SERVICES

• Provision of expert technical support to designers, buyers, producers and finishers of diecastings.

SPECIALISATION

• Vacuum die casting technology transfer to international clients of the new high vacuum die-casting technique : ZVAC.

• Diecasting product design and process development.

• Gating development and elimination of porosity.

BACKGROUND

• Since 1970, advancing automation, engineering and tool technologies in famous foundries and manufacturing companies.

VACUUM DIE CASTING

The ZVAC method was first used in January 1991, to make perfect parts in zinc alloy for IBM.

Since 2001, the vacuum technique has been used for hundreds of dies (molds), in foundries in China, Canada, Iran, UK and USA

Until 2004 the ZVAC vacuum method used to be called the ZV or ZZV method.

In 2004, the name ZVAC_® was chosen for vacuum die casting projects in Canada and USA.

The ZVAC vacuum method uses simple reliable engineering to make high quality castings, save money and satisfy the diecaster's clients.

Success with vacuum in diecasting results from the simplest approach, using fundamental engineering, attention to detail and educating all personnel about key topics, such as sealing and venting dies.

That philosophy has resulted in a vacuum die casting method which is very effective for eliminating porosity, and is the least expensive and most reliable vacuum die casting technique.

When properly applied, vacuum makes the diecasting process rugged.

So said Mr Morris C. Rowlett, former President and CEO of Ryobi Diecasting (USA) Inc., said at at a conference in Switzerland in 1995.

Ryobi have policy of using vacuum on every one of their diecasting machines.

A rugged diecasting process can produce good parts over a wider range of process parameters than the standard process.

In particular, vacuum makes die casting processes tolerant to variations in die lubricant application and air blast blow-off.

The effect of strong vacuum is so great, that shot speeds and pressures can be reduced.

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

Another major benefit of vacuum is that die casting wall thicknesses can be reduced.

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

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., where there were many casting experts, I showed that when done with meticulous attention to detail, 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 relatively easily and successfully.

APPLICATIONS OF VACUUM

Since 2001, ZVAC_® has been enthusiastically adopted by die-casting companies in China, Canada, Taiwan, UK and USA for magnesium, aluminium and zinc alloy diecast parts. And recently, there is growing interest from India.

The range of products now 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.

PERSONAL PROFILE : Chris Hoskyns BTech, CEng, MIET

I am a person with innate practical abilities, who left school at 16, after receiving an education which focused on manufacturing, artistic and creative skills. I was then was privaleged to receive an excellent engineering apprenticeship with the world famous automotive supplier, Joseph Lucas Ltd. After three years of apprenticeship Lucas, sponsored me to a four year degree course. The company is now part of TRW Inc.

My career in diecasting started in 1970, at the Lucas Diecasting Factory, with responsibility for developing all manual and mechanised trimming operations, and grew to include applying the latest advances in all areas of the process.

Along the way, I contributed to advancing the diecasting process, with innovations that were patented by Lucas Electrical Ltd., and later marketed and emulated by top machine makers Müller Weingarten and Buhler.

The range of processes developed and projects led, spanned from building fuel‑efficient furnaces, through application of 6‑axis robots to hot chamber Cast‑Quench‑Clip (CQC) diecasting cells and complete cold chamber foundry reorganisation, to: high speed 4 axis CNC machining with diamonds.

My latest and greatest contribution to die casting has been to show how to use vacuum at minimum cost and reap maximum benefit.

In 1998, after being Technical Manager for sixteen years and Technical Director for five years, at Dyson Diecastings Ltd, now, a subsidiary of the Alumasc Group, I set out to provide an international consultancy service.

The ZVAC vacuum technique is the main activity, with successful projects on machines ranging in size from 60 to 3,200 ton lock, for magnesium, aluminium and zinc alloys.