How to get the most out of your closed mixer

The three new software functions that you do not yet know to improve mixer production by 30%

I realized that too many of my customers still use only the basic functions of our closed mixer module, working either with time or temperature .

I thought then to write this article to present three very useful and often little used functions that could help you improve production by up to 30% (especially the last one).

Whether you have a new mixer or an old mixer equipped with our MyFlexPlant control software, knowing how to best use it will allow you to take advantage of every second and every kilowatt of energy. If time is money, energy is obviously money.

Numerous studies have been carried out which show that a mixing cycle based only on a variable (time, temperature or energy) is not very efficient. The reason is simple: the variables involved in the mixing process cannot be considered constant over time and repeatable.

This means that components worked in winter or summer behave differently; that the same component from different suppliers has a different behavior; that the work environment is not constant (think for example of cooling water).

In order to have a greater guarantee of cycle repeatability and to make it as close as possible to the laboratory formula, the best method is to set all three reference variables in the various mixing steps.

Function 1. Change of step with AND / OR logic

It should not be necessary but better to review the meaning of each of these quantities:

  • Time: indicates after how many seconds a program step is considered completed;
  • Temperature: indicates at which temperature (equal or higher) the step is considered completed;
  • Energy: indicates after how much electricity consumed by the main motor, the step is considered completed;

The fact of working with more variables means to indicate to the program to pass to the next step when more conditions occur simultaneously.

But even this approach could be incorrect, so I want to tell you the first complex software function you need to know: the AND / OR programming.

The programming page of the mixing phases presents this grid:

With this function you can set the phase change conditions with maximum precision.

The AND combination requires that all the conditions indicated (those that have a value other than “0”) are simultaneously respected.

The OR combination requires that at least one of the conditions of the OR line is respected.

In the example to have a step change it is necessary that at least 60 seconds have passed from the start step, the temperature is at least 85°C and at least 3.4Kwh of energy have been consumed. However, if the temperature exceeds 92 ° C, regardless of the other quantities, there would still be a change of step.

Why this function is important

If properly configured it allows you to solve the single problems you would have working with only one set-point.

For example, working only with time (as unfortunately many do), you are not guaranteed to have reached the correct temperature or you could have passed it if you have problems with cooling water.

While if you work only for temperature, you may have worked too little the compound or at least not optimally, especially if it is summer and the mixer is hot.

Although the use of energy as a step change condition is a more precise (and complex) method than the other two, this too does not guarantee you the right mixing time or the right temperature, for example if the piston pressure is not optimal.

Using all three parameters in AND allows you to verify:

  • that mixing has taken place for a minimum time
  • that the optimal pitch temperature has been reached
  • that a job has actually been done thanks to the energy consumed

The OR check for the individual items allows you to have an automatic loophole if something has not worked properly in the AND logics (for example if the compound is already too hot), avoiding premature hardening (if you prefer “curing”).

Function 2. Temperature curve at the threshold

If the first function is little used but is known, this is mostly unknown to many.

When we developed the first mixer control programs, over 20 years ago, we realized, thanks to the experience of the chemists we collaborated with, that only time, temperature or energy operation did not guarantee control over the temperature curve.

In practice, having so many parameters on which to act (rotor speed, piston pressure, time, energy, temperature) there was no control over how the temperature had to increase over time.

Furthermore, there was no possibility of mixing at a constant temperature in order to increase dispersion, especially in large mixers.

For this we have introduced the feedback on the temperature control to maintain the temperature of the compound within predetermined values in the step.

How the feedback on temperature control works

On the page for setting the mixer phases, for each configurable step, find the column Temp.R. (or TR in old versions):

By setting a minimum and a maximum temperature for the step in question, the system is told to act either on the number of revolutions or on the pressure of the piston (or both) to keep the temperature within this range .

The function works as follows:

  • A waiting time starts at the beginning of the step
  • After this time, if the temperature is lower than expected, the revolutions of the rotors or the pressure of the piston (or both) are increased by a set value
  • If the temperature is higher, rotor revolutions or piston pressure (or both) decrease
  • The control is repeated during the step at regular intervals and each time the temperature is checked to act in one way or another
  • Naturally there are parameters to indicate the minimum accepted rpm and the maximum ones, same thing for the pressure

A practical example is one where you want to work the compound, but you don’t want to heat it too much. Setting only a time would risk having a temperature that is too low or high, while setting a temperature would also lose control over how this temperature rises.

To use it at its best, it is necessary to divide the temperature curve on several steps so as to work finely on each step.

Or if you want to work at a constant temperature like tire manufacturers do, with a step you get to the desired temperature and then with a second step you work on time but activating the feedback control with a small temperature difference. This is a function that is not always present on the software of mixer manufacturers, it has been standard for us since 1997.

Function 3. Management of mixing cycle times

In discontinuous productions it is necessary to calibrate all the production on the slowest element of the processing chain.

Sometimes it is the mixer, at other times it is the calender or the open mixer.

In practice you can start a new cycle when you know you can download it.

The problem is that where production still depends on man, so when we do not have complete automation, the productivity of the operator is not constant and therefore the processing time is not.

This on a 7 or 8 hour shift also causes important differences on the kg produced by the line.

The cycle time management function prevents this from happening and encourages the operator to keep a steady pace over time. For each mixing formula, a series of parameters are present, some of these act on the cycle time:

These are Max Cycle Time and Cycle Time.

If set correctly, they allow two controls:

  • An alarm if the cycle lasts more than 420 seconds (in this case), an alarm that the operator will have to explain (Max Cycle Time) ;
  • Automatic start of the following cycle every 360 seconds, allows you to schedule and better program the production (Cycle Time) ;

Cycle Time parameter

Let us deepen the functioning of the Cycle Time parameter.

If this parameter is different from 0 and the system is set for automatic cycle start, once this time has elapsed (from the beginning of the cycle) the next cycle is automatically started (of course when mixer is ready). If automatic start is not set, the system accepts the operator’s start only if this time has elapsed since the beginning of the previous cycle.

In order to function correctly, the actual cycle time – including all the loading, cleaning, mixing and unloading phases – must be less than this value.

In other situations, assuming that the mixer is not the weakest link in the chain (the one that requires the most cycle time) the parameter should be set on the longest machining + a tolerance time T.

This ensures that you can work X cycles per shift. If this is not possible, if machine alarms have not occurred, the reason can only be on how the operators worked, who will have to explain why the times were not respected.

Conclusions

As you can see, these are several useful functions to allow you to better control your mixer and I can assure you that new fantastic features are being developed to help you further improve production and be a step ahead of the competition.

For this reason, it is important to keep the mixing module updated if you do not want your competitors to take advantage of the new features.

I hope this article was useful to you.

If you want to know in detail these functions and how to make the most of them, I remind you that if you have a service contract (Gold, Platinum or Diamond), you can call the Multi Data office for free.

Our technicians will connect with your software and show you in real time how to set these functions.

While if you need me, you can write to me at claudio.tosi@multidata.it or call me at +39 059 537902.

Buona vita

Claudio Tosi

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