Plenty of chips – perfect surfaces

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industrial

Plenty of chips – perfect surfaces

We are living in an increasingly digitalised world. Microchips provide the basis for this digitalisation – and they themselves are becoming increasingly more powerful. The main manufacturing processes for these semiconductors take place in high-vacuum systems, and Max Schilling AG supplies housing components made from special aluminium for the chambers of these systems. Due to the component size and in order to satisfy the enormous machining rate while adhering to high quality requirements, the milling specialists at Max Schilling AG rely on an STC 800 five-axis machining centre from Starrag.

Microchips are an integral part of computers and smartphones, but can also be found in many other electronic devices, machines and systems. The extent of the dependency that we have on these small electronic components was made clear during the chip shortage of 2021, when many machines and systems were not able to be manufactured to completion. In the automotive industry, production lines sometimes came to a standstill. Even electronic household appliances were occasionally unavailable for delivery.

The growing trend towards digitalisation has increased the demand for these semiconductors – which themselves are becoming increasingly more powerful – even further. It’s not just production volumes that are increasing: The technology being used to produce them is also becoming more and more sophisticated. To put things into perspective: Current microchips contain structures that have a magnitude of a few nanometres. (For comparison: A human hair measures around 30,000 nanometres in diameter.) These nanostructures are produced on extremely thin silicon wafers using vapour deposition, exposure and etching methods – in high-vacuum or even ultra-high-vacuum chambers that adhere to maximum cleanliness requirements.

“ Only by carrying out complete machining in a single set-up can we satisfy the requirements with regard to precision, surface quality and cost effectiveness.”

Paul Oberholzer, Operations manager and member of the board of management

Max Schilling: Assembly supplier for vacuum chambers

Andreas Tinner, sales manager and member of the board of management at Max Schilling AG, explains: “The essential expertise in the production of such semiconductors now lies in the process and no longer in the production system. For a good ten years now, microchip manufacturers have been purchasing the system technology from OEMs, who in turn obtain individual components and assemblies from supplier companies like us.”

Max Schilling AG is a machining service provider that specialises in optimum-quality precision parts. Since its founding in 1985, the company has developed from a pure parts supplier into a system integrator that also assembles, checks and supplies assemblies ready for installation. “Important customers come from the packaging and automotive industries,” explains Andreas Tinner. “In around the last ten years, we have succeeded in establishing another large pillar in the form of the semiconductor industry. We are commissioned by OEMs to manufacture various components and assemblies that are installed in vacuum systems.”

At Max Schilling AG, all signs point to growth. Since its involvement in the semiconductor industry, the number of employees has risen from 20 to 35. As the previous site in the Swiss municipality of Bilten did not allow any opportunities for growth, at the beginning of 2022, the company relocated its headquarters to Mollis in the canton of Glarus, ten kilometres away. Tinner and his colleagues are full of optimism for the future: “Over the next three years, the demand for semiconductors is predicted to be extreme. We hope that we will also be able to take a slice of the pie.”

Five-axis machining centre achieves a fine balance between high-performance rough machining and extremely fine finishing.

Five-axis simultaneous machining is mandatory

Over the years, Max Schilling has expanded its machine fleet to include fiveaxis machining centres, among other units. “When it comes to sophisticated aluminium structural components, fiveaxis simultaneous machining is mandatory,” explains Paul Oberholzer, another member of the board of management who holds the post of operations manager. “Only by carrying out complete machining in a single set-up can we satisfy the requirements with regard to precision, surface quality and cost effectiveness.”

The success of this approach to date has been confirmed by orders coming in from system manufacturers not just in the local region, but also from the USA. The enquiry regarding the supply of a certain large housing for high-vacuum chambers was one that was regarded as particularly interesting by the managers at Max Schilling. “Our most important customer in this segment approached us saying that they wanted to relocate the manufacturing of this housing from other locations such as Malaysia back to Switzerland,” reports sales manager Tinner. “We hesitated only briefly, since we did not yet have a suitable machine that would be able to machine the large parts with over one cubic metre of volume without readjusting the set-up.”

“So far, our investment has paid off. The chamber production is proceeding very successfully. With a single set-up, the housings come out of the machine in perfect condition after around ten hours.” Sales manager Andreas Tinner (left).

Powerful in both rough machining and finishing

The requirements for a five-axis machining centre of this kind are high. A fundamental requirement is to have a correspondingly large working area or collision circle. The machine must then provide powerful rough machining, since the degree of machining for the housings – which are made from a special aluminium alloy – is over 60%. Ultimately, though, it all comes down to the finishing. High-quality surfaces are required for the seal seats and in the interior in particular. “The seal is the most important thing about these housings,” explains Andreas Tinner. “Otherwise, it wouldn’t be possible to generate a high vacuum. And if the surfaces in the interior have a high level of roughness or even grooves, it becomes immensely more difficult to create a vacuum. In this case, it can take a number of hours for the pump to generate the high vacuum required.”

Hurdles such as excessively high procurement costs and long delivery times were initially encountered in the search for a suitable machine. Upon a visit to the Starrag plant in Rorschacherberg, however, Paul Oberholzer’s machining team finally found what they were looking for. The site is home to the Center of Production Excellence (CPE), where Starrag tests and optimises sophisticated new machining processes – and it was here that the team was able to see the STC 800 five-axis machining centre in action for themselves.

Starrag developed the STC series for the economic machining of very sophisticated structural components, multi-blades and casings with long cycle times. These machining centres stand out on account of their very good stability and excellent dynamic properties, as well as thanks to the tried-and-tested swivel head that allows for simultaneous five-axis machining. With a maximum workpiece size of 1,400 mm in diameter and height, as well as a permissible workpiece weight of up to 2,000 kg, the Starrag STC 800 satisfies other fundamental prerequisites.

First-class technological support

The concept of the STC 800 won over operations manager Oberholzer and the other managers at the company from the very beginning: “We were certain that the stability of the machine in combination with the right tools would guarantee perfect surfaces and was ideally suited to our large parts made of aluminium – which has proven true in our everyday operations today.”

The other general conditions also made the machine a perfect fit. In the CPE, the machinists from Max Schilling AG were able to test and optimise the STC 800 with their own parts prior to the purchase. Paul Oberholzer was full of praise for this: “The technological support was really first-class and considerably contributed to our decision to make a purchase. Starrag has an enormous amount of expertise when it comes to machining large structural components. The machine operators and technologists know exactly which screws need to be turned to resolve certain machining problems, for example to avoid vibrations and to improve the result. We learnt plenty from this.”

Ultimately, the price was also right, as Andreas Tinner explains: “A Starrag machine is no bargain, we were aware of that. And yet, as a medium-sized company, we also weren’t able to pay any price. In this respect, it was fortunate for us that we were able to purchase the machine at a somewhat reduced rate following its deployment as a demonstration and test machine – of course, after it had been completely overhauled and restored to a practically as-good-as-new condition.”

A chamber housing made from special aluminium: The machining rate is above 60%.

Ideal conditions for the vacuum chamber production

The machine was also available to be delivered on the desired date. Since the middle of 2021, the Starrag STC 800 has been running predominantly in a two-shift operation at Max Schilling’s new production hall in Mollis. The main components that are manufactured are housing components for vacuum handling chambers and for process chambers. PCD tools produce surfaces that fulfil all requirements. The parts are then pre-cleaned and rinsed several times. The assembly then takes place in a Class 7 clean room. In order to be able to supply the fully assembled assembly, Max Schilling has also invested in a clean room of this kind.

“So far, our investment has paid off,” reports Andreas Tinner with satisfaction. “The chamber production is proceeding very successfully. With a single set-up, the housings come out of the machine in perfect condition after around ten hours. We still haven’t had any complaints from our customers.” Instead, what they have received are new requests for housings in even larger dimensions. “We actually hadn’t expected such requests to come in so quickly. However, we have already reserved space in our new hall, which provides a suitable foundation to be equipped for further investment. And we’ll certainly be discussing this with Starrag.”