Optimum complete emptying with SinConcave® and ComDisc® technology.

Optimum complete emptying with SinConcave® and ComDisc® technology.

FAQ: Innovative complete emptying and wear and tear on the mixing plant

In this blog article we address some common questions from amixon® interested parties about the advantages of our innovative complete emptying and the wear factor of mixing plants. If you do not find the answer to your potential questions in this article, please contact us personally. We look forward to you!

It is undisputed that amixon® vertical single-shaft mixers produce ideal mixing qualities. But can such a flat-bottomed powder mixer empty to such a high degree that more than 99.95% of the filled powders are discharged ideally mixed?

Yes, this is possible and is actually achieved in practice with the help of several typical amixon® features: SinConcave® or SinConvex® and ComDisc®.

Each powder has specific rheological properties. These are influenced by greasiness, moisture, particle size, electrical charge, temperature, cohesion and adhesion. Residual discharge rates can be guaranteed by amixon® on a case-by-case basis once tests have been completed with your original products.

SinConcave®: The spiral mixing tools are tilted concavely towards the centre of the mixing chamber. 

The mixing device spirals then have strongly inclined surfaces so that free-flowing mixes flow downwards without segregation.  

ComDisc® tools are located at the back of the lower mixing unit arm.

They float through the mix and are of no significance during mixing. Only when the filling level drops do they tilt and clear the mix residues into the discharge outlet. ComDisc® tools work similarly to windscreen wipers. But they normally only touch the bottom of the mixer when the discharge is advanced.            

Are the discharged residues also ideally mixed?

Yes, your question is evident and highly relevant to all amixon® precision mixers. This question has therefore been investigated thousands of times by amixon®. In fact, the same findings have been confirmed again and again: Mixing good that lies on the floor is also mixed without dead space. It does not matter

  • what type of powder is present
  • whether or not ComDisc® tools are installed
  • whether the mixing tool has a SinConvex® or SinConcave® design or not.

The reason is derived from the rheology of the bulk solids. Every bulk material has an internal friction. This is only slightly reduced when it is moved. This is expressed in the drive torque to be applied by the mixing tool during mixing. The internal friction coefficient of the powder is always higher than the coefficient of sliding friction between powder and a smooth steel surface. For hygienic reasons alone, all parts of the precision mixer that come into contact with the product are machine-ground and very smooth. The average roughness Ra is less than 1 µm or optionally even less than 0.4 µm. From this fact it can be deduced that the mixing materials at the bottom are pushed in the direction of rotation by the mixing unit arm and flow around the mixing unit arm. In the process, they experience the upward movement and are integrated into the total flow.

Can such coefficients of friction (sliding friction coefficient) change?

Of course, we were also concerned with this question when the mixing system was developed about 40 years ago. Since 1980, thousands of such flat-bottomed vertical mixers have been manufactured. They are used successfully in almost all industries. Many are still working flawlessly for almost 40 years. All empirical data regarding mixing quality is positive.

Is it possible that a new vertical mixer mixes better than an older vertical mixer that is already showing wear?

We can report that the areas of a mixer that are subject to wear become particularly smooth. They are even polished to a shine by the mix. The coefficient of friction resulting from the "powder and metal" pairing is thus reduced. For this reason, you can be sure of the durability of your ideal mixing quality.

What would happen if the mixing goods are particularly abrasive?

If the wear continues to progress, there is a visible loss of material on the mixing tool. Then worn material should be replaced by manual welding. The filler metal should be particularly hard. The procedure is called "weld hardfacing". Such repair measures are carried out by amixon® experts on site in the mixer. Your mixer does not have to be dismantled. A few hours after the hardfacing, you can clean and start production again. It should be noted at this point that wear develops approximately with the square of the mixing tool speed. However, the mixing tools of the amixon® mixers rotate slowly, the circumferential speeds are normally only approx. 1 m/s to 2.2 m/s.

If the mixing tool is upgraded with a welding hard facing, doesn't the mixing vessel also have to be repaired?

Not usually. amixon® employees can quickly measure the thickness of the mixing chamber wall. We generally register very little wear there. In this respect, we see extremely little need for action on the mixing chamber.