SMAW(Shielded Metal Arc Welding )

also known as

Manual Metal Arc Welding (MMA ) , or Stick welding

Wide range of alloys (electrodes) available.

Low cost of equipment , available in most workshops.

Easy to apply no special skills required :

Relative high dilution of weld deposit (20-40 % )

2– 3 layers may be required to achieve maximum wear properties

Low Deposition rate ( between 1– 3 kg/ h )

(FCAW) Flux Cored Wire Welding (GMAW ) gas metal arc welding

High deposition rates from 2– 11 kg /h

Large range of alloys available to suit most application .

Easy to use.

Relative high dilution of weld deposit (20-40 % )

2– 3 layers may be required to achieve maximum wear properties

TIG (GTAW) Gas Tungsten Arc welding

Low dilution,

Good control of weld deposit

Low dilution (5-15 %)

Ideal for Hard facing of tools & dies

Low deposition rates

Limited range of alloys available.

High welding skill necessary

Gas (oxy-acetylene) Hard facing (OFW)

Excellent control over the deposit shape.

Minimum dilution of weld deposit (0-5 %)

Slow heating and cooling minimizes thermal shock of part

Equipment easily available at low cost

High heat input necessary

Low deposition rate

Not suitable for very large components

Powder Flame Spraying (Spray& Fuse)

A two step process where the powder is sprayed with a thermal spray gun and thereafter fused to achieve a dense coating

Low cost of equipment ,easy to use

Only low dilution with base metal

Exact control over deposit shape and thickness

Wide range of powders available

High heat input necessary for spray & fuse coating

(PTA) Plasma Transferred Arc surfacing with powders classified as nickel base, cobalt base and iron base

Low dilution of weld deposit (5-10 %)

Exact control over deposit thickness and shape,

Complete metallurgical bond between base metal and powder alloy

Automation is possible.

High deposition rate : up to 20 kg/h

Relative high cost of equipment

Limited mobility

High operator skill necessary

Other Processes Used

HVOF (High –Velocity Oxy –Fuel) spraying)

WFS (Wire flame spray)

CGS (Cold gas spray)

AS (Arc spray )

Processes Used for Wear protection

HVOF (High –Velocity Oxy –Fuel) spraying)

Low heat input, therefore workpiece remains relative cool with little change to either workpiece or sprayed material

Exact control over deposit thickness and shape and extremely thin coatings van be produced

Can be automated

Deposition rate from 2-15 kg/h

High cost of equipment

Limited mobility

Electric Arc Spraying (TWAS) (twin arc wire spraying)

High deposition rates (8– 20 kg/h)

Preferred process for corrosion protection

No or only limited dilution of deposit

Can be automated

Good control over deposit thickness & shape

Relative high cost of the equipment

Limited mobility

Exposure to electric arc and fumes ,

SAW (submerged arc welding)

Fast deposition

Ideal for large parts such as rollers etc/

Suitable for automatic application

Produces sound and smooth deposits

Limited range of alloys available

Not suitable for smaller parts

Special equipment necessary

High dilution