Part of the High Value Manufacturing Catapult alliance of seven leading manufacturing research centres backed by Innovate UK, the Nuclear AMRC
(Advanced Manufacturing Research Centre) has at its heart an open-plan 5,000m2
workshop containing over £35 million worth of ‘state of the art’ manufacturing equipment tailored for nuclear industry applications.
Working with a range of ‘challenging metals’, including specialist steels and exotic alloys, its machine tools are ‘protected’ by Vericut CNC simulation and optimisation software from Hove-based CGTech Ltd
Located on the boundary of Sheffield and Rotherham — and sitting alongside other University of Sheffield centres including the AMRC, Castings Technology International and nearby AMRC Training Centre — the Nuclear AMRC operates from an 8,000m2
research factory where staff apply “innovative and optimised processes” in machining, welding, inspection and other key areas of large-scale manufacturing technology.
Andrew Wright, principal production engineer for the Machining Technology Group within the Nuclear AMRC, said: “Although we are the only Catapult centre focused on one industry sector, providing expertise in reactor structure manufacturing and decommissioning waste management, we also support wider UK industry with large-scale manufacturing challenges. Even if it is not nuclear, it is preparing large-scale components for machining where our specialities lie.”
One of the key drivers for the centre is to take concepts that have passed TRL (Technology Readiness Level) 1 to 3 through and beyond the next phase of TRL 4 to 6.
Generally, this requires a two-thirds-scale demonstrator that proves the necessary capabilities before progressing to full manufacture, and all the machine tools in the workshop have been selected to accommodate large components.
Mr Right said: “We have some of the biggest machining platforms available for R&D in the world, accommodating workpieces up to 50 tonnes. For example, our Soraluce FX-12000 can accommodate workpieces up to 12 x 5 x 5m, which is like two double-decker buses parked next to each other. Moreover, it can automatically change the cutting head to one of five different options, giving a very flexible manufacturing solution.”
Alongside the large Soraluce boring centre is an HEC 1800 horizontal borer from Heckert (this accommodates workpieces up to 3.3m in diameter, 2.5m high and weighing as much as 20 tonnes), a Dörries vertical turning lathe (VTL) that can turn-mill parts up to 5m in diameter x 3m high, a Heckert HEC 800 that can undertake heavy-duty machining in both the vertical and horizontal axes, and a DMG Mori NT6600 for large-capacity multi-axis mill-turning. A number of smaller-capacity machine tools are also used. Program verification
Because most of the parts machined by the Nuclear AMRC feature complex geometries and limited clearance for cutting tool access — and are often just a batch of one — there is no margin for error and ‘protecting’ the machine tools has become second nature for the engineers at the Centre.
Mr Wright said: “With CAD/CAM programs generated in-house, all of the tool-paths for our machines have to go through NC code simulation; and since we started back in 2012 we have worked with CGTech’s Vericut, as it is vital that all our programs are proven in a virtual environment before being applied to the workshop.
“We have detailed models and operational processes for each of our machines, and with Vericut we can simulate to make sure there are no collisions between the machine’s structure, the component and the fixturing; we can even simulate the cutting tool to make sure it will neither gouge the raw material or be impinged trying to access tight working spaces.
“We recently completed a client’s prototype part on one our largest machines. There was a minimum of clearance between the machine structure and the large component; and without an accurate digital twin of the machine, component and tooling this would have been a very-high-risk process.”
The Nuclear AMRC uses a variety of CAD packages — including EdgeCAM, SolidCAM and Siemens NX — as this allows the Centre to work closely with varied clients and ‘state of the art’ tool-path generation algorithms. “The dedicated Vericut interface for each of the CAD/CAM software systems means we can run both side-by-side with an uninterrupted flow of data, with seamless integration allowing the software to share our master tool databases and fixturing database.
“Vericut checks the actual G code that the machine will run so it provides the most accurate version of real-world events before they occur. We do not prove out any CNC code on the machine tools, everything goes through simulation.” Machining techniques
The team at the Nuclear AMRC is always testing new machining techniques that meet both the geometrical requirements of the components and process needs of the industry, as well as addressing new material challenges such as high-entropy alloys (these are formed by mixing equal or relatively large proportions of five or more elements).
Mr Wright said: “To fully support such new techniques we now use the Vericut Force module, which is ideal when considering aspects of tool-life; the nuclear industry is conscious of parts being damaged and tool wear is a factor.
“When we are looking at how to machine a component, the NC tool paths to be applied will be checked using the Force analysis module to look for excess loadings on the tools. We can go back, tweak and alter settings for the machining, change cycles or even software packages.
“We have been known to use a completely different CAD/CAM package to get the most suitable tool-path. For rough machining, we have found that the Force module is exceptionally good at narrowing down the best options. We are also looking to see that we are not getting overloads, not going too deep or too wide on any cutting path. Force is an important part of what we do now.”
“What we can do as a research centre using Vericut and Force is find out where the limits of a process are and retreat slightly. We then know it is safe to run up to these parameters while achieving a consistent tool life that is proven and predictable.”