Extruder, slipformer, or both

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Extruder, slipformer, or both

In manufacturing hollow-core slabs, some producers prefer extruding, while others rather use slipforming. The reasons behind these choices are often based on historical grounds; different regions have had different building traditions and requirements. We have listened to our customers regarding their varying production demands of today, and can offer equally strong technology solutions for both extruding and slipforming.

When it comes to the quality of the end product, both technologies make for an excellent result, if the basics are in order. What then are the things to consider when deciding between an extruder and a slipformer, or perhaps even buying both? The precast industry, like so many others, is looking for flexibility factors, meaning that production is as even as possible without large peaks and especially without deep valleys. If you can make a great variety of products with the same machine, it is a tremendous advantage. The fact that you need to make only a minimum of alterations when changing between products is also of great value. Consolis is the largest manufacturer of structural precast concrete elements in Europe, and uses extruding and slipforming to almost the same degree. "It all comes down to what end products you wish to make and for what purpose", crystallizes Mr. Olli Korander, Managing Director of Consolis Technology. Through Consolis, Elematic has access to this vast experience of both production technologies and has used this effectively in designing extruders and slipformers of cutting edge quality.

Extruder for longer spans and lighter products

Traditionally, the northern parts of Europe have tended to lean towards extruding, as construction demands on hollow-core slabs have been for longer spans and lighter products. Cross-sections of more than 265 mm are especially economical to produce by extruding, and the savings in raw materials have been a valid reason for using this technology. Extruders, which have been modular since the 80's, provide ease and cost-efficiency in changing between slabs of different size, but are limited to hollow-core sections only.

Slipformer for robust products and variation

In many other parts of Europe, slipforming has traditionally been the more common production method, as it allows for the use of slightly more inconsistent raw materials while still producing a robust end product. With a slipformer, it is easy to make a variety of hollow-core cross-sections and a wide assortment of other products as well. These include T-beams, ribbed slabs, posts for vineyards and much more. Regarding the utilization rate of an investment, the many possibilities of the slipformer are a worth-while consideration. You only need to change a few parts to produce different products with the same machine!

Both are better

If you are planning to make small hollow-core and other products on the same bed, you need a slipformer for its versatility. Especially in a small plant, slipforming would be the most viable choice. In a larger factory, it can be more economical to make the hollow-core slabs, at least the thicker ones, with an extruder and the other products with a slipformer. The maintenance costs for a slipformer are lower than for an extruder, but then again an extruded slab is 10 percent lighter than a slab of the same thickness made by slipforming. Naturally, the heavier slipformed slab requires more concrete and occasionally one or two more strands to achieve the same span as with an extruded slab. You may well want to think about acquiring both a slipformer and an extruder, to combine the advantages of both. This was done by Consolis Latvia, for example, where the first slipformed hollow-core slabs in the country saw the light of day. Another company who has chosen this path is Elematic's long-time customer in Sicily, Gruppo Fauci.

Alla Siciliana

Italy is a country where the use of precast concrete goes back far in time. Gruppo Fauci was founded over a hundred years ago, although precast concrete production became part of the business only some twenty years back. The company has several plants and currently employs close to 300 people. Their activities cover all of Sicily and parts of the neighboring province of Calabria as well. The principal owner and managing director of Gruppo Fauci, Mr. Salvatore Fauci, Cavalier Ufficial, explains: "We acquired our first extruder in 1998, before that we only used slipforming. We make 500 mm hollow-core slabs with the extruder, as other machines cannot manage this size of slab." "We produce the other hollow-core slabs, which are between 200 mm and 400 mm thick, with the slipformer. The machines complement each other, and the choice of which technology to use is exclusively dependent on what product we intend to make, and for what purpose", Mr. Fauci continues. The main product of the company is T-beams, of which it makes 10 000 m/day by slipforming. These are used together with red clay blocks, another important product of Gruppo Fauci, to make floors for single family houses. Other slipformed products include concrete posts for vineyards, which are gradually replacing the old wooden posts.

In the end

As a conclusion, it can be said that for both extruding and slipforming, what counts is that the final product fulfils the set criteria. The construction company is likely to be uninterested in which machine the products were made with, as long as they meet their quality standards. If you are planning to acquire production machinery and need more information on how to best achieve the desired end result, we will be happy to provide you with all the expertise and knowledge it takes for you to make the most cost-efficient investment. It may be for an extruder, a slipformer, or for both.

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