M

Welding Glossary


 * Machine Welding ** - Welding with equipment, which performs the welding operation under the constant observation and control of a welding operator. The equipment may or may not perform the loading and unloading of the work. See automatic welding.


 * Manganese** is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature (often in combination with iron), and in many minerals. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels.

**Manganism** is a condition that occurs when someone has been exposed to toxic levels of manganese. Symptoms tend to mimic Parkinson's Disease and include gait disturbances, clumsiness, tremors, speech disturbances, and psychological disturbances.

Manganese Information for Welders


 * Magnesium -** is a chemical element with the symbol Mg and atomic number 12. Its common oxidation number is +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole. Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle


 * Manual welding ** - A welding operation performed and controlled completely by hand. See automatic welding, machine welding, and semi-automatic welding.


 * Melting Range ** - The temperature range between solidus and liquidus.


 * Melting Rate ** -The weight or length of electrode melted in a unit of time.


 * Melt-Thru ** - Complete joint penetration for a joint welded from one side. Visible root reinforcement is produced.


 * MERCURY - ** Mercury compounds are used to coat metals to prevent rust or inhibit foliage growth (marine paints). Under the intense heat of the arc or gas flame, mercury vapours will be produced. Exposure to these vapours may produce stomach pain, diarrhea, kidney damage, or respiratory failure. Long-term exposure may produce tremors, emotional instability, and hearing damage.


 * Metallic Bond ** - The principal bond, which holds metals together and which is formed between base metals and filler metals in all welding processes. This is a primary bond arising from the increased spatial extension of the valence electron wave functions when an aggregate of metal atoms is brought close together.


 * Metal Band Saw** - A metal band saw used in metal fabrication shops. It consists essentially of a toothed metal band coupled to and continuously driven around the circumferences of two wheels.

**Metal Fume Fever** is an illness caused primarily by exposure to certain fumes. Workers breathe in fumes from chemicals such as zinc oxide (ZnO) or magnesium oxide (MgO), which are themselves created by heating or welding certain metals, particularly galvanized steel. Chromium is also a hazard, from stainless steel. Cadmium, present in some older silver solder alloys can, in extreme cases, cause loss of consciousness within a matter of minutes. Iron itself, and so most simple steels, does not give rise to it.


 * Metal Transfer **

There are four basic modes of metal transfer:


 * * ** Short Circuit Transfer ** – Gets its name from the welding wire actually “short circuiting” (touching) the base metal many times per second. Some spatter is produced, but the transfer can be used in all welding positions and on all thicknesses of metal. || [[image:Short Circuit..jpg]] ||
 * * ** Globular Transfer ** – Named for “globs” of weld metal transferring across the arc in a gravity feed. Droplets across the arc are usually larger than the electrode diameter. It does not produce a very smooth weld bead appearance, and some spatter can occur. Usually limited to the flat and horizontal welding positions, and not used on thin metals. || [[image:Globular Transfer.jpg]] ||
 * * ** Spray Transfer ** - Named for a “spray” of tiny molten droplets across the arc, usually smaller than the wire diameter. Uses relatively high voltage and amperage values, and the arc is “on” at all times after the arc is established. Very little if any spatter is produced. Usually used on thicker metals in the flat or horizontal welding positions. || [[image:Spray Transfer.jpg]] ||
 * * ** Pulsed-Spray Transfer ** – For this variation of spray transfer, the welding machine “pulses” the output between high peak currents and low background currents. The weld pool gets to cool slightly during the background cycle, making it slightly different than Spray Transfer. This can allow for welding in all positions on either thin or thick metals. || [[image:Pulsed-Spray Transfer.jpg]] ||


 * Method ** - An orderly arrangement or set form of procedure to be used in the application of welding or allied processes.


 * MIG Welding (Metal Inert Gas) ** – MIG welding is also known as wire-feed welding, although it is possible to do wire-feed welding without the inert gas. Metals that are difficult to arc weld may be MIG welded. (2) ** MIG Welding ** (GMAW or Gas Metal Arc Welding) - Also referred to as solid wire welding. An arc welding process which, joins metals by heating them with an arc. The arc is between a continuously fed filler metal (consumable) electrode and the work piece. Externally supplied gas or gas mixtures provide shielding.


 * Mild Steel ** – Mild steel is steel with less than 0.15% carbon. (Also called low carbon steel). Most steel in common use is mild steel.

[|Miller Electric Mfg. Co.], with headquarters in Appleton, Wisconsin, manufactures arc welding and cutting equipment designed for manufacturing, fabrication, construction, aviation, motorsports, education, agriculture and marine applications.

Millermatic 200 GMAW/MIG Welder

Molybdenum ** Mould **
 * Molten Weld Pool ** –the molten weld pool is the liquid state of a weld prior to solidification as weld metal.

Return to Glossary Home Page