Latest News from Sonderschrauben Güldner: Updates and Developments

25.08.2026

Focus on the Fatigue Endurance of Stainless-Steel Fasteners

New Findings from the FOSTA P 1797 Research Project

Stainless steel fasteners are used in many industrial sectors where high corrosion resistance is required in addition to mechanical performance. Applications in which bolted joints are exposed to permanent cyclic loading are particularly critical – for example in mechanical and plant engineering, energy technology, or marine environments.

In mechanical engineering, the design of such joints is typically based on VDI 2230 Part 1 (2015), which is internationally recognized as a key reference for the calculation of bolted joints.

The basis for designing bolted joints is their fatigue endurance. However, for nut-and-bolt assemblies made from stainless steel materials, this aspect has so far only been insufficiently investigated and documented.

This is where the research project FOSTA P 1797, “Assessment of the Fatigue Endurance of Highly Cyclically Loaded Nut-and-Bolt Assemblies Made from Stainless Steel for Mechanical Engineering,” comes in. The project is being carried out by Wismar University of Applied Sciences and the Fraunhofer Institute for Large Structures in Production Engineering IGP in Rostock, together with industrial partners including Sonderschrauben Güldner. It is funded as part of the German Industrial Collective Research program, with DLR as the project management agency, based on a resolution of the German Bundestag and with support from the Federal Ministry for Economic Affairs and Energy.

Practical Background

The project is based on findings from preliminary investigations. Stainless steel fasteners, particularly those made from austenitic and austenitic-ferritic materials, can exhibit different behavior under high-cycle loading compared with fasteners made from carbon steels.

While carbon steel is often assumed to have a clearly defined fatigue limit, results indicate that this may be less evident in stainless steel fasteners. In some cases, fractures can still occur even at very high numbers of load cycles.

For practical applications, this means that existing assumptions may be too optimistic – with direct implications for component safety and joint design. Uncertainty in design, combined with a potential overestimation of fatigue strength in the high-cycle range, can lead to premature and unexpected damage or failure. This represents a product and safety risk, can result in costs for damage remediation, shorten product service life, and may ultimately affect a company’s reputation.

Objective of the Research Project

The aim of the FOSTA P 1797 research project is to systematically investigate the fatigue endurance of stainless-steel bolted joints and to create a reliable basis for future design rules.

The key influencing factors being examined include:

• steel grade and property class
• manufacturing process
• manufacturer influence
• size effect
• lubrication
• mean stress

The investigations are carried out in the form of fatigue tests in which nut-and-bolt assemblies are subjected to cyclic loading under realistic conditions.

Bridging Research and Practice: Güldner’s Role

As an industrial partner, Sonderschrauben Güldner contributes its experience in the production and application of fasteners to the project.

One key contribution is the targeted provision of test parts under defined conditions. This includes, among other things, the production of selected fasteners and fastening components from a single material batch. This makes it possible to examine specific influencing factors that are often difficult to isolate in real-world applications.

The close link between research and industrial implementation ensures that the results are not only scientifically sound but also directly relevant to practical applications.

Comparison of Materials

The project investigates, among others, austenitic, martensitic, and austenitic-ferritic stainless steels.

Austenitic materials such as A4-80 are characterized by high corrosion resistance and good ductility. Their strength is primarily achieved through cold working.

Martensitic materials such as C1-70, on the other hand, offer higher strength and hardness but are more sensitive to notches and have lower corrosion resistance.

An austenitic-ferritic material with a duplex microstructure, such as D8-100, combines high mechanical strength achieved through cold working with good corrosion resistance.

The direct comparison of these material groups makes it possible to better understand the influence of microstructure and material behavior on fatigue strength.

Influence of Material and Manufacturing

In addition to the material itself, the material condition and manufacturing process also play a decisive role.

In series production, fasteners are typically manufactured by cold forming. This process can create favorable properties such as continuous grain flow and compressive residual stresses, which may have a positive effect on fatigue endurance.

As part of the project, machined components produced from solid material are also being investigated. These components have different boundary conditions, such as interrupted grain flow or altered residual stress states.

The aim is to better understand the influence of these differences and to assess the extent to which laboratory investigations can be transferred to real series-production components.

Initial Findings and Expectations

The results and hypotheses available to date indicate that the fatigue behavior of stainless-steel fasteners needs to be considered in a more differentiated way than previously assumed.

In particular, the investigations indicate:

• a possible further decline of the S-N curve in the long-life fatigue range
• a significant influence on mean stress
• measurable differences between materials and manufacturing methods

In the long term, these findings could contribute to the adaptation of existing calculation approaches.

Benefits for Industrial Practice

The project provides important insights for industrial users.

In design engineering, the results enable more realistic dimensioning and a better balance between safety and weight.

In quality assurance, they help to better understand variations and to analyze the causes of fatigue failure more precisely.

In purchasing, they support decisions on when standard parts are sufficient and when specific requirements may be appropriate.

Outlook

The findings gained from the project are intended to contribute to the further development of existing standards and guidelines, in particular VDI 2230 Part 1.

This will enable a more reliable and, at the same time, more cost-efficient design of stainless-steel bolted joints in the future.

For companies, this means greater long-term safety, less over dimensioning, and a better decision-making basis along the entire value chain.

Download the technical article

Publications

• Fastener Technology International, Ausgabe August/September 2026
• FastFixTechnology.com, Verulam Media

26.06.2026

Family Day: A Successful Day with Perfect Summer Weather

Niederstetten, June 28, 2026 – Summer, sunshine, and plenty of good cheer: Our 2026 Family Day brought employees and their families together on our company grounds. With midsummer temperatures exceeding 32 degrees, everyone enjoyed eating, laughing, playing, and celebrating together starting at 12:00 p.m.

There was plenty to enjoy on the culinary front as well. In addition to delicious grilled fare—from bratwurst to steak sandwiches—Pinsamore provided more hearty specialties with freshly prepared pinsa. For a sweet and, above all, refreshing treat, Hohenloher Landeis from Künzelsau was on site with its lovingly restored 1985 VW ice cream bus. Especially with the summery temperatures, the delicious ice cream was a welcome treat for young and old alike. The perfect drinks came from the Riedbach-based FRANKEN BRÄU bar, which also did a great job of keeping everyone well-fed and hydrated.

A varied program of activities was on offer for guests of all ages. The children could let off steam on the bouncy castle, cool off with various water games, or get creative at the arts-and-crafts station. The activity where children made little stick figures was especially popular; it was led by the Royal Rangers from the Weikersheim Family Church—a wonderful activity that, of course, was a perfect fit for our company.

A caricature artist and a magician also provided entertainment, wonder, and many wonderful moments. Anyone in the mood for some exercise and new experiences could also try out an e-scooter, Segway, or similar vehicles (Spass Verleih & Events DL GmbH from Hünfelden).

Despite the intense heat, the family festival was a complete success. The relaxed atmosphere, the varied program, and the many personal encounters made the day a special experience for everyone involved. It was wonderful to see employees and their families striking up conversations with one another outside of their everyday work routine and enjoying each other’s company.

A heartfelt thank you goes to our organizing team – Linda Neber, Tabea Neumann, and Marcus Heimberger – for their excellent planning and execution of this thoroughly successful celebration.

04.05.2026

Sonderschrauben Güldner Celebrates 45th Anniversary

Niederstetten. Sonderschrauben Güldner was founded on May 4, 1981 – with two employees and a strong pioneering spirit.

Today, the company celebrates its 45th anniversary and is consciously using this milestone to look back together – while also creating space for the future.

A visible sign of this is the newly redesigned connecting corridor at the Niederstetten site, completed in recent weeks: the company’s history can now be viewed there permanently. At the same time, it creates room for the stories that still lie ahead.

Sonderschrauben Güldner is part of the Würth Group. From the very beginning, the company has been shaped by consultancy, reliability, and the ambition to find solutions even when standard products are not sufficient. Over the decades, Güldner has continuously evolved – with growing manufacturing expertise and the clear goal of ensuring stable, reliable processes. A key milestone was the establishment of its own production facility in Niederstetten; in 1996, the first custom fastener from in-house production was delivered there.

Today, around 110 employees work at the Niederstetten site.

On its 45th birthday, May 4, 2026, there was also a brief shared pause in the working day: a lunchtime barbecue brought everyone together, followed later by cake for all employees – a simple and informal way to celebrate the occasion together.

The anniversary also comes with a practical and symbolic gesture: all employees will receive an anniversary backpack. The idea is based on a regional expression: “Since everyone has their own ‘little bundle to carry’ – whether in private life or at Güldner – we thought it would at least be nice if it could be carried in a well-packaged way.”

Managing Director Dr. Markus Beckert also used the occasion to express his gratitude to the workforce:

“I would like to sincerely thank all colleagues who actively helped prepare and organize our anniversary – you are truly fantastic!”

Since 1981. Connections that last.

17.12.2025

Sonderschrauben Güldner celebrates anniversaries and looks back on a strong year

Niederstetten, December 17, 2025 - 125 years of experience in one room: eight employees were honored for their many years of loyalty

On December 12, 2025, Sonderschrauben Güldner hosted a Christmas party in the atmospheric Julius Echter Keller in Laudenbach. In a relaxed atmosphere, Managing Director Dr. Markus Beckert took the opportunity to look back on the year together with the employees. His conclusion: Despite the tense economic situation in Germany, Güldner is doing well. The company was not only able to maintain its position, but also drive forward important future projects - around 1 million euros were invested in 2025 to further strengthen its competitiveness.

Sustainability remains a key issue. The large photovoltaic system on the company premises continues to supply green electricity and noticeably reduces CO₂ emissions. The conversion of the vehicle fleet to electromobility is also progressing: most of the company vehicles are already electric, with only two combustion engines still in use. Employees also have the opportunity to charge private e-cars at the site at a reasonable price.

The highlight of the evening: honoring the jubilarians. Together, they have an impressive 125 years of experience and are an indispensable part of the Güldner family. Many of them completed their training at the company and have stayed ever since - a strong sign of cohesion and trust.

The following people were honored:

• Oliver Waldmann (Production) - 25 years
• Sergej Schneider (Production Planning) - 20 years
• Waldemar Kraft (Production) - 20 years
• Marina Pflüger (Administration) - 15 years
• Thomas Wetsch (Production) - 15 years
• Linda Schmid (Sales) - 10 years
• Dennis Keller (Production) - 10 years
• Frank Grischin (Production) - 10 years

With their commitment and loyalty, the employees celebrating their anniversaries have shaped the success of the company over many years. They received personal words of thanks, congratulations and gifts.