100 kilometres of fibre on a bobbin
The SAHM company from Eschwege is the global technology leader for winding machines for technical yarns, fibres and tapes. Bobbin weights of up to 500 kilograms can be perfectly wound with SAHM winding machines. For the machine types with automatic tube change, SAHM uses slim bearings and linear guides from Franke.
SAHM celebrated its 75th anniversary in 2020. An important station in the successful history of the company was the construction of rewinding machines for household sewing thread bobbins. Today, SAHM focuses on winding machines for technical yarns made of synthetic materials. SAHM machines are used, for example, to precisely wind carbon fibres for car body construction, security strips for bank notes, monofilaments and fibrillated tapes for artificial turf or surgical sewing threads.
With the competence for winding
SAHM's core competence lies in winding any material in such a way that it can be further processed without any problems. Winding parameters such as winding speed and thread tension differ from material to material. "Carbon fibres, for example, are very demanding because the material is susceptible to filament breakage," explains SAHM head of development Heiko Ebhardt. Particular attention must therefore be paid to the filament guidance." The range of spooled materials is wide. The carbon precursor material polyacrylonitrile, for example, is wound into spools weighing up to half a tonne. At another extreme are ultra-fine monofilaments, where 100 kilometres of thread can fit on one core.
Finding the right technology and the optimal winding parameters for every winding task is SAHM's great strength. "We see ourselves as a development partner for our customers," says Heiko Ebhardt. In this way, SAHM can always guarantee an optimal winding result: absolutely uniform and gentle on the material. Another characteristic of SAHM is the long service life of its machines. "There are many machines that have been in the field for 50 years and are still working perfectly," says the head of development, not without pride.
Productivity through automation
SAHM winding machines are used, among other things, in the production of man-made fibre material. In order to be able to wind continuously produced threads without rejects, SAHM has developed automatic winding machines. When one tube is fully wound, the machine switches to the second, still empty tube within seconds and fully automatically. SAHM offers automation solutions for the fully automatic supply and removal of cores and full bobbins.
In tests with our own design, we had the problem that it broke down because of vibrations and then had too much clearance. This no longer happens with the Franke slim bearings.Heiko Ebhardt, SAHM Head of Development
Ball bearing from Franke
For its automatically changing winding machines, SAHM uses thin-section ball bearings and linear guides from Franke. The thin-section bearings for SAHM are customised. By chamfering the races, a defined preload can be set. "This is a clever principle from Franke, because the desired preload is achieved without requiring additional material or space for it," finds André Wegner from the industrial agency AnWeTec, Franke's sales partner in northern Germany.
With the Franke thin-section bearings, a drum is supported in the winding machine, the rotation of which causes the automatic bobbin change. The technical challenge here lies primarily in the compensation of vibrations to which the bearing is exposed: "Wherever winding takes place, micro-vibrations always occur; this can never be completely ruled out," explains Heiko Ebhardt. "In tests with our own design, we had the problem that it broke down because of vibrations and then had too much clearance. With the Franke slim bearings, this no longer happens."
Linear guides from Franke
In addition to the slim bearings, Franke linear guides with needle bearing track rollers are also used in SAHM winding machines. They are used to always guide the yarn guide parallel and at the correct distance from the bobbin surface. The challenge in this case is precise and backlash-free adjustment and a low coefficient of static friction. Any jerky movement would impair the perfection of the bobbin set-up. "Basically, two contradictory requirements," notes development manager Heiko Ebhardt. The key to the solution here lies in the sensitive and reproducible adjustment of the force ratios. With its technology and competence, Franke always manages to deliver linear systems with the right tuning.
If, for example, we want flexible adjustments to delivery times, Franke is understanding and accommodating.Martin Schmidt, Purchasing Manager
"The cooperation runs silently. That means that everything works," Ebhardt praises the good customer-supplier relationship with Franke. His colleague, Purchasing Manager Martin Schmidt, also refers to the commercial processes: "For example, when we want flexible adjustments in delivery times, we find understanding and responsiveness at Franke". Both companies are a good match because their business activities are based on similar values. Schmidt especially appreciates Franke's reliability: "Franke's delivery reliability is very good, even in difficult times. If all our suppliers were similarly reliable, we would be very happy about that."
For 75 years, SAHM has been developing and building winding machines and winders for various application areas and industries and also offers solutions for upstream and downstream processes. SAHM is the technology leader for automatic winding machines for high-performance fibres, carbon fibres and cut film tapes. Research, development, planning, production and quality assurance are located at the company's headquarters in Eschwege in Hesse. With offices in the USA and China as well as worldwide commercial agencies, SAHM has an international presence. The company employs 220 people, including 18 trainees. Sahm has been part of the Austrian Starlinger Group since 2002.