Updated 05.05.2021
WELDING
with c oated electrode s m.m.a (SMAW)
Manual Metal Arc (also known as shielded metal arc welding) MMA welding is the most common welding process used by domestic users. It requires the use of an electrode holder and a filler metal called "coated electrode". This useful process does not use gas or a wire reel. It is cheaper than other processes and allows the welding of structural steels.
Process principle Gas protection
An electric arc is created between the electrode and the parts to be welded. The parts to be welded and the electrode melt. The weld pool is protected by the gas contained in in the electrode coating.
Weld pool Flux
Weldbead
Core wire
Slag
Welding parts
Applications
Agriculture
DIY
ADVANTAGE S • Easy to carry welding machine • No gas cylinder required • Low cost process • Easy to set up • Welding of most materials
Maintenance
Repair & maintenance
DISADVANTAGE S • Good control of movements is essential • Difficult to clean the weld due to slag
Coated electrode The core wire is the central part of the round wire electrode. usually made of steel, and its role is to conduct he electric current and to melt (filler metal). The different coatings are made up of a complex mixture which gives them their properties (rutile coating, basic coating, etc.).
Core wire diameter
Core wire
Flux
External diameter
WELDING
MMA c oated electrode Material and preparation steps Equipment required for MMA welding :
Set up MMA power source
1. Connect the electrode holder and the earth clamp
Earth clamp
to the unit, respecting the polarities (+/-). Coated electrode
2. Attach the earth clamp to the workpiece. 3. Choose the electrode according to the type of metal (steel, stainless steel, cast iron, aluminium) and the thickness to be welded. Position the electrode on the electrode holder.
Electrode holder
4. Select the intensity according to the information on the electrode packaging (intensity may vary depending on the type of electrode).
Cable
Electrode diameter Thickness / Intensity (A)
Electrode type and coating type: Rutile / Basic / Cellulosic
Diameter and length of the electrode Number of units packed
Protective equipment Before any welding operation, make sure you wear protective equipment:
Welding helmet
Protective gloves
Apron or protective suit
Safety shoes
Fume extraction
WELDING
C OATED ELECTRODE (MMA )
Consumables & accessories Magnet
MMA electrodes: electrodes for welding. Its coating melts to protect the weld pool. Selection criteria: - Material e.g.: steel, stainless steel, cast iron - Electrode diameter - Hardfacing
For positioning two parts to be welded. Selection criteria: - Suggested power and angle Hammer To remove the protective (slag) coating on the weld. Selection criteria: - Hammer length- Longueur du marteau
Electrode holder is used to hold the electrode during welding and to create the electric arc. Selection criteria: - Model (clamp-on or screw-on) - Power of the machine - Cable length and cable cross-section
Brush To clean the weldbead after welding. Selection criteria: - Material to be cleaned
Type of electrode The different types of electrodes: aluminium, steel, stainless steel, cast iron. Rutile coating (R) - U0> 40 V
Basic coating (B) - U> 70 V
Cellulose coating (C) - U0> 80 V
Has good mechanical characteristics. The release due to the burning of the coating limits its use to the assembly of mild steels. These are general purpose electrodes; very easy to handle in any position.
The electrodes need to be baked at 350°C for approximately 2 hours before use. Having the best mechanical characteristics, they are used for high strength fabrications and on steels that are difficult to weld (steels with high carbon and manganese content, low alloy steels, etc.).
Gives little slag but causes a high CO₂ content sulphur. It is mainly used for the execution of the first penetration passes in a downward position for the welding of gas and oil pipelines.
Welding assistance
Additional functionality
45°
ANTI-STICKING: Electronic device that automatically and punctually switches off the welding unit if the electrode sticks to the workpiece.<se
HOT START: Adjustable overcurrent on ignition when the electrode comes into contact with the workpiece. Prevents the electrode from sticking when the metal or the electrode are cold.
ARC FORCE: Provides overcurrent when needed to maintain the arc.
MMA Pulse (adjustable): Ideal for upright welding positions. Optional frequency adjustment.
Abacus To obtain a good quality weld, the user must adjust his machine according to the thickness to be welded. TYPE OF JOINTS
FLAT ANGLE
METAL SHEET THICKNESS (mm)
ELECTRODE DIAMETER (mm)
INTENSITY (A)
1.5
1.6
40
1.5 > 3
2.0
55
2.5 > 6
2.5
80
5>8
3.2
115
8>+
4.0
150-160
WELDING
with c oated electrode s
Choosing the right MMA welding machine Welding current
35 30 40 50 70
80
Ø Electrodes
90 100 110 120 130 140 160 180 200 220 250 280 300 350 400 1.6 2.5 3.2 4.0 5.0 6.3 CEL ALU
MMA PULSE
TIG LIFT
Single-phase GYSARC 100
-
-
-
-
GYSARC 120
-
-
-
-
GYSARC 160
-
-
-
-
GYSARC 200
-
-
-
-
GYSMI 80 P
-
-
-
-
GYSMI 130 P
-
-
-
-
GYSMI 160 P
-
-
-
-
GYSMI 200 P
-
-
-
-
GYSMI E163
-
-
-
GYSMI E200 FV
-
-
-
PROGYS 180A
-
-
-
-
PROGYS 183E
-
-
PROGYS 200A PFC
-
-
-
PROGYS 200 E FV CEL
-
GYSARC 220 FV CEL
-
PROGYS 220 E FV CEL
GYSARC 300
-
GYSARC 400
-
EXAGON 400 CC/CV
Single & Three Phase (FLEX) PROGYS FLEX 280 CEL
Three-phase
Tutorial video of GYSMI 160P