Process control at Warrnambool Cheese & Butter

Warrnambool Cheese & Butter's cheese processing facility is one of the most modern in Australia. With daily capacity for input up to 1.4 million litres of milk, the processing facility manufactures up to 145 tonnes of cheese in a 24 hour cycle. Primarily producing standard cheddar, the facility also produces low-fat cheddar, skim milk cheese, gouda, Romano and Swiss-style cheeses.

The Warrnambool factory sells wholesale cheeses to domestic customers and exports approximately 40% of output to Japan, Korea, the US and Europe and south-east Asia. To produce this volume of cheese products, the Warrnambool facility operates 24 hours/day during peak periods.

Warrnambool Cheese & Butter's consolidated Australian processing facility in Victoria has specified Bürkert pneumatic actuation valves, following the success of an original trial installation. Established in 1888, the Warrnambool Cheese & Butter Factory at Allansford is Australia's oldest dairy company.

The original Bürkert pneumatic valve bank Type 8640 installed at the Warrnambool Cheese & Butter processing centre is in an outdoor stainless steel enclosure. The valve panel pneumatically actuates process valves controlling hygienic flow, including support Type 2000 Bürkert process valves, to unhomogenised milk and cream storage tanks approximately 100 m3 in volume.

"The primary benefit we sought in using Bürkert's pneumatic valve banks was quality and robustness of the units to avoid air leakage, and give more accurate process control," said Warrnambool Cheese & Butter maintenance manager Mr Wayne Moore.

"Working together with Sam Coleman, we trialled the Bürkert pneumatic valve systems." Sam Coleman is the sales representative for Plant and Control Instruments (PCI), the local distributor for Bürkert Fluid Control Systems based out of Geelong.

The success of Bürkert's trial pneumatic pilot valve panels at Warrnambool Cheese & Butter was followed by more Bürkert pneumatic panel installations. These systems are primarily in the cheese-making facility and CIP, built as part of a major site expansion in June 2005.

Encased within stainless steel enclosures, the pneumatic valve panels at Warrnambool's cheese processing centre incorporate between 12 and 56 individual pneumatic valve units.

Electrical connectivity of the valve bank is achieved via fieldbus interface, common connection (parallel connection technique) or multipole interfaces. Bodies and connection modules are made of high-quality plastic (polyamide) and are easy to assemble by means of the built-in snap connectors. The module connection points are typically the site of pneumatic valve air leakage. Bürkert's specially engineered snap connectors and seals have built-in allowances for valve movement and friction, which significantly reduces the chance of air leakage. The leakage of air from pneumatic controls alters open/close periods and thereby diminishes the accuracy of process control.

Bürkert's pneumatic valves may be added to the banks in multiples of two and eight single valve units, with up to 24 valve functionalities per unit. Each unit has a flow rate to 300 L/min, low 1 W power consumption and is rated for 100% continuous duty cycle. Bürkert's valve panels are IP20 standard, with IP65 and IP67 available (with optional cable plugs). The valve units operate in ambient temperature -10 to +55°C, and pressure from vacuum to 16 bar.

The valve units are just 11 mm wide, with a modular configuration engineered for trouble-free adaptability to processes and retrofitting. This high degree of flexibility is complemented by hot-swap capability, necessary for 24 hour operation at the Warrnambool Cheese & Butter site.

The June 2005 Warrnambool factory upgrade introduced advanced process automation to Bürkert's 8640 valve banks directly integrating to the site-wide industrial network. Warrnambool's network facilitates monitoring and regulation of all manufacturing from centralised control hubs, for trouble-free process management. Close monitoring of processes and accurate control at all stages is vital to the production of uniform batches.

Linked to Warrnambool's site network, Bürkert's intelligent electronic feedback positioner Type 8630 is used with high-specification hygienic valves for accurate control of process inputs and flow.

Mr Moore said that precision process control is the cornerstone of repeatable batching, vital to high efficiency and consistency of the final product.