Choosing Welding Equipment

To better pick up a welding device you really need, it is advisable to use three tables below. The first allows you to select welding method depending on the type of weld material and weld seam. The second table describes how to choose a welding device depending on weld seam quality standards. And the third one lets you select welding equipment depending on required intensity of its work.

1. Choosing welding method depending on the type of weld material and weld seam:

 

Weld material	Carbon steel		Stainless steel		Aluminium
Thickness of material	up to 2 mm	more than 2 mm	up to 2 mm	more than 2 mm	up to 2 mm	more than 2 mm
Works Done
Tack weld assembly (short seams 20-100 mm)	ММА	ММА	ММА DC TIG DC	ММА DC TIG DC	TIG AC	TIG AC
Rod or section (shape) structure welding	ММА	ММА	ММА DC TIG DC	ММА DC TIG DC	TIG AC	TIG AC
Sheet structure short seam (up to 0.5 m) welding	ММА	ММА	ММА DC TIG DC	ММА DC TIG DC	TIG AC	TIG AC
Sheet strucutre long seam (over 0.5 m) welding	ММА DC MIG/MAG	ММА DC MIG/MAG	ММА DC TIG DC MIG/MAG	ММА DC TIG DC MIG/MAG	TIG AC MIG/MAG	TIG AC MIG/MAG
Lap welding	SPOT	SPOT	SPOT	SPOT	SPOT	SPOT
Bolt welding	SPOT	SPOT	SPOT	SPOT	SPOT	SPOT
Special body works	Spotter		Spotter

AC – alternating current;

DC – direct current.

MIG / MAG – semiautomatic electrode wire welding in shielding gas – inert (argon) or active (carbon dioxide). It's used to weld steels (including stainless) and aluminium alloys.

ММА – manual arc welding by clad stick electrodes. It's used to weld carbonic or stainless steel. Carbonic steel can weld using АС or DC, whereas stainless steel – by using direct current only.

TIG – manual welding by nonconsumable tungsten electrodes in shielding gas – argon. Direct current TIG (TIG-DC) is applied on steel, whereas alternating current TIG (TIG-AC) – on aluminium alloys.

SPOT – contact spot welding on lap joints or bolt welding by heavy current with pressure exerted upon.

2. Choosing welding device depending on weld seam quality standards:

 

Welding method	ММА	TIG	MIG/MAG	SPOT and Spotter
Weld Seam Quality Requirements
High standards	Inverter	TIG inverter	Semiautomatic device
Medium standards	Rectifier	TIG machine		Spot welding machine or gun, spotter
No strict standards	Transformer

Inverter – a power source for top quality ММА welding. Its circuit is fully electronic and built on high-frequency thyristors or transistors. Inverters are remarkable for high quality welding and small weight. There are DC or AC/DC versions.

Rectifier – a power source for ММА welding using direct current. The main section is a rectifying unit based on diodes or thyristors. Provides higher quality of welding compared with a transformer, and can be used to weld stainless steel.

Semiautomatic device – a combination of power source and electrode wire feeder to weld long seams. The feeder can be built in a power source (single-shell semiautomatic device) or outboard (double-shell semiautomatic device).

Spot gun – a portable low-power device for spot welding of thin pieces with a built-in power source and lever-operated compression.

Spotter – a universal unit for spot welding of thin pieces or bolt welding.

Spot welding machine – made of strong power source and device for compression of parts (mechanical, pneumatic, hydraulic) by means of massive copper electrodes.

TIG inverter – an inverter power source of DC or AC/DC with oscillator and gas charging valve.

TIG machine – for TIG welding of stainless steel (DC) or steel from aluminium alloys (AC/DC) based on diode or thyristor rectifier. It has an oscillator for high-frequency (HF) arc initiation and a gas charging valve.

Transformer – the simplest and cheapest power source for ММА welding using alternating current. It consists of power transformer and choke, and is used to weld structures that do not require high quality of weld seam.

 

3. Choosing welding equipment depending on required intensity of its work:

 

Welding equipment	Low load (duty rating up to 35%)	Medium load (duty rating 35% to 60%)	Large load (duty rating 60% to 100%)
Transformer	*	*	*
Rectifier		*	*
Inverter		*	*
TIG machine		*
TIG inverter			*
Semiautomatic device	*	*	*
Spot welding machine
Spot gun
Spotter	*	*
Plasma arc cutting		*	*

Duty rating (or load duration) – continious arc duration (current flow) which can be sustained by a specific type of welding equipment during simulated 10-minute cycle. Welding hardware work analysis shows that 60% duty rating (with work breaks taken into account) is enough for continious work during 8-hour shift.