- Why can’t you mix accurately with a ribbon or other type of paddle as you can with PHLAUER™?
- Why is PHLAUER™ a better investment?
- How to choose a size of mixer?
- Why can’t you mix 40% overfilled like Forberg?
- What about segregation on discharge?
- How do you remove lumps?
- Can we mix pastes?
- How does your discharge self-adjust?
1. Why can’t you mix accurately with a ribbon or other type of paddle as you can with PHLAUER™?
Ribbons can’t mix accurately because they have very poor end to end transportation and you cannot control the void size. It is always the length of the ribbon, so materials go together and roll apart.
Other paddle mixers us a different mixing method, typically to scoop off the bottom and throw over the top. There is not as much particle movement and products can roll apart.
2. Why is PHLAUER™ a better investment?
PHLAUER™ is a better investment because of its ability where you can predict, repeat and reliably produce a better product in high volume. You should compare your total installed cost, and calculate the cost per ton for one year, and add the additional profits from more material available to sell, power savings and savings in ingredients. Invariably the cost per ton is less.
3. How to choose a size of mixer?
Choosing a size: start with the production volume required per time period. The time required for the second cycle (if you can measure ingredients simultaneously with other activities) time for loading ingredients, mixing, liquid addition time, shearing and discharging.
Dividing the time into 60 will give you the cycles per hour. Divide that into the production and that will give you minimum but not usable size. To get to a usable size first divide by 0.8 to allow for inefficiencies, ingredient changes and interruptions. Then look at the hand-adds. If your recipe can accept bag weights, size up to remove the split bags. This is a judgment factor and it needs to be considered.
In some industries there is a minimum size or the labor for measuring ingredients gets out of proportion. If the size you calculate is not an industry standard, go up to the next standard.
4. Why can’t you mix 40% overfilled like Forberg?
The simple answer is that we fill nominally to 75% of rotor because we advertise our mix time, have a balanced rotor system, and even if it fluidizes, we the material within the reach of our rotor. If when installed, the product does not grow, then the customer has a bonus of being able to mix more. To size a mixer for 105% of rotor is being done, but it is against our judgment, because when the mixer doesn’t work at that fill, the standard answer is lower the fill level. Then you need some other magic to get your production.
Our mechanism cannot “drown” by loss of fluidization because that is not our mixing principle. So power is not a problem. The test where this 40% overload came from was done without an ammeter on the mixer, it was easy ingredients, (I have the study) and the Cv. ‘s were not reached within advertised mix time. There is some myth to the claim.
Our biggest concern would be the ability of the discharge to hold the material. “It depends” is common, but with fine powders I am quite certain their discharge would leak.
We use a minimum load torque to calculate what the power torque has to be, and in the door design all the deflections have to be less than the gasket compression or it will not hold powders.
If you are adding liquids, the system would be designed for the rated fill level. There has to be space to spray, and if you load in that space, the nozzles don’t have air resistance required to create a droplet.
Occasionally we get calls about overfilled mixers not mixing and what can we do. In some cases we can retrofit. All details have to be studied.
5. What about segregation on discharge?
Segregation on discharge: There are two main reasons why materials segregate from the mixer to a hopper, container or bulk bag and they are different sizes of particles rolling apart; and air getting trapped under the material, puffing up through and carrying the lighter ingredients and depositing on top. This is from different weights of particles and the fancy word is elutrification.
Roll apart segregation can be controlled by having the receiving container the same size as the discharge stream. The discharge can be a drop bottom or port as long as the receiver is sized correctly.
Elutrification has several medicines. Make your hopper no more that 1.3 x the batch size and limit the fall distance from a drop bottom. If the problem is even too severe for that, then control the discharge and run the material down a nearly vertical side (80 degrees) and make lots of opportunity for air to exit. Don’t overlook entrained air.
Also look at segregation exiting the hopper.
6. How do we remove lumps?
If it is a liquid application, we will try to prevent making lumps. If there are lumps in the ingredients, we typically add high shear with our Shearmakers. We have done systems with external devices, could be in line, such as centrifugal sifters.
7. Can we mix pastes?
Qualified, yes. Low viscosity pastes we can mix very well. However, our principle of mixing involves putting all the particles in motion when the motor starts. Some products cannot stand this much movement and the result is balls, or it wraps around the rotor and the particles don’t change place. We have to test.
8. How does our discharge self-adjust.
We don’t have an over-center lock because we have never seen one that didn’t release some pressure when it went over center. Our side door clamps do that. The reduced pressure allows the door to leak even if you do everything else right. Over-center can work in feed, but we are aimed at the industrial market.
What we do is hold the door by torque from one or two air cylinders with constant pressure on the door, and it can move slightly to self-seat. The air cylinder crank is installed so the full stroke of the air cylinder is not used, and this additional travel compensates for gasket set. If there is build up on the gasket, it stops the air cylinder and when the build up is removed, it can adjust back to its original position.