Asking questions about MIG/MMA heat input, penetration etc.

So I do not clutter up someone else’s thread with my innate questions about why MIG, why Stick etc. I thought best to add this post. Post in question is the one on multipass MIG welding getting towards MMA at the end. vif better on that thread then mods please move and/or edit.
We all try at times to weld metal together a lot thinker then we should be doing and I some times need to understand a bit more of the science to things, just my brain, so here goes.

As per the thread welding two bits of 10mm plate together fillet joint, choice either MIG or MMA.

Am I correct in presuming that with MIG one tries to go for root penetration for strength and in MMA one tries to go for Fillet size?

So why not go for Fillet size with MIG rather then penetration.

As I read it, current density is a factor and for say a constant 125 Amps, the electrode size will effect this. 0.8 MIG wire has a cross section area of 0.502mm2 so will have a current density 249 Amps per square mm.

A 3.2 rod has a csa of 8.8mm2 so would have a current density of 14.2 Amps per square mm

From my reading and trying to understand it all the heat input from a multi-purpose machine would be the same as the formula for ARC Energy is 60VI/v

VI is Volts x Amps
v is travel speed in inches or mm (depending on preference)
Heat input is down to efficiency and is 0.8 for MMA/TIG/MIG compared to sub merged arc at 1.
All from TWI web site.
So heat input is the same in both camps.

But trying to understand the figures would suggest that when joining thicker metals together multi-pass MIG could provide more fusion depth and still build up to the same fillet size then MMA with a 3.2mm rod at 125 Amps.

But the general consensus is the other way, why, what have I missed in my thinking?

Probably as clear as mud.

Adrian Penetration depth, fusion level and fillet size are all just as important with any of the 3 arc generated processes. We select our process based on its pros and suitability to the application. Eg. 1.5 mm stainless but joint. All 3 of those processes will do it. But Tig is the most suitable because cap height and penetration levels need to be kept under good control. 10mm filet. Tig would be my last choice even with high power it's gonna take ages and lots of localised heat. So that leaves me with a 250-300 amp mig or 120amp 3.2 mma. Mma runs high OCV some times as much as 100 volts which is why you can really burn off that thick rod at lower amperages and gain good fusion levels. Mig OCV is adjustable but usually 15-30 volts. So a lot more current is needed if it's to compete with mma on fusion/penetration depth. Fillet size is relevent to travel speed and number of runs this is the same in mig/mma. Increasing a fillet size by weaving or going sloooow will cause low mechanical toughness/strength.
Increasing the size of a fillet by multi passing adds strength not only because of the extra reinforcement but adding more runs refines the grain in the microstructure. (If done properly and heat in monitored). Both mma/mig are capable of welding 10mm fillets. Difference is only one of them will do it (properly) off a 13amp plug. I can appreciate the Open circuit volts is higher on MMA then MIG, but depending on machine the voltage when welding with MMA is more likely to be around 30 ~ 35 Volts The MMA machine being constant current. Higher voltages on start-up helping arc starting etc.

MIG being more of constant voltage so current is more dependent on wire feed.

Yes my questions do come from limited welders, my R-Tech i-180 will do MMA and MIG but can only supply the same energy to either at fill tilt. Will do 180 Amps MIG at around 28 Volts, but 150 Amps MMA at a slightly higher voltage around the 33 Vollts welding.

Both have a higher OCV volts typically 75 Volts for MMA and dropping to around 45 Volts on MIG.

Anyway I need to practice my Stick.

Adrian Ok let's say it like it is and cut the tecnobabble
You can easy put in a bad mig on such a joint that looks basically ok
If you put a 3.2 stick into it and it looks good it generally is good
A good welder with the right size plant could sort it either way with it being 10mm
If I had doubt in the mig plant I should stick weld it over mig
Reason is 12mm is as thick as you can go on single phase on such a joint
The safest recommendation is don't do nothing your not confident in if safety is involved
But why not do some test pieces to settle your mind No you don't get what I am asking, and it is not to be given bull with this is how it is done, but for someone to give me reasons I can understand and not comments as above by saying it is easy to but in a bad mig and if it looks good with stick it will be.

I wish to know why one technically picks MMA over MIG, for what actual reasons. Because when I look into it on the technical sites and from my limited understanding of it, the heat inputs for the same size of throat on fillet weld will be virtually the same for both processes.

Lincoln website technical pages have statements like this

"One main welding variable that has virtually no effect on weld penetration is arc voltage. While changes in arc voltage can result in minimal changes in weld penetration, the effect is very minor compared to welding current and the other variables just listed in this article. Arc voltage affects the arc length." and
"Ironically, many welders mistakenly think that arc voltage is the main variable which affects the level of weld penetration. Voltage is often improperly referred to as “heat”, where welders turn up the voltage or "heat" for perceived more penetration and turn down the voltage or “heat” for perceived less penetration."

The other factors being: Polarity, arc angle, travel speed, electrode diameter and shielding from my understanding.

So I read and get that 0.8 MIG wire at a set current should provide more fusion depth or penetration then stick due to diameter for any particular current, things like angle and arc speed being similar, both can have the same polarity.

But I could, and probably am missing something fundamental and that is what I am asking.

Yes if I get a chance and a decent press I will try 10mm steel with MMA at X amps and Y Volts and MIG at the same heat input and see if I can split them and what different pressures it takes for the same CSA test pieces.

Adrian Adrian your question has been answered.
But really when someone selects a process it's simply selected through practicality of the job in hand.
It's a fact mma will penetrate deeper than mig amp for amp.
It's also a fact that mig is twice as fast (roughly) than mma .
Tig can autogenously weld Stanley blades together.
Mma can be taken anywhere with a box of rods.
Mig requires the lowest form of skill.
These are the reasons with many more as to why a process is selected.
I don't see how Lincolns blur on arc voltage has anything to do with your question perhaps I'm missing something there.
If this isn't the answer your looking for then I for one can't help. Hi Richard;

I appreciate what you say and I am not saying you or anyone is wrong, I am not disagreeing with any of your statements you have listed there, but I guess I want to see and be able to understand the physics behind each of them rather then just take it as read.

The voltages bit came from your statement

Mma runs high OCV some times as much as 100 volts which is why you can really burn off that thick rod at lower amperages and gain good fusion levels. Mig OCV is adjustable but usually 15-30 volts. So a lot more current is needed if it's to compete with mma on fusion/penetration depth.

So I went off and searched the web looking at Welding penetration and found a Lincoln Page on the Variables that affect weld penetration. The thing I took from that was current. Now again I could be reading or getting points mixed up with reading to much, or about different processes.

http://www.lincolnelectric.com/en-gb/support/process-and-theory/Pages/welding-fundamentals.asp

I will be at college on Thursday and will ask if they have some papers on the theory behind the different welding techniques. Or can recommend something I can read (with pictures).

I know that no amount of theory will help in welding skills or laying good welds. But the reading and understanding keeps my mind active.

Adrian

Hi Richard;

I appreciate what you say and I am not saying you or anyone is wrong, I am not disagreeing with any of your statements you have listed there, but I guess I want to see and be able to understand the physics behind each of them rather then just take it as read.

The voltages bit came from your statement


So I went off and searched the web looking at Welding penetration and found a Lincoln Page on the Variables that affect weld penetration. The thing I took from that was current. Now again I could be reading or getting points mixed up with reading to much, or about different processes.

http://www.lincolnelectric.com/en-gb/support/process-and-theory/Pages/welding-fundamentals.asp

I will be at college on Thursday and will ask if they have some papers on the theory behind the different welding techniques. Or can recommend something I can read (with pictures).

I know that no amount of theory will help in welding skills or laying good welds. But the reading and understanding keeps my mind active.

Adrian

Under stand the physics behind mma/GMAW?????????? It's all here and in tutorials.

Personally I'd say you've got that information between both threads. If your looking for a metallurgical point of view this could be a bit of a As there are so many consumables , fluxes, gases etc you would be better off been specific about a consumable/flux/gas etc and better off asking AL/Hotrodder.

If your going to college to learn welding. Why not just concentrate on the actual process rather than swamp your self with metallurgy . Adrian,
It might well be how you think and understand things but I promise you find the best 12 welders in Lancashire and ask the question and they will look blankly at you then turn to each other and say " what the heck is this guy saying? " or words to that effect the actual words will be different and less suited for written form on a forum
If you find one who can answer it all to your satisfaction ask him to run a bead and see what you get. Thinking too much about what your doing is realy counter productive it's like working out velocity of a clay target angle speed of shot etc you will miss every time
Just look hard at it. Move mount shoot. Reaction over interaction
Of course I am sure you could look this up and work it all out just like you can the clay pigeon but you will likely miss
Running a critical weld most will spend a bit more time setting up run a test piece and test it
Until fairly recently nobody actually knew more than that switch there the other there and wire about here as readout was not so good and we didn't have computers that did more than play pong and crash out a lot

Adrian,
It might well be how you think and understand things but I promise you find the best 12 welders in Lancashire and ask the question and they will look blankly at you then turn to each other and say " what the heck is this guy saying? " or words to that effect the actual words will be different and less suited for written form on a forum
If you find one who can answer it all to your satisfaction ask him to run a bead and see what you get. Thinking too much about what your doing is realy counter productive it's like working out velocity of a clay target angle speed of shot etc you will miss every time
Just look hard at it. Move mount shoot. Reaction over interaction
Of course I am sure you could look this up and work it all out just like you can the clay pigeon but you will likely miss
Running a critical weld most will spend a bit more time setting up run a test piece and test it
Until fairly recently nobody actually knew more than that switch there the other there and wire about here as readout was not so good and we didn't have computers that did more than play pong and crash out a lot

Are you suggesting people who can weld don't understand the therory behind it and people who have spent time learning about it can't weld to a standard? Bold statement I must say if I've got that right. I see nothing wrong or negative in trying to learn more about the process. So long as it's controlled learning. The negative can have effect by trying to take in too much too quick and nothing actually sinks in. especially if it's a complex involved subject like metallurgy. Gaining info off this forum from guys like AL isn't going to hurt. You'll either understand it or you won't. I'm not that clued up on metallurgy and yet I'm as interested in the subject as the op. I certainly wouldn't think for a second clever people in the field are useless with a torch. There are people on here that so prove that theory wrong. I have met plenty who can repeate what they have read or been told years back but when you haven't got a remote and calling out to your mate for an adjustment what do you say. That's the point I am trying to make

Guys above thier mid forties finished thier time before sets had reasonable read out of performance so how exactly do you expect them to think in such terms as first recourse
It's always going to be " give me s tad more wire" or knock the Dail down a midges " etc

What you see feel and hear. If it was any different you could just issue a booklet but as already stated speed of travel. Length of arc angle of dangle are so much more relivent
Perhaps a little exaggeration to make the point clear and you can't learn this from a book or chart No your right there Kent there is no substitute for hands on experience but all these things play a part and there is a lot more to it. For example knowledgable guys that qualify as "true" welding engineers design complex structures calculated in such a way to eliminate stress points. They also design the wps's which will (if followed) create welds more suitable/stronger than twiddling knobs and going by sound. If a weld fails the welding inspector will say why it's failed the metallurgist can design/improve consumables to suit. I understand your an old school fabricator and you know your stuff as you've done it long enough. You can set your machine up and lash out strong welds. Guess what I can too. I am not a qualified metallurgist or a welding engineer. But I would like to say I could be one or the other One day as I'm on the right tracks, in the right job and have got a few things already under my belt that get me on that ladder. When ever a post comes up about a guy wanting codings/quals you don't seem that keen to agree with it but things have changed since the 80's and to be taken seriously these are the things that we need to approach. OK not been around today, visit to Huddersfield then looking at Kitchen tiles etc.

But look chaps, I am not trying to start an argument on here, I know full well that there is one thing to understand the physics/maths/theory behind the welding and another to just know how to do a good weld one comes with study, and one comes with practice and following guidance given by others.

I spent a few years at University in Electronics and a life time in repairing things and designing radio systems, I learnt how a transistor works, not at the atomic level but understanding valence bands, doping to give extra electrons etc. I can and have designed circuits from my general understanding, the spec sheets of devices etc.

So all I am trying to do is understand some of the theory behind welded joints, I have not found that in the tutorials on here but what I have found is the techniques to weld.

All down to the post on someone asking could one use MIG multiple runs and being told to use MMA. When I looked up things on the internet, I got contradicting statements to what has been mentioned, but I would like to understand it all in context.

I started a simple worksheet for myself, say a fillet weld, throat size and length of weld, I will start working out how much wire is needed and how much of a particular MMA rod is needed, I will move on to current densities, heat input and time to lay the weld, (if I can find deposition rate stuff), and hopefully get a bit more of the understanding, and I will be happy, so lets not start any arguments, I will get to satisfy my mind eventually and I will continue to practice the welds as described to me by others when I can.

Adrian Hi ad. I don't think you would of found contradicting info on the net had the full facts been known.
The question was related around a 150 amp mig or mma for 10mm section.
Anyone suggesting the a hobby mig with as many runs as you like and as much prep work as needed is going to perform that joint as strong as 1 run either side with mma is incorrect. Regarding the two processes (providing the units are up to the job) BOTH will happily weld it nice and strong. As mentioned lots of times now you will need a mig with a minimum of 250 amps behind it to gain the fusion levels required to make it strong. If (which was the case) 10mm joint needed welding strong to cope with load and it needed doing with a 13amp plug then mma is the only suitable process.

MMA welding might seem complex at first, but it's one of the most straightforward welding methods you can learn. 

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This technique utilizes a coated electrode and an electric arc to join metals together, making it ideal for both workshop projects and field repairs.

MMA welding, also known as Manual Metal Arc welding, Shielded Metal Arc Welding (SMAW), or stick welding, is a versatile process that works well in challenging conditions where other welding methods fail.

This guide walks you through the essential equipment you need, key techniques to master, and how MMA welding compares to other methods so you can decide if it's right for your projects.

What Is MMA Welding?

MMA welding, also known as stick welding, stands for Manual Metal Arc welding. It’s a welding process where the welder uses a coated metal rod (called an electrode) to create the weld. 

The electrode melts and forms the weld joint while also producing a gas shield and slag to protect the weld from contaminants. 

MMA welding is widely used because it’s versatile, works outdoors, and doesn’t require shielding gas from a tank. It’s popular for construction, repair jobs, and fabrication because it can handle rusty or dirty metals and is relatively simple to set up.

Also Read: Tungsten Electrode Color Chart Guide for Welders

How MMA Welding Works?

Manual Metal Arc welding creates welds through a simple but effective process. You strike an electric arc between a flux-coated electrode and your base metal.

The intense heat from the arc melts both materials. This creates a pool of molten metal that forms your weld joint.

Key components work together during welding:

• Electric arc - Provides heat to melt metal (reaches over 6,000°F)
• Flux coating - Protects the weld from air contamination
• Electrode core - Becomes filler metal for the joint 
• Slag layer - Forms on top to shield the cooling weld

The flux coating does two critical jobs. It creates a gas shield around the weld pool to prevent contamination. It also forms slag that covers the cooling weld.

You must replace electrodes regularly since they get consumed. The electrode melts and becomes part of your finished weld. This makes stick welding different from other welding methods.

SMAW is compatible with various metals, including mild steel, stainless steel, and cast iron. The process gives you good control over weld quality and penetration.

Essential MMA Welding Equipment

MMA welding requires specific equipment to create strong, reliable welds. The welding machine provides steady current control, different electrode types suit various applications, and proper polarity settings ensure optimal performance.

Welding Machine and Power Sources

You need a constant current welding machine for MMA welding. This type of machine maintains a stable current even when the arc length changes during welding.

Most MMA machines provide a welding current ranging from 50 to 350 amperes. The amperage you choose depends on the size and material thickness of your electrode.

A good rule of thumb is approximately 40 amps per millimeter of electrode diameter. For example, a 3.2 mm electrode typically requires around 130 amps.

Modern inverter welding machines are lightweight and portable. They offer better arc control than older transformer models.

Your welding machine connects to welding cables that carry current to the electrode holder and work clamp. High-quality cables minimize voltage drop and enhance performance.

The amperage setting on your machine must match the specifications of your electrodes. Too low creates poor penetration. Too high burns through thin metal.

Best MMA Welding Machine You May Also Like

 Types of Electrodes (Flux Coatings)

Different flux coatings on electrodes create different welding characteristics. Each type works best for specific jobs and positions.

• Rutile electrodes are the easiest to use. They start easily, produce low spatter, and work well for general welding tasks. These electrodes suit beginners and everyday repairs.
• Basic electrodes contain low hydrogen and create deeper penetration. Use these for critical joints that need high strength. They require dry storage and proper welding helmet protection due to intense arc.
• Cellulosic electrodes burn off quickly and work well for vertical and overhead positions. However, they produce higher hydrogen levels than basic types.

Iron powder electrodes increase metal deposition rates. They help you weld faster on thick materials and production work.

Store electrodes in dry conditions. Moisture creates porosity and weak welds.

Read More: Welding Rod Types Explained: How To Choose the Right One

Electrode Polarity and Settings

Your welding machine can run on AC or DC current. The polarity affects heat distribution and penetration depth.

• DC Electrode Positive (DCEP) puts more heat in the base metal. This creates deeper penetration and works well with most electrode types.
• DC Electrode Negative (DCEN) concentrates heat at the electrode tip. Use this for thin materials or when you need less penetration.
• AC current alternates between positive and negative. It provides balanced heat and works well for general welding tasks.

Check your electrode packaging for recommended polarity settings. Using wrong polarity creates poor arc characteristics and weak welds.

Match your current type to the electrode specifications for best results.

Advantages & Disadvantages of MMA Welding

MMA welding offers excellent portability and works on many metals, but it requires more time and skill than other welding methods. The process creates slag that needs removal after each weld.

Advantages 

1. Highly Portable Equipment: You don't need gas tanks or complex setups with MMA welding. This makes it ideal for outdoor work or remote locations where other welding methods are not feasible.

2. Works on Many Metal Types MMA welding handles a wide range of metals effectively. You can weld: 

• Cast iron
• Stainless steel
• Carbon steel
• Mild steel

3. Low Cost and Simple Setup The equipment costs much less than MIG or TIG welding machines. You only need a power source and electrodes to get started.

4. No External Shielding Gas Required. The electrode coating provides all the protection your weld needs. This saves money and eliminates the hassle of gas bottles.

Limitations

1. Slow Welding Speed: MMA welding takes more time than other methods. You must stop frequently to change electrodes, which slows down your work.

2. Slag Removal Required. Every weld creates a slag layer that must be chipped off and cleaned. This adds extra steps to your welding process and takes more time.

3. Heavy Skill Dependence: Your welding quality depends heavily on your technique. Poor skills can cause:

• Porosity in the weld
• Poor fusion between metals
• Weak joint strength

Limited to Thicker Materials, MMA welding works best on materials thicker than 1/8 inch. Thin materials often burn through or warp easily.

Where Is MMA Welding Used? Common Applications

MMA welding is ideal for heavy-duty jobs and outdoor work, where other methods often struggle. It handles thick metals well and works effectively on various types of steel and iron.

Industries & Situations

You'll find MMA welding used most in construction work. Bridge building, pipeline work, and building frames rely on this method. The equipment is easy to move around job sites.

Maintenance and repair shops utilize MMA welding on a daily basis. You can fix broken machinery, cracked equipment, and worn parts. It works well when you need to weld in tight spaces.

Heavy steel work is where MMA really shines. Shipyards, steel mills, and fabrication shops depend on it. You can weld thick steel plates and heavy structures.

MMA welding handles tough conditions better than other methods:

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• Works in windy weather
• No need for gas bottles outdoors
• Functions in rain or high humidity
• Suitable for dirty or rusty materials

Farm equipment repair often uses MMA welding. You can fix tractors, plows, and other machinery right in the field.

Suitable Metals and Material Thickness

MMA welding works best on iron and steel materials. You'll get the strongest welds on mild steel, carbon steel, and low-alloy steels. These are the most common metals for this process.

You can also weld other metals with MMA:

• Stainless steel (needs special electrodes)
• Cast iron (requires pre-heating)
• Nickel alloys (for high-temperature work)

Material thickness matters a lot with MMA welding. It works best on metals thicker than 1.5mm. Thin sheets often burn through or warp.

For thick materials, you can make multiple passes to achieve the desired result. Each pass adds more metal and strength. Steel plates up to several inches thick are possible with the right technique.

The thicker the metal, the higher the amperage you need. Your electrode size must match the thickness, too.

MMA Welding Techniques & Tips

Getting the right technique takes practice. Keep a steady arc length of about 1/8 inch from your electrode to the metal.

Use a 20-degree drag angle when welding flat surfaces. This means tilting your electrode slightly in the direction of your movement.

Essential Setup Tips:

• Clean your metal surface before starting
• Choose the right electrode for your material type 
• Set the proper amperage based on the electrode size
• Ensure a good ground connection

Move at a steady speed across your weld joint. Too fast creates a weak weld. Too slow burns through the metal.

Keep your hand steady and maintain consistent movement. Practice drawing straight lines on scrap metal first.

Common Problems to Avoid:

• Long arcs that cause porosity and weak welds
•  Wrong electrode choice for your base metal
• Dirty or rusty surfaces that create poor bonds
• Inconsistent travel speed

Watch your puddle as you weld. It should be smooth and even. If it's too wide, you're moving too slowly or using too much heat.

Strike your arc like lighting a match. Quickly touch the electrode to the metal and pull back slightly. This starts the arc without sticking.

Practice different positions once you master flat welding. Vertical and overhead welding need different angles and techniques.

Control your heat input by adjusting amperage. Thicker metal needs more heat. Thinner metal needs less to avoid burn-through.

MMA Welding vs. Other Welding Methods

MMA welding differs from other popular welding methods in several key ways. Understanding these differences helps you choose the right technique for your project.

Gas Requirements

• MMA welding needs no shielding gas, making it simpler to set up
• MIG and TIG welding require gas bottles, which adds cost and complexity
• This makes MMA welding better for outdoor work where wind can blow gas away.

Ease of Learning 

• MMA welding sits between MIG and TIG in difficulty
• MIG welding is the easiest method for beginners to learn
• TIG welding requires the most skill and practice to master.

Equipment Costs MMA welding equipment costs less than other welding types. The basic setup is simple and portable. MIG and TIG welders need more expensive machines and accessories.

Best Applications MMA works well on thick metals and outdoor projects. MIG welding excels at thin materials and fast production work. TIG welding produces the cleanest, most precise welds but takes longer.

Versatility You can use MMA welding in more locations than gas-dependent methods. It handles rough conditions better than MIG or TIG welding.

Final Thoughts

MMA welding stands out as one of the most reliable and versatile welding methods available today. You can use it on various metals and work in challenging conditions where other methods might fail.

The equipment is portable and simple to set up. This makes it perfect for fieldwork, repairs, and outdoor projects where mobility matters.

Key advantages you get with MMA welding:

• Works on thick and thin materials
• Handles windy and dirty conditions well
• Equipment costs less than other welding methods
• No need for shielding gas
• Can weld in any position

You will need to practice to get good results. The technique takes time to master, but the skills you learn will serve you for years.

Consider MMA welding when you need:

• Strong, durable welds
• Work in outdoor environments
• A budget-friendly welding solution
• Equipment that travels easily

The slag removal step adds extra work compared to other methods. However, this small trade-off is worth it for the strength and reliability you get.

Whether you're a beginner or experienced welder, MMA welding gives you a solid foundation. The skills transfer well to other welding processes too.

Your choice of electrodes will determine the quality of your welds. Take time to learn which rods work best for different materials and situations.

FAQs: MMA Welding

MMA welding raises numerous practical questions regarding equipment compatibility, material limitations, and common issues. These answers address the most pressing concerns welders encounter when utilizing this versatile process.

Is MMA welding the same as stick welding?

Yes, MMA welding is the same as stick welding. Both terms describe the exact same welding process. MMA stands for Manual Metal Arc welding. Some people also call it SMAW, which means Shielded Metal Arc Welding. The process uses a flux-coated electrode that looks like a stick. This is why most people call it stick welding.

Can MMA welding be used for aluminum?

You can weld aluminum with MMA welding, but it's not the best choice. The process works much better on steel and iron. Aluminum creates challenges because it conducts heat quickly. It also forms an oxide layer that makes welding harder. TIG welding works much better for aluminum projects. MIG welding is also a better option than MMA for this metal.

What's the best MMA welding machine for beginners?

Look for an inverter-type MMA welder with both AC and DC output. This gives you more flexibility with different electrodes. Choose a machine that can handle and electrodes well. These are the most common types you'll use as a beginner. Pick a welder with good arc stability and hot start features. These help you start your welds more easily.

Make sure it has at least 160 amps of output. This lets you weld thicker materials as your skills improve.

Why does my MMA weld have slag inclusions?

Poor cleaning between passes causes most slag inclusions. You must remove all slag before adding the next weld layer. Fast travel speed can trap slag in your weld. Slow down and let the slag float to the surface properly.

Wrong electrode angles can also cause this problem. Keep your electrode at the right angle for clean slag removal. Low welding current makes slag harder to control. Increase your amperage within the electrode's recommended range.

What are the common weld defects in MMA?

Porosity happens when gas gets trapped in your weld. This comes from wet electrodes or contaminated base metal.

Undercut occurs along the weld edges when the current is too high. It also happens if you move the electrode too fast.

Lack of penetration means your weld didn't go deep enough. Increase your current or slow down your travel speed.

Cracking can occur due to cooling too quickly or using the incorrect electrode. Preheat thick materials to prevent this problem.

Can MMA welding be done underwater?

Yes, you can do MMA welding underwater with special equipment and training. This process is called wet welding. You need waterproof electrode holders and special electrodes designed for underwater use. Regular equipment won't work safely. Only certified commercial divers with welding training should attempt underwater welding. The risks are very high without proper certification. The weld quality underwater is lower than welding in air. Many underwater welds need post-weld heat treatment to improve strength.

For more information, please visit builders warehouse welding machine.