The birth of a fully automated, self-learning and digital foundry in the magnesium die casting industry

When output is low and input is high, productivity is very low. Improve quality and you reverse this situation. Output goes up, input goes down, and productivity shoots up. The idea to build quality by inspection is wrong and the results are poor quality and high costs. Doctor W. Edwards Deming is best known for his work in Japan, which commenced in 1950, and created a revolution in quality and economic production.

In 1998 MAXImolding, a division of Jacobsen Real-Time X-Ray Machinery Inc., adopted his approach - build quality by prevention of defects - by understanding and tuning up the manufacturing process, and focusing on the cause of the defects. In 2001 light alloy wheel manufacturing process was analyzed and fine-tuned at UBE factory in Sarnia, Ontario, Canada with specific focus on reducing the causes of the defects.

Putting theory into practice 

To accomplish this, first manual x-ray picture feedback was used to set up the casting machines to produce fewer defects in the first place. While this approach is possible, it requires a very skilled level of people involved with setup of the machine and process. Firstly, the person interpreting images of wheel must be an expert in analyses of the x-ray imagery, and then the same person or different must be expert in process adjustments and interpretation of the inspection findings.

The second person must take the quality inspected part and convert the knowledge about the actual part into a set of relevant parameters that can be applied to input of the machine to hopefully produce new part with better and more exact quality characteristics. This was a reason why this method was not adopted on a large scale.

To mitigate these challenges, a further leap step improvement was necessary, but was not possible with existing casting machines. Therefore in summer of 2006 from scratch a totally new vertical semi-solid machine was developed. An operator on a casting machine should be replaced and a fully automated self-learning digital foundry was born.

Magnesium is reusable and environmentally friendly

Alloying magnesium with aluminum, rare earths, zinc, or zirconium increases its strength to weight ratio, making the alloy very suitable wherever weight reduction is important, and where it is imperative to reduce inertial forces. The high specific strength and stiffness of magnesium are very desirable characteristics in applications wherever the weight of the product is an important feature.

Besides having these innate characteristics, magnesium is also environmentally friendly. It is easily segregated from the recycling stream and is recoverable by re-melting. In addition, even if not recycled, it will naturally dissolve into magnesium oxide, which is harmless to people and to the environment.

Our research of the state of the art in the die casting industry, as well as magnesium Thixoforming studies done by Doctor Frank Czerwinski show, that the use of the magnesium alloys, where lightweight and material strength are required, will contribute to greater fuel economy and environmental conservation. 

Costs are passed on to the customer

Having inspected millions of die casting parts, we have observed universally adopted patterns of trying to improve quality by inspection, rather than by closing the loop by integrating inspection into process. Most often, the inspection process is separated from the die casting process, meaning that bad parts are just separated from good and re-melted. The energy cost of re-melting is added to part cost and passed on to the customer without long-term considerations of the effect of this practice on the long-term survival of the die casting industry. 

No wonder the plastics industry and not die casting, is the predominant employer these days and developing so rapidly. Our die casting industry is still stuck in fifties, while plastics has moved into the 21st century.

Magnesium alloys have some unique solidification characteristics, such as excellent fluidity, less susceptibility to hydrogen porosity, and thus, better castability over other well-known cast metals such as aluminum, zinc and copper. High-pressure die casting is the most common method of casting magnesium alloys. There are two types of high-pressure die casting processes: hot chamber die casting and cold chamber die casting.