TWI services for companies in the
UK's Yorkshire and Humber region
Case studies
New Contract, New Market Sector
Warming to Friction Stir Welding
Plastics joining at the speed of light
Adhering to sound advice
Game, set, and match...sporting goods business gets stuck in
Burning desire to succeed
Laser Welding for Pressure Vessel and Pipework Fabrication
New Contract, New Market Sector
| Hydraulic Control Unit produced by Denley Hydraulics |
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Yorkshire-based Denley Hydraulics is profiting from a new business stream it has been able to enter with technical assistance from materials engineering specialist TWI. The opportunity to break into a new market sector was too tempting for the hydraulic systems manufacturer to overlook, particularly when a large contract was also on the cards.
Denley Hydraulics, based in Heckmondwike, West Yorkshire, design and manufacture complete hydraulic systems, including valves, cylinders and electrical controls. They tendered for a job from a major oil company, and won the contract, with the pre-requisite that they attain pertinent welding qualifications to satisfy the client's stringent quality system and high standards.
The order was for the production of hydraulic control cabinets. Fabrication of the entire unit takes place in the workshop before it is taken into the field for connection to the processing system - an operation that takes little effort, thanks to the bespoke design of the unit.
Having already provided support for Denley in re-qualifying their welders for their on-going orders, TWI experts working from its South Yorkshire base, were able to provide onsite technical and practical assistance for the development and subsequent qualification of welding procedures, and the qualification of their welders for this specific application. The areas of interest for qualifications were the tungsten inert gas (TIG) shielded arc welding of thick wall 316L austenitic stainless steel pipe in position, and metal active gas (MAG) shielded arc welding of stainless steel plate to make up the hydraulic unit and the pallet respectively.
Having proved that their welders had the ability to produce high quality welds using the required techniques, Denley were confirmed as suppliers of the hydraulic units for the project, and were awarded the lucrative contract worth £800k, with the knock-on effect of safeguarding six jobs within the company.
TWI assisted Denley Hydraulics through a technology transfer programme supported by the European Regional Development Fund, Objective 1 South Yorkshire and Yorkshire Forward, which allows TWI to support small and medium sized companies in the Yorkshire and Humber region.
If you think your company could benefit from similar assistance, please contact TWI Technology Centre (Yorkshire) on 0114 269 9046.
Warming to Friction Stir Welding
| TWI's Nathan Horrex examines a number of friction stir welded panels, assembled as they would be for the cladding of a building |
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A Leeds based manufacturer of solar assisted heat pump systems improved quality and examined the potential to cut costs by using innovative welding technology, following feasibility trials by TWI under a regionally funded business support programme. Endoenergy Systems Ltd are co-ordinating the Endohousing project - an initiative funded by the European Commission under the Energie Programme to investigate using renewable energy sources to supply heating and hot water in houses.
Endohouses are designed to demonstrate the potential for making major savings in space heating and cooling costs in houses using the endothermic technology. A key feature of the energy saving system is the array of liquid filled aluminium panels that act as solar energy collectors and heat exchangers. These panels can form the roof of the house, wall cladding, or could be a standalone structure. Further information about these thermal systems can be found on the Endohousing website: www.endohouses.com.
The panels are constructed from aluminium extrusions with end-caps welded on to seal the units, and manifold connections to allow circulation of the liquid around the system. The standard method of fabrication of the panels is TIG welding. However, the end product was not totally satisfactory, in terms of cosmetic appearance and weld integrity. Through the FriSC programme, TWI was able to offer Endoenergy the opportunity to fabricate the panels using friction stir welding.
The scope of the work included:
- Designing the end-cap joint
- Determining the tool design and welding parameters suitable for the fabrication
- Designing the fixture for holding the assembly during welding
- Completing welding trials
- Testing the welded panels
- Continued support after the completion of the programme, including provision of the process parameters required to produce satisfactory welds.
Success at each stage of the work demonstrated to Endoenergy that friction stir welding is a viable alternative for the fabrication of their panels, with several advantages over TIG welding, including ease of automation, speed of fabrication, minimal cosmetic post weld finishing operations and appearance of the finished weld.
The FriSC programme, supported by the European Regional Development Fund, South Yorkshire Objective 1 and Yorkshire Forward allows TWI to provide free and subsidised technical support to small and medium sized companies in the Yorkshire and Humber region, which, in the case of Endoenergy, equated to a £15,000 product development programme.
Plastics joining at the speed of light
A Leeds-based manufacturer is boosting competitiveness by adopting advanced laser welding technology. Barkston Plastics has reaped the benefits of free advice available through the Joining Forces Yorkshire and Humber technology transfer programme.
The company recently identified a need to improve the reproducibility of the production of a range of polypropylene tanks used to contain liquids in photographic processing equipment, and so called on the expertise of TWI to help.
The tanks are currently assembled by attaching end plates to a formed cross section using manual hot-gas welding - a labour intensive operation, which is dependant on skilled technicians.
Tony Blackmore, Technical Director at Barkston, commented, "Because customer demand had trebled in the past year, it was imperative that the company reviewed alternative welding techniques. Barkston required speed, reliability and an automated process."
An initial Product and Process Review identified a number of possible welding methods. A follow-on Feasibility Study then demonstrated that laser welding could match the performance of hot-gas welding, with greater reliability, and offer an improved appearance to the components. Finally, a mini R&D project moved this process closer to routine production.
The R&D work explored conventional laser welding and also looked at applying the innovative Clearweld ® laser process in tests on samples provided by Barkston. It confirmed that laser welding was suitable and defined the best operating procedures.
Although equipment costs are higher, the resulting quality and capacity improvement is enough to show that the process is extremely promising for full scale production.
The benefits of the laser welding process for Barkston are:
- Increased automation allows improved quality and better reproducibility.
- Continued design flexibility for the polypropylene tanks. Additionally, a laser welding system may be used for other product lines.
- A cleaner and more efficient process, because molten plastic is contained within the joint, and the only plastic melted is that needed to create the weld.
- A significant reduction in the time required to weld a component.
Barkston is currently reviewing the options with its customers, with the objective of manufacturing demonstrator parts in a production environment.
TWI's help was under the Joining Forces Yorkshire and Humber technology transfer programme funded by Yorkshire Forward and Objective 1. The programme aims to boost growth, competitiveness and innovation in the region's engineering manufacturing companies.
Adhering to sound advice
| HVOF spraying system |
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When a leading surfacing specialist found difficulty in executing bond strength trials on high velocity oxy-fuel (HVOF) coatings, it turned to TWI for a solution to its difficulties.
The company's coating adhesion tests had failed because it was unable to obtain an adhesive with sufficient bond strength to test the coatings to the exacting standards of ASTM C633-01.
As part of TWI's Joining Forces Yorkshire and Humber programme, Scarborough based Dowding and Mills contacted TWI to accept its offer of a Product and Process Review and Feasibility Study, free direct technical support.
The task the company faced corresponded closely to an area of expertise held by TWI's surfacing team. It involved applying a tungsten carbide cobalt chromium coating to mild steel test coupons using high velocity oxy-fuel spraying. The ultimate objective of the work was to demonstrate that the coating would adhere to a substrate material used in fan manufacture.
So, sourcing an adhesive with sufficient bond strength to test the coatings proved crucial. Without this vital element, the joint fails between the adhesive and the coating. To test the coating properly the joint should fail between the coating and substrate.
TWI was able to provide the very high strength adhesive and, using its Instron 8500 test machine, successfully carry out the tests to the specification.
Before it consulted TWI, the client company was achieving adhesive strengths of about 8800psi. The minimum requirement for an HVOF coating is 9500psi. The strengths achieved by ten tests following TWI's work averaged well over 10000psi.
TWI's help was available to Dowding and Mills under the Joining Forces Yorkshire and Humber technology transfer programme. The programme aims to boost growth, competitiveness and innovation in the region's small and medium-sized companies.
Game, set, and match...sporting goods business gets stuck in
Goose feathers and cork seemed like a rare choice of engineering materials to TWI, when it was first approached by a company under the Joining Forces Yorkshire and Humber programme.
| The oversized shuttlecock - one of the more unusual joining applications TWI resolved with a Product & Process Review |
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But to its client, Echelon Sport, one of the world's leading shuttlecock manufacturers, they are everyday materials. So when it presented TWI with a unique joining problem, the challenge was irresistible.
The company is in the early stages of creating a variant to the game of badminton. It's a scaled-up version of the indoor game and uses bigger and heavier shuttlecocks ideally suited for use at the beach and park, where wind considerations can seriously put you off your stroke.
For manufacture of its range of conventional shuttlecocks, several methods for joining the flights to the nose are already in use. One of the most successful is a mechanical push fit which is particularly well suited for joining nylon flights to the cork or synthetic polymer nose.
The nose deforms easily to accommodate the appropriately shaped flight base and springs back to complete the mechanical lock.
But for the up-scaled outdoor version, Bigmington as it's known, a new and unique set of problems presented itself. TWI was asked how to join the large spherical polymer foam nose of the oversized shuttlecock to its equally oversized nylon flights. Free technical support from Joining Forces enabled Echelon to review and investigate their options.
The push fit approach was not sufficient to retain the two components completely and a hot melt adhesive looked to be the most likely and the most cost effective solution.
Further investigation into how the adhesive should be applied concluded that by using simple tooling, a gun or dispensing arrangement could be used to fill the 25mm deep recess in the nose, and allow the flights to be inserted while the adhesive stayed molten.
The hot melt adhesive solution has much to commend it to the client. It requires a short hardening period, the capital equipment is inexpensive and cheap to run.
On top of these basic requirements for cost effectiveness, the process demands very little operator training and is easy to stop and start during production.
TWI's help was available to Echelon Sport under the Joining Forces Yorkshire and Humber technology transfer programme. The programme aims to boost growth, competitiveness and innovation in the region's small and medium-sized companies.
Burning desire to succeed
A visit to Bray Burners of Leeds by Geoff Eames of TWI Technology Centre (Yorkshire) showed that interest in the help to be gained from a Product and Process Review was strong throughout the company.Bray Burners make many burner types, using various joining methods. Seeking advice on joining technology for a new type of cylindrical burner, the main thrust of the review was to look at the TIG welding process used to join stainless steel cylinder butt joints and end caps, and resistance welding for cylinder to flange applications.
| TIG welding of cylindrical pre-mix burner |
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The primary aim was to obtain the optimum production parameters during the prototype stage.
Advice was given on lengthening electrode tip life and angle by better gas coverage. This also served the purpose of improving cleanliness of the HAZ area.
MAG welding of venturi to the body flange resulted in an oversized weld so it was recommended that TIG welding is a better process for this application.
Such changes, while not major, result in real benefits to the whole production process thus improving productivity and profit margins.
Technical Manager for Bray Burners, Eddie Hart was particularly pleased with the help received, 'Working with TWI has significantly improved our understanding of welding processes and their sensitivity. TWI has successfully directed suggested improvements to increase product quality and reliability'.
TWI's help was available to Bray Burners under the Joining Forces Yorkshire and Humber technology transfer programme.
Joining Forces Yorkshire and Humber aims to boost growth, competitiveness and innovation in the region's small and medium sized companies. For more information and how your company can benefit, contact - TWI Technology Centre
(Yorkshire) Ltd on 0114 269 9046 or e-mail:
richard.smith@twi.co.uk.
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