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IMPACT-329 S
1. Machine preparation
Align the spindle in a lathe and turn a suitably wide and deep groove in the hardened face to remove all stellite down to clean, pure base material Make room for at least two layers of weld metal. 2. Weld preparation
Suggested jig for holding
Welding should as far as possible be carried spindles.
out in the horizontal position. A suitable jig should be prepared, holding the spindle in a tilted position allowing it to be rotated.
3. Preheating
Preheat the valve head evenly to 50–200 °C and maintain during welding. Preheating temperature depending on type of alloy in valve.
4. Welding
Electrodes should be dried at 250 °C for 1 hour prior to use. The Unitor miniheater electrode quiver may be used for this. Keep the arc short and hold the electrode as near as possible to 90°C to the work piece.
Put the first bead towards the outer side of the groove Second layer or top layer First layer or buffer layer Note: Each layer can consist of several beads
Welding with IMPACT-329 S does not require any other electrode. In order to minimise heat effects, the welding should be done in stages. Place the first bead towards the outer side of the groove, and do about one third of the circumference. Then start at the oppsosite side and do the second bead so it finishes where the first one started. Finally do the third, starting where the first one finished. For large diameter spindles the bead should be done in four parts. Large diameters Small diameters
3.01
Welding bead sequence
Grind the starting and stopping point of each bead. Also grind the bead itself to remove possible slag and spatter, in order to obtain a smooth transition between beads. Control the temperature adjacent to the welding zones and do not start the next bead until the base metal has regained the correct temperature.
5. Cooling
When the top layer is completed, the spindle should be immersed in insulating material or dry sand in order to ensure slow cooling.
6. Final machining
After cooling, machine to correct tolerances, use toolbit quality H1 or K10 with negative 4° cutting angle, low turning speed and fine feeding.
Ensure slow cooling.
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