BMK-8 U / BMK-12 W
15
The following welding methods are possible when using the BMK-8U / BMK-12W SOYER stud
welders:
• Short-cycle drawn arc stud welding without shielding gas and ceramic ferrules.
• Drawn arc stud welding using ceramic ferrules as auxiliary aid.
• Drawn arc stud welding using shielding gas as auxiliary aid.
Preferably use shielding gas as auxiliary aid. The use of ceramic ferrules as auxiliary aid, however, is
necessary when carrying out particularly critical welding works as e.g. welding works during which the
gun has to be held in a horizontal position or above the head.
3.2
Stud welding
The PH-3N stud welding gun with control cable and shielding gas equipment is the standard gun to be
connected to the BMK-8U / BMK-12W stud welders. These operating instructions only refer to the
BMK-8U / BMK-12W stud welders.
For information regarding the stud welding guns to be used and their setting, please refer to the
respective operating instructions.
3.2.1
Short-cycle drawn arc welding with shielding gas
With this method, a gas mixture containing 82% of Argon and 18% of CO
2
(e.g. Corgon®18*)
is used as
auxiliary aid.
This shielding gas protects the welding point from the atmosphere and simultaneously supports the
weld pool. Moreover, it ensures a concave fillet weld upset formation with a blank metallic surface,
thus reducing the risk of corrosion and obtaining an improved dynamic behaviour of the welded joint.
An accurate bulging, to scale or in a calibrated or reproducible type, is not possible when welding with
shielding gas without using any auxiliary aid. Stud welding with shielding gas can be carried out at
much shorter intervals as no ceramic ferrules have to be fitted and removed in each welding process.
*) Corgon®18 is a gas mixture of Linde AG in D-82049 Höllriegelskreuth
R
3.2.2
Short-cycle drawn arc welding with ceramic ferrules
The ceramic ferrule fulfils the following functions:
• It centres the electric arc.
• It protects the welding point from the atmosphere.
• It ensures the exact formation of the weld upset.
• It prevents too rapid cooling of the weld pool.
• It partially protects against spraying sparks.
To ensure a perfect and accurate weld upset, each stud requires a ceramic ferrule matching its
diameter and shape. After every welding process, the ceramic ferrule must be knocked down and
replaced by a new one. Usually this method allows you to weld in any position.
IMPORTANT INFORMATION
Ensure ceramic ferrules are absolutely dry.
3.3
Construction of the BMK-8U / BMK-12W stud welders
The BMK-8U / BMK-12W stud welders have a handy, compact and robust design.
The carrying handles on the top of the housing allow easy transport so that the stud welders can be
used at different work places.