IKA RW 20 digital Package, Mechanical Stirrer, Complete System, 0009011600

Macro-rheology and mechanical power transmission

The mixing of structurally viscous or highly viscous fluids requires the application of substantial and, above all, constant torque, which cannot be generated by purely magnetic couplings due to physical limitations. The IKA RW 20 digital is designed as a classic mechanical overhead agitator and utilises a robust, two-stage spur gear transmission for power transmission. This kinematic architecture enables the motor to optimally convert its electrical power into mechanical torque across two defined speed ranges (60–500 rpm and 240–2,000 rpm), depending on the rheological requirements. This reduction ratio is essential from a process engineering perspective in order to overcome the fluid’s flow resistance when dispersing media with a dynamic viscosity of up to 10,000 mPa·s, without thermally overloading the drive.

Fluid mechanics and axial flow profiles

The 4-bladed R 1342 propeller agitator included in the package defines the primary fluid dynamics within the reaction matrix. Driven by the rotational energy of the shaft, the specific geometric orientation of the propeller blades generates a strong, downward-directed axial flow (vector). This fluid-dynamic suction continuously draws the sample material from the surface into the thermodynamic centre of the vessel, forcing it to deflect radially at the bottom and thus generating three-dimensional vortex turbulence. This flow profile prevents the gravitational sedimentation of solids and ensures the metrologically homogeneous mixing of aqueous to medium-viscosity batches with a volume of up to 20 litres.

System dynamics and metrological reproducibility

The transfer of kinetic energy into viscous media induces massive counterforces which, if the system is not adequately secured, can lead to high-frequency resonance vibrations or torsional fractures. The system’s structural stability is ensured in the package by the solid R 1826 plate stand and the R 182 cross-sleeve. These solid metal components completely absorb the shear forces and vibrations generated by the motor, guaranteeing rigid, coaxial operation of the stirring shaft. A key metrological advantage of the system is the hollow drive shaft: it enables the user to physically push the stirring rod through the motor block. This allows for stepless adjustment of the immersion depth (shear zone) relative to the liquid level in the vessel, without having to alter the vertical locking of the entire motor block to the stand.

Technical details

• Product type: Mechanical overhead stirrer (complete package)
• Gearbox architecture: Two-stage mechanical spur gearbox
• Kinematic characteristics (Speed I): 60 – 500 rpm (focus on maximum torque)
• Kinematic characteristics (Speed II): 240 – 2,000 rpm (focus on hydrodynamic turbulence)
• Viscosity limit: 10,000 mPa·s
• Maximum mixing volume: 20 litres (based on H₂O)
• Flow profile (R 1342): Axial flow, suction from top to bottom
• Metrology: Digital LED display for precise speed measurement
• Mechanical advantage: Pass-through stirrer shaft for variable immersion depths
• Chuck: Clamping range 0.5 to 10 mm in diameter

Scope of delivery

• 1 x IKA RW 20 digital drive unit (stirrer)
• 1 x IKA R 1826 plate stand (solid cast iron base)
• 1 x IKA R 182 cross-sleeve (to prevent torsion)
• 1 x IKA R 1342 propeller stirrer (4-bladed, stainless steel)

(Important note: Reaction vessels or media are not included in the scope of delivery!)

Customised requirements & accessories

The RW 20 digital Package is a universal fluid mechanics setup. For complex non-Newtonian fluids or highly viscous, paste-like matrices, where a propeller stirrer would merely create local cavities in the mass (without macroscopic mixing), switching to a different stirring tool is essential. For highly structurally viscous gels, use the anchor stirrer (R 1330) to generate shear stresses close to the wall, or the dissolver stirrer (R 1300) to apply extremely high radial shear forces during pigment dispersion. Please contact our procurement service at any time for the tribologically and fluid-mechanically correct configuration of your stirring tools.