the welding rods or wires being used and Material Safety Data Sheets (MSDSs) specific to each product. An MSDS lists the potentially hazardous ingredients in a product and provides instructions on how to avoid being overexposed to such ingredients. If an MSDS is not included with your purchase of a welding product, contact your local distributor or the manufacturer of the product directly and ask for one. Most of the MSDS sheets are available on the manufacturers’ Web site, free of charge.
Oxyacetylene cutting produces a very hot flame temperature of 5,720 degrees F. It can make quality cuts in steel. However, plasma cutting severs any metal by using an air stream heated to more than 30,000 degrees F that is forced to flow through a very small hole. The arc intensity is so high that it melts metal rapidly and cuts thin sections of steel much faster than oxyfuel. (Figure adapted from ESAB’s Oxyacetylene Handbook with sketch by Walter Hood)
Fumes
Because welding fumes can be hazardous, keep your head out of the fumes and always use adequate ventilation. You need to minimize your exposure to welding fumes. Avoid rising smoke and keep any smoke from entering the breathing area under the welding helmet.
Never weld in an enclosed area, such as a car trunk, without some form of forced ventilation, such as a fan. Shielding gases, including both argon and carbon dioxide, are heavier than air and sink to the bottom of an enclosed area, causing a reduction in oxygen leading to dizziness and unconsciousness without warning signs.
Protective Clothing
Aways wear the proper protective clothing. Ultraviolet radiation originating from the arc is harmful to the eyes and skin. Therefore, wear a longsleeved shirt and button it to the top, which blocks arc rays from reaching exposed skin. Special gloves made from thin, flexible leather are available for TIG welding.
You only have two eyes and need to protect them, so always wear safety glasses. Also, use a face shield when grinding. Many eye injuries result from metal particles accumulating in the eyebrows during grinding and falling into the eyes at a later time. On television how-to and restoration shows, weldors do not typically wear long-sleeved shirts and proper clothing, which is an unsafe practice that doesn’t set a good example. In fact, such programs generally include a disclaimer indicating that simulations were made for TV viewing and normal safeguards were not used. Unsafe practices seen in those programs should not be imitated. Proper clothing is necessary.
Read and understand published safety information for your welding equipment and filler metals. Welding fumes can be hazardous; keep your head out of the fumes and always use adequate ventilation. Exposure to welding fumes can be substantially reduced by avoiding rising smoke and keeping the smoke from entering the breathing area under the welding helmet. Never weld in an enclosed area such as a car trunk without some form of forced ventilation.
AWS Literature
For additional details about welding and cutting safety issues, consult ANSI Z49.1, Safety in Welding, Cutting and Allied Processes, a document available from the American Welding Society (AWS). At the time of this publication, this was available as a free Web site download. In addition, most manufacturers of welding products have safety information available on their Web sites.
The ultraviolet radiation from the arc is harmful to eyes and skin. Always wear a long-sleeves shirt and button it to the top so no arc rays reach any exposed skin. Wear welding gloves with cuffs and always wear safety glasses. You only have two eyes, so protect them. When grinding, use a face shield. Electrical shocks can kill, so don’t touch live electrical parts.
