Reclaiming resources

A new integrated production system could see high-value machine parts remanufactured on site in a single process, cutting costs and reducing carbon emissions, according to the UK consortium working on the initiative.

The Reclaim project (Remanufacture Using Laser Cladding, Inspection and Machining) is led by CAD/CAM company Delcam, working alongside Renishaw, Electrox, TWI, Precision Engineering Technologies, Cummins Turbo Technologies, Airfoils Technology International (ATI) and De Montfort University in Leicester. Its ultimate aim is to incorporate a string of processes that are currently carried out at different locations and often by different companies — for example, part inspection, machining preparation for welding, welding, finished machining then final inspection — into a single machine that takes up no more than 2m2 of shop-floor space.

Prof David Wimpenny from De Montfort University, which initiated the Technology Strategy Board (TSB)-funded project, said: 'Remanufacturing is a very resource-efficient way of recycling and prolonging the life of a component — instead of reforming a part from scratch, you apply the repair just where you need it.

'Remanufacturing is widely used in Asia and the US, but it has been a bit of a Cinderella industry in the UK. But as there is now an issue with resources and energy, we have got to switch to a more resource-efficient approach. If the original part, or 80 per cent of it can be reused, why should we throw it away? It is a more sustainable manufacturing approach.'

The process Reclaim is proposing to replace is currently highly labour-intensive, with skilled engineers deciding by sight whether a part can be remade, then manually cleaning it, welding it up, dressing it by hand then grinding it back to the original shape.

By contrast, according to the Reclaim team, the new process could apply the same level of discipline and control to remanufacturing as is currently expected in original manufacturing operations.

After being cleaned and manually inspected to see if it is suitable for remanufacture, the component in question would be put into the machine. Inside, the part would be inspected automatically, the damaged area precisely quantified using inspection heads developed by Renishaw, and then Delcam software would be used to develop the machining-preparation path.

Delcam's CAM package would then be used to develop the cutting path for the CNC machining tool to take away the surface metal to prepare it for welding. The same software would be used to control the laser cladding, carried out by a specialised laser cladding head designed to produce high-integrity repairs. The machining tool would be used again to remove excess metal to take it back to the original CAD data, and the part is then automatically re-inspected.

Wimpenny said: 'You would take off the machine something that looks like a new part. It also prints out an accompanying quality integrity report for that part.'

The device will be built based around a standard milling machine that has been adapted with some additional part-handling features. The core of the machine would be a standard three- or five-axis milling machine, depending on the complexity.

Wimpenny added: 'We are not trying to build a completely new machine tool, which would cost a fortune, but build it around a standardised production machine that has been adapted for the purpose. This keeps it low cost and allows manufacturers to adapt their existing milling machines for the Reclaim process.'

Critically, the machine could be adapted for a variety of different parts, so a key element of the project is to work out how the batch size affects the economies of scale. In remanufacturing, although the number of each different part to be repaired in a given period can be roughly estimated, it is seldom entirely predictable. Wimpenny claimed the machine would even be able to identify parts without a serial number and adapt the process to them using Delcam-developed software.

The target market for Reclaim will be specialist remanufacturing companies that want to upgrade from their manual process to using one of the new machines for higher-value products — £20 plus — for automotive, aerospace and defence applications. Project partners — including remanufacturing company Cummins, and ATI, which specialises in the repair and overhaul of turbine blades for the aerospace industry — are giving their input on what they would want out of a finished product.

Wimpenny said: 'We know the demand is there. In times of recession, people become tuned into saving money, and even a 20 per cent saving on a part can become very attractive to an end user. Not only will there be a reduction in cost, there will also be an improvement in quality and consistency of quality as you are not relying so much on manual processes.'

There could also be long-term environmental benefits, according to Wimpenny. If, for example, the piston on a truck needs to be repaired and there has been a slight change in piston-crown geometry that improves efficiency, this could be built into the next remanufacturing phase, allowing a certain degree of evolution of products toward the latest design efficiencies.

Among the other project partners, Electrox is designing a new cladding head for the process that will be able to cope with the various geometries that are being thrown at it. It will need to be designed to be compact enough to fit into a standard machine tool and get into all the tight corners of parts that have been damaged.

Precision Engineering Technologies, a small machine-tool integrator based in Leicester, will use its experience in adapting CNC machining tools to new applications to make the Reclaim system retrofittable to existing equipment.

Renishaw has a wealth of expertise in metrology and inspection, and is currently involved in selling equipment to companies, such as Rolls-Royce, which have high-end remanufacturing requirements.

Delcam has experience in generative machining, which involves inspecting a part and then adapting the cycle according to the results, as opposed to machining blind from CAD data. Wimpenny said: 'One of the problems is very few parts — such as turbine blades — actually conform to the CAD model as they have usually been hand-settled as part of their original manufacturing process. When we rebuild them, we have to include that element of variation in the actual product and adapt the process accordingly.'

De Montfort launched the programme and its role is working out how much energy and materials could be saved using the Reclaim process and what the cost benefits are. It is also involved in developing the cladding head with Electrox, using the specialised prototyping machines and design capabilities at the university.

The project started in September 2008 and will run for three years with the aim of launching an exploitable project the following year.