Electrode Welding (Mma); Electrode Welding Procedures - Stel TIG μP 253H AC/DC Manual De Instrucciones

TIG µP 253H AC/DC
TECHNICAL DESCRIPTION
6.0 – ELECTRODE WELDING (MMA)
6.1- PROCEDURES AND TECHNICAL DATA FOR ELECTRODE
WELDING
- Arc welding with coated electrodes is a procedure with which two metal parts are
joined by exploiting the heat generated by an electric arc which is sparked
between a fusible electrode and the material to be welded.
- Current generators for the electric arc (welding machines) may be fed with direct
current or alternating current; the former can weld any kind of electrode, while the
latter can weld only electrodes intended for alternating current.
- The constructive characteristic of these generators ensures an excellent degree
of stability of the arc even when its length varies as the electrode moves closer or
farther away, due to the movement of the welding operator's hand.
- The electrode is composed of two fundamental parts:
a) the core, which is of the same material as the base
(aluminium, iron, copper, stainless steel) and has the function of inserting
material in the join.
b) the coating, composed of various mineral and organic substances mixed
together; its functions are:
- Gas protection. A part of the coating, volatized at arc temperature, sends air
away from the welding zone, creating a column of ionized gas which protects the
molten metal .
- Supply of bonding and scarifying elements. A part of the coating melts and
supplies elements to the weld pool which combine with the base material, forming
slag.
- It may be said that the manner of melting and the characteristics of the deposit of
each electrode derive from the type of coating and from the core material.
- The principal types of coating are:
- Acid coatings. These coatings offer good weldability and may be used with either
alternating current or direct current, with the electrode gun connected to the
negative pole (direct polarity). The weld pool is very fluid, so electrodes with this
coating are essentially suitable for welding on a flat surface.
- Rutile coatings. These coatings give the weld seam an extremely good
appearance, so they are widely used . They can weld with either alternating
current or direct current, with both polarities.
- Basic coatings. These are used essentially for welds with a good mechanical
quality, even though the arc tends to splash and the appearance of the weld seam
is inferior to that produced with the rutile type. They are generally used with direct
current, with the electrode on the positive pole (inverse polarity), even though
60
ENGLISH
COD. 6910000030
STEL s.r.l. – Via del Progresso n° 59 – 36020
Loc. Castegnero (VICENZA) - ITALY
TEL. +39 444 639525 (central.) – +39 444 639682 (comm.)
FAX +39 444 639641 – E-mail:stelgroup.com
http: www.stelgroup.it
TIG µP 253H AC/DC
TECHNICAL DESCRIPTION
6.0 – ELECTRODE WELDING (MMA)
6.1- PROCEDURES AND TECHNICAL DATA FOR ELECTRODE
WELDING
- Arc welding with coated electrodes is a procedure with which two metal parts are
joined by exploiting the heat generated by an electric arc which is sparked
between a fusible electrode and the material to be welded.
- Current generators for the electric arc (welding machines) may be fed with direct
current or alternating current; the former can weld any kind of electrode, while the
latter can weld only electrodes intended for alternating current.
- The constructive characteristic of these generators ensures an excellent degree
of stability of the arc even when its length varies as the electrode moves closer or
farther away, due to the movement of the welding operator's hand.
- The electrode is composed of two fundamental parts:
a) the core, which is of the same material as the base
(aluminium, iron, copper, stainless steel) and has the function of inserting
material in the join.
b) the coating, composed of various mineral and organic substances mixed
together; its functions are:
- Gas protection. A part of the coating, volatized at arc temperature, sends air
away from the welding zone, creating a column of ionized gas which protects the
molten metal .
- Supply of bonding and scarifying elements. A part of the coating melts and
supplies elements to the weld pool which combine with the base material, forming
slag.
- It may be said that the manner of melting and the characteristics of the deposit of
each electrode derive from the type of coating and from the core material.
- The principal types of coating are:
- Acid coatings. These coatings offer good weldability and may be used with either
alternating current or direct current, with the electrode gun connected to the
negative pole (direct polarity). The weld pool is very fluid, so electrodes with this
coating are essentially suitable for welding on a flat surface.
- Rutile coatings. These coatings give the weld seam an extremely good
appearance, so they are widely used . They can weld with either alternating
current or direct current, with both polarities.
- Basic coatings. These are used essentially for welds with a good mechanical
quality, even though the arc tends to splash and the appearance of the weld seam
is inferior to that produced with the rutile type. They are generally used with direct
current, with the electrode on the positive pole (inverse polarity), even though
60
ENGLISH
COD. 6910000030
STEL s.r.l. – Via del Progresso n° 59 – 36020
Loc. Castegnero (VICENZA) - ITALY
TEL. +39 444 639525 (central.) – +39 444 639682 (comm.)
FAX +39 444 639641 – E-mail:stelgroup.com
http: www.stelgroup.it