Welding Tips

[87wildside]

I have gathered some info on MIG welding that can make it easier for you to learn at home. This is how I have learned and still learning. If any one has anything to add feel free but please don't whore up this thread as it's for referance.

[87wildside]

This is from Miller Weldings web site http://www.millerwelds.com/education...articles8.html

MAKING A SOUND MIG WELD


The ability to make a good MIG weld is extremely important to the success of an auto repair technician. In fact, almost every welding repair made on a unibody car, light truck or van can be made with the Metal Inert Gas (MIG) welding process. For this reason, there are well-accepted standards and practices for producing sound MIG welds.
Note: This article is written for the person with a basic familiarity with welding who wants to practice and improve their welding technique. The process of arc welding poses several potential hazards that must be guarded. Therefore, all information relating to the safe operation of welding equipment and welding processes must be fully understood before attempting to begin work. Always read and follow the safety information in the operator's manual or contact the manufacturing company when in doubt.

What Needs Welding?

The front driver's side corner of a vehicle receives more damage than any other area. Parts damaged in this area include the upper rail, frame rail, radiator core support, and fender aprons. Other parts often damaged include the rear body panels, trunk floor, and lower rear rails. To make these repairs, the technician must thoroughly master all-position welding. It is important to practice so that you feel confident with making sound welds in all positions.
One way to become confident in your welding quality is to use a simple welding machine, such as the Millermatic® 185 from Miller Electric Mfg. Co. It comes complete with a package to get you started, including a 6 ft. power cord with plug, 10 ft. MIG gun and cable assembly, and 10 ft. work cable with heavy duty clamp. The package also includes a gas solenoid valve, flow gauge and 5 ft. gas hose, and factory installed running gear/cylinder rack.
Before making a repair weld, make test welds on material of the same type, thickness, and joint configuration. Visually inspect and destructively test the practice weld to ensure that it is sound before welding on the vehicle. Fine tuning the welding parameters and your technique on test welds improves the quality of the repair.

Welding In the Flat Position

For a flat joint, such as a butt joint, hold the gun at a 90 degree angle to the workpiece, directing the filler metal straight into the joint. A small, back and forth motion with the gun can help fill a large gap or when making multiple passes.
For a fillet weld on a T-joint, keep the gun at a 45 degree angle, or equal distance from each piece. When making multiple weld passes, the work angles change slightly. This helps avoid uneven weld beads and undercuts.
For a fillet weld on a lap joint, angle the gun between 60 and 70 degrees. The thicker the metal being welded, the greater the angle.
Plug welds should be made with the weld in the flat position if at all possible. Using a spiral-type technique, weld in a slow motion around the edges of the hole, making a complete circle before working toward the center (starting the spiral too soon can create pinholes). When welding around the edge, angle the gun slightly, somewhat like you would for a lap joint. Keep the gun perpendicular when filling the rest of the hole.

Horizontal

Because of the effects of gravity, the gun work angle must be dropped slightly by 0 to 15 degrees when welding horizontally. Without changing the work angle, the filler metal may sag or rollover on the bottom side of the weld joint. The travel angle, whether using a push or a drag technique, generally remains the same as for a weld joint in the flat position.
On thick metal when making multi-pass welds, or to bridge a slight gap where fit-up is poor, weave beads may be used to fill a weld joint. A back-and-forth weave, with or without a slight arch, is used in the horizontal position. A slight hesitation at the top toe of the weld helps prevent undercut and ensure proper tie-in of the weld to the base metal.
Voltage and amperage settings for welding in the horizontal position are usually the same, or very slightly less, than settings for welding in the flat position. However, note that if the wire diameter is too large, the resulting heat and size of the weld puddle may be too great to allow the weld puddle to freeze quickly, and the weld may rollover.

Vertical Positions

Vertical welding, both up and down, can be difficult. This makes pre-weld set-up very important for making high quality welds. Since you are fighting gravity, consider reducing the voltage and amperage 10 to 15 percent from the settings for the same weld in the flat position.
Know when to weld vertical down and when to weld vertical up. For vertical down welding, the welder begins at the top of a joint and welds down. This technique helps when welding thin metals because the arc penetrates less due to the faster travel speed. Because vertical down welding helps avoid excessive melt-through, welders sometimes place very thin materials in the vertical position even if they can weld them in the flat position.
When welding vertical down, angle the gun slightly back into the weld puddle at a 5 to 15 degree angle. For thin metal where burn-through is a concern, angle the gun slightly up and pull it downward (i.e., direct the wire away from the weld puddle). Either way, keep the electrode wire on the leading edge of the weld puddle. A very slight weave may help flatten the weld crown.
The vertical up technique - beginning at the bottom of a joint and welding up - can provide better penetration on thicker materials (typically 1/4 in. or more). The travel angle of the gun is a 5 to 15 degree drop from the perpendicular position. A slight weaving motion can help control the size, shape and cooling effects of the weld puddle.
Making a plug weld in the vertical position is somewhat similar to making a vertical up fillet weld. For a vertical plug weld, the filler metal is deposited upward along one side of the hole. Then, another bead is deposited from the bottom to the top on the other side of the hole. Alternate sides until the hole is filled. For thin metal, use a similar technique, but weld in the vertical down position to prevent burn-through.

Overhead Position

Drag, push or perpendicular gun techniques can be used for welding overhead. But, because of gravity, travel speeds must be fast enough so that the weld metal does not fall out of the joint. Also for this reason, weave beads should not be too wide. Using smaller diameter electrodes (e.g., .023 in.) and lowering the voltage and amperage help keep the weld puddle small and more controllable, too.
Work angles and travel angles for the overhead position can be thought of as the same angles for the flat position, only upside down. However, be sure to keep the gun nozzle clean, as spatter can build up much faster when overhead welding. Also, because the shielding gas flows upward, you may have to increase the gas flow rate to ensure proper coverage.

Travel Speed and Stickout

Travel speed and electrode extension (or stickout) also influence the shape and quality of a weld bead to a significant degree. Travel speed is the rate at which you move the gun along the joint. Many experienced MIG welders can determine the correct travel speed by judging the weld puddle size - in relation to the joint thickness - and keeping the arc on the leading edge of the puddle.
Stickout is the length of unmelted electrode extending from the tip of the contact tube. Changing the stickout - which occurs with variations in the distance of the contact tube to the workpiece - causes the voltage and amperage to vary, as well as changes the shape of the weld bead.
Generally, maintain a stickout of 1/4 to 1/2 in. Note that when starting a weld, a short stickout helps ensure a good, hot start; a longer stickout - once you've established the arc - can help bridge a gap when encountering poor fit-up. [Note: Long stickouts promote poor starts.] For critical welds, maintain a constant stickout

[87wildside]

This is a good site with video that I have found very useful. http://www.mig-welding.co.uk/

This is another good site with lots of info and links. http://www.thefabricator.com/ArcWeld...le.cfm?ID=1083

Good thread http://forums.hybridz.org/showthread.php?t=135675

[87wildside]

This is another copy & paste only this time it is from Lincoln Electric's site. This will help you chose MIG or Flux core welding.
http://www.lincolnelectric.com/knowl...icles/list.asp

MIG vs. Flux-Cored: Which Welding Process Is Right for You?



You are about to make the plunge and buy your first wirefeed welder. Being a toolguy (or gal), you don't want to waste your money on a toy that goes out with the trash in a few weeks. You most likely are very comfortable building things from wood, but you always wanted to step up to steel. You probably want to run it off of 115 volt input, so that it is very portable, but maybe stepping up to the 230 volt input machines with the option of welding thicker material(more than ¼") is a valid point. You think the decision-making process is over when you are hit with yet another question - which welding process will you use? . . . GMAW (MIG) or FCAW (flux-cored)? If you are like most novice welding operators, you may be confused as to the differences of these two choices. The best answer depends on 3 things. First, what you are welding. Second, where are you welding it. And Third, the surface finish of what you are welding. We will help you to decipher between the two processes, then describe advantages and disadvantages of each and wrap up by giving you usage tips. Ultimately, we hope to help you decide on a solution that will give you the best results for your application. The suggestions here are conservative and should be attainable by a beginner. Welding is a skill and an art about 95% can learn to do. Very few baseball players are able to hit over .350 in the majors. Very few welders have the skills to make picture perfect welds. It is critical to have good eye/hand coordination and a steady hand. Arc practice time is the only instructor that will teach you to truly set the machine properly. With basic motor skills, practice and patience, you should attain success at making sound welds.
The Definitions Gas Metal-Arc Welding:
(GMAW) as identified by the American Welding Society, is also popularly known as MIG (Metal Inert Gas) and uses a continuous solid wire electrode for filler metal and an externally supplied gas(typically from a high-pressure cylinder) for shielding. The wire is usually mild steel, typically copper colored because it is electroplated with a thin layer of copper to protect it from rusting, improve electrical conductivity, increase contact tip life and generally improve arc performance. The welder must be setup for DC positive polarity. The shielding gas, which is usually carbon dioxide or mixtures of carbon dioxide and argon, protects the molten metal from reacting with the atmosphere. Shielding gas flows through the gun and cable assembly and out the gun nozzle with the welding wire to shield and protect the molten weld pool. Molten metal is very reactive to oxygen, nitrogen and hydrogen from the atmosphere, if exposed to it. The inert gas usually continues to flow for some time after welding to keep protecting the metal as it cools. A slight breeze can blow the shielding away and cause porosity, therefore welding outdoors is usually avoided unless special windscreens are erected.
However, if done properly, operator appeal and weld appearance are excellent with MIG and it is most welders' favorite process to use. Good technique will yield excellent results. The properly made finished weld has no slag and virtually no spatter. A "push" gun angle is normally used to enhance gas coverage and get the best results. If the material you are welding is dirty, rusty, or painted it must be cleaned by grinding until you see shiny bare metal. MIG welding may be used with all of the major commercial metals, including low carbon steel, low alloy steel, and stainless steel and aluminum with potential for excellent success by a novice.
Aluminum MIG
Welding aluminum requires much more than just changing to aluminum wire. Get comfortable welding steel first. Since aluminum is very soft, it requires aluminum drive rolls that have a U-groove and no teeth to bite or cause wire flaking. Cleanliness of the wire and base metal are critical. Wipe the material with acetone on a clean shop rag. Use stainless steel wire brushes that have only been used on aluminum. Drive roll tension and gun length must be minimized. A Teflon, nylon or similar gun liner is needed to minimize friction in feeding the wire and 100% pure Argon gas is required for shielding. Special contact tips are often recommended. Special gun movement techniques are often highly desirable. It is a challenge, but it can be done.

Self-shielded 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 has spatter. When finished, the weld is covered with a slag that usually needs to be removed. A "drag" angle for the gun is specified which improves operator visibility. The settings on the wirefeeder / power source are slightly more critical for this process. Improper technique will have results that are magnified. This type of welding is primarily performed on mild steel applications outdoors. The Innershield® .035" NR®-211MP is often used for the 115 volt machines and the .045" Innershield NR-211MP is typically used in the 230 volt machines. Farmers have found that these products can save a planting or harvest by repairing a broken machine out in the middle of the field in record time.

General Usage Rules
MIG

As a rule of thumb, it is recommended to use a compact 115volt input (or 230 volt) MIG wirefeeder/welder indoors on clean new steel that is 24 to 12 gauge thick. 12 gauge is a little less than 1/8" thick. 24 gauge is less than 1/16" thick. The smallest wire(.025") will make it the easiest to weld the thinnest(24 gauge) material. The .030" diameter wire will weld a little faster deposition rate. If you need to weld 1/8" to ¼" thick material with MIG, you will need the higher capacity compact machine which will require 230 volt input. The higher amperage range of this machine can better handle your welding needs in a single pass and you may not have to waste time with second or third passes. The 230 volt machine could also run .035" diameter wire. To MIG weld material more than ¼" thick, you need a higher capacity truly industrial machine. If most of your welding will be performed indoors on clean material that is less than 1/8" thick, a MIG machine that operates on 115 volts is probably your best bet for economic reasons in that a 230 volt input machine will be more expensive.
Flux-Cored
The flux-cored process is only recommended on materials as thin as 20 gauge, a bit thicker than the 24 gauge we said for MIG. In general, this process is best for welding thicker materials with a single pass, especially if you need to weld outdoors such as to repair a tractor out in the field. A 115 volt flux-cored machine using an electrode such as .035" Innershield NR-211-MP will generally allow you to weld steel up to ¼"thick. Note that this is more than double the thickness maximum of 12 gauge with MIG on 115 volts. With the proper electrode on a proper machine, such as .045" Innershield NR-211MP, and a 230 volt input machine, you can weld steel up to 1/2" thick. Note that NR-211MP requires that the machine be setup for DC negative polarity.
Advantages/Disadvantages
While there are advantages and disadvantages to both processes, we will try to outline for you some of the most common.
MIG
Advantages

• The best choice when cosmetic appearance is an issue since it provides lower spatter levels than flux-cored. The arc is soft and less likely to burn through thin material.
• The lower spatter associated with MIG also means no slag to chip off and faster cleaning time.
• MIG is the easiest type of welding to learn and is more forgiving if the operator is somewhat erratic in holding arc length or providing a steady travel speed. Procedure settings are more forgiving.
• If you are skilled and get specific proper guns, shielding gas, liners, drive rolls, and electrode, MIG can weld a wider range of material including thinner materials and different materials such as stainless, nickel alloys or aluminum.

Disadvantages

• Since a bottle of external shielding gas is required, MIG may not be the process of choice if your are looking for something that offers portability and convenience. MIG also requires additional equipment such as a hose, regulator, solenoid(electric valve) in the wire feeder and flowmeter.
• The welders first job is to prepare the surface by removing paint, rust and any surface contamination.
• MIG has a soft arc which will not properly weld thicker materials (10 gauge would be the maximum thickness that MIG could soundly weld with the 115 volt compact wirefeed welders we are referring to or ¼" with the 230 volt input compact wirefeed machine.) As the thickness of the material(steel) increases, the risk of cold lapping also increases because the heat input needed for good fusion is just not possible with these small machines.

Flux-Cored
Advantages

• The Self-Shielded electrodes are optimal for outdoor procedures since the flux is built into the wire for positive shielding even in windy conditions. An external shielding gas and additional equipment are not needed, so setting up is simpler, faster and easier.
• The flux-cored process is most suited for applications with thicker materials as it is less prone to cold lapping.

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 both MIG and flux-cored processes though a special package is usually needed to change from one application to the other. Drive rolls, shielding gas, gun liners and contact tips and procedure settings need to be addressed when changing processes.
Choosing Wire
Another area that may cause the novice welder some concern is how to choose the best wire. Proper electrode diameter is related to plate thickness and the welder you have. A smaller wire makes it easier to weld thinner plate. For a 110 volt input MIG machine, an electrode such as Lincoln's .025" SuperArc® L-56™ is the smallest available size and the easiest to use on very thin material. A .030" SuperArc would weld slightly thicker material a little faster. For flux-cored, a 110v machine would run a .035" wire (such as Lincoln's NR-211-MP) because this is the smallest size made and this is all the machine can run. For a 230v MIG machine, most people are welding heavier plate and step up to the .030" or even .035" diameter solid electrode such as .030" or .035" Super Arc L-56 because they deposit weld metal faster and they can weld heavier plate. For flux-cored with the 230 volt input machine, most people move up to Lincoln's .045" diameter Innershield NR-211MP for plate up to ½" thick.
Realize that these small machines are excellent at what they do, but they cannot do everything. Electrodes for production welding, hardfacing to resist wear, and most specialty electrodes will exceed the capacity of these machines. You must be careful to match the output voltage of your machine with the voltage of the electrode and the appropriate wire diameter and wire feed speeds to make sure you have a compatible system.
Tips for All
1) It is very important to get a good, solid work connection. This means you should thoroughly clean or grind the surface of the metal where attaching the work clamp and use a tightly attached work clamp so electricity can easily flow through the workpiece and back to the welder. Paint and rust are insulators. Remove them. This is a very common mistake to overlook.
2) Put the welder on a separate circuit breaker that is properly fused as stated in your Operators Manual. This is not another strand of Christmas lights. You are melting steel at around 5,000 degrees F. You cannot weld with inadequate input power. Don't even try.
3) Good fitup is a big plus. Weld joints are laps, fillets and butts. Avoid gaps whenever possible to minimize burnthrough problems. This is especially critical on thin sheet metal.
4) Keep the gun cable as straight as possible for smooth wire feeding. Don't sharply bend it.
5) Make sure the contact tip looks good(not elongated or melted) and it is tightened to the diffuser.
6) Cut the wire at an angle to a point before starting to weld for better starts.
7) Use correct electrode stickout and maintain it as well as proper welding procedures.
8) Make sure the driverolls feed smoothly with proper tension.
9) Relax and try to hold the gun as steady and smooth as possible.
10) Make sure you observe and follow all welding safety precautions as specified in your Operators Manual. Pay special attention to the potential for electric shock, arc rays that can burn skin and eyes, fire and explosion, and proper ventilation. For more details, consult ANSI Z 49.1.
Happy Welding.

[Hammer Head]

Good deal.. although I use my MIG w/out the gas (it works just as well but creates more 'splatter')

[87wildside]

Yup and that would be FCAW or flux core arc welding as long as the polarity is reversed and you are using the flux core wire. If not that could be why you welds "look like monkey throw up" and they will be weaker.

I figured I would add some things I have found out on my own.

• Watch the puddle

You don't want to watch the ark itself because you won't be watching what you are doing

• Try a different lens

I was having a hard time seeing the puddle and found that lens come in different tints. The one that came with my helmet had a bluish tint and the one I replaced it with is a green tint. My welds got 10 X better in a matter of minutes.

• Go Slow!

The biggest problem most people have when they first start welding is going to fast. I too had this problem and it was hard for me to figure out on my own.

• Welding different gauges together

Set your welder to the thicker gauge and drag the puddle onto the lighter gauge. I recommend practicing on scrap that is the same gauges before you try on the work piece.

• Wire brush

If you start/ stop and restart a weld. Wire brush it before you restart.


I may add to this latter when I think of more.

[Hammer Head]

I've got the polarity switched.. I just don't have pretty welds like you do.. hahaha

[hillbillycd]

Try turning up your wire feed or turn down your power. If it's something your are going to paint or try to keep pretty try using splatter sheild on the areas around the weld to keep them clean. It's easy to wipe off the splatter with a rag or hand wire brush. Practice is the best thing thou.

[boxcarracer963]

what is the best type of welding to start out with?

[87wildside]

IMO Mig or Flux core. Most Mig welders can be converted back and forth to Flux / Mig. Mig welding is more for thin work (body work) and Flux core is for heavier gauge. Post #4 of this thread goes into more detail.