Correct maintenance of MIG/MAG welding torches – Basic knowledge and helpful tips

• About the authors                                                       
• Introduction
• Checklist: before starting welding                                        
• Gas nozzle
  • Reasons for gas nozzle wear
  • Main load on the nozzle: weld spatters
  • Anti-spatter agents for pre-treating gas nozzles
  • Careful handling of cleaning tools
  • Avoid misuse of the torch head
  • Cracking or failure of gas nozzles        
• Contact tip
  • Quality characteristics of contact tips
  • Signs of wear and tear in contact tips and their causes
  • Premature replacement of the contact tip     
• Welding torch neck
  • Heavily stressed parts of a torch neck
  • Prevent overheating
  • Never bend a torch neck yourself    
• Cable assembly for MIG/MAG welding torches
  • Cable assembly length
  • Proper storage of a cable assembly
  • Protective hose as additional protection 
  • Coolant maintenance
• Liners
  • Characteristics of different welding wires
  • Characteristics of different liners, wire liners & co.
  • Tips for handling liners 
  • Wire sticking – a problem with many causes
  • Wire feeder connections as an error source
  • Cutting the liner correctly to size
  • Lack of pre-dressage of the wire
  • What you need to know about drive rollers
• Machine side connection & control cables
  • O-rings
  • Electric contact connections
  • Control cables                                                                                                   
• Editorial team

MIG and MAG welding torches are constantly exposed to heat and radiation, attacked by weld spatters and are often misused as hammers, for example. They are required to perform at their best, regardless of whether they are used in a small workshop or in a harsh industrial environment. They are an everyday work tool that you want to be able to rely on, and must, even when “things get hot”. This makes proper maintenance of welding torches even more important, as this can extend their durability and thus their service life. Especially today, where time is more precious than ever before.

This e-book is all about the good care and maintenance of MIG and MAG welding torches and their consumables – from the contact tip and gas nozzle directly at the process to the torch neck and wire feeding, through to the wire feeding rolls in the wire feed unit of the power source.

This e-book is intended to provide users, welding specialists, welding supervisors and production managers with an overview of the proper maintenance and care of MIG/ MAG welding torches, so that production costs can be kept low and quality and output correspondingly high. It shows how good, regular maintenance significantly extends the life of a welding torch, and thus ensure that its performance level is maintained at a constant level.

Please use this e-book as an introduction to the maintenance of MIG/MAG welding torches. Make it easy for yourself to identify problem areas, prevent premature failures and individually adapt the handling of the torches.

The following components are subject to preventive care and maintenance measures and are highlighted in this e-book:

• gas nozzle
• contact tip
• torch neck
• cable assembly
• wire feeding
• machine connection and control cable

If you consult this information and the tips for the preventive care and maintenance of your MIG and MAG welding torches, and implement them, you will certainly enjoy your torches and the welding result for a long time.

Gas nozzles are the wear parts that are closest to the process and thus the most exposed to heat, radiation and mechanical stress. These conditions are only one influencing factor on the service life of a gas nozzle. Another major influencing factor is weld spatters, which are an unavoidable part of the MIG/MAG process. Although they can be reduced by optimising the process parameters – they can never be 100 percent avoided. They can stick or burn on in the gas nozzle and other wear parts, such as contact tip, tip holder and gas diffuser.

The base material of most gas nozzles is copper, or a copper alloy. Gas nozzles made of brass usually have a shorter service life and dissipate heat poorly. Copper is an excellent heat conductor and is easy to process. At the same time, copper is very resistant. If heat is absorbed via the gas nozzle, a copper gas nozzle also dissipates it quickly, which generally increases its service life. If an insulated gas nozzle is used – with a high-temperatureresistant plastic insert – the heat is blocked in the front end and inadmissible heating of the torch neck, the handle and the cable assembly is avoided in this way.

Gas nozzle coatings such as a nickel alloy act as a separating layer to the base material and ensure that weld spatters are not burnt in or adhere so quickly. In addition, a nickel coating reflects light and heat and thus additionally reduces heat absorption from the welding process. The cooler the gas nozzle, the lower the spatter adhesion, because these either do not stick at all or can be easily detached. Coatings also increase the service life of the gas nozzle. Alternatively, or in addition to coating, a release agent can also be applied to reduce spatter adhesion.

In case of short arcs and spray arcs, fine droplets separate when the wire is melted. The materials distributed by short circuit (short arc) and by the action of high currents and without short circuit (spray arc). Please pay particular attention to regular cleaning of the gas nozzle. In the case of spray arcs, a higher heat load of the gas nozzle occurs compared to the short arc, due to the higher currents.

The choice of arc depends on the thickness of the sheet to be welded and the welding speed. Special arcs under these three types of arcs reduce the accumulation of spatters. However, this requires a lot of knowledge, skill and sensitivity for the entire welding process. You can find out more about this in the blog “Cause of weld spatters: MSG welding and arcing”.

The right chemical separating agent

Even with optimal workpiece preparation, the attachment of particles cannot be avoided in the long term. An additional preventive care method is to spray the gas nozzle with an anti-spatter spray or to immerse it in a pasty non-stick agent before welding.

Welders like to use so-called cleaning pliers. These are inserted into the gas nozzle and rotated, thus removing adhering particles mechanically. However, one disadvantage of this method is that the scraping not only removes weld spatters, but also removes the base material of the gas nozzle body piece by piece. The inner wall of the gas nozzle becomes rougher with each use of these pliers, and particles from the welding process adhere even more easily. As a result, the gas nozzle wears out faster. Anti-spatter agents facilitate cleaning and often prevent weld spatters from adhering very tightly, thus requiring the use of pliers and heavy scraping. Instead of pliers, a stainless steel brush can be used, whose soft bristles avoid scratches in the gas nozzle.

Causes that often lead to premature wear of the gas nozzle & first aid tips

1. Poorly adjusted process with high spatter formation.

• Adjust the welding parameters as optimally as possible.

2. Inadequate cleaning and pre-treatment of the workpiece – increased spatter.

• Before welding, always ensure that the workpiece is free of residues or deposits from previous work steps.

3. Coarse tools are used to clean the gas nozzle – damage to the coating. Weld spatters can adhere more easily to scratches.

• To prepare the gas nozzle, use only suitable chemical agents to reduce spatter adhesion. Attached weld spatters are then all the easier to remove.

4. Workpieces are straightened by tapping or hammering with the gas nozzle – deformation of the gas nozzle or even the entire torch neck.

• Avoid misuse of the manual welding torch and its spare parts.

5. Welding torches and gas nozzles that are not designed for this output are used for high currents – the gas nozzle gets too hot.

• Always use a welding torch that is designed for the application.

The following illustration of the cross-section through a torch neck shows where the susceptible parts are located.

Gas nozzle seat

There are welding torches with push-on and versions with screw-on gas nozzles. When push-on gas nozzles are used, it is advisable – especially if the gas nozzle is frequently changed, replaced or twisted – to look at the gas nozzle seat. Signs of wear can occur that make a change of the torch neck necessary. A sure sign that the torch neck needs to be replaced is a gas nozzle that is no longer firmly fixed in place.

Sometimes there is not enough coolant in the cooling unit, so the coolant level must also be checked at regular intervals. From time to time, the coolant should also be replaced due to contamination of the liquid. Particles in the coolant can settle in channels in the torch neck and thus reduce the flow.

Why only coolant, and never water, should ever be used for torch cooling, is explained in detail in chapter »Cable assembly for MIG/MAG welding torches« genau erläutert.

Air cooled welding torches

Temperature damage due to overheating usually occurs with air cooled welding torches when welding is carried out longer with higher parameters than permitted for the torch. The permissible load is usually specified for 35% or 60% duty cycles. The overload becomes visible as a result of above mentioned discoloration of the wear parts. With extreme stress due to heat, discoloration even occurs on the torch neck. For this reason, it is essential to use a welding torch suitable for the task and not to burden it beyond its technical performance limits. In case of doubt, it is better to use the next higher size torch or a suitable liquid cooled welding torch.

Causes that lead to premature wear of the welding torch neck & first aid tips

1. Misuse of the torch neck as a hammer – deformations occur that lead to an undersupply of the welding torch with coolant and, as a result, to overheating. The insulation sleeve can also break.

• Avoid misuse of the torch neck.

2. Loose fitting gas nozzle – the gas nozzle seat may be worn, due to frequent changes of the gas nozzle.

• Change the torch neck.

3. Unauthorised bending of the torch neck – live parts are damaged – greatest risk!

• Ask your torch manufacturer about curved torch necks. There are special torch necks, and even flexible torch necks, for special applications.

4. With liquid cooled torches with exchangeable necks: O-rings at the interfaces between handle and torch neck are too dry and shear off.

• Grease the O-rings when changing the torch necks.

5. Welding torch overheated – there are discolorations on the gas nozzle and/or on the torch neck.

• Use only welding torches suitable for the task. If in doubt, use a welding torch with a higher power specification.
• Reduce the duty cycle.
• With liquid cooled torches, check the cooling circuit for faults.

6. Welding torch overheated – reduced coolant flow. The coolant lines at the machine connection are buckled.

• Check the coolant level and replace dirty coolant. Electro corrosion particles settle and clog the channels. Never use water as a coolant!

7. Welding torch overheated – there is air in the cooling system.

• Before welding, give the coolant enough time to arrive at the very front of the torch neck and flow through the entire system.
• Check the lead time and lag time settings of the welding machine.

The table below shows the characteristics of the most common welding wires:

The wire material itself is an influencing factor on the friction intensity. The degree of purity of the production with possible residues from drawing soap and the like plays a no less important role. If these are brought into the process, this will have an impact on the quality of the weld seam. Contact your wire supplier directly if you repeatedly encounter problems with the degree of purity of the wire.

In order to avoid wire feed problems, the selected liner must match the material surface of the wire. In addition, the liner must be able to withstand the high thermal loads during welding without changing its structure and properties. The right size ratio of welding wire to the diameter of the liner is also an essential point that must be observed. Up to 95 percent of problems with the wire feeder are due to the incorrect diameter of the liner being used.

PTFE plastic liners

This Teflon^® plastic liner is ideal for stainless steel because it has excellent sliding properties. It comes in the colours blue, red or yellow, is heat resistant up to a maximum of 260°C and is also suitable for welding standard stainless steel wires and CuSi wires. When stainless steel wire is welded, it is essential that carbon steel – the abrasion of a wire core – does not get into the weld pool and contaminate the process.

Carbon PTFE plastic liners

This Teflon^® liner has graphite as a bonded lubricant and has very good sliding properties with its carbon content of up to 20%, because the surface is friction minimised. The colour code is grey-black and it is used in manual MIG/MAG welding torches, both air and liquid cooled. Owing to its good sliding properties, this liner feeds aluminum wires and welding wires with special alloys extremely well.

BPL plastic liners

These are regarded as the jokers for welding aluminum wire, wires with special alloys, cored wire and stainless steel wire. This liner, made of plastic with the PTFE fluorine/ compound PPS O2 (semi-crystalline polyphenylene sulphide), with its ceramic additive and a stainless steel inlet tip, provides excellent sliding properties and is often used when problems arise with other liners. It is heat stable up to 260°C and can be used with all air and liquid cooled MIG/MAG manual torches for wire thicknesses up to 1.6 mm. Colour codes are orange and petrol.

PA plastic liner

Its low thermal stability of only up to a maximum of 65°C allows this polyamide liner to be used exclusively as a combined liner – ideally in combination with a brass liner, the length of which should be kept as short as possible in order not to reduce the very good sliding properties of its high surface hardness. A critical thermal load is thus counteracted. This PA liner can be used for all welding wires in air cooled and liquid cooled MIG/MAG welding – even in the CMT^™ (cold metal transfer) process from Fronius^® or comparable processes from other manufacturers.

PA combination plastic liner

With this polyamide plastic liner with a brass liner attachment, the good sliding properties of the PA liner come together with the thermal stability of the brass liner. This plastic core is mainly used in liquid cooled MIG/MAG manual welding torches and is used for steel wires, stainless steel wires and filler wires or as wire feed for the TIG cold wire system.

The length of time that liners can be in use depends on many factors. These start with the choice of the right liner for the welding wire used and go all the way to the drive rollers that transport the wire into the process. In the following you will find out which measures can be taken to prevent premature wear of liners and what may be the cause of and solution for occurring wire feeder problems.

The most common reasons for the premature failure of wire feeder systems are:

• Wire sticking
• Non-deburred edges when cutting
• Incorrect contact pressure of the drive rollers
• Using the wrong wire core
• Wrong size of liner
• Poor wire quality with rough surface or dirt

The standard welding errors undoubtedly include wire sticking. This is caused by the wire burning on inside or at the contact tip and making further wire feeding impossible. Causes and solutions for this can be:

The wire has too much slip in the wire feed and runs irregularly

The pressure rollers must be tightened. With each feed, the pressure of the wire feeding rolls can be easily adjusted.

Too much friction in the wire feeder due to cable assembly being too long

If the cable assembly is very long, the use of a push-pull welding torch helps. The wire is pulled further, and can thus be fed at a uniform speed, with the help of a motor installed in the torch body.

Unnecessarily high frictional resistance due to wrong liner

The characteristics of different liners are explained directly before this subchapter and provide a good help for a correct preselection.

The entire welding torch is insufficiently cooled, the contact tip is thermally overloaded. There can be several causes for this:

• The coolant level is too low and needs to be topped up
• The coolant flow is partially blocked and needs maintenance
• The cable assembly is bent and must be placed more loosely
• The general wear condition of the welding torch is too high, the torch needs maintenance
• The torch is overloaded and a more powerful torch must be used for the welding parameters
• The wrong contact tip was used
• If none of these causes apply, talk to your welding specialist. Other factors can come into question in case of a thermal overload of the contact tip and these must be considered individually.

Each individual part on a MIG welding torch has connection points. The wire feeder is no exception. Any connector through which the welding wire is conveyed represents a potential hazard point.

When changing a torch neck, care must always be taken to ensure that the connectors are attached stably, firmly and without burrs. The main liner, or the liner through the cable assembly, must be connected to the wire liner of the torch neck without hindrance. Check that there is no gap between the main liner and the neck liner.

Each welding wire from a drum or wound onto a spool has a twist or pre-dressage. This winding usually forces the wire to return to the original shape it had in the drum or spool. As a result, the welding wire never runs absolutely straight into the wire feeder and rubs on the inside of the liner. In this case, the smallest grated particles of the wire can get into the wire feeder and clog it. As soon as this happens, the only thing to do is to change the liner.

A straight wire can be inserted most easily and without major friction into a liner and thus also into the contact tip. In order to increase the service life of the liner and also the service life of the contact tip, a wire straightener can be attached to the rear end of the wire feeder before the welding wire enters the actual feeder. These devices are not absolutely necessary, but they can help to avoid premature wear of the liner.

The drive rollers or wire feeding rolls must not be ignored when the liner is being serviced. In order to prevent problems with the wire feed, one thing applies above all to drive rollers: wire feeding rolls and welding consumable material must match in terms of size and type.

Different wires require different drive rollers. As a rule, there are two grooves for different wire diameters on a wire feeding roll. If the diameter of the wire to be welded changes, the wire feeding roll is simply turned in the unit. The grooves are V-shaped (V groove) for steel wire, U-shaped (U-groove) for aluminum wire, or have a so-called perforated U shape for cored wire. There is no one-size-fits-all or at least uniformly standardised specifications for wire feeding rolls. This explains the wide variety of greatly different designs with regard to the material of the rollers, their quality, as well as the diameter and width of the grooves.

If there is any uncertainty as to whether the wire feed is still intact, a mechanical tensile test will help.

This is carried out as follows:

• Loosen or release the wire feeding rolls
• Place welding torches on a level, or only minimally angled if possible
• Pull the wire by hand through the welding torch

The following rule applies here: if the wire cannot be pulled through by hand, both the welding wire and the liners must be checked.

The aim should always be the lowest possible force that is required for pulling through. However, the correct range for an application varies greatly, because several factors play a role, such as different wire types, the length of the welding torch or the diameter of the wire.

Causes that lead to problems with the wire feed and premature wear of the wire liner & first aid tips

1. Uneven wire feed – wire has too much slip.

• Adjust the pressure of the wire feeding rolls.
• Check that wire feeding rolls match the wire installed.

2. Uneven wire feed – incorrect inner diameter of the wire liner.

• Check that the wire liner matches the wire diameter.

3. Uneven wire feed – very high frictional resistance.

• Use only liners that match the wire. To do this, use the table in this chapter.

4. Uneven wire feed – abrasion particles are clogging the liner.

• Clean the liner with compressed air. Use a cleaning fleece.

5. Uneven wire feed – cable assembly is too long.

• Avoid unnecessarily long cable assemblies, which are probably also laid in narrow radii as well.
• Use a torch neck with a lower bending angle to reduce friction.
• Check whether a wire with better quality can be used.
• Use a push-pull welding torch if a long cable assembly is needed in conjunction with a wire that is hard to feed.

6. Uneven wire feed – the wire feeder is not continuous and is not flush with the contact tip.

• Make sure you feel a slight pressure on the liner when screwing in the contact tip.

7. The liner wears out excessively fast – the liner being used does not match the wire.

• Choose the right material for the welding wire or combination material of the liner. To do this, use the table in this chapter.

8. The liner wears out excessively fast – wire has no pre-dressage creates too much friction in the liner.

• Attach a wire straightener at the rear end of the wire feeder.

9. Wire “builds up”, so-called “nest formation” – burr at the end of the wire gets stuck.

• When cutting the wire, always deburr the edges.

10. Wire “builds up”, so-called “nest formation” – incorrect inner diameter of the wire liner.

• Check if the wire liner matches the wire diameter.

11. Wire “builds up”, so-called “nest formation” – the wire feeder is not continuous and is not flush with the contact tip.

• Make sure you feel a slight pressure on the liner when screwing in the contact tip.
• Use a push-pull welding torch if a long cable assembly is needed in conjunction with a hard-to-feed wire.

12. Wire “builds up”, so-called “nest formation” – frictional resistance is too high.

• Abrasion particles are clogging the liner. Clean the liner with compressed air. Use a cleaning fleece.

13. Wire “builds up”, so-called “nest formation” – cable assembly is too long.

• Avoid unnecessarily long cable assemblies, which are probably also laid in narrow radii as well.
• Use a torch neck with a lower bending angle to reduce friction.
• Check if a wire with better quality can be used.
• Use a push-pull welding torch if a long cable assembly is needed in conjunction with a hard-to-feed wire.

We hope that in this e-book you have been able to find a lot of valuable information and tips for the correct handling and maintenance of your MIG/MAG welding torches. If your equipment is properly maintained, nothing stands in the way of productive work, good welding results and enjoyment of your the MIG/MAG welding torches for a long time.

Your suggestions and comments on this e-book are welcome.

The following contributed to the creation of this e-book:

ABICOR BINZEL, Germany

Boris Rinn, Product Manager MIG/MAG Manual Products

Prof. Dr.-Ing. Emil Schubert, Technical Director CTO

Herbert Burbach, Art Director

Carmen Laux, Marketing

Christine Rinn, Marketing

Stefan Schneider, Marketing