High-Shear Disperser with Saw-Tooth Blade

What is the High-Shear Disperser with Saw-Tooth Blade?

A high-shear disperser uses a toothed or saw-tooth disc rotating at high speed in an open vessel to wet and disperse pigments, fillers and powders in viscous liquids. It is the standard tool for paint, ink and coating laboratories.

Overview

The disperser has a motor on a height-adjustable stand and a shaft carrying a flat disc with serrated edges, often called a Cowles-type blade. The disc rotates at 500 to 6,000 rpm at tip speeds of 15 to 25 m/s, generating a doughnut-shaped flow pattern in the vessel. Powders are drawn into the vortex and sheared between disc teeth and the liquid. Disc diameter is typically one third of the vessel diameter, and the vessel is usually a round can of 0.5 to 200 L. The system handles viscosities from 100 to 50,000 mPa·s, which is higher than typical rotor-stator batch mixers. Variable speed and a lift allow easy operation. Dispersers do not produce the fine droplet size of a rotor-stator but are very effective for pigment wetting and deagglomeration.

How does it work?

A high-shear mixer rotates a rotor at high tip speed, commonly 10 to 40 m/s, inside or next to a fixed stator. Fluid is drawn axially into the rotor, accelerated outward, and forced through the narrow gap between rotor and stator, typically 0.2 to 1 mm, and through slots or holes in the stator. In the gap the fluid experiences very high shear rates, often above 20,000 s⁻¹, plus turbulence and cavitation, which break droplets and particles and wet powders. Disperser-type heads use a toothed or saw-tooth blade in an open vessel. Main components are the motor and drive, the mixing head with interchangeable generators, a shaft with seals, a vessel or inline housing, and speed control. Results depend on tip speed, gap, generator geometry, viscosity and batch time.

What are the key features?

• Saw-tooth disc generates a toroidal flow for pigment wetting
• Speed of 500–6,000 rpm with tip speeds of 15–25 m/s
• Height-adjustable stand with motorized or manual lift
• Handles viscosities from 100 to about 50,000 mPa·s
• Interchangeable discs sized to one third of vessel diameter
• Variable-frequency drive with digital speed display

What are the technical specifications?

A typical high-shear disperser with saw-tooth blade configuration offers speed range of 500–6,000 rpm, tip speed of 15–25 m/s, vessel volume of 0.5–200 L, disc diameter of 40–300 mm, viscosity range of 100–50,000 mPa·s and motor power of 0.37–15 kW. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The High-Shear Disperser with Saw-Tooth Blade is used in paint and coating dispersion, ink pigment wetting, filler and resin mixing, adhesive formulation and ceramic slurry preparation. Across the wider High-Shear Mixers class, laboratories also deploy it for emulsion and cream preparation, pigment and filler dispersion and pharmaceutical suspension development.

Which standards and certifications apply?

Relevant standards and methods include IEC 61010-1, EN ISO 12100, ISO 13320, ASTM E2651 and GB 4793.1. Certification candidates for this model are CE, RoHS and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Secure the mixer on a stable stand or clamp and keep the head fully immersed before start-up to avoid air entrainment and dry running of the seal. Use guards and emergency stops, and never operate with loose hair or clothing near the shaft. Keep the gap between rotor and stator clean, since worn generators lose shear efficiency and should be inspected regularly. Flush or clean-in-place between batches to avoid cross-contamination. Control temperature, since shear heats the product, and use jacketed vessels or cooling where needed. Sanitary seals and polished surfaces are important for pharmaceutical and food work. Comply with IEC 61010-1 and machinery safety standards, and record speed, time and temperature for batch documentation.

How do I select the right High-Shear Disperser with Saw-Tooth Blade?

Choose the saw-tooth disperser for wetting and deagglomerating pigments and fillers in viscous paints, inks and resins. Use a rotor-stator for fine emulsions. In the RFQ, specify vessel diameter, viscosity, solvent type, speed range and whether an explosion-protected motor is required.

How does it compare with other High-Shear Mixers variants?

Select a high-shear mixer by batch size, viscosity, target particle or droplet size and process type. Batch rotor-stator mixers suit volumes from 0.1 to 100 L and offer interchangeable generator heads. Inline models process continuous or recirculated flow and give narrower size distributions. Vacuum emulsifiers combine shear with degassing and heating for cosmetics and ointments. Dispersers suit pigment and filler wetting in coatings and inks. Powder-induction designs draw powders into the liquid to prevent lumps. Check tip speed, motor power, generator options such as coarse, medium and fine slots, and materials of construction such as 316L stainless steel. Consider cleanability, sanitary design and seals if the products are pharmaceutical or food grade. Verify noise levels and safety guarding, and ask for trials if particle size specifications are critical.