New ways for efficient cleaning of moulds

| Editor: Janina Seit

Efficient cleaning of moulds in foundries has long been problematic due to stubborn base coatings. But now a chemical manufacturer and a blasting technology firm are combining their expertise in coatings and combination dry ice blasting to find a solution.

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The left casting shows the yellowish coating which was partially removed with combination blasting (metallic silvery area). One half each of the right casting was cleaned with pure dry ice blasting (dark area) or combination blasting (bright area).
( Source: Asco )

Hüttenes-Albertus is an international manufacturer of chemical products for use in coremaking and mouldmaking processes in foundries. The company has recently established a partnership with blasting technology specialists Asco Carbon Dioxide Ltd to investigate systems for the removal of mould coatings using dry ice and combination blasting.

Foundry operations greatly rely on correct mould and tool cleaning. This is especially true for moulds and core boxes since an efficient cleaning process does not only increase quality but also boosts productivity and lowers costs. After speaking to specialists at a number of foundries, both companies realised that the removal of mould coatings still presents a problem. At the moment, heavy metal casting foundries need to remove the mould´s finishing coating several times a day. In addition, a regular removal of the base coating and an occasional roughening of moulds is required, the latter playing an important part in the adhesion of coatings. The removal of the finishing coating is mostly unproblematic and can be done efficiently with pure dry ice blasting, a common practice in the foundry industry. However, when it comes to the removal of the base coating and roughening process, pure dry ice blasting is of limited use, as the procedure is lengthy and mostly doesn’t achieve the desired effect. Pure abrasive blasting with sand or glass beads has been found to be too aggressive and damages the surface of the moulds. It also causes high secondary pollution.

Hüttens-Albertus' Product Manager Klussmann and Asco Area Sales Manager Hinze look forward to being able to offer customers a complete package consisting of application engineering and optimised coating.
Hüttens-Albertus' Product Manager Klussmann and Asco Area Sales Manager Hinze look forward to being able to offer customers a complete package consisting of application engineering and optimised coating.
( Source: Asco )

Special coatings for porous moulding surfaces

But now Hüttenes-Albertus has developed a special coating composition for smoothing porous moulding surfaces. The fine base material the company uses isolates the mould´s ground and protects against thermal stress. Ascojet’s associated cleaning method employs the Combi blaster 1708 which is said to use gentle cleaning with dry ice pellets and the additional, abrasive effect of a special additive. Udo Hinze, Area Sales Manager Dry Ice Technology for Northern and Eastern Germany at Asco, explains: “Depending on the process requirements, the abrasive material can be added to the dry ice stream. The cooling effect of the dry ice offers high material protection even while blasting with dry ice and additive. Persistent contamination like the basic coating can be removed effectively thanks to the added abrasive material. In addition, moulds can be roughened so that the newly applied coating adheres perfectly."


Less blasting material makes operations quieter

Hinze also points out that little or no blasting material is needed, resulting in almost no secondary pollution. The higher cleaning performance of the blasting unit is also said to allow for less compressed air leading to less noise. Another advantage of Ascojet blasting units is claimed to be that moulds don’t have to be disassembled which is why production can continue immediately after cleaning. This should eliminate costly production downtimes and quality losses as well as increase process safety.

The company is currently running tests to find the optimal parameters for blasting pressure and amounts of dry ice and abrasive material. Developers are also investigating the possibility of “repairing” coatings by means of a partial removal of deposits without stripping the whole coating. The partnership hopes to offer a complete package to foundries in the future, consisting of application engineering and optimised coating.

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This article was first publishes by ETMM.

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