The mineral deposits are primarily composed of calcium and magnesium carbonates. Carbonates, which are generally insoluble, are precipitated by heating water containing soluble calcium and magnesium bicarbonates. Bicarbonate is thermally unstable and will decompose to form carbonates and thus limescale when heated.
Factors influencing scale deposition:
• The higher the (temporary) water hardness, the more scale will form.
• The higher the pH (alkaline pH) of the water, the greater the tendency to scale
• The higher the temperature to which the water is heated, the more scale build-up will be present.
Precipitation and scaling on channel walls increases dramatically when the water temperature exceeds 60 degrees Celsius. It also depends on the hardness of water, so in some areas the problems caused by limescale are greater than in others. To counteract limescale problems, most injection molders deploy some form of water treatment to minimize the risk of mineral-based deposits such as calcium or magnesium.
The DS2 cleaner is recommended to remove limescale from calcium and magnesium deposits.
Another type of deposit is formed during the corrosion process. These can be solid, water-insoluble deposits (such as incrustations during the microbial corrosion process) or scale – a layer of solid corrosion products or hard iron oxides. Like other deposits, they are dangerous to the ducts, restrict the flow and reduce the efficiency of heat removal.
Rust-based scale in the channels of water-cooled molds will typically have a high concentration of iron oxides / corrosion by-products. This is mainly because companies use “closed-loop” water systems where the concentration of iron oxide is up to seven times higher than in regular tap water. Another reason for the formation of deposits from the corrosion process may be the water left in the channels after the cleaning process. The dissolved oxygen in the water reacts with steel causing corrosion.
The DS1 cleaner is recommended for descaling with a high concentration of iron oxides.