Interview: “Rheocasting is not a substitute for die casting, but a strategic extension with better products.”

Mr Niklas, why has the process not yet gained widespread adoption despite its undeniable advantages?

Fabian Niklas: This is one of my favourite questions, because rheocasting is not new. The first investigations were carried out by Professor Flemings at MIT between 1971 and 1973. So, the knowledge has existed for a very long time. The interesting question is: why is it still not widely used in series production? And there are several reasons.

First: die casting is simply an excellent process. It does a great job and delivers components that are perfectly adequate and economical for many applications. As long as that is the case, there is little pressure to change anything.

But now we are reaching points where the limits of conventional die casting become visible. Achieving helium tightness at 180 bar is not possible in die casting. The high thermal conductivities required for modern applications cannot be achieved with standard die casting alloys. And when it comes to topics such as gigacasting, with flow lengths of two or three metres. If you still need good properties and stable quality at the end of the filling, a slurry performs significantly better. This is precisely where rheocasting shows its strengths.

From my perspective, this is where a crucial development comes in: a process such as the RheoMetal process from Comptech, which is not temperature-controlled and therefore produces the same slurry conditions reproducibly every time, is a real game changer. Stable solutions of this type are still relatively new to the market. They have only been available since around 2020. That means many of the applications we are seeing today have only recently become realistically viable for serial production.

Third: market and marketing. And here the classic chicken-and-egg problem appears. OEMs and Tier-1 suppliers say: “Rheocasting would actually be ideal, but are there enough foundries that can really do it properly? Only if they exist will we design components for it.” On the other hand, the foundry says: “Where are the orders? If the OEM does not send out RFQs, why should I invest time in it?” That completely blocks scaling, because both sides are waiting for the other to make the first move.

Are there other reasons?

Fabian Niklas: Another point that is often underestimated is that rheocasting is not only about automotive. Many non-automotive applications, are even better opportunities. But you only find them if, as a foundry, you actively market the properties – in places where these industries actually are: on social media, at conferences in other sectors, and in communities outside the traditional die casting bubble. If you do not generate interest there, those projects simply do not exist for you.

And even if someone does appear and says, “I would like 10,000 to 20,000 parts per year,” the request is often rejected because it is not 100,000 parts and not from a major OEM customer. Yet many interesting and often more profitable applications start exactly like that and only grow afterwards.

In short: rheocasting has not become widespread because die casting was long considered “good enough”, because process technology was not stable enough for serial production, and because as an industry we have not actively developed and marketed new applications. Now the applications are emerging, the process technology has matured, and the topic needs to be brought consistently to the market.

Which technical or economic factors make scaling and serial integration of rheocasting difficult?

Fabian Niklas: For many foundries, switching from die casting to rheocasting is extremely difficult because rheocasting places very specific requirements on the process and the tooling.

What typically happens is this: “paper is patient”, so people want to test it themselves. They take some mould that is already near the end of its life, mount it on a university or technology demonstration machine and run a few trials. The result is: “Oh, it does not work at all.”

So the problem lies in the test setup?

Fabian Niklas: Exactly. Without preparation, without a proper tooling concept, and without process know-how, it is very easy to “prove” that it does not work.

And that leads to a second point, which often hinders scaling even more than the technology itself. If I simply try to convert existing die casting parts to rheocasting, the benefit is often limited. Instead, I need to identify new applications where the properties of rheocasting provide a real advantage. Otherwise, foundries will simply end up cannibalising their own business. But identifying new applications requires active marketing and business development. In many foundries that function barely exists. Most of them wait for the customer to come to them.

In the current crisis environment, another factor is that many companies avoid external support because they fear others might copy their ideas. So, they try to do everything alone – and then wonder why it does not work. The result is that the technology gets labelled as “not ready for series production”, even though it was simply approached in the wrong way.

Looking ahead: what role will rheocasting play in the industry in a few years – or will it remain a strategic niche?

Fabian Niklas: For me, it is important to emphasise that rheocasting does not replace die casting. It expands the range of products that can be manufactured in a die casting cell.

Seen that way, it is an excellent tool to replace declining volumes and low-margin standard products – especially from the automotive sector – with higher-margin rheocasting products from other industries. That makes a foundry far more resilient. If I earn margins of 20–30 per cent on a component, a ten per cent increase in electricity prices does not worry me. I have enough buffer to absorb that. I can afford skilled employees, I can invest and keep my production stable. This is where rheocasting shows its real strength: not as a replacement for die casting, but as a strategic extension with better products.

But that does not happen automatically.

Fabian Niklas: No, it does not happen on its own. It requires companies to really engage with the process and identify the right applications. These are often not the typical “let’s convert an existing die casting component” projects, but entirely new applications where rheocasting provides a real – I would say “unfair” – advantage.

It also requires new gating and venting concepts, process expertise, and a serious approach to marketing, because many of these industries have no portals and often do not even know what die casting is. You have to find ways to create interest among your ideal customers. How do I reach people I do not yet know? How do I explain what is possible?

I believe that for foundries that want to remain economically successful, rheocasting is exactly the process needed to strategically expand die casting production. Those who believe that what they have been doing for the past 30 years is the only viable approach will gradually disappear, because volumes will continue to decline. With the increasing share of electric vehicles, they will fall even further, because EVs require fewer cast parts, and many new components fall into different clamping force ranges.

I believe rheocasting will be a decisive factor in determining whether a foundry will prosper in the future or not. And you can already see today that foundries which strategically utilise the process are performing very well economically. I see this in North America, China, and India. At the moment, however, I see it less in Europe. Here, many are still waiting and watching.

Read the first part of the interview on EUROGUSS 365.