Practical Welding Exercise 1
Single pass wet weld desposit 'Bead on plate'
Start off by practising this simple drag technique. The Drag Technique involves attempting to allow the electrode to consume itself with as little interference as possible.
Providing the electrode remains in contact with the work it will be consumed at a specific rate, this rate is a direct consequence of the current and the lead angle thus; the drag technique tends to lead to a natural characteristic welding speed. To allow for minor changes in travel speed, an increase in the lead angle will result in a slower rate of travel. Conversely, a shallow lead angle will result in an increase in travel speed. An angle of between 35 - 40° is used as this allows for safe bubble departure, which would otherwise cause turbulence in the weld puddle.
- Remove from surface any rust or scale by brushing
- Mark plates as shown
- Ensure a firm ground/return lead connection at all times
- Prepare electrode
Lightly remove the waterproof coating from the end of the electrode by rubbing it against a file. Then place the electrode exactly where you wish to start, call to make it hot. Now, one of two problems may happen, firstly the arc is struck, but sticks to the work, or nothing happens at all. For the latter, keep rubbing the electrode gently up and down until the arc is struck. For the former, break off the electrode and with the power still hot, scrape the electrode as if striking a match and then retry.
- Avoid tangling of welding cables and ensure you are not between the cables
- Maintain an eye level view at approximately the same level as the plate
- Weld across yourself, not towards yourself, i.e. stand at 90° to the plate
- Deposit a series of single pass welds along the full length of the plate, ensuring at least 25% overlap of the subsequent passes using the ‘DRAG’ technique only
- Ask for the current to be made cold immediately after welding
Things to Watch Out for: Keeping your lead angle, travel speed and slope angles correct. If you keep your lead angles as required, your travel speed will stay pretty much as necessary. As for depositing the weld in the correct place, keep a very close eye on your slope angles and the previous deposit. Practice makes perfect and remember to experiment with the current settings.
NOTE: Only make the welding machine hot when ready to weld. Ask for the current to be made cold immediately after welding. For the bead on plate exercise, the progression of welding along the plate is away from you, i.e. so that your next weld is behind the previous deposited one.