6
Start-up and weld quality check
Page 33
Stud welding units
Operating manual
Date:
July 2021
INTRA 2100/1400
07.2021 / EN
Rev.:
A
6
Start-up and weld quality check
6.1 Notes about stud welding
Before welding starts, the stud welding instructions must be followed.
They contain important information for achieving good weld joints.
1.
Of course, good weld joints are only achieved with technically perfect devices.
Observe the safety measures and instructions in Chapter 2.
2.
Studs and ceramic rings must be stored dry, because rust on the stud tips and
damp ceramic rings decrease weld quality. Damp ceramic rings can be dried in an
electrode drying oven, for example.
3.
The weld elements and workpieces must be suitable for welding. Use only material
combinations indicated in the operating manual
(
see Chapter 1.4 “Material combinations”).
4.
The surface of the base material at the weld point must be even and metallically
blank, so that there is contact between the workpiece and weld stud for the ignition
process. Note that roughness greater than 80 µm in the welding zone should not
be exceeded.
5.
Contaminations of the welding zone, such as rust, scale, zinc, paint, moisture,
greases and oils must be removed immediately before welding. In most cases, it is
enough to briefly grind them off with an angle grinding machine or wipe them off
with a dry cloth.
6.
Workpieces made of aluminium or workpieces with aluminium coating must be
cleaned only with a rust-free (V2A) wire brush. Otherwise, harmful oxides will get
worked into the base material.
Anodized workpiece surfaces must be stripped (such as with caustic soda).
7.
At low workpiece temperatures, the base material must be preheated to prevent
harmful hardening of the material:
Limit value: - at S235:
0°C
- at S355: +5°C
The welding location must be adequately protected against rain and snow.
Otherwise, welding must
NOT
take place.
8.
The “blow effect” (or “arc blow”) impairs the quality of the stud weld connection.
“Blow effect” describes when the arc is diverted by external induction fields that
mainly originate in asymmetrical current movement. Causes and remediation
actions are detailed in Chapter 4.4 “Connecting the workpiece”.
9.
Always lay the welding and earth cable without loops. This can largely prevent
electromagnetic influences.