Welding is used in all types of repairs of machinery or molds. It\u2019s cheaper and saves time to weld rather than make a new part or parts from a mold. What may surprise you, however, is that there are different types of welding, depending on your needs.\n\n\n\nWhat is micro welding? Micro welding is an arc welding process done at extremely low amperages, using a high powered microscope. It\u2019s normally done on smaller, delicate components and the technician is essential to making the process complete successfully.\n\n\n\nMicro welding is a state of the art process that is also referred to as precision welding. We\u2019ll go into micro welding in more detail and explain other forms of welding in the paragraphs below.\n\n\n\ncredit to openpr\n\n\n\nWhat Is Micro Welding Used For?\n\n\n\nMicro welding is anything smaller than the traditional welding process, even as small as .0003 inches. It uses tungsten inert gas (TIG) in welding equipment about the size of a pen.\n\n\n\nHere's a cool video demonstrating some of what it can do and what it's used for.\n\n\n\n\nhttps:\/\/youtu.be\/Y1G7BE6usaM\n\n\n\n\nIt\u2019s a tricky operation since often micro welding requires the surrounding area to be unaffected by the heat. Technicians use powerful microscopes to see the tiny arc and to obtain the precision they need. It calls for extreme concentration. The mechanics of it are as follows:\n\n\n\nElectric current is passed through tungsten electrode to grounded work pieces, creating heatArgon or helium gas used to form an arc and shield surrounding area from contaminantsHeat is generated at point of arc gapMolten pool is establishedFiller rod introduced into molten pool\n\n\n\nMicro welding can be used on almost anything, including:\n\n\n\nStainless steelBronzeTungstenCopperTitaniumNickleIron\n\n\n\nBrass and galvanized steel are not great for micro welding. The zinc content can cause welding issues. \n\n\n\nImagine you work in a specialized machine shop and a customized tool has just broken. A great way to fuse that back together is micro welding. This is a real advantage over having to remake a piece and only one of the many uses for micro welding.\n\n\n\nEngineers use dies, which are specialized tools to cut or shape other material. Some of these are small and intricate, so when they are damaged, micro welding is one way to salvage the die, preventing serious downtime in any industry. It takes far less time to micro weld and repair a customized tool than it does to produce an entirely new tool.\n\n\n\nFor batteries, you can weld tabs to terminals. For automotive, you can weld PCB tabs together. The list of items you can micro weld is almost endless. Basically, if it\u2019s metal (except for aluminum) you can micro weld it. \n\n\n\nWhat Is Pulsed Micro TIG Welding?\n\n\n\nMicro welding evolved from traditional TIG welding, with the difference being that micro welding uses extremely low amps, usually less than 10. One type of micro TIG welding is pulsed TIG welding. The current can run up to 300 amps but is generally much lower than that. Pulse durations generally last up to 4 seconds and have a plasma discharge. Pulse welding features a power supply with a non-consumable electrode.\n\n\n\nPulse welding is generally an edge welding process. As the tungsten electrode is withdrawn from the weld surface, the melting process starts from the outside and penetrates inwardly. Pulse welding can be used to add additional material, like fill wire, or you can melt and fuse parts together without the need for fill wire.\n\n\n\nMicro TIG welding is especially good for these industries:\n\n\n\nAutomotiveMedicalElectronics\n\n\n\nPulsed arc welding or micro welding has these advantages:\n\n\n\nSolder-free processHighly durable weldCan join high melting point metals or dissimilar metals\n\n\n\nMicro TIG welding hasn\u2019t been around that long. It was only invented a little over 50 years ago.\n\n\n\nWhat Is Fine Spot Micro Resistance Welding?\n\n\n\nResistance welding joins two metals together. It generates friction heat when force is applied and uses that heat for welding. In resistance welding, a welding head holds the metal between a positive and negative electrode and applies pressure. A welding power supply applies electric current to the metal to be welded. The current melts the metal after pressure has been applied.\n\n\n\nFine spot welding does not need specialized technicians to run the process. Spot welders can also be relatively inexpensive, and you can get a DIY kit from several companies, including this one from Causin (check it here on Amazon). Of course, fully prepared spot welding kits can be much more expensive, costing upwards of $200.\n\n\n\nSpot welding is performed at a very low voltage with a very high current. The pulse timing is critical, and a perfect weld is timed down to the millisecond. It is the most widely used resistance welding method. The main reason for spot welding is to join two or more light gauge overlapping metal sheets.\n\n\n\nThe technique for resistance spot welding is as follows:\n\n\n\nClean the metal sheets you want to weld togetherMake sure the electrodes are also cleanUse two copper electrodes at the same time for clamping the metal sheets togetherLet the current pass through the electrodes into the metal sheetsThe generated heat will melt the metal sheets at the desired spot\n\n\n\nThis process works so well because the copper is an excellent conductor of heat while the metal is not. Because of this, the heat remains in one spot where the copper electrodes are touching and does not spread across the metal. The metal is melted at the correct spot and the joint between the sheets is formed.\n\n\n\nThe advantages of resistance spot welding are numerous:\n\n\n\nLow costDoesn\u2019t need highly skilled workerWarping of parts is eliminated (It does leave some indentation)Joint is highly uniformCan be done by automatic or semi-automatic operationMultiple pieces can be done in quick succession\n\n\n\nSome disadvantages of this process are listed below:\n\n\n\nEquipment can be costly unless you make it yourselfSome metals need special surface preparationThick jobs are not easy to weld\n\n\n\nSpot welding can be used for attaching braces or pads and can have a multitude of other uses. It is most commonly used in the automotive and aviation industries.\n\n\n\nWhat Is Thermocompression Micro Welding?\n\n\n\nThermocompression welding, or bonding, creates a solid body diffusion between two objects, rather than a melting at the contact points. It requires a lot of force at a very high temperature to create a metallurgical bond between two surfaces. One of the most common bondings of this type is gold to aluminum.\n\n\n\nThermocompression welding requires a specially designed electrode to provide a high degree of precision to the welding zone. This is more precise than any other micro welding technique. The electrode bonds in such a way that the two halves to be welded can remain isolated. It allows for fine control welding and prevents damage to electrically sensitive components.\n\n\n\nUnlike other types of welding processes, thermocompression welding creates no liquid phase. Instead, it relies on high temperatures and a long bond time of one to several hours. Temperatures for the bonding process should reach higher than 572F. The material to be bonded must be clean and must contain no scratches or particles that could cause air gaps.\n\n\n\nThermocompression welding is used most often between a bonding wire and a substrate metallization. The required heat is applied either by a heated capillary or by mounting the substrate on a heated stage. Most processes use some of both.\n\n\n\nMetal to metal thermocompression welding provides some advantages:\n\n\n\nEnables hermitic sealEnables mechanical supportEnables electrical contactNo risk of structural degradationNo risk of electrical shortOffers good connection when soldering or welding is not possibleLow heat inputNo melting\n\n\n\nHigher temperatures and pressure can lead to higher toughness bonds. Thermocompression welding is a good process if you\u2019re not using two very small materials. Where micro welding is used for precision jobs, thermocompression welding is used more for bonding larger items, such as metal sheets, together.\n\n\n\nWhat Is Laser Welding?\n\n\n\nimage courtesy of researchgate.net\n\n\n\nWhile micro welding uses electric current to generate heat, laser welding uses light energy to rapidly heat the weld zone. Laser welding melts the filler rod along with the adjacent point of metal joining. The light energy intensity is controlled by:\n\n\n\nBeam sizeVoltagePulse widthSingularity\n\n\n\nNo current flows through the welding zone and there are no electrical connections to the weld. With micro welding and resistance welding, heat is generated in the work piece by electrical current flow. With laser welding, there\u2019s simply a laser beam being used to melt the filler rod and base material. Microscopic magnification is used in both processes.\n\n\n\nLaser welding requires a straight line of sight between the laser beam and the weld zone. If you don\u2019t have a straight line of sight, the weld will not work efficiently. Laser welding is most often used in automated welding procedures.\n\n\n\nHeat in laser welding is highly focused and does not affect the surrounding weld area. You can even complete the weld while holding the metal in a bare hand. This means even heat sensitive areas can be laser welded with little chance of damage.\n\n\n\nLaser welding is used frequently in the automotive industry, in an automated fashion, to weld automotive parts together. However, it\u2019s also used in jewelry and medical industries to put together metals on a more micro level.\n\n\n\nLasers are becoming the go-to welding method for many of these industries for the following reasons:\n\n\n\nPrecision - this method offers a high level of control and accuracyCan create complicated joins - You can weld dissimilar materials and hard to reach areasLow heat application - Low heat minimizes component distortion as it results in less thermal strain being placed on the parts\n\n\n\nLaser welding is relatively low cost and creates strong and reliable welds, allowing businesses to increase efficiency while keeping costs to a minimum.\n\n\n\nMicro TIG Welding Versus Laser Welding\n\n\n\nBoth micro pulse welding and laser welding produce very strong welds. However, the way the welds are approached is quite different. Laser welding uses a light beam, while micro welding uses an electric current and an arc to fuse metals together. While laser welding can control both spot size and amount of energy that is discharged, micro TIG welding can only control the amount of energy. This means laser welding can give you a smaller weld spot size.\n\n\n\nHere are the advantages of micro TIG welding:\n\n\n\nAllows deeper penetration, especially on silver. Laser welding is not great on silverWill only weld conductive materials - this is good when other materials are close to the weld areaCan control energy to lower levels\n\n\n\nThe advantages of laser welding are:\n\n\n\nCan be used to smooth out and polish areas that have been welded togetherDoes not require a grounding clipCan control weld spot size\n\n\n\nChoosing between the two welding methods depends on the materials you are using, and the weld spot.\n\n\n\nDifference Between Brazing, Soldering, And Welding\n\n\n\nWelding is the art of joining two pieces of metal together. So is brazing. So is soldering. But what is the difference between these three processes and when should you choose one over the other?\n\n\n\nBrazing - Brazing involves the use of a filler metal to create a bond. It does not melt the base metals to make a join. It involves temperatures above 800 degrees.Soldering - This method is like brazing but uses a tin and lead alloy filler metal. It melts around 390 degrees.Welding - Uses a gas (often argon or argon\/helium in micro welding) to create an arc and melt metal into a pool, creating a weld. Filler metal is added to the weld to help create a join.\n\n\n\nHere\u2019s when you should use the three methods:\n\n\n\nBrazing - Use to join dissimilar metals using a filler rodSoldering - Use to join electronic partsMicro TIG welding - Use to join similar metals at a very high temperature\n\n\n\nBrazing and soldering do not create as strong of a weld as Micro TIG welding, but they are good for small, delicate parts.\n\n\n\nThe Science Behind Welding\n\n\n\nBefore TIG welding, most welding was done using a high intensity flame. It was messy and sparks could get anywhere. With the advent of TIG welding, an electrical arc creates the heat.\n\n\n\nIn TIG welding, you use a power supply to provide the energy. One lead acts as a \u201cground\u201d and connects to the welding material. The other lead attaches to a handheld gun.\n\n\n\nThe welding gun has a conductive tip Ade out of tungsten. You quickly tap the tungsten tip to the base metal and then withdraw it just a bit to create an arc. An arc is formed when the electrons are ionized as the electricity tries to complete the circuit.\n\n\n\nThese arcs create a large amount of heat and light. The higher you push the amperage, or power supply, the higher the temperature of the arc.\n\n\n\nYou move the arc in a circular motion to create a weld pool of melting metal. As the two metal pieces melt, a fusion takes place, allowing the two metals to become one. Once the melt has started, filler is added separately, lending strength to the weld, and filling in any gaps between the two pieces.\n\n\n\nThe important thing to note is that the two metals being joined need to have a similar melting point. If they don\u2019t, one metal will melt faster than the other metal and could result in a failed weld.\n\n\n\nHere\u2019s an easy to remember guide for Micro TIG welding:\n\n\n\nArc - Creates the heat that fuels the meltMelt - Necessary to create the fusion for the metalsFiller - A metal used to strengthen the joinShield - Arc welding requires a shield. TIG welding uses gases to contain other gases from contaminating the weld poolCool - Some people use water to quench the heat, but it is recommended to let the weld cool down naturallyClean - Clean and smooth the weld, not only for appearance but to allow the coating to bond better\n\n\n\nThe Final Word\n\n\n\nBlacksmiths invented welding by using heat and a hammer to fuse two metals together. In 1800, the electric arc was discovered, but it would be over 80 years before people started using it to join metal. As it was developed in the early 20th century, demand grew higher for this faster and more efficient method, leading to the developments we see in welding today.\n\n\n\nThe pros of arc welding are:\n\n\n\nCreates the strongest bond between two similar metalsCheaper and faster than bolting or rivetingCan be automated in certain instancesStronger than trying to heat and mold two shapesSafety from the strong bond\n\n\n\nBecause of this, manufacturing and many other industries rely on Micro TIG welding for their production line. It creates safe, strong joins and micro welding can be used on the smallest components, and in an environment with other fragile components.\n\n\n\nMicro welding equipment is small, so it\u2019s easy to maneuver. Offering superior control while controlling the heat of the weld gives welders the freedom to weld small pieces that were previously considered to be a loss. This saves money and time for industry. It has also created a new industry in micro welding, with specialized shops cropping up all over the country.\n\n\n\nMicro welding is here to stay, or at least until the next technological breakthrough happens.