Thomas Tunnock Ltd is renowned for their famous Camamel Wafers, Snowballs, Camamel Logs, and Tea Cakes

A major part of the success of these products is Tunnock's own brand of chocolate made to a secret recipe from a blend of cocoa liquor, two famous brands of proprietory chocolate, sugar and lethicin.

Customer requirements

To improve efficiency, the chocolate production section was relocated a step at a time. This ensured no loss of output given that they need 60 tonnes of their creamy milk chocolate a week and a significant tonnage of dark chocolate to meet demand.

A hygienic and reliable conveyor  was required to transfer the sugar and chocolate ingredients to a pre-mixer for delivery to a series of chocolate conches where they are mixed with liquid components. The chocolate mass is worked in the conches until it reaches that special Tunnock's flavour and smoothness.

Spiroflow solutions

 It was Tunnock's own engineers who suggested a Spiroflow Flexible Screw Conveyor to load the dry ingredients into the pre-mixer as several are successfully used on other applications around their factory.

Samples of sugar and the two propietary brands of chocolate  used to produce Tunnock's special chocolate flavour were sent to us for trials in our test facility in Clitheroe. One brand was supplied as a crumb and the other as a traditional slab. Although standard spiral, with a round cross-section, coped admirably with the sugar and the chocolate crumb, the required rate could not be achieved with the slab chocolate. It tended to smear and build up on the spiral.

However, we have a spiral with a bevelled cross-section. This was specifically developed for difficult products and has proven its worth on materials that readily smear or which are cohesive. Neddless to say, the bevelled spiral solved the problem! It works by placing more suface area on contact with the product for greater propulsion whilst preventing build up on the active surface.

The system installed at Tunnocks in an excellent example of the capability and versatility of Spiroflow Flexible Screw Conveyors. It delivers three different ingredietns from three separate feed points to the pre-blender.