Doughnut manufacturer gets a rise out of Siemens equipment

Just how is it possible to extrude, cut, bake, fry, glaze and cool over 3000 doughnuts an hour? According to Krispy Kreme, a company that has been producing and retailing doughnuts to the general public from outlets around the world since 1937, the answer is to use a totally integrated automation solution from Siemens, as it is now doing at an increasing number of its UK facilities.

Krispy Kreme selected Siemens after evaluating automation suppliers, their products, services and global presence .The selection was based upon which company best fitted their business requirements for their planned entry into overseas markets.

As part of the expansion a number of new UK facilities were established to meet growing demand for its products on this side of the Atlantic. The individual units that make up the doughnut ‘production lines’ are shipped from the US to the UK. The production line modules are then carefully removed from its containers and moved into location, which can either be a complete new building or an in-store retail outlet. Siemens engineers then oversee the assembly and installation process before taking control of commissioning and final customer testing.

“It sounds like a simple process but it can be quite tricky,” explains Jim Dyke A&D Service & Support, “Particularly when the installation is in a retail outlet, which means we have to work outside normal opening hours and normal industry expectations. The existing US customer relationship was promoted with support from Mr Malcolm Evans of the A+D Global Support Team, based in Atlanta USA to A&D businesses around the world to align with the timing of new Krispy Kreme store openings.

To date Krispy Kreme has installed the TIA based systems at its retail outlets in Korea, Australia, Mexico and Canada and most recently in Tesco stores at Watford and Slough, Selfridges in Birmingham, Harrods in London and Bluewater Shopping Centre in Kent. The systems have also been instated at dedicated Krispy Kreme facilities at Enfield, New Malden and Birmingham. These act as mini ‘factories’, mostly supplying Krispy Kreme retail kiosks at nearby train stations.

The Siemens TIA solution comprises a SIMATIC S7-300 PLC that is linked by PROFIBUS to four Micromaster variable speed inverter drives (there are remote I/O on the PROFIBUS network). There is also an MPI network linked to a 10 inch HMI near the ‘proofer’ and to a 6 inch HMI at the cooling tunnel, allowing the operator to view and control the doughnut manufacturing process from either end of the production line. The systems also use SIRUS contactors, overload breakers and low voltage switchgear.

Step-by-step, the Siemens solution allows Krispy Kreme to: measure and weigh the dough; automatically extrude the dough; slice it into individual doughnuts; transfer the doughnuts to a proofer for 35 minutes where they are allowed to rise under controlled heat and humidity conditions; transfer them to a fryer for 110 seconds at 180oC; flip the doughnuts to fry the other side; transfer them to a tank where they are glazed; return them around a ‘retail curve’ where drooling customers catch sight and smell of freshly produced doughnuts; and send the finished products through a cooling tunnel so they can be handled comfortably enough to be manually filled to customer specification. Siemens has installed two types of doughnut production line for Krispy Kreme with different capacities: a line that can produce 220 doughnuts every hour, and a 65 per hour line.

Return on Investment

According to Mr Dyke, one of the main benefits for Krispy Kreme is that the Siemens solution has become a tried and tested process. “Automation eliminates any risk,” he says, “particularly in terms of weighing, speed, control and feedback. The solution provides automation where there was none before.”

Brendon Stenson, Siemens Project Expert, adds: “Another major benefit is that we provide Krispy Kreme with a one-stop turnkey solution. Siemens take care of all the installation, commissioning, servicing and breakdown requirements, so Krispy Kreme has one point of call: Siemens. Whether it’s a mechanical, electronic or software issue, even if there is a problem with third party equipment such as mixers or chillers, Krispy Kreme can call Siemens and we will either remedy the situation ourselves or arrange for it to be done by a qualified and vetted subcontractor.”