Due to the increased requirements for the quality of castings used for a wide range of parts (products, blanks) in mechanical engineering, metallurgy, instrument making, aircraft manufacturing, automotive manufacturing, equipment and facilities of the defense-industrial complex, as well as other industries, great attention has begun to be paid not only to their mechanical, operational and special characteristics, but also to surface quality.
Today, both foreign and Ukrainian foundry enterprises are actively equipping their production shops and sites with modern equipment for the manufacture of castings in molds from cold-hardening mixtures (hereinafter referred to as CCM), as one of the priority and effective casting technologies.
The main disadvantage of using CTS for making castings is the possibility of formation of a burn on their surface, which is formed due to strong heating of the surfaces of the molds and rods during pouring with the melt and its crystallization. As a result, the synthetic resin that is part of the CTS burns out, the melt partially penetrates into the pores between the grains of the filler mixture and thereby leads to hardening or even destruction of the casting molds and rods.
To eliminate the listed drawback in the technological process of manufacturing castings, it is advisable to use non-stick coatings, which increase the surface strength of molds and cores.
When making castings in HTS molds, quick-drying alcohol-based non-stick coatings are more often used.
Such coatings do not require long-term thermal drying, as well as curing of casting molds and cores in the appropriate areas, foundry shops or sections, which in turn increases the productivity of the technological process of manufacturing castings.
Ukrafovorit LLC offers the following effective quick-drying non-stick coatings, namely:
PERMA-COTE 100S – quick-drying coating based on zirconium silicate. Used for application to sand molds/cores in the production of steel castings, as well as for castings made of cast iron, alloy cast iron and spheroidal graphite cast iron.
A fast-drying magnesite-based non-stick coating – PERMA-COTE 400S is used for application to sand molds/cores in the production of high-manganese steel castings, as well as for thick-walled gray iron and spheroidal graphite iron castings.
PERMA-COTE 300S – quick-drying non-stick coating based on corundum. Used for application to sand molds/cores in the production of steels, gray, wear-resistant and high-strength cast irons, as well as for non-ferrous metals and alloys.
PERMA-COTE 327S is a fast-drying non-stick coating based on aluminosilicates and graphite. It is used for application to sand molds/cores in the manufacture of castings from gray, high-strength cast iron, small (up to 50 kg) steel castings and castings from non-ferrous alloys. Also available are non-stick coatings based on aluminosilicates and graphite – PERMA-COTE 230S.
The listed coatings are suitable for all binding systems. The coatings are applied to the walls of casting molds and rods by brushing, spraying. In addition, methods of coating by dipping, as well as pouring into casting molds and rods, can be used.
The following methods of drying such non-stick coatings are possible: self-drying and ignition.
Self-drying (air drying) provides a more ductile layer of non-stick coating and does not lead to its cracking. The speed of self-drying depends on the temperature and humidity of the air where the molds and cores are stored.
Firing drying, as shown in Figure 1, significantly reduces drying time and also provides a stronger coating layer, as well as further drying the mold and rods.
The process of drying non-stick coating by ignition
To achieve the required density and viscosity of the listed non-stick coatings, it is recommended to dilute them with isopropyl alcohol or ethanol. It is recommended to check the degree of readiness of the coatings using a viscometer or Baume hydrometer.
All of the above coatings must be stirred well before use. Non-stick coatings must be stored in a dry place, away from heat sources.
Such non-stick coatings are supplied in metal buckets weighing from 25 to 80 kg (Fig. 2).
Fig. 2 Packaging of quick-drying non-stick coatings: Perma-cote 100S (a), Perma-cote 327S (b), Perma-cote 400S (c)
Thus, today the range of quick-drying coatings for CTS is expanding. The above quick-drying non-stick coatings allow you to obtain castings from various types of alloys with a high-quality surface without defects. It is distinguished by an acceptable combination of indicators that can meet the requirements of CTS casting technologies and low cost.
In addition, these coatings reduce the drying or holding time of molds and cores when preparing them for pouring with melt. This, in turn, allows to increase the productivity of technological processes for the manufacture of castings for various purposes and improve the economic performance of casting.
For detailed information and assistance in selecting materials, as well as consultations on recommendations for the use of non-stick coatings, please contact the company’s technical department, whose coordinates are listed on the website of UKRFAVORIT LLC.
How to contact us?
Write to us: info@ukrfavorit.com.ua
Call: 0800 33 92 85 (free).
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