Every line has its bottlenecks, and in theory they can be reduced primarily by replacing or boosting the performance of individual machines. This phenomenon is most pronounced in lines that were assembled from different machines at different stages of the company’s development. Such “patchwork” lines typically suffer the greatest losses, as the fastest machine must wait for its slower predecessors. That is why at Milbor PMC we follow a project-based approach – we build lines in which machines are matched to one another and whose performance levels correspond. When integrating our equipment with machines from other suppliers, we always verify their actual performance and select the remaining components on that basis.
One might assume that optimisation is such an important topic that companies continuously monitor this aspect and treat it as a priority. In practice, this is rarely the case.
Working in the fruit business has its own specific character. Operators change regularly, poorly motivated workers give little of themselves, and the rush at the peak of the season overshadows attention to detail. It is no surprise that in such conditions there is little room to consider whether everything is actually running at full capacity. And if it is not, then the investor has effectively thrown part of their money away. Knowledge of what needs to be checked is also lacking. Yet this is actually quite straightforward. The average line throughput is indicated by the statistics from the checkweigher or the tray sealer.
The concept of throughput in fact covers several distinct terms:
EXAMPLE: A tray sealer closes packages at an instantaneous speed of 100 punnets/min. During a one-hour cycle, the operator stopped the entire line for 5 minutes to change the head on the labeller. As a result, the average throughput of the sealer in that cycle dropped from 100 to just under 92 packages per minute.
The average throughput of the entire line is limited by the weakest link – the machine with the lowest capacity. If in your packing line the tray sealer and labeller can operate at 110 packages per minute, but the weigher only reaches 70 packages per minute, the capacity of the subsequent machines in the line will not be fully utilised.
In the video below, Piotr Milewski describes the bottleneck issues in the blueberry busienss:
A sorter screens out fruit that fails to meet the criteria of the packing cycle – it acts as a sieve that eliminates a proportion of blueberries. During periods when the quality of the input is lower, we can speak of up to 40% of fruit being screened out. If the nominal throughput of the sorter is, for example, 2 tonnes/h, then over the course of an hour as much as 800 kg of blueberries may be removed from the process, with only 1,200 kg per hour reaching the weigher. A low sorter throughput means that the subsequent machines in the line cannot operate at full capacity, simply because they have no input to work with. And conversely – high throughput on the blueberry sorter will allow the subsequent machines in the line to achieve better results.
The design of the machine itself also affects how quickly fruit passes through it. A good example here is the G3 Evolution weigher, in which a conveyor belt transports fruit evenly. The machine does not wait for all weighing heads to fill up – just four full buckets are sufficient for the weigher to fill the punnets. Those that have not yet reached the required weight will be packed in the next cycle. Individually, we are talking about a saving of just a few seconds, but over the course of a full working day this represents a tangible reduction in time compared to a weigher that waits for all heads to fill. The speed of the G3 Evolution is also influenced by its construction. The components where fruit is most exposed to impact are made of soft silicone, which effectively cushions the falling fruit. A perfect example is the belt onto which blueberries drop from the hopper positioned above. Thanks to such solutions, the fruit does not lose its firmness – it rolls smoothly and is more attractive to the consumer. Some companies working with less gentle machines reduce their speed in order to maintain good fruit quality. This comes at the cost of the overall line throughput.
The causes of bottlenecks may vary, but their result is always the same – lower revenue. A grower with their own packing facility, bound by contracts with retail chains, must deliver the product on a specific day. If their packing line does not operate fast enough, they must outsource the packing. This means a lower margin per punnet (approximately 20–50 cents per package), additional logistical obligations, and the risk of fruit damage or underweight packages. On the other hand, if we are talking about a packing company that adjusts the volume of fruit to the capacity of its line, a lower line throughput will translate proportionally into lower sales.
Although the causes of slowdowns on a packing line can vary greatly, the result usually remains the same – less money in the investor’s bank account. If you are not packing, or doing so more slowly than you could, you are earning less. In a business where the requirements of discount retailers are very demanding and customer expectations are rising, every tonne counts. Diagnosing and eliminating bottlenecks is one of the first steps towards better earnings – and it is easier to take those steps alongside practitioners from the blueberry world. 13 years of experience in the industry, our own farm and nearly 300 completed automation projects mean we know the blueberry sector from every angle. We also know the bottlenecks of packing lines, and thanks to our technology we are able to diagnose and eliminate them. If you would like to find out more on this topic, fill in the form and let’s talk about optimising your packing facility.
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