Why Use a Vacuum Mixer?
Vacuum mixers can be used to mix a wide variety of materials. They help reduce oxidation, improve quality, shorten processing time and make more efficient use of materials.
This small vacuum mixer is ideal for spatulating stones, plasters, die materials and alginates under vacuum to produce smooth, dense and detailed casts or impressions.
Medical and food applications
Vacuum emulsifying mixers can be used for a wide range of applications, including food processing and pharmaceutical manufacturing. They are particularly useful in blending liquids with solid or powdered ingredients that cannot be mixed using conventional mixers. The vacuum-created by the machine allows the agitation to take place without introducing air bubbles, which can spoil a product and cause it to go bad more quickly.
These devices are often made from stainless steel, which is resistant to corrosion and can withstand high temperatures. They are also easy to clean, which helps to keep them safe for use with sensitive materials. Some medical and food applications require the mixer to adhere to strict standards, so it may need to be sterilized before every use. The device can be broken down and inspected for signs of contamination by representatives of the company that uses it.
Typical vacuum mixers have paddles that can be adjusted to accommodate different types of mixes. The paddles move in a three-dimensional figure-8 pattern, pulling from both sides and then moving to the center. This method of mixing is gentle on ingredients that are incompatible or have differing shapes, sizes and densities. It is also ideal for mixes that require a high level of sanitation, such as bakery mixes, ready-to-eat salads and medical-grade plastics. In addition, this type of mixing is highly effective for avoiding the loss of active ingredients by allowing them to evaporate into a gas phase bypassing the liquid phase.
Powder dispersion in liquids
Whenever powders are dispersed in liquids, the quality of that dispersion depends on how well every single powder particle is wetted and spread out. This is a crucial factor in all applications where agglomerations are undesirable, whether it be for taste or texture, thickening agents, colour pigments, matting agents, reinforcing fibres or catalysts.
Insufficient dispersion causes incomplete de-agglomeration or re-agglomeration of the dispersed particles and results in particle sizes that are larger than those of the primary particles. This also means that the resulting slurry is less vacuum mixer stable over time and may suffer from swelling, dissolution or breakage.
To overcome these problems, powders that are difficult to disperse need high shear mixing equipment to avoid lumping or clogging. Batch mixers with the mixing unit inside the tank are the ideal solution because they deliver the high shear forces needed to reliably disperse difficult powder ingredients. Dosing the powder directly on the surface of the liquid and transporting it quickly down towards the mixing head in controlled vortex ensures optimal wetting, preventing the formation of agglomerates.
The Silverson Flashblend is a powder-into-liquid system that uses a Venturi effect to suck the pre-wetted powder into the process liquid stream using high suction power. The powder is then fed through a rotor and stator device to disperse it at maximum shear and intensity. The result is a perfectly homogeneous slurry with no rafting or agglomeration.
Impregnation of filler agglomerates
Vacuum mixers are an effective mixing solution for high viscosity materials. The vacuum created by the mixer removes air bubbles from the product and makes it easier to achieve a smooth, uniform texture.
The use of a vacuum mixer also allows the formulation to be processed at a lower temperature, which can help to reduce oxidation and improve the quality of the finished product. It mixer manufacturer can also reduce the risk of contamination by keeping the mix free from bacteria and other contaminants.
It is essential that the correct type of filler is used in vacuum processing to ensure the maximum tensile strength is achieved. Typical inorganic fillers tend to form aggregates in the continuous polymer phase due to surface energy minimisation, and these can decrease membrane gas selectivity. To overcome this, the inorganic filler agglomerates can be impregnated with a polymer coating prior to mixing, which helps to increase the tensile strength of the composite by decreasing the stress at the polymer-filler interface.
A vacuum mixer is an ideal choice for impregnating the inorganic filler with a polymer to create a robust composite with good tensile properties. The mixer can be fitted with a disperser or cowles blade to facilitate material flow into the agglomerates. This is particularly important for the creation of a high tensile strength composite, as the agglomerates are likely to be exposed to shear stresses during the forming process.
Dental applications
Vacuum mixing is often used in dental applications where the compound mixture must be completely free of air bubbles. In addition, the mixture must be thoroughly homogenized to ensure the formation of a smooth and consistent mixture for a high-quality final product. The vacuum environment also helps reduce oxidation, which may occur when oxygen is present in the mixture. This can degrade the finished product and cause premature failure in some products, such as coatings and personal care items.
Many types of batch mixers can be converted for vacuum operation. These include a variety of single-shaft devices such as agitator or rotor/stator mixers used in batching low viscosity formulations, double planetary mixers for blending powders and liquids or high-speed saw-tooth dispersers for high-viscosity formulations. Vacuum mixers can be used with a variety of liquids, including lubricants and solvents. They can also be equipped with a range of features, such as an electronic programmable timing system, hands-free option, vibration and vacuum sensing.
The Vac-U-Mixer can be used for spatulating stones, plasters, die materials, investments and alginates to produce smooth and dense impressions. Using this type of vacuum mixing in dentistry allows for the investment and casting of crown, bridge or inlay patterns that are free of air bubbles. Each machine is available in five different sizes, with bowls made of rigid clear plastic or stainless steel. A variety of drive nuts are available for each size model to match your existing equipment.