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Multihead Weigher Accuracy and Controls
Thomas Bornemann, Director Sales & Marketing at Hastamat, says an automatic weigher in general fills a maximum of 0.3 to 0.5 grams above the nominal filling weight, and customers can set their own plus/minus levels. With the right model chosen up front, speed does not affect accuracy. He recommends separating weighing logic from the main PLC, using a main controller plus small controllers in the load cells.
Key takeaways
- Thomas Bornemann says that in general, automatic weighers fill a maximum of 0.3 to 0.5 grams above the nominal filling weight, and customers can set their own plus/minus levels.
- If the right model is chosen from the beginning, Thomas Bornemann says accuracy has nothing to do with speed.
- Because the weigher evaluates thousands of possible combinations, Thomas Bornemann says weighing control should be separate, combining a main controller with small controllers integrated into the load cells.
Common questions
- How accurate is a multihead weigher?
- According to Thomas Bornemann of Hastamat, in general the result is a maximum of 0.3 to 0.5 grams above the nominal filling weight. Customers can also set their own plus and minus levels on the weigher, which changes the giveaway, or average, somewhat.
- Does weigher speed affect weighing accuracy?
- Not really, according to Thomas Bornemann of Hastamat. He says that if you choose the right weigher model from the beginning, accuracy has nothing to do with speed in the end, which is why the model choice at the start of a project matters.
- Should weighing logic run in the main machine PLC or a dedicated controller?
- Thomas Bornemann of Hastamat says it should be separated. A weighing system needs a lot of computing capacity because it evaluates thousands of possible combinations, so it uses a combination of a main controller and small controllers integrated into the load cells.
Transcript
Tom Rougeux, President, Piepenbrock Packaging
So let's talk about accuracy and weighing. How accurate should an automatic weigher and weigh and fill system be in normal production? How accurate are these weighers?
Thomas Bornemann, Director Sales & Marketing, Hastamat
So in general, we are talking about maximum 0.5, 0.3 gram higher than the nominal weight, the filling weight, yeah.
Tom Rougeux
0.3 grams.
Thomas Bornemann
0.3 grams, but also here the customer can set their own plus minus levels on the weigher, and this also change a bit the giveaway, let's say, or the average.
Tom Rougeux
Okay, and does speed change when accuracy changes? Are they related?
Thomas Bornemann
Not really, not really. If you choose the right model from the beginning, then it has nothing to do with the speed at the end.
Tom Rougeux
Can a weighing system automatically compensate for changes in product variability? So if a product varies quite a bit, how can a weighing system help and what are the limitations of a weighing system when the product varies quite a bit? Say for instance, beef jerky, how does a weighing system help pack beef jerky and what are the limitations of a weighing system with beef jerky?
Thomas Bornemann
I would say the limitations are finally could be the volume, the final filling volume of the product. So that could be a limitation, but not must be, because we also here, we have different kinds of bins, you know, to be able to use the same weighing system for different kinds of product volumes, yeah, at the end.
Tom Rougeux
Okay, so here's a technical question for you. Where does the weighing logic live or where should it live? Should it live in the main machine PLC or should it be in a dedicated weighing controller on the machine, and why?
Thomas Bornemann
I mean, we discussed before already about the capacity of the computer, and the weighing system needs a lot of capacity, yeah, because if we talk about thousands of possible combinations, then it's not only to split or to have their own control system. This is also a combination with a main controller and single small controllers which are integrated into the load cell already, yeah.
Tom Rougeux
Okay.
Thomas Bornemann
So the question, the answer from my side is here clear, yes, you have to separate it, yeah.
Tom Rougeux
Because it has quite a bit of computational control. Okay.
