Deritend to maintain Royal Mint's induction furnaces

Deritend's Induction Services Division is based in Walsall, West Midlands. It has just been awarded a two-year contract by the Royal Mint to service and repair induction melting equipment used in the furnaces at the production facility in Llantrisant, South Wales. The reasons given by the Royal Mint for giving the contract to Deritend are the ability to deliver on short lead times, combined with extensive experience and a technical understanding of induction furnace technology.

The Royal Mint uses some of the most advanced coining machinery available, with the Melting, Rolling and Blanking Unit housed in one of the most up-to-date foundries in the world. Strips of metal are continually cast from large electric furnaces, reduced to the required thickness in a tandem rolling mill, and transferred to large blanking presses. The blanks are then softened and cleaned in the Annealing and Pickling Plant before the final processing in the Coining Press Room. Here the blanks are fed into coining presses where the obverse and reverse designs, as well as the milling on the edge, are stamped onto the blank simultaneously.

20,000 tonnes per year, 700 coins per minute

The Royal Mint operates 24 hours per day, seven days per week, using four large furnaces with a combined capacity of over 20,000 tonnes a year. These furnaces feed the coining process that can produce over 700 coins per minute. Because of the speed and continuous nature of the operation, maintenance windows are time-critical. Deritend Induction Services proved itself on several occasions prior to the contract being signed by delivering fast turnarounds on the repair of coils for both a Wertli induction channel furnace and a Birlec induction furnace.

Mike Moore, of Deritend Induction Services, describes the induction heating method as a non-contact process where heating takes place in a single loop (or channel) that passes around the coil and, at the same time, through a laminated steel core. This forms an electrical circuit when the loop is filled with molten metal. As soon as power is applied to the coil, a strong electromagnetic field is created, causing current to flow through the already molten steel and further heat it. As hot metal rises and leaves the inductor, it raises the temperature of the entire molten charge.

The intense nature of the foundry process eventually wears down the laminations and the coils, which have to be repaired or replaced. The challenge then is to have the correct materials and skills to be able to return the furnace to a fully operational state as quickly as possible.

Like any other manufacturing operation, it is important the Royal Mint keeps its plant operational. This contract enables Deritend to plan for routine servicing, put more resources into preparing for emergency repairs, and ensure a high level of service 24 hours per day, helping the Royal Mint meet its production targets.

An online portal has also been set up by Deritend to allow staff from both Deritend and the Royal Mint to track and monitor the maintenance cycle of critical components in the furnaces such as coils. By building up a repair history, it will be easier to predict and plan further ahead for routine maintenance and should also highlight any frequent problems that can then be investigated and proactive countermeasures employed to reduce occurrences.