A process that until recently defied automation has finally been brought into the 21st century by systems integrator Clint Johnson of Control Freaks, who has developed an all-Mitsubishi Electric solution. Johnson has automated a machine for producing biscuit crumbs, breakfast cereal and snack foods, replacing a labour intensive manual process with one that guarantees consistent results. "The basic process is to mix ingredients into uniform pellets and dry them," explains Johnson. "Sounds easy enough, but the devil is in the detail." Getting a consistent mix was difficult, and the liquid content needed to form pellets tended to cause the entire mix to clag up into one stodgy amorphous lump. The system includes two horizontal spiral blade mixers. These are run backwards and forwards at different speeds to achieve a thorough mix. "There is quite an art to the speed profiles we use, each product seems to require a unique pattern of fast and slow, forward and backwards. We have stored those profiles as recipes on a Mitsubishi FX3U PLC (programmable logic controller), which controls a number of 15kW E700 and D700 variable speed drives on the mixer axes over an RS485 network."
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