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When reducing the head count is no longer an option
When faced with such challenges, the manufacturer is bound to turn to the immediate and obvious ‘reducing the head count’ which has so often been the option of first choice. Having done this in the past, reducing the head count is no longer an option without the risk of cutting corners in manufacturing with the ever-present consequence of producing sub-standard product, causing more rejects, rework, scrap and, if the product has already been dispatched, another costly recall. Inevitably, the manufacturer turns to automation, perhaps with some success in spite of a long ROI. If this works well enough, it might allow the eventual reduction in head count which was doubtless a major part of the justification, without the risk of a quality compromise. Some quick wins would be autocoding, and even auto line set up in some cases where the product specifications and label changes only require changes to the software parameters all achieved with minimal operator involvement, other than calling up, through the keyboard, another product. This might need the manual intervention of a label reel change and/ or the adjustment of guide rails to suit, plus minor statistical checks throughout the run to ensure compliance, but little more.
Automation – small beginnings This limited application of automation is seen by many as the minimum requirement, as it virtually eliminates operator set-up errors and can dramatically reduce changeover times. These simple automation checks can do much to improve efficiency, especially as the whole line can be set up through no more than the call up of a product from the data base, removing the need to go to each machine in turn to configure it. In a line with, say, ten product or label changes per shift, such ease of set-up would not only reduce errors and increase accuracy, but could save say 15 minutes per changeover. That’s a total saving of 150 minutes in a single shift. We have seen some production lines with 20 product changeovers per shift. Without simple automated assistance, such lines can spend more of an 8-hour shift ‘in production’.
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Problems often arise when companies attempt to take such automation to the next level by, for example, reducing the number of line operators to further justify the introduction of another filler/packing machine that promises even greater speed.
Genuine OEE or PE? In our experience, one thing that manufacturers often forget is the need for total process optimisation and line balancing. Many will boast to us that their OEE (Overall Equipment Effectiveness) is around 80%. When we do our ‘Gemba’ factory walkthroughs, we often find that they are calculating OEE incorrectly, by leaving out their product changeover times or perhaps leaving out Availability entirely, or not including Quality, so what their OEE consists of is little more than ‘Performance’, i.e., the number of packs produced within a given period, “so should have produced 1,000 packs in the hour but we only made 800. And we had a few rejects, better knock off another 20 packs for quality wastage, so our OEE is about 78%”. It doesn’t get much less scientific than that!
In an attempt to show his contempt for the flexibility in setting key metrics to be contained within an individual’s choice for OEE, Dr Donald Wheeler, a friend and colleague of Dr Edwards Deming, said:
the processing area, from goods inwards to finished products, must be taken into account. Where this isn’t done, an improvement in one part of the process will cause a bottleneck further along the process.
Automation bottlenecks When this happens in chilled ready meals for example, where pre-mixed sauces are prepared, if the sauce processing area gets too far ahead of itself, then because the product cannot be used in time, it can become an area of wastage, even though the OEE in the packaging area still looks good. Another quite unrelated example was in a whisky bottling operation many years ago when the company installed a filling machine to fill one litre bottles of whisky at 600 bottles per minute. Unfortunately, when this multi-million-pound installation was up and running, it couldn’t be run at more than 300 bottles a minute, because the infrastructure to get the empty bottles onto the line quickly enough and to remove the filled cases to pallets quickly enough had not been fully considered. These two areas therefore needed further significant investment before the initial speed of the filling line could be experienced.
Going back to extending automation, it seems obvious that the whole production process must be taken into account and not just the OEE of the packing line. I believe this was what Dr Wheeler was referring to in his somewhat cynical reference to OEE. For OEE to be meaningful, we have to take into account the processing area, otherwise it is easy to have, and we have frequently seen this, batches of product awaiting packaging because, good as the packaging might be, the batch processing is faster. So, ideally line balancing, to include the whole of
Deciding which process is suitable for automation These problems are everywhere and they are likely to be more frequently experienced, as the supermarkets, in general, require frequent, even daily deliveries as they don’t want to to hold stocks. This forces the manufacturers into producing shorter batch runs and frequent product changeovers. Exactly the opposite situation that is genuinely experienced when faster line processing is attempted. More appropriate for such applications where frequent changeovers are the norm, is to find automated processes that help to achieve faster product/label changeovers.
CONTACT:
Harford Control
www.harfordcontrol.com; 01225 764461
Automation | September 2022
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