Technische Universität Kaiserslautern


Fachbereich Elektrotechnik und Informationstechnik

Mobile Measurement- und Automation System for Extruders


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MoMAS and Extruder Automation
The Functions MoMAS Can Perform
How MoMAS functions
What MoMAS Is Made Up Of


>>>>>>>>>> Current News <<<<<<<<<<<<<


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The Mobile Measurement and Automation System was installed and put into operation at SAPA Extrusions in Offenburg in May 2001.


Thanks to the efficient logistics and a motivated crew the installation, commissioning and handing over could be effected in a matter of a few days. Since installation it has been in continuous use and is yielding increased productivity and enhanced quality. 

An inventory of the production statistics for the period May to September 2001 yielded the following figures.

Statistics for the period May to September 2001

No. of billets extruded

Mean extrusion rate mm/s

Mean error of 


Standard deviation of Jaustritt



30 381


12.1° C

3.89° C

Without MoMAS

26 180


(28.8° C)

4.21° C

Total number of extrusions: 56 561
Percentage of extrusions with MoMAS: 56 %

A version on MoMAS for uncomplicated installation and commissioning by the extruder personnel themselves is now available. Main feature of this version is that it facilitates isothermal extrusion even in manually operated extruders. The system can be applied for a wide range of extruders with or without velocity control loop and with or without PLC control.

Necessary hardware:

  • Pyrometer for profile exit
  • Instrument for billet temperature
  • Position sensor for ram position
  • MoMAS Interface Unit and Industrial PC


  • The Pyrometer and Position Sensor outputs are connected to the Interface Unit.
  • The signal corresponding to the position of the adjustment knob manipulated by the operator is fed to the Interface Unit.
  • The Industrial PC is initialised with the operating parameters.


MoMAS is designed for extruders in which the operator adjusts the extruder input - be it the oil flow of the hydraulics, be it the reference input to the velocity control loop - by turning a knob attached to to a potentiometer. The fist extrusion cycle is performed by the operator as usual by setting a constant input. During extrusion, the operator input and the exit temperature are displayed as functions of the ram position continuously in the monitor. Simultaneously the operator input and the exit temperature are fed to the computer.

Manual isothermal extrusion

At the end of the cycle the operator inspects the profile surface, chooses a suitable reference input for the exit temperature and feeds it to the computer. Also the measured billet temperature of the 2nd billet is fed to the computer. Using this data the computer calculates the optimal run of the input (potentiometer position) for the 2nd cycle and displays the run on the monitor. The operator then starts the second cycle and manipulates the potentiometer knob in such a way that the run of the input he gives follows the optimal run in the monitor. Tests have shown that the choice of an input with three levels is easy to be followed and at the same time a good approximation of the ideal optimal run. The subsequent extrusion cycles are performed similarly.

Implementation and results in an industrial extruder

The system could be set up and put into operation within three hours. As the system is totally non-invasive no additional safety measures were necessary.
The acceptance by the operator was very good because the operation requires no special shills and is essentially the same as before with an additional aid.



Runs of process variables in an industrial extruder


The above figures show runs obatined during production.


A new Demo-Version of the  Mobile Measutrement and Automation System (MoMAS) software developed for application in extruders is now available. The software contains the original programs for signal processing and control as well as the console dialog for the operator. Also part of the software are a simulation of the extrusion process and the optimization algorithm for achieving isothermal extrusion.

Extruder managers and suppliers interested in the application of the system can obtain the software after giving details of their extruder in the check-list and sending it by fax or email to the Lehrstuhl für Regelungstechnik und Signaltheorie at the contact address given below.

A detailed description of MoMAS and its application, can be downloaded here.




MoMAS and extruder automation

The Mobile Measurement- and Automation-System for Extruders (MoMAS) is a system for optimising the operation of extruders for metals with the goal of achieving high productivity and enhance product quality. Basis for the optimisation is the mastering of the thermal processes underlying the extrusion process. In particular MoMAS consists of measurement and control sub-systems which serve to achieve tight control of crucial variables such as extrusion rate and exit temperature. This leads to a high and consistent product quality.




By virtue of the variety of options it offers, MoMAS provides operators and managers of extrusion plants with a flexible and effective tool which can be employed to achieve various optimisation and automation goals. Thereby the operator can himself select the degree of automation with which MoMAS operates. Most importantly, he can start off by operating the extruder manually and still exploit the information of process variables acquired and supplied by MoMAS. This provision for introducing the automation in steps alleviates its application and makes it easily acceptable on the part of operating personell.
MoMAS controls the exit temperature by suitably varying the extrusion rate automatically. It can be employed to achieve a reduction in the extrusion time per billet by employing exit temperature control in conjunction with a successive lowering of the furnace temperature. In case controlled tapered heating is possible, MoMAS can be employed to obtain constant exit temperature with constant extrusion rate.

The functions MoMAS can perform

A first important and useful function of MoMAS is that it measures various process variables such as exit temperature, extrusion force, ram velocity etc. continuously and displays runs of the runs of these variables in the current and previous cycles. Also displayed is information such as the extrusion time per billet, idle times between cycles and the mean and standard deviation of the exit temperature over the cycles.
The second main function of MoMAS is calculating the optimal input functions employing data of the previous cycles and displaying these at the start of each cycle. The operator can select the run of the input, e.g. the extrusion rate, proposed by MoMAS or a modified version of this and apply it to the extruder. Furthermore, a direct on- line control is superimposed during the extrusion.


How MoMAS functions

The core of MoMAS is the exit temperature measurement and control system which is employed to maintain the exit temperature at a constant predetermined value. The control consists of a combination of Predictive FEeed- Back and Adaptive Feed- Forward (PFEBAFF) control. The extremely robust off- line open-loop control in conjunction with the on- line closed loop permits a variety of possibilities for optimising the extrusion process. The off-line technique facilitates the application of non-causal filtering for lag-free smoothing of the pyrometer signal and the elimination of effects of the inherent sluggishness of the extruder.

What MoMAS is made up of

MoMAS hardware consists of an industrial PC with Windows operating system, a plug in card for interfacing the computer with the process, an interface to acquire the analog signals, a pyrometer for measuring the exit temperature and a sensor for ram position. This is supplemented by signal processing, control and optimising and data handling software.

What the pre-requisites for installing MoMAS are

MoMAS can also be installed in an existing extruder plant to upgrade the performance. Pre-requisite for the installation is a hydraulic system which has an axial piston pump with adjustable stroke (swashplate). A PLC system (e.g. SIEMENS S5) and a furnace with temperature control would be of advantage. The installation of MoMAS is non-invasive - existing equipment including software is practically unaffected.

How to introduce MoMAS in an existing extruder plant

To ease the acceptance of MoMAS in existing extruder plants, it is made up in such a way that it can be installed in successive stages as follows:
  1. Installation of equipment for temperature measurement and visualization of process variables
  2. Implementation of semi-automatic operation: Installation of a computer system for determining the optimal extruder velocity trajectory at the beginning of every cycle and displaying it to the operator
  3. Implementation and commissioning of the fully automatic operation in which the optimal velocity trajectory is generated and applied by MoMAS itself

A switch-over from automatic to manual operation mode can be effected at any time with ease.

For individual extruders the Control and Signal Theory Group offers to work out an automation concept with the Research and Development Center of Extrusion, TU Berlin and eventually test it in conjunction with the 8 MN extruder at the center.

Additional features

All the process data is stored and can be archived and retrieved.

Where to get acquainted with MoMAS in operation?

MoMAS has been installed at the Research and Development Center of Extrusion, TU Berlin. For a visit contact the addresses given below.

For further details contact: