Fabricator ups welding robot usage to 90%

Having not increased its manual welding team for some years, robotic arc welding content at UK Newfield Fabrications factory will be approaching 90% after further robot installations.

Two Motoman robotic arc welding systems installed towards the end of 2007 and another on order of another for delivery in July this year will bring robotic arc welding content at Newfield Fabrications up to 90%.

The latest Motoman robots form part of a GBP 1.5 million investment in new plant spent over the past 18 months.

In addition, Newfield is spending GBP 750,000 to increase its factory area by 40% to 70,000ft2, which will be completed in September 2008.

The family-owned fabricator was established in 1965 by Don Binns and is currently run by second-generation managing director, David.

He commented, "When the latest Motoman cell arrives, which will be our sixth, we will be well on the way to increasing automated welding of mild steel in our factory to over 90%, as we have not added to our manual welding team for a number of years".

He said it was increasingly difficult to find manual welders.

Even so, the main reason for automating the welding function was to achieve repeatability and accuracy.

Binns explained: "We are required to produce many parts to a tolerance of +/-1mm and often the welds are visible after assembly, so cosmetic appearance is also important".

Binns said that robots allow Newfield to provide an improved, more consistent product.

He added: "Together with our CNC production machines, which also hold close tolerances, they underpin our accreditation to the automotive quality management standard, ISO/TS 16949:2002".

Newfield's early success was founded on producing chassis and suspension fabrications in low to medium batch sizes for ERF and Foden.

Commercial vehicle work, including for major engine manufacturers, remains a large part of the subcontractor's turnover.

The firm is currently one of the top fabricators in the UK, operating 24h/day, five or six days a week.

David Binns recognised back in the late 1980s that people were becoming less and less willing to work as a manual welder owing to the demanding working conditions.

It meant that skilled welders were scarce and expensive to employ.

He started to mitigate the problem in 1987 by installing the first robot cell to create extra welding capacity and increase turnover.

A couple of other robot welding systems followed a few years later.

* Automation advances - a decade later, after winning sizeable ongoing orders for producing parts for excavators and other off-road vehicles, David Binns decided to increase his company's use of all types of automated production plant.

He invested in Trumpf and Bystronic CNC laser systems for cutting plate up to 20mm thick, CNC press brakes rated up to 4000kN (400 tonf) - including 8-axis models from Amada, as well as automatic saws, CNC lathes and machining centres.

The first Motoman twin-station, automated welding system was installed at Newfield in 1997.

It comprised a 6-axis industrial robot serving an RM2 automatic turntable.

The turntable carried two positioners of 250kg load/2m length capacity.

The cell replaced one of the original robot welding systems and a second, similar cell has since been added.

There were two main reasons for Newfield originally choosing Motoman equipment, and subsequently standardising on welding cells exclusively from this supplier.

1 - The cost and reliability of the robots.

2 - The quality and performance of the workpiece positioners, which Motoman also manufactures.

Binns said that most robots on the market are reliable, but they are only as good as the handling systems that manipulate the components being welded.

Very often, robot companies buy in third-party handling systems.

He reasoned: "What we like about Motoman is that they produce the positioners as well, so they can control their quality and interface them seamlessly with their robots, resulting in turnkey welding cells that are functional, accurate and easy to program from the pendant controller".

* Gantry-type robotic welding cell - one of the latest systems to be installed at Newfield is a large gantry welding cell based on a single inverted Motoman SSF2000 robot travelling in a 7.9m x 1.8m x 1.2m working envelope.

It accesses two work areas, allowing set-up and component removal to be carried out off-line while welding is in progress.

The positioners, which rotate around a horizontal axis at each station, have two servo-powered fixtures and a tailstock that allows the centre distance to be adjusted to suit the size of the workpiece.

The gantry cell has a Kemppi 520A weld package and includes automatic Moto Tac torch calibration and Comarc seam finding for tracking longer weld seams.

The cell mostly welds numerous types of large fabrication for the revolving frame of 360-deg excavators produced by a major manufacturer of off-road vehicles.

One set of fixtures accommodates all variants, each of which is welded automatically in one process, with only minimal hand finishing needed.

The largest component measures 3.5m x 1.4m x 0.5m and weighs 750kg including the fixture.

Previously, the fabrications were welded in piece-part form in a smaller Motoman cell based on a UP6 robot serving an RM2 twin-station turntable with two positioners of 500kg load/2.6m length capacity (the cell currently on order is of similar specification).

Manufacturing using the smaller cell was time-consuming and required extensive manual welding to complete the fabrications.

The reason was that as the individual elements were smaller owing to the limited capacity of the robotic welding system.

* Costs savings - Binns said that there are significant cost savings to be gained when such a fabrication is completed in one hit rather than two.

Eliminated are interim handling and extensive final manual welding, which can easily over-run and reduce job profitability.

Overall weld quality is also better and work planning is easier.

Other parts currently being produced in the gantry cell include smaller chassis parts for the general commercial vehicle market and for specialist trucks, such as those used for refuse collection and recycling.

However, components up to 8m long by 2.6m diameter and weighing five tonnes can be manipulated, giving Newfield the flexibility to produce much larger work in the future.

* Automating simpler fabrications - a Motoman ArcSystem 2000 has been installed at Newfield for automating the simpler fabrication jobs, especially those that require only flat seams.

The cell is equipped with a UP6 robot and 1,000kg payload turntable in a single-lift cabinet complete with roof, pneumatically operated access door and interior lighting.

Direct drive on all axes assures rapid robot movement and +/-0.08mm positioning accuracy.

Binns said that for repetitive batch runs, components can be fixtured and welded faster and more consistently than a skilled welder can produce them manually.

Manufacturing cost is reduced, as the operator can clean and deburr parts in addition to loading and unloading them while the robot is welding.

The ArcSystem is therefore playing a key part in Newfield's strategy of cost-effectively driving up the amount of robotic welding on site to increase turnover without adding to the existing level of manual welding.

Nearly 40 line items have so far been produced, five of which have been reallocated from the other Motoman cells, as they did not need positioning during welding.

Overall the robot welding cells in the Sandbach facility fabricate some 200 line items.

All Motoman systems, including the one on order, have twin workstations that not only allow virtually uninterrupted production, but also permit different fabrications to be fixtured at each station.

It is Newfield's policy to run two jobs concurrently on each of its robot welding systems to increase flexibility of production, which is further enhanced by swapping fixtures between the different Motoman cells.

All jigs and fixtures are manufactured in-house, which takes cost out of the jobs and ensures quality and consistency.

Binns said: "In addition to having quantifiable production benefits, robotic welding has a further advantage in that customers are impressed when they see that degree of automation in our works".

He concluded: Furthermore, whereas the prospect of manual welding puts people off coming to work here, modern robotic welding does just the opposite - it attracts staff of a better calibre to our company.".

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