ROSS Mixers shares insights on its portfolio and how the 3D printing sector benefits from its product line

Aug 27, 2023

ROSS Mixers shares insights on its portfolio and how the 3D printing sector benefits from its product line.

Since 1842, Charles Ross & Son Company (ROSS Mixers) has produced industrial mixing, blending, drying, and dispersion machinery, offering custom and standard designs to match diverse processing needs.

With experience gained from over 180 years serving the manufacturing world, how can enterprises using 3D printing benefit from ROSS systems?

The raw materials, or feedstock, used in additive manufacturing play a crucial role in the 3D printing process. To produce a high-quality 3D print, the feedstock must also be of consistently high-quality.

Given that most feedstock are mixtures and not single-component materials, mixing and blending technologies play a crucial role in the additive manufacturing process.

Strength, texture, appearance, conductivity, durability and other key properties in the finished product are directly impacted by the mixing operation. Selecting the right mixing equipment is therefore the first step to achieving formulation accuracy and batch-to-batch repeatability.

In the 3D printing industry, ROSS has supplied a number of equipment and mixing solutions, optimized for the production of a range of materials.

Moreover, The company’s product line serves a wide range of applications within the global chemical, pharmaceutical, food, plastics, composites, adhesives, coatings, and electronics industries.

ROSS Mixers’ industrial portfolio

ROSS Mixers Tumble Blenders are ideal for the production of metal and alloy powders used in 3D printing. Indeed, Tumble Blenders, out of all the dry blending technologies, are the best option for handling heavy batches while minimizing mechanical wear.

With diffusion as the main mechanism for mixing, tumble blending is a low-impact process, ideal for processing abrasive solids and friable ingredients. This process is also frequently used when making precise blends containing trace ingredients or additives.

These Tumble Blenders also ensure proper blending, essential for producing high purity, chemically homogenous, spherical powders within a target particle size distribution. This also enables excellent flow properties and high packing density.

Another key benefit of ROSS Mixers Tumble Blenders is their double cone and V cone vessel geometry. This allows for complete discharge of the blended material which translates to high yield, lower risk of contamination and easy cleaning.

ROSS Mixers High Shear Mixers (HSM) are designed for low-viscosity applications requiring high levels of shear forces and intense turbulence. These mixers are well suited to 3D printing applications such as dispersion of pigments, additives and filler into resins or waxes; polymer suspensions, ceramic slurries; lubricants (like silicone emulsions and Teflon suspensions); and binder solutions.

High Shear Mixers are available in batch (vertical) or inline (horizontal) configurations, and include a rotor that turns at high speeds within a stationary stator. This process achieves extremely fast mixing, with rotor tip speeds often reaching speeds between 3,000 and 4,000 ft/min. This breaks down agglomerates and reduces the size of droplets.

ROSS Mixers also offer their SLIM (Solids/Liquid Injection Manifold) Technology, a key development in rotor/stator design. This high-speed powder induction system, that can be added to ROSS High Shear Mixers, creates a vacuum behind the rotor. This vacuum can be used to inject powdered (or liquid) ingredients directly into the high shear zone.

This process is ideal for powders that don’t easily mix with liquids. For instance, feedstock or intermediate materials thickened with fumed silica, carboxymethyl cellulose, hydroxyethyl cellulose, carbomer, bentonite clay or xanthan gum often benefit from powder induction via a SLIM system.

ROSS Mixers Multi Shaft Mixers offer similar dispersion, emulsification, and homogenization functions as High Shear Mixers. However, these machines can turn over viscous materials, mix under vacuum and provide tighter temperature control.

Two popular configurations of these machines are the Triple-Shaft Mixer, consisting of a High Shear Mixer, a High-Speed Disperser and a Three-Wing Anchor, and the more cost-effective Dual-Shaft Mixer. This configuration is composed of a High-Speed Disperser and a Two-Wing Anchor.

These mixers offer superior viscosity and heat transfer capabilities compared to single shaft devices. Moreover, they are closed systems, offering benefits in vacuum mixing such as higher density, superior dispersion quality, better tensile properties, less defects and longer stability.

Common applications for Multi-Shaft Mixers include polyvinyl alcohol solutions, plastisol and other thermoplastic inks, rubber blends, polyurethane-based composites, reinforced epoxies, and other filled resins.

ROSS Mixers Dual and Triple Shaft Mixers. Photos via ROSS Mixers.

ROSS Mixers also offer a range of Planetary Mixers, ideal for the production of 3D printer feedstock with high viscosity.

The ROSS Double Planetary Mixer is ideal for the production of 3D printer feedstock with high viscosity, and is optimized for viscous formulations up to 6 million cP or more.

This offering incorporates two identical blades which rotate independently while orbiting the blending vessel on a common axis. The two blades move throughout every point in the product zone, physically contacting the entire batch in only 36 revolutions throughout the vessel.

Because the blades of these machines run at relatively low speeds, these mixers can tolerate abrasive applications, including metal or ceramic dispersions in polymer, wax or resin binding agents. Equally, shear-sensitive materials, such as hydrogels and syntactic foams, are extensively produced in Double Planetary Mixers.

The ROSS PowerMix is a hybrid planetary disperser combining high and low speed agitation for mixtures that start out very fluid and thicken up throughout the batching process.

From water-like viscosity to around 2 million cP, the PowerMix can impart high shear at any stage. Moreover, both agitators are independently controlled. This allows flow patterns and shear rates to be finely tuned as the product undergoes changes throughout the mixing cycle.ROSS Mixers also offer a four-shaft design, with their Planetary Dual Disperser (PDDM). This robust system combines two planetary blades with two high-speed dispersion blades. This allows solid additions to be produced in larger quantities and shorter intervals. Agglomerates disintegrate faster, and turnover is extremely efficient even if the material is particularly dense or sticky.

ROSS Mixers Interfacial Surface Generator (ISG) Static Mixers are especially well suited to injection molding and extrusion applications. Indeed, ROSS claims that the ISG Static Mixer is one of the most broadly used static mixer models in injection molding and extrusion applications.

The use of static mixing has been shown to enhance the quality of injection molded and extruded products. The molten material is injected through a series of static mixer components fitted before the die assembly inside the nozzle. The static mixer can rectify multiple discrepancies in the extruded stream within a very brief length of pipe.

Thermal homogenization, consistent density and density, improved mixing of colors and minimal additives, effective utilization of all raw materials, eradication of streaks or clouds in the final product, high quality, and yield are just some of the benefits.

ISG Static Mixer elements. Photos and Images via ROSS Mixers.

ROSS Vertical Mixers for drying and blending plastic resins and nylon pellets

Plastic resins absorb moisture from the surrounding environment. Water accumulates on the surface, and if the plastic is hygroscopic, inside the polymer. Drying is crucial because excess moisture in the initial resin material can cause lower strength, visual defects, and poor performance of the finished part.

ROSS Mixers Vertical Blender/Dryers with vacuum capability are “well-proven” drying equipment for plastic resins. Vacuum drying is an effective technique for manufacturing heat-sensitive plastics without worrying about thermal degradation because it requires relatively low temperatures to drive off moisture.

Once the vacuum is established, the mixture of low absolute pressure, gentle heat, and slow agitation rapidly force moisture from the bulk material. Vapors produced during the process are filtered and condensed. If applicable, a receiver gathers the condensed liquid for safe disposal or reuse.

Nylon pellets are frequently mixed with other plastics, covered with lubricant powder, or combined with intensive pigments and other additives.

In some cases, reducing the moisture content of the pellets is required to avoid deficiencies in the final product and process discrepancies. Over-drying can harm the flow behavior of nylon pellets, so drying to an ideal level is critical. The adaptable Vertical Blender is distinctively suited for achieving all of the above goals.

Ross Vertical Blenders can also blend nylon pellets with other solid additives or polymers of virtually any shape and size. Vertical Blenders use the same process on nylon pellets as plastic resins.

ROSS Double Planetary Mixers mixing equipment for dental composites

Dental composites are reinforced with glass and ceramic particles. Double Planetary Mixers are time-tested tools for preparing dental composites.

Newer helical blade designs provide better blending and more straightforward managing of viscosity peaks as high as 6 million centipoises. Ross High Viscosity “HV” Blades (US Patent No. 6,652,137) are the “first of their kind,” with an accurately angled contour that produces a specific mixing action.

Ross Double Planetary Mixers are used for abrasive materials worldwide and are typically hard-chrome plated or covered with Kynar (polyvinylidene fluoride) or aluminum oxide. The paste becomes discolored when abrasive composites are mixed in a traditional stainless steel mixer (stainless steel particles are integrated into the formulation).

Even minor contamination is unacceptable in dental composites, where accurate optical properties are crucial.

To learn more about this technology report, or to request a quote, fill out ROSS Mixers’ request form.

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Alex is a Technology Journalist at 3D Printing Industry who enjoys researching and writing articles covering a wide variety of topics. Possessing a BA in military history and an MA in History of War, he has a keen interest in additive manufacturing applications within the defense and aerospace industries.