Enhancing quality and performance in existing precast production facilities

7/20/2016

Construction activity continues to grow in Germany and Europe. Many manufacturers of precast concrete components are currently gearing up to meet future demands and are retrofitting their existing production facilities with the aim of maintaining their success in the fiercely competitive precast market in the future.

Their objectives in this streamlining work range from exchanging ageing components, to enlarging production space right up to replacement investments such as in robot formwork technologies, for example, or the renovation of formwork pallets and many other improvements.

 

Initial situation
The first automated systems for manufacturing precast concrete components were commissioned in the 1980s. The construction industry, especially at the beginning of the nineties and driven strongly by the reunification of Germany, experienced a boom time that led to a great number of new production facilities. Many of the factories erected during that period are still in operation today 20-30 years later.

Parallel to this, the technology of machines, control systems and formwork has continually advanced over the last few decades. This means that an immense potential for optimisation exists in current plants. With relatively reasonable investment, existing systems can be optimised both in performance and in quality, particularly in respect of the final product. Weckenmann stands out as a specialist for modernisation.


Various possible approaches to modernisation
The starting point in optimising a facility is a careful analysis and inventory of the complete system – beginning with concrete preparation right up to loading the finished concrete element.

Weckenmann Anlagentechnik GmbH & Co. KG has already accompanied the most varied of customers in modernising their facility. Their specialists first examine the facility from head to foot and evaluate the data gathered. After the appropriate analysis, the customer is shown its actual state with the potential improvements possible.

Formwork pallets after renovation by Weckenmann

An example of modernisation drawn from practice with prior analysis and inventory of an existing facility


With the aim of maintaining their position as one of the leading companies in the fiercely competitive precast market, Ziegelwerk Arnach GmbH & Co. KG from the Allgäu, Germany, decided, amongst other things, to optimise and modernise their current production line. One of the company’s objectives was to manufacture 20,000m² more precast per year.

The analysis by the Weckenmann specialists found that this goal could be attained by utilising just on 1m more per pallet. The first step was to optimise pallet layout. A mixed utilisation of pallets has been made possible by adding two stacking points and one more run-off system. This means that pallet utilisation can be exploited more effectively. In addition, a new hoisting device was set up over two pallet positions, thus ensuring the best possible level of flexibility.

The hoisting device was additionally equipped with a radio remote control in the formwork stripping area. This, in turn, enhances operator flexibility in work, since – now released from the device – he can carry out other work at the same time as operating the machine. Alongside more effective pallet layout utilisation, other intermediate stations plus new pallet stations in the formwork stripping area were created for optimising pallet flow. This has eliminated any waiting times when pallets are changed.

The existing formwork system was modified to formwork with integrated magnets for a more effective and ergonomic operating process within the overall system. Besides saving time during formwork positioning and stripping, this has also achieved more exact placement and better concrete component quality (sharp edges with the components as the formwork no longer shifts).

Added to this is a new automated formwork transport system with cleaner/oiler for bringing the formwork profile directly from its stripping to its positioning point. A new workplace system with a catwalk at pallet level and rack system for storing inserted components directly adjacent to the formwork positioning point ensures that work is carried out ergonomically. The length of the route taken is also substantially less than before when the storage of magnetic parts, formwork and inserted components was still located on the pallet’s short side.

Last but not least, ZW Arnach Gmbh & Co. KG invested in a fully automated concrete spreader, so that the exact amount of concrete – nothing more, nothing less – is discharged. The results of this modernisation are really quite impressive – their stated goal was exceeded by far.

 

Examples of selective streamlining in existing precast facilities


Automated concrete spreaders
Employing automated concrete spreaders enhances efficiency and productivity in a precast facility. An automated concrete spreader doses the concrete discharged constantly and precisely. Discharge tolerances with automated concrete spreaders are in the region of approximately 2-3%, depending on uniform concrete consistency. This means no varying concrete panel thicknesses any more, thus generating savings on concrete.

If the thickness of a concrete panel deviates 5mm from specified dimensions (concrete panel too thick) and assuming that 1,000m² concrete panels are produced per day, potential savings of around € 70,000 per year are possible. The new concrete spreader has paid itself off in a very short time.

Renovating formwork pallets
The formwork system and, in particular, formwork pallets play a crucial role in the quality of precast. Groves and unevenness on pallet surfaces are reflected in the precast component’s surface. Over the years, the edge formwork has also been affected in many cases. Pallet renovation is often an interesting alternative to new pallets. The pallets are sand-blasted, realigned, ground and polished; the edge formwork is toughened up or exchanged if needed. The result is quite striking; the pallets are like new. It has been demonstrated that renovating formwork pallets generates cost benefits of between 50 to 60% in comparison with purchasing new ones.

Cutting-edge formwork system with integrated magnets
Good precast quality is ensured by using high-grade formwork profiles with integrated magnets. Dimensional inaccuracies and poorly formed edges with precast components plus the reworking arising from this at a construction site are a thing of the past. The formwork profile systems are precise and firmly fastened to the pallet. The changeover to formwork profiles with integrated magnets can be carried out with reasonable expense even with existing formwork robot systems. A plastic coating offering permanent protection against corrosion is applied to Weckenmann magnets and, as an option, to the complete formwork profile. On top of this comes the time saved during formwork positioning and stripping since fewer parts have to be handled.

Application with a new formwork transporting and cleaning system plus “SCOP”
Cleaning and oiling formwork profiles constantly and automatically is important for a well-functioning formwork system. Transporting formwork profiles with a hand-drawn cart and manually cleaning them consumes much time but is still commonplace in many existing precast facilities. An autonomous transporting/cleaning/oiling track eliminates handling formwork profiles in this laborious and time-consuming way. In a system for floors, new investment in a SCOP machine enables five work sequences to be carried out at one single pallet station: gather transverse formwork sections, clean, oil and plot the pallets plus the subsequent placement of transverse formwork sections. Formwork stripping can be often handled in systems with the appropriate formwork robot technology. It is quite possible for formwork stripping, pallet cleaning/oiling and subsequent formwork positioning to be carried out at only one pallet station.

The solution can be adapted precisely to spatial and logistical factors and be retrofitted at any time to any system.

Electric control unit
Particularly with existing systems, the topic crops up of new master computer technology or new machine and/or circulation control units with correspondingly simpler visual operations via a touch panel. This can apply to complete circulation systems or else just individual machines. Action is needed at the latest when no more spare parts can be obtained for the existing control unit.

Integration of an additional offline pallet line with suction turning device
With the aid of additional offline pallet stations, it is possible to obtain a more efficient pallet/material flow with relatively little expense. It means that time-sensitive work processes can be decoupled from each other. This possibility exists at almost every position in the system. Bottlenecks in production are then a thing of the past, since waiting times no longer occur in the actual material flow. A dramatic improvement in performance can be attained by such process optimisation.


Conclusion

Every system definitely has its own potential for optimisation and can be dramatically improved in performance and quality by means of carefully prepared smart solutions. Often it is not just exchanging a machine 1:1 that is the be-all and end-all! The entire production process has to be reviewed from A to Z. Organisational measures can also substantially enhance system efficiency.

There are numerous reasons why companies have chosen Weckenmann as their cooperation partner. Amongst these is the fact that this system specialist with its headquarters Dormettingen is permanently engaged in further advancing the development of its machine technology. This commitment is, of course, reflected in the long service life of its products with the added benefits of a good price/performance ratio and a qualified after-sales service. Other crucial factors include professional advice, reliability, quality and the extremely competent execution of its customers’ projects – in which customer wishes and specialist suggestions for improvement can be managed together in an uncomplicated and flexible manner.

As was mentioned at the beginning of this article, very great advances in terms of quality and performance can be attained with relatively reasonable investment in an existing system.

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