What Are Mixer / Extruder Mixers Used For?
Mixer/extruder mixers are used for mixing high viscosity or high solids products including silicone rubber, butyl rubber, composites, carbon fiber materials, ceramics, chewing gum and candy nugget, sealants, and adhesives.
What Are Some Of The Other Names For A Mixer/Extruder Mixer?
Mixer/extruder mixers, also known as mixer/extruders, double arm mixers, sigma blade mixer, Z-blade Mixers, kneaders, masticators, or Mogul mixer.
What Is The Mixing Mechanism In A Mixer/Extuder Mixer?
Mixing is accomplished in a mixer/extruder mixer by a pair of blades called sigma or Z-blades, Naben or fishtail blades or dispersion blades. Mixer/extruder mixer blades are most often tangential, rotating at different speeds. Mixer/extruder mixer blades can also be overlapping, rotating at the same speed. Mixer/extruder mixers can drilled to provide a path for heating fluid to pass through the blades to pre-heat the blades and auger.
How Are High Viscosity Or High Solids Products Discharged From A Mixer / Extruder Mixer?
Mixer/extruder mixers discharge high viscosity or poor flowing products by an auger or extruder screw.
What Are The Units To Describe Viscosity?
When considering a mixer/extruder mixer, viscosity must is an important consideration. Liquid viscosity or resistance to change in flow is most commonly described as Poise or Centipoise (Cps). Some industries prefer Stokes. Krebs is often used in the paint industry. Another viscosity measurement terms is Pascal-second (Pa·s) equivalent to newton-second per square meter (N·s m–2).
Viscosity can be measured with various viscometers or Rheometers.
What Other Technical Termss Describe Liquids Viscosity And How Do These Related To A Mixer/Extruder Mixer?
Rheological terminology is used to describe how stress applied to a liquid and the changes its deformation or flow characteristics.Describing the thickness of viscosity a liquid is described by rheological properties. The two categories are Newtonian and non-Newtonian liquids.
- Newtonian liquids include water and most solvents. Agitation or other stressors do not change the viscosity of a Newtonian liquid.
- Non-Newtonian liquids change in viscosity with stress. Non-Newtonian liquids will change their viscosity when agitated, pumped or otherwise stressed in a mixer/extruder.
- Thixotropic Liquids: The most common non-Newtonian liquids are Thixotropic liquids. Also known as shear thinning liquids. The viscosity of these liquids is reduced when mixed in a mixer/extruder mixer. Catchup is a Thixotropic liquid which thins when shaken as we all know is necessary to get the catchup to flow from the bottle.
- Dilatant Liquids: Dilatant liquids are shear thickening which is an important consideration for a sigma blame mixer because blade speed may need to be reduced, and larger drive motors installed. The water-starch experiment often done in high-schools is an example. The low viscosity starch slurry thickens and does not splash when an object is dropped into it because the viscosity spikes rapidly with the stress of the object hitting it.
- Pseudo Plastic Liquids: Pseudo-plastic liquids increase in viscosity but only for a short time when the stress is applied. An example of pseudo-plastic liquid is Mayonnaise.
- Rheopexy LiquidsL Lastly, we have the rare Rheopexy liquids which increase in viscosity over time with stress or mixing. Examples are printer inks and gypsum pastes.
What Other Issues Should Be Considered When Designing A Mixer/Extruder Mixer?
Other process issues that must be considered in the design of a mixer/extruder mixer is how to get the solids and liquids into the mixer/extruder mixer, necessity of purging with inert gases, creating vacuum or pressure inside the mixer/extruder mixer or heating or cooling the mixer/extruder mixer.
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