Issues to be considered before installing an automation system
To ascertain whether an extruder plant is suited for automation with a system such as MoMAS®, it is necessary to consider following points.
Is an enhancement of product / process quality to be achieved?
Is an increased product output required?
Is a new market sector being envisaged?
Does the customer ask for proof of ranges of process parameters held during production?
- Hydraulics and ram position / speed control adequate: Some extruders have profile speed control which is not suited for operating the extruder with varying speed which is mandatory for iso-thermal extrusion. Iso-thermal extrusion demands a speed which generally varies with the ram position. Check whether the actual ram speed follows changes of the set point closely.
- Billet furnace temperature control For a constant reference input to the billet temperature control loop, all the billets coming out of the furnace should have the same axial temperature run, after the steady state has been reached. If the reference input is changed, the actual billet temperature should follow it with a lag at most of 2-3 billets.
- Puller control: When the ram speed changes with the reference input, the puller mot ion control should ensure that the profile speed follows the changes.
- PLC capability for data transfer: This is a vital requirement. MoMAS ® receives measurement data sent by the PLC during extrusion and the process data and the measured billet temperature during the idle time between 2 cycles. It transmits the optimised data (reference inputs for the billet temperature control and ram speed) to the PLC also during idle times between two cycles.
The success of any system which is added to the extruder depends upon the will of the operator to make it work and his competence. The crew should be capable of operating a new system and have the spirit to exploit its potential.