It is also an advantage to stand out from the market when manufacturing fasteners. And so the purchase of two new 7-stage servo presses from Nedschroef Machinery was definitely a strategic decision for Arnold Umformtechnik. The new system technology can be used to manufacture more complex functional parts and high-quality products.

"The new NC714 not only offers an additional forming stage, but also a number of technological advantages. For example, the cut-off quality provides a better initial state for forming. And with the shorter feed length, it is now possible to produce shorter parts," says Andreas Stern, listing some of the advantages. He has been working as a design engineer at Arnold Umformtechnik for six years and designs parts for the 5-, 6- and now also the new 7-stage press. He was also involved in the procurement process for the machine.

Tobias Kraus, who also works in this area, adds: "Previous machines worked with a flywheel drive. With the complete servo drive, we now have a completely new drive concept at our disposal. The machine can run at any speed without having to build up energy beforehand. Accordingly, the system also has the full pressing force at any speed."

Equipment features enable greater flexibility

The servo technology allows the speed to be individually adapted to the part during the process. The transfer also ensures uncomplicated transfer to the next forming stage. The high-speed cutting system works at 10 m/s. As a result, the wire section is hardly deformed and a uniform volume distribution is achieved for the subsequent forming process. Due to the high volume consistency and the cut-off quality, short lengths can also be produced.

Another feature of the press is that the seven stages can be reduced to six. In this case, the seventh stage is replaced by a roller unit. This allows threads, knurls, small recesses or other simple shapes to be produced inline, for example. This means that ultimately there are also cost benefits, as work steps are eliminated. The machine, which has a total pressing force of 1,100 kN, is equipped with an integrated inductive preheating system. This makes it possible to produce complex stainless steel molded parts. The die cooling and heating system also facilitates the production of stainless steel molded parts. This has a positive effect on the service life of the tools, as tool wear is significantly higher with stainless steel than with steel.

Expansion of the range of parts that can be produced

For Arnold Umformtechnik, the new press also means a stronger position on the market. "We can now produce components that we previously had to reject, such as stainless steel formed parts, and the sequential forming options give us a better understanding of the forming process. The results of the simulation can thus be better checked with regard to their reality," explains Tobias Kraus.

Special materials are also to be processed on the press due to its versatile lubrication options. For example, Arnold Umformtechnik is focusing on stainless steel and copper formed parts, which are becoming increasingly important, especially with regard to electromobility. "Parts that are sensitive to impact points are also to be produced on the Nedschroef NC714 due to the gentle discharge. In addition, short parts are to be produced due to the high volume consistency thanks to high-speed cutting, as well as transport-critical parts," says Andreas Stern.

Realize complex application-specific components

The two new systems have been in operation at the Forchtenberg-based fastener manufacturer since April 2018. And the experience with the press has been very good. "Errors during the forming process are detected more quickly so that the machine shuts down without destroying a tool. For example, the machine recognizes when a part is not inserted correctly and then stops," says Stern. During the first adjustment attempts during initial production, the ejector system also quickly detects tools that are not optimally adjusted. These can then be precisely adjusted for series production.

However, the new system technology also has another benefit. For example, parts that were previously produced on a precise but larger press can now be produced on this press with a price advantage. And last but not least, there are numerous possibilities for the realization of complex application-specific components and customer applications. For example, the new servo press can be used to produce complex steel parts and stainless steel molded parts, copper contact pins and bushes, stainless steel double collar bushes, wheel axles, hollow knurled parts, precise press-fit elements and drawing parts with a certain degree of complexity.