Page 92 - CITS - Welder - Trade Theory

WELDER - CITS

Gas Welding Filler rods, Specifications and sizes

Objectives : At the end of this lesson you shall be able to
• state the necessity of filler rods and name the different types of filler rods and their sizes
• select filler rods for the jobs to be welded by gas.

Filler rod and its necessity:
Pieces of wires or rods of standard diameter and length used as filler metal in the joint during gas welding process
are called filler rods or welding rods. To obtain best results, high quality filler rods should be used. The actual
cost of welding rods, is very small compared with cost of job, labour, gases and flux. Good quality filler rods are
necessary to:
- reduce oxidation (effect of oxygen)
- Control the mechanical properties of the deposited metal
- Metal caused by fusion.

While welding, a cavity or depression will be formed at the joints of thin section metals. For heavy/thick plates a
groove is prepared at the joint. This groove is necessary to get better fusion of the full thickness of the metal, so
as to get a uniform strength at the joint. This groove formed has to be filled with metal. For this purpose a filler rod
is necessary. Each metal requires a suitable filler rod.
Sizes as per IS: (1278 - 1972)

The size of the filler rod is determined from the diameter as: 1.00, 1.20. 1.60, 2.00 ,2.50, 3.15, 4.00, 5.00 and
6.30mm. For leftward technique filler rods up to 4mm dia are used. For rightward technique up to 6.3 mm dia.
issued. For C.l. welding filler rods of 6mm dia. and above are used. Length of filler rod:-500mm or 1000mm.Filler
rods above 4mm diameter are not used often for welding of mild steel. The usual size of mild steel filler rods used
are 1.6mm and 3.15mm diameter. All mild steel filler rods are given a thin layer of copper coating to protect them
from oxidation (rusting) during storage. So these filler rods are called copper coated mild steel (C.C.M.S) filler
rods .All types of filler rods are to be stored in sealed plastic covers until they are used.
Types of filler rods:
Definition of filler rod:
A filler rod is a metallic wire made out of ferrous or non-ferrous metal to deposit the required metal in a joint or on
the base metal.
Types of filler rods:
The following types of filler rods are classified in gas welding.
- Ferrous filler rod

- Non-Ferrous filler rod
- Alloy type filler rod for ferrous metals
- Alloy type filler rod for non-ferrous metals
A ferrous type filler rod has a major % of iron. The ferrous type filler rod contains iron, carbon, silicon, sulphur and
phosphorous. The alloy type filler contains iron, carbon, silicon and any one or many of the following elements
such as manganese, nickel, chromium, molybdenum, etc. The non-ferrous type filler rod which contains elements
of non-ferrous metals. The composition of non-ferrous type filler rods is similar to any non-ferrous metal such
as copper, aluminium. A non-ferrous alloy type filler rod contains metals like copper, aluminium, tin, etc. Along
with zinc, lead, nickel, manganese, silicon, etc. Selection of the correct filler rod for a particular job is a very step
for successful welding. Cutting out a important strip from the material to be welded is not always possible and
even when it is possible, such a strip cannot replace a recommended welding filler materials. Composition of a
filler metal is chosen with special consideration to the metallurgical requirement of a weldment. A wrong choice
due to either ignorance or a false consideration of economy may lead to costly failures. IS: 1278-1972* specifies
requirements that should be met by filler rods for gas welding. There is another specification IS: 2927-1975*which
covers brazing alloys. It is strongly recommended that filler material confirming to these specifications is used.

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CITS : C G & M - Welder - Lesson 14-26 CITS : C G & M - Welder - Lesson 14-26