System Strobel GmbH & Co KG develops and manufactures ambulances, vehicles for transporting patients and tool carts for the fire department, all for rescue services and relief organizations around the world. Everything is carried out in-house as much as possible, which means that the Aalen-Wasseralfingen-based company manufactures its own parts and is responsible for assembly. Its motto is: "Quality that saves lives." The machines on the shop floor are equipped with specialist Horn's high-quality precision tools. The DR small chamber system is used for the parts of the mid-feed stretching machine.
When Thomas Strobel helped a rescue service optimize the interior of an ambulance in the early 1980s, he immediately started System Strobel as well. They built a first ambulance in 1985, a year later a first stretcher table. Meanwhile, they make between 350 and 400 vehicles a year, making them one of the largest manufacturers in Europe.
"That first ambulance is still in use today. After all, functionality, ergonomics and quality are central to everything we do. That is why we develop and build as much as possible ourselves," says Marcus Wittek, group leader of the machining department. "We buy the chassis from well-known manufacturers, but the construction of the cases from aluminum sandwich panels is done in our factory. Even the extruded aluminum edge profiles to hold the sandwich panels together are developed and produced by us.
That includes aerodynamic signal lights (blue light), electric running boards and many other components. And our carpentry shop provides the interior fittings for the furniture." When it comes to stretcher tables, they have also accumulated a great deal of knowledge at System Strobel. The systems are air-sprung, tiltable and laterally adjustable.
Machining operations are required in the production of mechanical parts for the vehicles and fire card tables. Thus, all metal workpieces are produced using various CNC machining centers. Marcus Wittek and his team are also constantly looking at how to optimize machining operations. "One of the problems was reaming bores," Wittek explains. "We have some, often larger parts that are already cast or extruded. Here it is important that the bores fit exactly on top of each other, so that the parts of the stretcher do not block each other when they are moved later."
For reaming, Wittek and his team switched from an HSS reamer to Horn's DR small reaming system. "We no longer liked the performance, machining time and precision of the earlier tools. New developments in stretchers with even finer mechanical and electrical components made it necessary to rethink the reaming process," Wittek explains. Thus, he contacted Horn's specialists. "We have already solved numerous problems with our powerful reaming system," says Stephan Weiß, field service engineer at the precision tool manufacturer: "For the machining operations at System Strobel, the DR small reaming system was an ideal solution."
The diameter range of the tool's four system sizes runs from 7,600 to 13,100 mm. The blades can be changed quickly and easily. The high flexibility in cutting materials, cutting edges and shank systems allows them to be used for many applications. The DR small clearance system significantly reduces the cost per hole, increases productivity, and, thanks to the changeover system, simplifies the operator's work. The separation point between shaft and changing head allows high power transmission with a changing precision of less than 5 μm. The interchangeable shanks are secured with a central clamping screw. Steel or carbide shafts are available in versions with through-holes or blind holes. They differ mainly in terms of internal coolant supply, which is also important at System Strobel. "Good cooling is crucial for perfect results when reaming deep holes in aluminum. Reaming the holes is now done at a feed rate of vf = 6 m/min. Machining time is two-thirds shorter than with the previous tools," Wittek says. "We save a lot of time, and also the performance of the tool and the quality of the reamed bores are excellent." Information on exact tool life is not yet available, but the tool has machined 2,000 bores so far - with no signs of wear.
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