Furan Kaltharz / Kaltharz Process

This classical all-purpose method for production of nearly all types of castings features:

  • Low binder addition level
  • Low viscosity
  • Long storage life
  • Good through curing
  • Low odor
  • Low emissions during sand mixing and mold filling. The permissible MAK (TLV) levels are generally underrun to a considerable extent.
  • Easily recoverable used sand
  • Nitrogen-free grades of resins that are particularly suitable for high-quality steel castings
  • Reactive, rapidly curing specialty resins offering short stripping times. Use of aggressive activators is consequently unnecessary
  • Low-sulfur systems for high-quality ductile iron. The total sulfur level is nearly halved. This also offers a marked decrease in SO2 emissions during and after pouroff.

Nitrogen-free furan cold resin systems for steel casting – now also with less sulphur

Most of the furan cold resins in use today are condensation products from furfuryl alcohol, urea and formaldehyde. The urea is responsible for the more or less high content of nitrogen in these resins. A furan cold resin with 75% furfuryl alcohol contains 3.5% nitrogen, on average. A simple method of reducing the nitrogen content is by raising the furfuryl alcohol to 90% and more.

However, this also entails a number of disadvantages:

  • These resins are highly reactive. Curing is difficult to control. This is particularly the case during the warm season. 
  • Resins high in furfuryl alcohol are very brittle. The time for demoulding must be observed exactly because the curing process lacks elasticity. Otherwise parts of the mould may break away during demoulding. These parts must then be repaired and/or glued, which is a very time-consuming process. 
  • The price of these cold resins is defined almost exclusively by the furfuryl alcohol component, i.e., the resins are extremely susceptible to the development of raw material prices of furfuryl alcohol.

Despite such drawbacks, these resins are recommended for the production of steel castings and are used in foundries. Even if they are low in nitrogen (0.6 – 1.0%), they are not nitrogen-free. Nitrogen can enter the surface of the casting by diffusion and cause defects (blowholes, cracks) near the surface. Even thick coats do little to prevent diffusion. The nitrogen content in furfuran is therefore of particular importance for reclaimed sand because nitrogen tends to accumulate in used sand. For this reason, nitrogen-free furan cold resins are recommended for used sand. Hüttenes-Albertus, as leading manufacturer of furan cold resins, developed the first nitrogen-free cold resins and introduced them to the foundry industry decades ago. Now Hüttenes-Albertus has succeeded in developing the nitrogen-free cold resin type S 107 R that can also be used together with the activating agents for a sulphur-reduced system.

In addition to the absence of nitrogen in cold resin S 107 R and the well-known advantages of the reduced sulphur content, the cold resin S107 R has other positive properties:

  • Elastic phase during demoulding,
  • Little addition of binder to obtain the required strength,
  • Less disposition to hot cracking due to the special recipe of cold resin S 107 R, 
  • Very good flowability of the moulding material,
  • Low emission during mould body production.

The range of cold resins from HA contains even more nitrogen-free resins with furfuryl alcohol contents between 55 and 80% for different requirements in steel foundries.

Contact

Please contact our product management team for detailed information and further questions on our Furan Kaltharz systems:

Tel:     +49 211 5087 -213 / -214 

Fax:    +49 211 50 77 57

E-Mail: pm@huettenes-albertus.com