Saving dough: The built-in programming language and analog I/O of Baldor's SmartMove motion controller is helping eliminate scrap on a hearth bread and roll processing line for the leading USA baker, Pepperidge Farm.

Dough is tricky stuff to handle, so much so that it will move of its own accord when it's being conveyed along a process. So, photoelectric eyes are often used to detect if dough balls are off-line and could cause a problem. But this technique is so coarse that slightly off-line dough can end up being stretched and cut into unacceptable shapes, creating scrap.

This was the situation on a hearth bread and roll line at the Lakeland, FL plant of one of the USA's major nationwide bakers, Pepperidge Farm. They asked automation experts PACE to devise a better control system. PACE engineer Brian Romano decided to employ an LED beam array - a component used in light curtain safety systems - to provide precise data on the actual position of the dough ball, and then to correct the problem by shifting a conveyor section in real-time using a servo-driven cylinder.

Baldor's SmartMove was a natural choice for the motion controller, because of its built-in analog I/O, and for its Mint programming language: "Mint really makes a difference to productivity" says Brian Romano. "You're using clear high-level commands, just like BASIC but with extra motion functions, and you can add comments to document programs." This is almost revolutionary compared to most other manufacturers' products, he notes, which often involve assembler-style programming using cryptic mnemonic codes, and sometimes highly restrictive program structures - making systems more difficult to modify and maintain. On average, Mint can reduce program size and implementation time by up to a third, he estimates.

At Pepperidge Farm, a 100-line program is loaded into SmartMove's non-volatile memory to automatically correct dough position on a short conveyor section before it reaches the 'stretcher board'. This program detects the edge and the width of the dough ball as it passes the beam array, then uses Mint's math capability to compute any necessary correction, and move the servo-driven cylinder.

Baldor's simple operator panel is connected to the SmartMove to provide some basic controls over the process, and to display error messages. Thanks to built-in operator interface keywords in the Mint language, this was implemented using just 20 lines of code: a half day's work for PACE even though this was the first time they had used this accessory. This level of flexibility is unusual in the servo controller industry, Romano notes; other controllers typically require you to source your own man-machine interface components and write custom code for them using a serial link.