How Do Silverson High Shear Mixers Operate?

Silverson Machines are internationally known for their range of high shear mixers. These mixers have become popular because of the quality, reliability, flexibility and batch-to-batch consistency which they can provide. But what makes a Silverson mixer so much more effective than conventional mixing equipment such as stirrers and agitators?

The Rotor / Stator Workhead: The Heart of Mixing

The rotor/stator workhead is at the heart of every Silverson mixer. ‘Shear' is the most basic definition of cutting. Silverson high shear mixers accomplish this ‘cutting' process by employing rotor blades to rotate within a stationary stator.

High-speed rotation of the rotor blades produces a strong suction, drawing liquid and solid material up from the vessel floor and into the centre of the workhead. 

Centrifugal force then drives the materials to the workhead periphery, where they are subjected to a milling action in the precisely machined clearance between the rotor blade tips and the inner stator wall. 

Severe hydraulic shear ensues as materials are forced at high velocity outward through stator perforations and recirculated back into the main mass of the mixture.

The material discharged from the head is thrown radially at high velocity in the direction of the sides of the mixing vessel. At the same time, new material is continuously suctioned into the workhead, continuing the cycle of mixing.

Why Silverson Mixers Thrive over Traditional Agitators

What sets Silverson high shear mixers apart from the common agitator or simple stirrer is the localized region of high shear and blending contributed by the rotor/stator configuration. 

Conventional mixers exert motion more dispersed over the volume, but they lack extreme shear forces or undue recirculation such as Silverson mixers deliver.

Due to this, Silverson mixers can:

• Generate particle or droplet size distributions that are smaller
• Disperse solids, emulsify liquids, dissolve materials at higher rates
• Maintain excellent batch consistency and uniformity
• Reduce mixing times by orders of magnitude in the majority of applications
• Versatility with Interchangeable Workheads

One of the major strengths of Silverson high shear mixers is their flexibility. There is a variety of interchangeable workheads that allow the stator perforations to be tailored to the requirements of specific applications or process conditions.

As all Silverson rotor/stator workheads are constructed to the same precision tolerances and geometrically equivalent throughout their product range, results obtained in the small laboratory models can adequately be used to predict production scale unit performance. 

Scale-up is thus a simple task to accomplish since it allows process engineers to have confidence that observed behavior under trial will transfer to production scale.

Applications, Scale and Practical Use

Silverson high shear mixers are used across a broad spectrum of industries — food and cosmetics, right through to pharmaceuticals, chemicals, inks and coatings — in any process involving efficient mixing, dispersion, emulsification, or particle size reduction.

A very appealing advantage is that a Silverson mixer will accomplish the tasks which would otherwise be performed by multiple pieces of equipment (agitators, dispersers, homogenisers), thereby making plant layouts simpler to plan and lower in capital costs.

Because small-scale mixers are a true imitation of production machine tolerances, laboratory or pilot trial outcomes can be used to predict performance in large scale mixers. This level of scalability is frequently quoted by customers when ordering investment in Silverson equipment.

For more information or to book a high shear mixer trial specifically tailored to your process, please contact Silverson Machines.