Robotic MIG Torch Maintenance Guide

The schedule for conducting maintenance checks is up to the discretion and planning of the individual doing the checks and their supervisor or manager.

Some routine maintenance can occur in between shifts or during breaks such as cleaning off the fixture or changing consumables.  

Other more involved activities like greasing the robot’s joints may occur less frequently and during a longer scheduled downtime. 

The most important action you can take is putting together a plan to maintain the equipment in which you have invested so that it serves you well for many days, weeks, months and years to come. 

Below are the various items to look at to ensure proper maintenance of your robotic welding system.

Tool Center Point Check

Checking the robot TCP (tool center point) and insuring its accuracy is critical to robotic welding performance and results. Follow the robot manufacturer’s instructions for checking and maintaining the TCP. 

Should you find your TCP location is off:

1. Tighten consumables to the manufacturer’s torque specifications. If the manufacturer does not provide torque specifications, the general rule of thumb is one quarter turn past finger tight

• Avoid cross-threading the contact tip, as this will cause the contact tip to be at an angle to the swanneck
   

2. Ensure clutch safety mount is in the home position
    
3. Inspect the clutch safety mount for movement and replace if it‘s worn.
    
4. Create a TCP Check Program in the robot utilizing the pointer on the cleaning station
    
5. Check the TCP once a week or if the welds start to move off seam

• If weld is moving out of seam:

1. Check contact tip for wear/spatter buildup
2. Run check on TCP program to look for a bent swanneck
3. Look for spatter build up on fixture
4. Check part trim edges to make sure part is to print

6. Program the robot so the arm, robotic MIG torch and cable are clear of tooling and the weld cell wall - this prevents worn cables, insulating disc breakage and bent swannecks
    
7. Check your TCP to discover if the swanneck is damaged or bent, and if it is bent:

• Determine type of swanneck. Some manufacturers print or engrave the part number on the neck

1. Manufacturer
2. Amperage
3. Type: air-cooled or water-cooled
4. Degree or angle of bend (180°, 22°, 45°, custom)
5. Length

• Use a swanneck inspection fixture to adjust the tolerance of the neck to the TCP after an impact
• If the swanneck is unable to be properly bent back to original TCP, then procure and install a new swanneck from your spare parts inventory, crib, local welding distributor or the original manufacturer

Torch Cable

The torch cable is the primary carrier of current, shielding gas, and welding wire.

There are two styles of robotic MIG welding torches:

Over the arm torches are routed exterior to the upper arm of a welding robot

Through the arm torches are routed interiorly through a designed hole in the upper arm of the robot

Fraying, tearing and breaking of the internal copper strands is caused by the repetitive twisting, bending and stretching motion of the robot. 

This causes the cable to lose its conductivity and create resistance or heat. 

Some ways to determine if the torch cable is failing:

1. Feel the cable immediately after welding:

• Does the cable feel hotter in one area?
• Is the cable extremely flimsy in one spot?
   

2. See if the torch cable or components shows signs of discoloration (blue, purple, orange, gold)

• Periodically check neck, cable, and power pin connections. Loose connections can cause overheating and premature failure
   

3. Tight bends and loops in the cable should be avoided. With over the arm robotic torches, counterbalances can be attached to or above the robot to help eliminate excessive bends and keep the cable clear of welding fixtures and hot weldments.
    
4. Avoid rough surfaces and sharp edges that can cause tears and nicks in cable jacket which can cause premature failure.
    
5. Periodically check all ground cables and connections.
    
6. Use anti-seize on all threaded connections.
    
7. Ensure your torch cable length is properly sized for the application.  This is especially important with through the arm torches. Excessive slack (more than ~2“) or overly-taught (short) cables will lead to premature failure.

Weld Fixture

Weld spatter, metal shavings and other debris may accumulate on the weld fixture over time resulting from the manufacturing process. 

This buildup of material can negatively impact part fit-up and sometimes prevent a part from seating properly in the fixture prior to clamping and welding. 

There are numerous methods for cleaning the fixture:

1. Compressor air can be used to blow spatter and debris from the fixture

• Ensure proper safety equipment (goggles, ear plus…) are worn
• Be certain no one else is present in the area prior to blowing off debris
   

2. Additional tools may be required to remove spatter if some time has elapsed since the last cleaning.

Troublshooting Matrix

Here is a troubleshooting matrix to assess possible causes of porosity and solutions to evaluate. While shielding gas is one of the more common reasons for porosity, it could be the result of other components within your robotic welding setup, as well.

II. Wire Feeding

A general rule of thumb is:

• V-groove drive rolls for solid wire
• U-groove rolls for aluminum and other soft metals
• Knurled drive rolls for flux core wire

Wire dereeling

It is important to have your wire feeding system set up for success from the moment it leaves the spool, coil, reel or drum. The wire conduit should be straight with as few bends as possible.

Any bends should be gradual. Ensure the conduit is clean by regularly blowing out the build up of wire dust and debris.

The dereeler should be set up with minimal drag, but enough to keep the wire from despooling when welding stops. 

Please take care to keep these containers upright when transporting and moving into place.

1. Select a package that is large enough to minimize wire changeovers, but not so large that the same wire will remain on the shop floor for more than a couple of weeks.
2. Consider the type of filler metal package used. For instance, recyclable filler metal packaging can reduce costs and labor for properly separating and disposing of recyclable and non-recyclable packaging materials. 

Wire Feed Troubleshooting

If your robotic torch is experiencing wire feed issues, apply the steps in this matrix to assess possible causes and test solutions.

IV. Peripherals

Torch cleaning stations, wire cutters, wire straighteners, neck inspection tools, TCP inspection tools anti-spatter fluid applicators/injectors are all additional equipment that can protect the robotic welding system investment, maximize its effectiveness and reduce costs.

This equipment is particularly helpful in minimizing downtime that leads to offline maintenance or repairs of the equipment or its components (e.g., the robotic MIG torch, cables or consumables). Unfortunately, some companies view this equipment as an unnecessary cost and don’t realize that it can play an important role in improving quality and increasing productivity. 

Peripherals require an up-front investment, but the payback period is relatively short and within 12 to 18 months.  

For example, a reamer, also called a nozzle cleaning station or torch cleaning station, minimizes spatter build-up in the nozzle and with it the opportunity for electrical shorting between the contact tip or gas diffuser and the nozzle that could lead to premature failure of the robotic MIG torch or consumables. 

Failure of the torch or the consumable, of course, increases the cost for replacements and requires downtime for changeover — downtime that puts the robot offline and stops it from making parts and making money. 

A clean nozzle also allows for good shielding gas flow, thereby minimizing quality issues that could be costly to repair.

Torch Cleaning Stations

1. Use the reamer/cutter to remove accumulated spatter as needed. Anti-spatter spray can be applied independently between ream cycles.
    
2. Torch Cleaning Station cycles can be “hidden” during table indexing or part loading to minimize downtime.
    
3. Ensure the unit is supplied with the manufacturers recommended air pressure which is typically 87-116 psi (6-8 bar). Air supplied must be clean filtered air while under load to ensure optimal results.
    
4. Ensure the torch is programmed to the proper position. 

Broken Reamer Cutter Blades

1. Be certain the nozzle is concentric to the cutter blade during reaming and the insertion depth on the nozzle goes past the gas holes on the diffuser.
    
2. Apply anti-spatter liquid and/or increase reaming frequency to prevent excessive spatter buildup in the nozzle (which can break cutter blades). 

VI. Wire Liners

Remedy

A good preventive measure you can take is to blow the liner out with compressed air monthly.

Length

When a liner is cut too short, it typically leads to wire feeding problems like bird-nesting. Some manufacturers print markings on the outside of the weld cable to show when the cable is twisted, providing welding operators the opportunity to straighten it fully in order to measure for the correct liner length. Other manufacturers offer liner gauges as a guide.  

Some manufacturers offer optional spring-loaded modules that work in conjunction with a front-loading liner in order to minimize issues if a welding operator cuts the liner to an incorrect length (too short). These modules are housed in the power pin and put forward pressure on the liner after the welding operator installs it from the front of the torch. They allow up to 25 mm of forgiveness if the liner is too short. 

Remedy:

When installing a new liner, be sure it will be compressed after cutting. When installing the gas diffuser and contact tip or rear liner retaining nut, the diffuser or rear retaining nut should compress the liner inside the torch. This will ensure there are no gaps in the liner supporting the welding wire and avoid potential wire bird-nesting.

Type

Wire liners come in a wide variety of sizes and materials. 

The key to selecting the proper liner is to first identify the following:

1. Make and model of welding torch (e.g. – ABICOR BINZEL WH500)
2. Welding wire type (e.g. – ER70S-6)
3. Welding wire diameter (e.g. – .035” or 0.9 mm)

Softer wires like aluminum typically require softer plastic or Teflon based liners for wire feeding to avoid damaging the wire as it feeds through your torch.

Size

Always make sure to select the correct diameter liner for the diameter wire being used.

1. Using too large of a liner for too small of a wire may allow the wire to wander, causing poor wire feeding and/or premature liner failure due to excessive wear. 
2. If a liner is too small for the wire diameter, the wire will not be able to feed smoothly, resulting in poor weld quality and potentially an erratic arc and a clogged liner.

Remedy:

Work with your authorized welding distributor in selecting the correct liner for your welding wire type and diameter

Set Screw

Some torches are not designed with a liner retained by set screw, but if the torch manufacturer has designed a set screw to hold the liner in place, it is important to utlize this feature for proper liner performance.

Wire Pull Test

One useful way to check if the liner is good and sized properly is to perform a pull test.

1. Disengage the wire feed drive rolls
2. Straighten the welding torch to minmize bends and twists
3. Pull the wire through the torch by hand and feel the amount of resistance

A well-practiced rule of thumb is if you cannot pull the wire by hand, both the wire feed system and the liner need evaluation.

Liner is Discolored (Full Length)