Sheffield Forgemasters is the first UK foundry to adopt a state-of-the-art mould and core coating technology, further improving its high-integrity castings and creating greater efficiencies.
The technology enables Forgemasters to apply a coating of uniform composition and thickness to its moulds, used to form the largest and most complex steel castings in Europe.
The coating reduces preparation time, enhances casting surface finish and enables easier removal of refractory material from the casting. Installing the coating system at a six-figure cost is part of the engineering specialist’s on-going investment programme, which reached £50M in October and has seen the company plough all of its profits back into the plant, in order to capitalise on technology and skill to break into new markets.
Simon Alexander, foundry director at Sheffield Forgemasters, said: “It essentially enables us to create an even coating of the moulds and cores, and because the control system is automated, it eliminates manual preparation of the coating slurry. As the new process works on a closed system, we have also dramatically reduced the amount of waste slurry.”
The coating acts as a sealant and barrier between the mould and the molten steel and its use reduces the amount of work required to clean and finish each casting once it is removed from the sand and resin mould.
Forgemasters’ new coating initiative is a two-part system consisting of two computer controlled coating preparation plants by Foseco Ltd, designed to deliver slurry coatings with consistent viscosity and density, and a dedicated core and mould drying oven, supplied by Omega Foundry Machinery Ltd, to control the drying of the coating.
Forgemasters use a water based zircon slurry, which used to be mixed by hand to dilute it followed by manual quality control testing. This inevitably lead to inconsistent coating quality and thickness. Seasonal temperature variations in the foundry also complicate the traditional manual approach. In the new system, the slurry is temperature controlled and automatically diluted and tested. It is then pumped to an application nozzle for the operator to direct over the sand mould. The uniform composition and density of the slurry enables ‘flow coating’ of cores and moulds to achieve a constant and accurate thickness layer.
Any excess coating is collected and recycled. Trials are now taking place to develop spray application for use on large moulds or core sections that cannot be directly flow coated. The system’s mobile oven reduces the drying time for coatings from several days to an astonishing four hours from start to finish. Mounted on rails, the oven is able to service four separate areas, each measuring 4m2 , where items are placed ready for drying.