Die spraying is an important process step during pressure die casting because it directly influences the whole cycle and therefore the production costs.
Automatic application of separating agent reduces consumption and ensures good parts in short times while maintaining constant casting quality.
High productivity is important in order to hold one’s own in an increasingly tight world market. The requirement for maximum die production with unchanging die quality, however, can usually only be achieved if the whole casting process runs without interruption and the individual parameters are consistent to a high degree. Automatic die spraying is one of the most important parameters. The spraying process should be completed quickly in order to save time, be as efficient as possible, i.e. apply the minimum amount of separating agent in order to decrease the total production costs. (Photo 1)The main tasks of die spraying are:
- Application of separating agent,
- Lubrication of the moving die half,
- Removal of impurities
- Die cooling
An important basic condition for optimal spraying is that the die surface is sprayed evenly and gently. The separating agent application influences the die lifetime. The high cooling rate of the tool surface during spraying means a high strain on the die material with regard to temperature fatigue strength. The high thermal tension can cause cracks in the die.
The Modular Spraying Tool WOLLIN PowerSpray PS 16
A modular spraying tool is assembled using standardized individual parts like in the “LEGO“ system and then adjusted exactly to the die geometry. Spraying nozzles with ball nozzles that can be directionally adjusted can be located at important locations in order to spray the fixed and moving die half in one go.
Modular spraying system
A spraying tool can be built very quickly using the modular spray tool technology from Wollin GmbH, Lorch, Germany. The modular system allows for almost any adaptation to the die contour. An advantage of such a “mask spraying tool” is that no tubes have to be attached. These often cause interruptions as they can be bent easily.
A spraying tool should be designed with nozzles that spray vertically to the die surface so that the complete die can be sprayed from one spray position, thus avoiding time-consuming travelling (Photo 5)
Environmentally friendly separating agent application that is gentle to the die (micro spraying) WOLLIN EcoSpray
Well-known manufacturers have developed water-free oil-based die separating agents in order to avoid temperature instabilities within the die. These mean improvements in quality, environmental protection and production.
The new generation of water-free separating agents have high adhesive properties, which can be reliably applied to the die using the newly developed WOLLIN spraying nozzles. The Wollin company‘s comprehensive application technology already allows an even more efficient spraying result.
The advantages of micro spraying
- Shorter spraying times
- Reduction in separating agent consumption
- Less air consumption
- No waste water
- Free from biocides!
- Low noise emission
- Reduction in thermal shock
- Reduction of energy costs
- Longer die lifetimes
During development safety and environmental aspects were taken fully into account. The authorised separating agents from various manufacturers were rechecked for fire hazard and smoke development.
In order to use the advantages of micro spraying to the full, a good die cooling is required.
Due to the reduction of the temperature shock that occurs when strong cooling with water takes place, thermal cracks can be reduced and the die lifetime considerably lengthened. Various separating agents that can be used up to a die temperature of 400°C are already available on the market. These are available for aluminium as well as magnesium casting.
Dosing nozzle DD1
Our latest new development in the area of spraying technology is the patented dosing nozzle DD1. This makes it possible to constantly spray a quantity of separating agent after it has been adjusted on the nozzle.
Quantity adjustment is via a dosing spindle in the range 0 to 0.119 ml/per impulse.
The very fine dosage possibility means that the dosing nozzle DD1 is especially suitable for spraying of waterfree concentrates, i.e. in those areas where active agents should only be applied in very small quantities.
The dosing nozzle can be mounted on all Wollin PS16 spray strips. The flexible configuration of the spraying tool means that it is possible to design one circuit for water (e.g. for cooling the die) and another as a separating agent circuit for oil.
This technology has shown as a milestone for a higher productivity at a lot of customer applications, particularly at the production of structural parts.
By the use of the very small application of the spraying agent quantities, our customer achieved a exellence result of part quality.
The fast and professional implementation of this technology take place from our application technicans.