Washdown valve terminals keep dough rolling in

When filling machine specialist Apple Engineering was asked to develop an automated dough ball handling machine Festo pneumatic components were part of the recipe.

When filling machine specialist Apple Engineering was asked to develop an automated dough ball handling machine for a leading food processing company, the operational specification initially looked daunting.

The machine was required to deposit accurate amounts of garlic butter in the centre of each dough ball, and had to be capable of accommodating production rates of over 14,000 dough balls an hour.

Furthermore, it was to be installed at the wet end of the bakery production line - where it would be subjected to regular washdown - yet had to offer high availability to minimise production downtime.

Apple Engineering has built up an enviable reputation for supplying the food processing industry with filling machines that provide exceptionally high deposition accuracy.

When it was founded in 1985, this Hull-based company launched one of the most accurate and reliable volumetric depositors on the market, and has maintained this leadership position through aggressive research and development.

It now produces seven different sizes of volumetric depositor, capable of handling deposit weights from as little as 1g up to 2kg, as well as a wide range of associated automation equipment, and offers extensive custom systems capabilities.

In this case, Apple Engineering's customer - like many food processing companies with important brand reputations to protect - was keen to ensure that the dough ball filling machine would not introduce any health hazards into its process or impact on HACCP (Hazard Analysis Critical Control Point) compliance.

As a consequence, the company specified that all pneumatic parts of the machine must be manufactured and supplied by Festo, which produces components designed specifically to minimise the risk of contamination.

Typically, these include FDA-certified microbial growth-resistant tubing, cylinders with corrosion-resistant surface finishes, and components such as valve terminals that feature smooth enclosures and optimised spacing to prevent particle entrapment.

According to Steve Smith, Managing Director of Apple Engineering: "This particular application required a high performance and robust design, particularly as garlic butter is considered a 'problem product'".

"Because the filling system is used at the wet end of the production line, it is in a high risk area in terms of bacterial contamination".

"Also, dairy products such as garlic butter are very temperature critical; they need to be handled at the lowest possible temperature to minimise health risks and maintain product consistency, but this makes it far harder to pump and dispense them with accuracy".

The filling machine uses a nested conveyor to transfer dough balls from a buffer hopper at the end of the bakery's production line to the garlic butter injection stage; the conveyor is indexed to ensure that each batch of dough balls is accurately aligned with the machine's multi-injector depositor before the garlic butter is dispensed.

Apple Engineering and Festo collaborated extensively on the choice of valve terminals and cylinders for the machine.

Most of the cylinders are Festo DSNU models, with custom stroke lengths.

These small DIN/ISO6432 standard units feature very clean lines and high grade stainless steel piston rods, making them ideal for food processing type applications.

For the control valve terminals, Apple Engineering chose to use Festo CDVI models, which offer environmental protection ratings up to IP69K, have smooth easy-clean surfaces, and are designed specifically to tolerate the type of washdown chemicals used in the food industry.

As Andy Fraser, Apple Engineering's Technical Director, points out: "We selected CDVI valve terminals for several key reasons".

"The dough ball filling machine is subjected to rigorous cleaning at the end of every production shift, using aggressive cleaning fluids to break down greasy butter deposits and thoroughly sterilise the equipment".

"This is an extremely hostile environment for automation control systems, and the fact that CDVI valve terminals do not require a protective cabinet makes them very cost-effective and simplifies system integration".

"The valve terminals' ability to tolerate such a severe washdown regime is also a major contributing factor in minimising machine downtime after each production run".

"However, perhaps the most significant advantage of this washdown capability is that the valve terminals can be mounted immediately adjacent to the pneumatic cylinders, using very short air supply tubes".

"This reduces system losses and helps maximise the dynamic performance of this filling machine".

The filling machine was installed at the customer's bakery earlier this year.

Following resolution of a few teething problems during the commissioning phase it has proved to be highly reliable, with a performance that exceeds the original design specification.

Both Apple Engineering and its customer are particularly pleased that they chose to use Festo CDVI valve terminals for all the control functions, and consider that these components contribute significantly to the machine's usability and throughput capabilities.

So the next time you're purchasing Italian-style dough balls in a supermarket, spare a thought for how the garlic butter came to be accurately placed in the centre of each one.

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