K  COREMAKING/BINDERSInternet-PDF from “Casting Plant & Technology “ 4 / 2013, pages 8 – 10
© Giesserei-Verlag, Düsseldorf
Authors: Antoni Gieniec, Dr. Jens Müller, Pierre-Henri Vacelet, ASK Chemicals GmbH, Hilden

Innovative binders for eco-friendly
and highly productive processes
The continuous evolution of castings with regard to their complexity and increased dimensional
accuracy as well as environmental aspects have an impact on the choice of core and molding material, the coating as well as – in particular – the binder. This article provides foundrymen with anoverview of recent developments in various binder systems

The foundry industry in Germany has
found itself under intense competitive pressure for many years now. Environmental regulations and the interests of local residents often mean thatfoundries have to implement measures
aimed at reducing emissions. Fulfillingthese requirements often entails highlevels of investment, unfortunately often with little financial payback. Of
course, expectations are also increasing
in terms of the demands placed on thecasted parts. Foundries have to be able
to turn the complex ideas of the designengineers into reality. Ultimately, casting buyers ruthlessly choose on pricealone when placing contracts, regardless of whether they are buying for theautomotive industry or for mediumsized mechanical engineering companies. Good quality and on-time delivery are expected as a matter of course.

Modern emission-reduced coldbox HE binder systems
The environmental disadvantages of
conventional binders result from theircomposition, with the main constituents being a phenol formaldehyde
resin in solution in part 1 and diphenylmethane diisocyanate (MDI) insolvents in part 2. The pyrolysis triggered by the hot melt during castingcauses the release of BTX (benzene,toluol and xylene) and further aromatic compounds from which benzene derivatives arise. The air that ismixed with this must be immediately extracted and purified – a complex
and expensive process. For this reason,

Casting Plant & Technology 4/ 2013

Low-emission and high-performance binder solutions promote a sustainableproduction of sand cores and associated castings (Photo: ASK Chemicals)

ASK Chemicals, Hilden, Germany, initiated a series of detailed investigations
into the development of new cold box
binder systems.
The starting point for the development concept was to improve the efficiency and yield of the system throughincreased reactivity and therefore reduced use of binders for the core production. This has been achieved withthe aid of a newly developed procedure

involving resin synthesis with specially coordinated solvent combinations.
The resulting reactivity of the binders provides the cores with enoughstrength to ensure that the subsequent
process steps can take place without
any problems.
The core strength achieved in thisway makes core production more reliable, while at the same time reducingrejection rates (Figure 1).

Using less material also means lesscondensate, which can otherwise bedeposited in the molds and then needs
to be removed with a lot of care andeffort. Cleaning times are significantly reduced as a result. Consequently,
productivity is dramatically increased
thanks to increased mold availability.
In summary, this development will deliver savings and important economic
benefits for foundries.
HE (high-efficiency) cold box binder
systems are therefore much more efficient than standard binder systems. Although they cost more, the potentialsavings and additional benefits associated with their use easily recoup this outlay. The additional boost to the availability of the molds, the reduced reject
rates and the reduced operating costs
for core shooting can amount to several tens of thousands of euros per year.
The advantages for foundries areclear: Emissions are significantly reduced, costs associated with materials, storage and disposal are cut dramatically, and production becomes
more efficient overall.

Figure 1: A comparison of strength curves

Innovative polyurethane no-bake systems and furan resin
systems with reduced emissions
Of course, the primary concerns whenit comes to make the best choice ofpolyurethane no-bake systems or furan resin systems are performance andcost-effectiveness. But any analysis of
the cost-effectiveness of mold production technology must look beyond justthe price per unit weight and also consider yield, processing parameters (processing and mold release times) andthe quality of the products produced
using this binder. Technology is increasingly being assessed in terms ofenvironmental aspects such as emissions during mold production andduring casting. The regeneration capacity of the released sand should also
be taken into account in cost analyses.
The sand-related technical properties of a polyurethane no-bake system and the resulting strength values
are excellent, as is the ratio of sandmixture processing time to mold release time, and this enables a dramat-Figure 2: Noxious emissions (BTX) from a PUNB standard system comparedwith PEP SET Quantum

ic increase in productivity. One of thestrengths of the polyurethane nobake technology is the excellent surface quality of the cast part, but thisis countered by the relatively highemissions (­Figure 2), the strong odor
and the smoke produced during casting. These factors are likely to hinderwidespread acceptance of this technology in European foundries. With
the development of the PEP SET Quantum Binder, this hurdle has been overcome. Thanks to this new technology,
the smoke intensity can be reduced by
between 40 % and 50 % comparedwith a standard polyurethane system. The performance-to-cost ratio ofa PEP SET Quantum System is among
the best in the field of self-hardening
processes.

A latest-generation binder has also
been developed in the field of triedand-tested furan resins. The development of new resin qualities with a level of furfuryl alcohol below 25 % as amonomer was initiated by the classification of furfuryl alcohol as “toxic”. The reduction in the proportionof monomer furfuryl alcohol in a furan resin is made possible thanks to a
special technique for the condensation reaction. In the process, the sandand casting-related technical properties remain virtually unchanged. By
contrast, measurements in a number of foundries have shown that theFA emissions can be reduced by up to75 % (Figure 3).

Casting Plant & Technology 4/2013

K  COREMAKING/BINDERS

Potential of inorganic coreproduction
For many years, inorganic core production has been much more thanjust an alternative to conventional methods. However, the advantages of inorganic binders are not restricted to merely the avoidance ofemissions. The omission of complex
exhaust air systems, reduced maintenance requirements for tools and machinery, and the resulting increase inproductivity in casting processes are
just some of the advantages of inorganic technology.
Inotec by ASK Chemicals offers users
huge potential in terms of the castingtechnology and component properties. Instead of the limitations formerly experienced regarding the temperature control of molds in aluminum
casting caused by the generation ofcondensates during the casting process with organic binders, the inor-ganic system offers whole new levelsof freedom and potential [1, 2]. Many
OEMs in the automotive sector are already incorporating these findings intheir designs for new engines capableof withstanding even higher operatingpressures while reducing overall consumption.

Summary
The need to reduce emissions while
keeping production on a commercially
viable footing demands innovative solutions. This is also especially relevantin the field of core production, because
the use of suitable binders can deliver
high efficiency values.
In this process, the ability of thefoundry to compete remains themost important objective: quality andfunctionality as well as costs are decisive factors. Environmentally friendly conduct is increasingly taken forgranted.
One major aspect of research and development at ASK Chemicals are lowemission and high-performance binder solutions that promote a sustainableproduction of sand cores and castings.

www.ask-chemicals.deFigure 3: Reduction of FA emissions by up to 75 % due to the use of Magnaset

References:www.giesserei-verlag.de/cpt/references

Casting Plant & Technology 4/ 2013