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Mitsubishi Electric has revealed how its automation products are enabling Omega Foundry Machinery to offer temperature compensation and an enhanced user interface on its sand mixers.

The ‘sand’ used for casting operations in foundries is actually a mix of sand, resin and catalysts that aid setting.

The proportions of the ingredients have to be accurately controlled in order to achieve the optimum setting qualities needed to ensure that sand moulds consistently produce high-quality castings.

The proportions of the ingredients required are, however, dependent on the ambient temperature.

Omega Foundry machinery has long offered its customers the option of automatic compensation for this variation, but recently decided to extend this benefit to all purchasers of new machines, without increasing its prices.

To do this, the engineers at Omega knew that it would be necessary to make savings in other areas and turned their attention, in particular, to the automation system used on the machines.

At the time, this comprised a programmable controller (PLC) and several variable speed drives, the exact number depending on the configuration of the machine.

To provide access to the drives for the purposes of changing operating parameters, they were mounted through an aperture in the front door of the control panel and covered with a lockable cover – an arrangement that involved complicated and costly metalwork.

The machine’s user interface was principally made up of pushbuttons, switches and indicator lights, augmented by a small, text-only message display.

All of the interconnection between the major components used conventional wiring.

Discussions with application engineers at Mitsubishi Electric suggested, however, that the company’s automation components – in particular the GT1155 colour terminals, FX-series PLCs and D700 inverters – would make a more versatile and cost-effective design possible.

The key would be the use of the RS485 multi-drop connection feature supported by these devices, which would, in effect, allow them to be daisy-chained together with a single network cable, eliminating much of the wiring in the control panel.

In addition, the GT1155 HMI terminal, with its full graphical support and associated keypad, would replace almost all of the pushbuttons, switches and indicator lights.

It could also be programmed to follow the operating parameters of the D700 drives to be accessed via its screen and keypad, so the expensive mounting arrangements required to allow direct physical access to the drives would no longer be needed.

Mark Lewis, technical director of Omega Foundry Machinery, said: ‘Presented with these potential benefits, it was an easy decision for us to redesign our automation system around the latest Mitsubishi products.

‘The savings we made, combined with the attractive pricing of the products themselves, made it possible for us to achieve our objective of offering temperature compensation as a standard feature on our machines.

‘In addition, the large memory capacity of the FX PLC and its convenient programming system have made it possible for us to develop one single program that we use for all of our mixers – we simply enable and disable blocks of software according to the machine’s requirements.

‘With just one program to maintain instead of dozens, we can concentrate our efforts on upgrading performance and developing new features,’ Lewis added.

For Omega’s engineers, loading the resulting upgrades into machines that are already in the field is a quick and easy task, as the FX-series PLCs support standard Flash memory cards for program transfer.

The GT1155 HMI terminal used in the new machines has opened the door to further important benefits, according to Mitsubishi Electric.

Its graphical display is intuitive for machine operators and provides them with detailed real-time machine-status information.

The display is also used to call the operator’s attention to alarm conditions, such as low air pressure or low sand levels.

In the event of a problem, it can be used to access detailed diagnostic information.

Mitsubishi Electric Automation Systems

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