A window on welding technology

editorial image

Recently members of the Northern Ireland branch of the Institution of Agricultural Engineers (I Agr E) were privileged to get a tour of the bright modern technology training facilities at the South West College (SWC) Dungannon campus.

SWC, operating at four centres, has a current total enrolment of almost 20,000 students across 400 separate courses.

The course contents emphasise Training for success, Steps to work, Step-up for re-skilling and, amongst other topics, it offers higher level apprenticeships and a four year foundation degree course.

The College has gained Grade 1 status awarded by the Education and Training Inspectorate (ETI). This places it amongst the top four of 350 colleges in the UK and the only one in Northern Ireland to achieve this recognition.

The courses are designed to meet the needs of employers including the Co. Tyrone based manufacturing sector for aggregate screening and crushing equipment. There is an Innovation in Partnership arrangement with Terex Powerscreen who design, manufacture and supply complete products in this sector for world markets.

The I Agr E visitors saw a live demonstration of computer aided design, simulation and testing on the hydraulic control systems of engine driven installations. Students on this combined course regularly get the opportunity to travel abroad and get on-site practical experience with service dealerships.

Welding technology

Alaistair Booth (Curriculum Manager within the SWC’s Department of Training) and his staff at SWC presented an up-to-date summary of welding technology. There was also a back-up exhibition of the latest welding equipment by Allister Moore Welding and Engineering Supplies Ltd.

As well as supplying equipment and accessories (through being the Northern Ireland dealership for ESAB and others) this company also provides on-site training and testing for welding procedures to the current BS EN ISO 15614 Quality Standards. They also brought along a portable Fronius welding simulator on which trainees safely gain experience in achieving perfect tip-to-work distance, tilt angle and travel speed when using the torch or electrode holder.

The trainee can subsequently replay the sequence and note progress and any aspects requiring further attention.

One of the main franchises is held for Swedish company ESAB, which was formed in 1904 at the start of manual metal welding, and is now a world brand for welding and cutting equipment. One of ESAB’s founders, Oscar Kjellberg, invented the consumable flux coated welding electrode and his initials, OK, still appear on their welding rod packs.

The ESAB product range includes welding and cutting equipment for manual or automated operation, accessories, welding consumables and personal protective equipment (PPE).

The visitors were impressed to learn how welding technology has been developed and to see what equipment is now available. This ranges from lightweight portable air-cooled welders to the wide range of inverter types with their improved efficiencies and automated electronic features such as Hot Start (for optimal striking of the arc), anti-stick and mains voltage compensation. This provides a controllable weld pool with minimal spatter.

For some applications it is just necessary to select material type and sheet thickness and the machine selects the best settings automatically.

During his presentation, Mr Booth summarised the main types of welding techniques which include:

Manual arc welding in which the operator holds a consumable rod electrode ( typically 2.5,3.2 or 4.0 mm. diameter) at a fixed clearance in the work as it melts in the electric arc. Mains current is transformed and rectified through the welding set. The flux coating on the rod melts in the arc to form a protective gas cloud which prevents oxidation (rusting in steel) of the molten metal as it cools.

The traditional heavy oil cooled welder (many of which are still used on farms) has given way in the market place to portable air cooled compact more efficient high-frequency inverter transformer types.

Inert gas welding systems have now mainly taken over in production fabrication work. M. I. G. (metal inert gas) types also use a DC transformer/rectifier and a consumable metal wire electrode is continuously metered out through the electrode holder along with inert gas to protect the molten joint as it cools.

This process provides a smooth, spatter free weld and can be manually operated or automated through selectable settings from a database. The T.I.G. (Tungsten inert gas) system works in the same way and is especially suited to welding thin section metals.

AC current is used for welding aluminium, DC for stainless or mild steel with a negative electrode. The chosen polarity affects the balance of heat distribution between the electrode and the work base plate unlike the AC system where the distribution stays around 50/50. The latest techniques provide the control and flexibility for welding or brazing of a wide range of metal types.

Welding standards

Graham from Allister Moore Welding explained some of the aspects of weld quality assurance such as Coded welding certification to BS 5614 for 10mm to 40mm work.

The welder being assessed has to produce three runs of one fillet to the acceptable standard to support their three year certification. The completed test piece is sent to the Edinburgh test station for assessment. CE marking is authorised after a specified check list has been completed and recorded for the work.

Live demonstrations

The evening included a demonstration of plasma cutting. This fusion process uses a very high temperature arc in an ionised plasma column between a non-melting electrode and the metal work piece to provide a very clean cut. It can be programmed to copy a wide range of patterns and is now widely used in manufacturing to make components. Live demonstrations of welding were also provided as well as the opportunity to use the welding equipment in the booths.

Following a most interesting and informative evening, which concluded with some question and answer items, branch member Harry Barr thanked Mr Booth and the SWC staff, as well as the team from Allister Moore welding, for making it all happen.

More details about the South West College’s activities and courses can be viewed at www.swc.ac.uk

More about Allister Moore Welding Supplies Limited services and products can be viewed at www.moorewelding.com