3 mma welding – Kemppi Master S 400 User Manual

Page 11

3.3 MMA welding

In manual metal arc welding (MMA), the filler material is melted from the electrode to the

weld pool. The rate of welding current is selected on the basis of the electrode size and

welding position. The arc forms between the electrode tip and work piece. The melting

electrode coating forms a gas and slag shield, which protects the molten metal in transfer

to the weld pool and during solidification. As the slag solidifies over the hot weld metal, it

prevents weld metal from oxidation. This slag coating is removed after welding e.g. with a

chipping hammer. When removing the slag coating, ensure you protect your eyes and face

with suitable equipment.
For more info, visit www.kemppi.com > Welding ABC.

3.3.1 Filler materials and equipment

Master S series can be used with most of the common electrode types for DC welding. For

welding with cellulosic electrodes, the optional kit should be fitted. Electrode sizes for the unit

are listed in Technical data section later in this manual. Follow the welding specifications given

on the electrode package.

Check that the welding cable and earth return cable connections are hand tight.

If a cable connection is loose, it will result in a decrease of welding performance,

overheating of the connection, and it may affect your product warranty cover.

Select and mount the correct electrode type firmly in holder.

3.3.2 Earth return cable and clamp

If possible, always fix the earth return cable and clamp directly to the welding work piece.

Clean the connection surface of the clamp from paint, dirt and rust.

Connect the clamp carefully so that contact surface is as large as possible.

Finally check that the clamp remains fastened.

3.3.3 Manual metal arc welding (MMA)

Select your required welding parameters according to the manufacturer’s filler material

recommendations and the joint to be welded.

Select the required polarity (+ or –) of welding current cable (normally + ) and

earth return cable (normally –) according to the filler material manufacturers

recommendations.

Select MMA welding mode by pressing the process selection button on the control

panel.

Select a suitable welding current by adjusting the current adjustment knob.

Make a small test weld to check the selections made.

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