Method Engineering and Process Modelling
Around 100 people attended the EICF Technical Workshop on Method Engineering and Process Modelling in Sheffield on 12th and 13th May. During the two-day event, delegates from around the world learned the complexities of effective method engineering which requires an in-depth understanding of fluid dynamics, heat transfer and alloy solidification.
Speaking prior to the event the EICF’s Carlos Olabe told Foundry Trade Journal:
In recent years the design of gating systems has been assisted by the development of computer aided process simulation. These process models, substantiated by an adequate database, are now sufficiently mature to enable skilled foundry engineers to design effective gating systems and to simulate mould fill and solidification in the ‘virtual world’, whilst minimising the number of trial iterations required in the ‘real world’. Also, predictive process modelling can assist in predicting grain size, residual stresses and part-deformation providing a significant amount of information to define a sound product engineering definition.
Manual Caballero of Ecrimesa explained how MIM is pushing investment casting towards larger castings. However, he warned that the industry needed to push the limits to improve the quality. He said: An increasing number of parts that are less than 50g are moving towards MIM I would say as many as 95 per cent will soon be produced by this method. For example, small turbine components for future automotive requirements will be produced using MIM as there is a growing demand to move to a high quality, complex part. But batch size is particularly important when making the move to MIM. However investment castings in the region of 1g to 30kg are more likely to remain as investment castings.
He said that currently it is not possible to produce all alloys in MIM. We need to meet sintering tolerances, he said. The maximum is ten degrees so this is a limitation for MIM.
In their presentation on ‘Improving the mould fill simulation capability and its role in inclusion reduction’, Xabier Esquisabel and Ignacio Dominguez of PCB used the sporting analogies of football and cycling. They considered the TRL technology relationship level to look at what they called ‘defectology’. They said the solution was well developed for diecasting and sand casing but that more needed to be done for investment casting.
Dr Julio Aguilar of Access said the casting engineer, simulation engineer and software developer needed to work very closely together. In a presentation entitled: ‘Numerical prediction of misruns and porosity for investment casting applications’, he said it could take up to seven days to simulate a casting cluster of 12 blades which resulted in the need to rely on other tools such as rapid manufacturing. The situation can be timely and unreliable every metal has a different morphology and things like gas permeability of the mould have to be taken into account.
Access uses a two-chamber crucible and tundish system with a rotating shell mould to the blades, under relatively low pressure. He told delegates: The orientation of the blades is also relevant to push the melt in and avoid misruns.
To optimise pouring and ensure the whole melt goes through the centre of the funnel, the crucible is tilted. By using centrifugal casting, the parts are filled correctly but the filling time can be too long for us so we have changed the system to reduce the filling times from 1.4s to 0.9s.
The production of a shell mould and casting takes three weeks, simulation takes five days. Numerical simulation pays important attention to points which we find difficult to predict so it has helped us improve our system. However, the meshing system has to be fast enough and fine enough to solve thin part issues.
The delegates were particularly impressed with the presentation from Vanessa Indrizzi, a PhD student at the University of Birmingham, who described a project and research into ‘Improving the accuracy of investment casting mould simulations.’ She discussed two techniques tilting the crucible and the pouring of the metal.
Sabina Gucci of Precicast SA explained how the company, which produces over 300 products, uses modelling at every stage of production. She said: We have no time to modify dies so time constraints are vey limiting, thus pre processing data is a critical matter.
Inspection Techniques Move Forward
Stephanie Adolf of GOM mbH warned: “Companies start thinking very late about quality control in the casting process chain.
She informed delegates about the products produced by GOM to help in the field of optical metrology such as 3D co-ordinate measurement techniques, digitising and deformation measuring.
She said: The manner of inspection is changing and we now only require a few functions. Measuring reports are also being shortened.
The most advanced inspection possibility currently is FTA/PMI where the CAD department is forced to think about the quality control in your part this is a great time saver. By staying within the digital world you don’t have to deviate into analogue. In the next five years, FTA/PMI will be the way forward and will be used more and more.
EICF president Steve Irwin said, as a company, GOM was an absolute game-changer for the investment casting industry.
Marco Aloe from ESI Group looked at simulation trends of the future. We try to address many points with the virtual world. We have developed optimisation in the software instead of virtual predictions. In doing this we ask the software to tell us the most influential parameters then we optimise these, he said.
He shared the details of four major projects with delegates including how heat treatment framework has been added to the software to enable it to now measure after a part has been heat-treated.
He also revealed that the company had further developed and evolved its centrifugal flow model and was investigating developing an electro magnetic model for induction heating/heat treatment. The latest project ‘AMAZE’ looks at developing a modern technology to predict the lack of fusion or distortion.
The objective of the workshop was to illustrate in a practical manner the importance of method engineering and the excellent support provided by process modelling tools. Other speakers were: Badarinath Kalkunte of ESI Group, Paul Tennant from Rolls-Royce plc, Will Jeffs from Castings Technology International, Steve Leyland of Uni-Pol Group and Dr Antton Melendez from TECHNALIA.
Profit From Our Expertise
On the second day of the Method Engineering and Process Modelling Workshop delegates toured the facilities at Castings Technology on the Advanced Manufacturing Park (AMP).
Welcoming delegates, CT’s Barry Jackson explained how the organisation is now well and truly back in the casting community fold and now has a good balance between commercial and research strategies thanks to the organisation’s technology, expertise and long-standing services to the cast metals supply chain.
CT is currently undertaking a‚¬20m investment programme with the support of aerospace technology funding, which includes the building of a new 1000kg titanium metal melting facility which will be the largest in the world, a large scale shelling facility, the re-location of the laboratories, a 1200m2 extension to house a vacuum heat treatment furnace, and a new fully enclosed facility for the finishing of large castings.
Having moved to the AMP in 2006, CT has continued to develop its facilities. CT can now take part in many collaborative funded projects through organisations like Innovate UK and EPSRC.
CT currently employs over 60 engineers and cast metals experts and has 175 member companies with 70 per cent being foundries and foundry supply companies.
For many years, CT has developed new near net shape processes and a variety of technology packages such as Replicast®, Repliwax®, MEGAshell® and Patternless® and it was the ideal works visit for many of those on the workshop.
Jackson said: We have witnessed a sharp uptake in demand from small foundries and we have various technology support packages. In addition we have an operational facility where we can offer process technology demonstrations, and design and get involved in pre-production of castings in high performance alloys. We can also help with the migration of proven designs, materials and manufacturing techniques basically we can help take a company from blue skies thinking to actual production.