The ZVAC vacuum method uses simple reliable engineering.

Mr Morris C. Rowlett, former President and CEO of Ryobi Diecasting (USA) Inc., said at at a conference in Switzerland in 1995, that vacuum makes the diecasting process rugged and that it was Ryobi's policy to use vacuum on every diecasting machine.

The effect of strong vacuum is so significant that in some cases shot speeds and metal pressures can be reduced.

Also, with high vacuum, the number and size of overflows can be reduced.

Another experience has been that vacuum can enable die casting wall thicknesses to be reduced.

In its first application in production in 1991, in UK, ZVAC imediately reduced the scrap rates of difficult complex parts from over 40% to less than 1%.

The name of ZVAC was applied to the technique in 2004, prior to that it had no name.

BACKGROUND TO VACUUM

Until 1990, my experience of the devices commercially available for vacuum diecasting, was that they were unreliable and expensive. But in 1991, at Dyson Diecastings Ltd., I showed that when implemented with attention to detail and simple techniques, vacuum can widen the capability of the die-casting process, reduce scrap rates to insignificant amounts, and enable very thin and complex parts to be made consistently with very good quality.

APPLICATIONS OF VACUUM

Since 2001, ZVAC_® has been adopted by die-casting companies in China, Canada, Taiwan, Iran, Egypt, UK and USA for magnesium, aluminium and zinc alloy diecast parts.

The range of products benefiting from ZVAC is diverse:

• automotive parts such as engine cradles, transmission transfer cases, console fascias, carburettors and oil pumps

• electronics parts such as heat exchangers, heat sinks, enclosures, computer parts and hi-fi units

• products for office and domestic environments, such as: gold and chromium plated parts for lighting, bathroom fittings, kitchen appliances and door furniture

• defence products.

In general, the die cast parts which benefit most from vacuum, are those which receive expensive secondary processing like: polishing, plating, powder painting, machining, impregnating, PVD coating with TiN, ZrN or CrN.

ZVAC vacuum die cast parts did not require impregnating, hence yielding a saving and making the production leaner.