The Future for
Extruder Control By Paul Girdham, DSL Systems Ltd
A good control system will be able to store these values for many years and together with effective traceability allow you to check back in case of customer complaints. Having such a ‘helpful’ control system gives the operator more time to run other parts of the plant, additional extruder lines, operate a Fork Lift Truck and so on, knowing that the control system will call for help when parameters are drifting towards out-of-tolerance or when it’s time for a quality reading. OEE (Overall Equipment Efficiency) is the gold standard for working out how well your manufacturing process is utilised and, if built in, gives everyone actual evidence of ‘how things are going’. When it comes to production throughputs and waste, it’s really Controlling an extruder remains partly a manual process requiring operator input, especially during start-up, but the more automation the less work an operator has to do to look after it. Many extruders come with their own manufacturer’s control systems but there are significant benefits to having a complete integrated endto-end control system for the whole plant where the extruder is just one part, locking in operator knowledge and experience. The ideal system can be illustrated by an example of a brand-new pet food product about to be manufactured. The production manager together with the nutritionist, vet and marketeer can set up the complete formula, operating parameters and quality set-points, probably derived from a similar product. This would include all additions into the extruder conditioner and extruder parameters including speed, load, timings, and so on. Other settings such as throughput rates, temperatures, die parameters, knife settings can all be pre-set, even if the operator has to temporarily override some on start-up. It’s even better if you can copy a similar product’s settings and then adjust what’s required. After the run is complete, the system should remember the settings so that the next time the same product is run, the extruder can start producing saleable product faster, minimising waste and lost time. After a run has completed, all data can be analysed, everything from the initial batch parameters, hand additions, alarms, extruder and cooler parameters and downstream values, all in one place and therefore simple to adjust parameters for the next run. The operator
useful to have the complete picture including individual batches with actual material inclusion rates, to analyse and compare against different products and production runs. The ability to look at a complete run where individual batches provide the weights of raw materials and compare this to the finished product out, whether from packing or tote bags is invaluable in investigating efficiencies and waste. Expectations for full traceability includes all raw materials from the warehouse including tracking of individual lot numbers of every raw material, each IBC / bulk liquid into the extruder conditioner including reworked material and all the way to the final finished product pack. Whilst the actual control of an extruder and its ancillaries is often considered a lower level, the level of information and logged information details used to be called the mid-level and sometimes called MES (Manufacturing Execution System). Some companies are now calling this mid-level “Edge Computing”. And if you have many manufacturing plants around the country you may hear about Cloud Computing but the important thing to know is what information you want when. A complete end-to-end integrated control system means that there is only one support company to contact in case of problems or required modifications. The actual extruder control is not dependent on a separate computer and the choice of PLC can be the same as all the other PLCs already on site, reducing risk of failure, simplifying support, spares and technical knowledge. This all leads to improved efficiencies, giving you the edge.
doesn’t have to think about things which are automatically set up by the control system. The latest systems can prompt the operator to take quality readings at the appropriate time depending on the production run length,
Paul Girdham is a Senior Consultant with
entering readings into the control systems and highlighting values
DSL Systems Ltd who design and supply
which are drifting towards out-of-tolerance and making adjustments
Control Systems
in good time.
Pet Food Supplement 2020
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