Baker Perkins twin-screw extruder and pre-conditioner

Company: Baker Perkins

Equipment Snapshot: A new generation of extrusion equipment for the food industry has been launched by Baker Perkins. The SBX Master twin-screw extruder range for cereal, snacks, ingredients and other food applications has been re-designed and a new pre-conditioner added to the range to increase flexibility.

The flexibility of the SBX Master extruder has been improved by increasing power, torque and speed. This, along with a range of barrel lengths, increases the variety of end products that can be made while barrel diameters between 50mm and 125mm give an output range from 500 to 2,300kg/hr.

Improved cooling also contributes to broadening the range of products that can be made, and additionally improves quality and consistency. The new design features water distribution channels for cooling located closer to the internal surface of the barrel to improve both responsiveness and the rate of heat transfer. Flow rate is increased, and cooling can be controlled and adjusted to individual product profile.

The SBX Master is now a totally modular machine, so future extension of the barrel and all the associated services to expand or change a product portfolio is speedy and straightforward.

The arrangements for mounting the die and cutter have been simplified to make changeover, cleaning and maintenance faster and safer. The die is supported on a hinged arm that enables it to be moved quickly and safely, especially when hot, while the cutter slides in and out of position on rails. This is a pneumatically-powered, pushbutton-operated system that automatically puts the cutter directly in front of the die as soon as the extruder is ready, leaving only fine adjustment to the operator. This minimises time and waste generated during set-up, changeover or, if a blade change is required, during a run.

A gearbox condition monitoring system that reduces unexpected downtime is available on all new SBX extruders and can also be fitted to existing machines. This simple system continuously monitors the frequency and amplitude of vibrations within the gearbox, allowing the ongoing condition of vital components to be measured.

The principal benefit is elimination of unforeseen loss of production due to gearbox repair or replacement: maintenance scheduling is significantly enhanced.

The preconditioner is a new addition to the Baker Perkins SBX Master range that increases flexibility and throughput, especially when applied to denser and/or shear-sensitive materials. It is particularly advantageous when processing pellets for flaked cereals, pet products, and half-products formed in the extruder and expanded elsewhere – flaked cereals and multi-grain loops are typical. It is also ideal for protein products where energy input in the preconditioner replaces mechanical shear energy in the extruder in order to avoid protein damage.

The preconditioner comprises two processing chambers, each fitted with a mixing shaft, which provide a first-in, first-out process flow. In the first chamber high intensity mixing for the dry and liquid ingredients takes place while steam is injected to heat and hydrate the ingredients. The second chamber allows the energy and moisture to equilibrate throughout the preconditioned mass, minimising clump formation and achieving an optimised mix profile for subsequent processing by the extruder.

Hygiene levels are high: a large vertically-rising door allows unrestricted access to both chambers for cleaning while an optional manually-installed water spray bar is available to loosen stubborn material build-up from the internal surfaces and mixer shafts.