The thread is the invisible backbone of our modern world. With STUDER’s high precision universal cylindrical grinding machines and their intuitive software, customers can easily and efficiently produce threads of the highest quality, even for demanding industries.

Few machine components are as omnipresent and important as the thread. This ingenious principle—a helical slot that converts rotational motion into linear force—was developed thousands of years ago in early advanced civilizations, used in ancient times for presses and water-lifting mechanisms, and, through standardization during the Industrial Revolution, became the foundation of modern mass production. Today, it literally holds our modern world together, whether it’s a screw from the hardware store, the ball screw in an electric power steering system, or the thread on a medical implant. The rule is: The higher the demands placed on the thread, the more challenging its production becomes.

High-performance threads are usually produced after the workpiece has been hardened; at this stage, the workpiece often can no longer be turned or milled but can only be ground. In this process, a specially profiled grinding wheel transfers the negative image of the thread profile onto the workpiece under synchronized CNC control. This process places the highest demands on the grinding machine in terms of precision: Tolerances are in the range of a few micrometers, reliable reproducibility is of the utmost importance, heat buildup quickly leads to grinding burn, and even the slightest vibrations affect surface quality. All of these are grinding technology challenges with which STUDER is thoroughly familiar. The modern universal cylindrical grinding machines from the Swiss technology company enable high-precision thread grinding for industrial applications.

“There are numerous advantages for customers in being able to perform grinding operations on a universal cylindrical grinding machine rather than having to rely on a specialized machine,” explains Daniel Huber, CTO of Fritz Studer AG. The long-established manufacturer began developing innovative software in conjunction with a controlled C-axis for this demanding manufacturing technology in the mid-1990s. Today, all STUDER universal cylindrical grinding machines in the current portfolio are capable of thread grinding with the appropriate software option. This universal machine concept offers clear advantages. Cylindrical, profile, and thread grinding in a single setup eliminates setup errors and ensures higher positional accuracy. Those who previously operated specialized machines or outsourced parts are now consolidating operations onto a single machine, saving floor space and bringing value creation in-house. It is therefore no surprise that one in six STUDER machines delivered is equipped for thread grinding.

Whether ISO metric threads, fine threads, mounting threads on tool holders, tapered threads, or internal and external thread gauges: On all STUDER models, the C-axis and software-based profile correction allow for the production of the vast majority of standard industrial components. “And for workpieces with a large lead angle, such as multi-start ball screws, worms, or extruder shafts, we introduced the A-axis as a swiveling grinding spindle axis in 2013,” explains Huber. It is available on the S41 and S22—a revolutionary mechanical solution that did not previously exist for universal cylindrical grinding machines.

Another groundbreaking STUDER technology for thread grinding is WireDress®. Based on the principle of electrical discharge machining, this dressing technology for external and internal grinding on the S41 and S22 enables contactless dressing and profiling of metal-bonded diamond and CBN grinding wheels directly in the machine at full operating speed. The grinding wheels conditioned in this way are extremely sharp, reduce the risk of grinding burn, and can grind threads directly from solid stock. The result is significant productivity gains compared to conventional dressing methods. The intelligent STUDER coolant nozzle system, SmartJet™, has also been specifically further developed for thread grinding and prevents grinding burn. With the most powerful thread grinding configuration in the STUDER portfolio, even the hardest materials with steep lead angles can be ground reliably, such as carbide threads for tool holders, high-precision ball-screw threads in drive technology, or robotic lead screws in high-volume production.

All customers benefit from a well-designed software ecosystem that enables even less experienced users to get off to a safe start in thread grinding and reduces errors. StuderThread first creates the dressing program for the grinding wheel. The library of all common ISO standard threads included in the software, along with the ability to graphically configure multi-start threads or roughing and finishing teeth on milling cutters, significantly reduces programming time. During the dressing process, ExactDress uses Acoustic touch sensor technology to verify whether the grinding wheel profile is fully conditioned. The dressing process is automatically repeated until the grinding wheel is optimally shaped across its entire profile. InOneThread then takes over for the grinding cycle. The smart software graphically visualizes the thread grinding process on the screen in advance and suggests optimal cut sequences. The entire operating process is designed to be intuitive, and should any questions arise, customers always have access to STUDER’s reliable customer care as well as training from competent experts.