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As a precast manufacturer, you have probably pondered whether to invest in spare and wear parts of original equipment manufacturer or slightly less expensive parts of an external provider. In this blog, I will shed light on the question why it makes sense to keep you millimeters in place and use those more expensive original parts.
Cross-sections according to the drawings
To start off, when I visit hollow-core slab factories, I have often seen slabs being produced, the cross-sections of which do not match the drawings. It is alarming that only a few pay attention to this difference; a blind eye is too easily turned to a difference of a few millimeters as it doesn’t strike as significant, and it is difficult for many to see how much concrete is lost annually if the slab cross-sections are not what they should be. Also, that “wasted” concrete and the amount of money spent on it is difficult to prove, since, unfortunately, people sometimes consider it as a part of the hollow-core slab production process. On the other hand, when ordering spare and wear parts for extruders, it is easy for the purchasing department to put down the numbers and show how some parts are cheaper and big “savings” can be reached when choosing them. But that’s not really the truth.
Save costs by saving concrete
The truth is that the clearest, biggest savings come from the savings in concrete, which is by far the most expensive part in the hollow-core slab production. Roughly speaking, concrete / strands account for about 55% of the slab price and wear parts for only 3%. Hence, it is really a no-brainer to see how to make savings if you want to save on production costs.
Here are a few examples of what kind of numbers we are talking about.
It hasn’t been long since I visited a factory that used copy screws and sleeves. Their six-hole and 200 mm slab cores were 15 mm smaller than the cross section in the drawings. Furthermore, they were happy with the slab. Together, we calculated that they were using about 2 cubic meters more concrete on each cast bed compared to if the cross section would have matched with the drawings. This was a shock to them. By casting four beds a day, they wasted 8 cubic meters of concrete – money – every day, 48 cubic meters a week, 192 cubic meters a month, almost 2,500 cubic meters every year. I think this clearly highlights the importance of suitable and properly fitting spares and wears.
Also at the same factory, the extruder settings weren’t the most efficient and their 200 mm slab height was 206 mm. They were also happy with it, until I went through it together with them and we could see that the 6mm oversized slab meant an extra cubic meter consumption of concrete per each cast bed.
So, in practice, they used almost 3 cubic meters more concrete for each bed than they needed to which meant that it was actually expensive to save in spare and wear part purchases.
As said earlier, the savings that come with the right spare parts and proper machine settings are hard to realize because they are not a clear sum of money indicated on a particular line.
Often, one ends up in the above described situation slowly, step by step, when no one notices how the production costs are rising. The situation is simply accepted, even if the profit drops, and savings are sought from spares and wears. As things get worse, it could be called a negative chain reaction.
So the answer to the initial question – why millimeters are so important – is because when you have your millimeters in place, you will save a lot of money. Also, when you use original spare parts, it is easy for an Elematic specialist to make the best settings for your extruder.
If you want to discuss the importance of millimeters in hollow-core slab production further, I will be happy to hear your opinions and shed more light on the subject.
Mikko Hellman, Service Engineer, Customer Service Dubai,