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Troubleshooting Guide For Arc Welding Systems

The welding process is one of the most complex of all the manufacturing processes and frequently the least understood. Welding systems occasionally seem to develop a personality of their own and problems sporadically occur that cause great frustration to the end user. Climatic variations such as barometric pressure changes, atmospheric moisture content and cosmic radiation can have some effect on the weld process according to the welding power supply used, electrodes chosen, material to be welded, and the welding parameters chosen. It is thus important to ensure the welding setup is capable of absorbing certain minor external variations without significant effect on final weld quality and consistency.

In order to have consistent output, the welding system should receive consistent input. The single approach to troubleshooting should be to answer the question: what changed? If the system was welding properly in the past then something changed to cause the problem. As you proceed through each step below, think about what may have changed in your weld procedure.

General Welding Problems

Problem Possible Cause Test/Solution
1. Excessive Electrode Consumption Inadequate/excessive gas flow Test for correct gas flow (consult charts for gas flow guide)
Improper size/or geometry of electrode for current required Use larger electrode(consult guide for proper geometry)
Excessive heating in holder Check for proper collet contact
Contaminated electrode Replace electrode (erratic results will continue as long as contamination exists)
Electrode oxidation during cooling Depending on welding application, keep gas flowing for 5 to 15 seconds after stopping arc
Using shield gas containing excessive oxygen or moisture Change to proper gas purity

2. Contaminated Electrode Base metal is dirty or greasy For surface cleanliness use appropriate chemical cleaners alcohol, wire brush, or abrasive
Contaminant elements that out gas may exist within the base material itself If possible, improve base material. Modify welding parameters to accommodate outgassing effect
Check for electrode contamination Remove contaminated portion of electrode, regrind electrode

3. Tungsten Contamination of Work Piece Tungsten touching molten pool Keep tungsten out of molten pool
Tungsten shedding Use a quality Tungsten electrode grinder to sharpen electrodes
Electrode melting and alloying with base metal Use less current or larger diameter electrode

4. Porosity in the Weld Entrapped gas Impurities(hydrogen nitrogen, air, water vapor) Purge air from all lines prior to striking arc, remove condensed moisture from lines; use welding grade (99.9%) inert gasCheck that correct shield gas mixture is in use
Defective gas hose or loose hose connections Poor quality gas hoseCheck hose and connections for leaks
Oil film on base metal Clean with chemical cleaner not prone to break up in arc. Be sure base metal is dry before welding

5. Electrode Material Be sure electrode material is not changed. Try an electrode from another box or a stored reference box Different electrode materials offer varying arc start and current carrying abilities

6. Electrode Material Quality Use electrode from older or newer stock to see if problem persists A batch of electrodes may have varying quality (unusual)

7. Electrode Dimensions/Geometry Be sure electrode dimensions are appropriate for application Electrode tip geometry varies according to the welding application. Consult guides for information

8. Cable Layout In so far as possible, try to layout cables from power supply to welding torch as straight as possible Occasionally, cables are coiled like a garden hose. The coil becomes a giant inductor causing resistance that reduces starting energy. Inductance effects can also be caused by having welding power cables very close to grounded steel plates

9. Extension Cables Ensure that any extension cables are of adequate capacity Low quality/capacity cables will result in voltage drops and hinder starting

10. Gas Quality Gas quality/purity must meet standards. Check to see if suppliers have changed. Try a bottle of gas of a higher purity grade than normally used and see if problem persists. Low gas quality or oxides in gas can oxidize part and contaminate electrodes during welding. Even the best suppliers occasionally have problems.

11. Material Quality/Specifications Be sure materials you are welding do not have contaminants within their metallurgical structure. Check to see if there has been a change in material suppliers. Contaminants in the material can out gas during welding causing inconsistent weld quality. Arc wander or weld penetration variations may be a result of changes in certain trace minute elements in the material

12. Incorrect Voltage Check power supply for correct input voltage. It may be necessary to check voltages throughout the day to be sure that fluctuations are within the scope of the power supply. Voltage may be drawn from other equipment or facilities at peak times of the day. This will reduce voltage available for the power supply to initiate an arc.

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Problems Related To Arc Start, Arc Wander & Weld Process Consistency

Problem Possible Cause Test/Solution
13. Weld Program Check to ensure weld program parameters have not changed. Changes in arc starting peak and background amperage, and other parameters will affect system operation

14. Part Tolerances and Weld Joint Consistency Check if tolerances for joint geometry have changed Intimate part contact is necessary at weld joint for quality welds

15. Base Material Has Surface Contamination Check that cleaning procedures are followed and each set of cleaning tools is used for each type of material Surface contaminants such as oil, dirt, or oxide can hinder arc start and weld consistency by out gassing during welding and adhering to electrodes.Contaminants may also cause problems with AVC control of arc distance.

16. Gas Coverage Issues Check that gas pre-flow and post flow times are adequate.Ensure the area where arc is to be struck is sufficiently free of Oxygen and that gas flow is adequate. Do not weld in a drafty environment Insufficient gas coverage will cause contamination of part and electrode. High flow rates can create turbulence and inhalation of gas into the area.Oxygen in the arc area results in electrode contamination’s. Lower flow rates with longer pre-flow can improve arc starting. Post-flow of5-15 seconds eliminates oxidation of electrode during cooling Inadequate gas flow during welding results in excessive electrode use. Drafts can push oxygen into the arc area.
Defective regulators, flowmeters, or hoses Check for leaks or damageUse high quality parts for gas systems
High weld speed causes part to travel out from under shield gas area before weld is cool Use trailing shield gas

17. Grounding Problems Make sure clamps and clamp inserts are clean of oxidation.Make sure ground cable/clamp is not worn Oxidation and/or worn equipment can cause poor ground between part and clamp/inserts which may hinder arc starting and cause arc wander and other inconsistencies

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Tooling And Fixtures

Problem Possible Cause Test/Solution
18. Welding Equipment One piece of welding equipment may be malfunctioning while others are functioning correctly Try the same weld with the same batch of electrodes on another system using the same weld program and set up

19. Tooling & Fixtures Tooling doesn’t make good contact with part. Tooling wears and must be replaced or cleaned.
Tooling is dirty or not grounded properly. Check for loose grounds or wrong size ground wire.

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Equipment Troubleshooting Steps

*** make sure you are qualified to perform these troubleshooting steps before proceeding ***
Problem Possible Cause Test/Solution
20. No Lights Come on When Powered Up Input power problem Ensure system is plugged in
Missing or low voltage Check fuses. Check all voltage levels. Check voltage taps for correct settings. Check rectifier secondary voltages
Recirculator not on Be sure circulator plugged in. Low/No water. Check for water flow. Check flow switch interconnect to power supply. Check fuses

21. Overheat Lights Come On Overheating of unit Allow 3-5 minutes "cool down" time. Check for short between nozzle and electrode. Check transistors; as this component starts to wear, it begins to draw more current. If condition is not resettable, return unit to factory for service

22. Difficulty in Arc Starting Torch assembled incorrectly Check condition of electrodes and/or plasma nozzles
Low voltage problem Check for missing or low voltage. See "General Welding Problems"

23. Arc Does Not Transfer Loose, missing cable connections Check tooling for loose or poor ground
Power supply not recognizing start signal Check all connections. Troubleshoot with schematics

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Plasma Arc Welding

Problem Possible Cause Test/Solution
24. Erratic or poor-appearing pilot arc Worn torch parts. Check and replace required parts.
Improper electrode setting. Adjust setting.
Contaminated plasma gas. Check gas line for leaks.
Moisture in torch or leads. Plug tip and allow gas pressure to increace.
Contaminated coolant. Check coolant for contaminants.

25. Welding arc will not transfer Torch standoff too high. Reduce standoff distance.
Power supply not properly connected. Check work lead negative lead contactor control cable.
Faulty electrode in torch. Check for sharp point and clean appearance of electrode.

26. Welding tip damaged on start-up Improper installation of torch parts. Check installation procedure.
Improper electrode setback. Correct electrode setting.
Incorrect polarity Check negative and positive leads for proper connections; check range switch of power supply.
Plasma gas flow rate too low. Increase flow rate.
Excessive current level. Reduce current or use tip with larger orifice.
Inadequate coolant flow. Check flow rate and pressure; check coolant filter.
Contaminated gas. Check gas line for leaks.
Moisture in torch. Check torch and hoses for leaks.
Contaminated coolant. Check coolant for contaminants.
Tip touching workpiece. Increase standoff distance.

27. Tip damaged after a period of welding Inadequate coolant flow. Check flow rate and pressure; check coolant filter.
Excessive current level. Reduce current or use tip with larger orifice.
Plasma gas flow rate too low. Increase flow rate.
Moisture in torch. Check torch and hoses for leaks.

28. Not getting required penetration Plasma gas flow rate too low. Increase flow rate.
Inadequate current level. Increase current.
Electrode setback at minimum. Increase setback distance.
Travel speed too high. Decrease travel speed.

29. Porosity in welds Contaminants on workpiece. Clean workpiece.
Plasma gas flow rate too high. Reduce flow rate.
Inadequate shielding gas coverage. Increase flow rate or use additional trailer shield.

30. Slight undercutting in toe area of weld Travel speed too high. Decrease travel speed.
Plasma gas flow rate too high. Decrease flow rate.
Orifice size in tip too small. Use tip with larger orifice.
Electrode setback at maximum. Decrease setback distance.
Inadequate current level. Increase current.
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