Sun umbrellas in the parking lot, sun umbrellas at the entrance, sun umbrellas in the stairwell, sun umbrellas in the meeting area, sun umbrellas in the showroom, sun umbrellas in the assembly hall. A visit to Bahama GmbH in Reichshof, North Rhine-Westphalia, leaves no doubt about what is produced here: sun umbrellas. However, these are not ordinary sun umbrellas, but very high-quality products primarily for gastronomy and hospitality, which stand out from the competition and especially from sun umbrellas from the hardware store due to their quality features and the technology used.
Bahama originated from Becher Textil- und Stahlbau GmbH, which started manufacturing tarpaulins for trucks and tent roofs for the fairground industry in 1950. Large umbrellas have been the focus since the 1980s, and Bahama acquired the know-how for sun sails in-house in 2018. There are 75 employees working in Reichshof.
Sun umbrellas in the wind tunnel
The robust, durable umbrellas not only provide shade but also offer protection from wind and weather. To provide a wind guarantee, Bahama tested them in the wind tunnel at Mercedes-Benz. The result: Stationarily mounted umbrellas can remain open almost all year round and withstand wind speeds of up to 130 km/h.
The smallest sun umbrellas from Bahama measure 2 x 2 m, while the largest cover an area of over 140 square meters with dimensions of 12 x 12 m. Bahama produces several thousand umbrellas each year, with an increasing trend. Customers can be found worldwide, especially in countries with plenty of sunshine. However, most umbrellas remain in Germany. The 4 x 4 m large Jumbrella is the best seller.
An umbrella consists of 150 to 180 individual parts, depending on the type. About 80 percent of these are aluminum components, which the company machines on seven CNC machines in three or four axes. Steel, stainless steel, and plastic make up a small proportion. The main column in the center and the struts are made from extruded profiles. The material is not mass-produced but is pressed specifically for Bahama using special tools. The reason for this is the special functions that the manufacturer integrates into the components.
If the term 'full equipment' only brings car purchases to mind, one has not yet seen Bahama's accessory list. From side walls and theft protection to LED lighting, heating lamps, Wi-Fi, USB charging ports, and speakers, all the way to a TV screen for public viewing, everything is possible. Bahama provides the desired configuration starting from a quantity of one umbrella.
Tools instead of a new machine
The connection to the tool manufacturer INGERSOLL came about rather coincidentally. When a new machine for machining was to be purchased, there was the opportunity to view the corresponding model at the INGERSOLL TechCenter in Haiger beforehand. Although the machine purchase was temporarily postponed, the technicians from Bahama came into contact with the tool specialists from INGERSOLL, for whom a task was quickly found.
When machining a specific component, we repeatedly encountered problems and therefore asked INGERSOLL whether a special tool could reduce the processing time, but above all increase process reliability,” reports Sven Altmann, Head of CNC / Metalworking at Bahama. The 84 mm long aluminum part serves as a mounting bracket for an electric switch. It automatically turns the LED lighting on and off when opening and closing the umbrella with a sliding bushing. Four of these elements are installed for each umbrella with lighting. Originally, Bahama manufactured the component with three HSS tools and then switched to carbide end mills. However, the results remained unsatisfactory.
Since Reichshof is not far from Haiger, we simply took a look at it on-site,” explains Christopher Hees, Application Engineer at INGERSOLL. The blank for the component is sawed off from a profile bar. Depending on the batch, there are deviations in the material of 0.1 to 0.4 mm. Certain tolerances always arise in the extrusion process. Bahama manages quite well with the majority of its parts and can take them into account.
Extrusion part presents challenges
This was not achieved with this mounting bracket. “With the extruded part, we often had difficulties finding the exact center for the drilling,” explains Altmann. In addition to the centering of the 72 mm deep hole, tight tolerances had to be maintained. There were also issues with process reliability, as an interrupted cut was required here. The hole runs through an already existing long hole, which later receives a threaded pin for guiding the switch on the finished component.
Bahama produces several thousand pieces of the relatively complex component each year. Christopher Hees compared possible manufacturing times and tool technologies and came to the conclusion that the use of a special tool is worthwhile. After some considerations, INGERSOLL chose a tool with a solid carbide carrier, soldered PKD cutting edges, and long guide rails.
Johannes Post, Product Manager PKD-CBN at INGERSOLL, explains the importance of the system for process reliability: “The tool is equipped with a slightly executed taper. When it comes to the interrupted cut, it is still well guided in the rear area, which was previously drilled. The guide rail provides secure guidance until the exit from the interrupted cut.
Chip formation is slowed down
The pre-drilling of the raw part can always vary slightly. To counteract this and to obtain as little radial forces as possible, INGERSOLL opted for a 180° cutting edge at the tip. The tool is designed as a step drill, which also creates a second diameter with another, laterally attached cutting edge. To achieve the shortest chips with the material AlMgSi05, which has a low silicon content, required not only the right tool and the cutting parameters set by INGERSOLL but also a suitable processing strategy. With a multitude of imperceptibly short stops of the feed, the chips are repeatedly broken before they can cause problems.
The collaboration with INGERSOLL was already very pleasing to us during the planning phase, and we were very satisfied with the two delivered tools," assures Sven Altmann. While the previously used carbide tool took two and a half minutes per hole, the component is now finished in just under 20 seconds. The gain in process reliability is also important to Bahama because 16 parts are always clamped and processed one after the other on the DMG CMX 1100 V. If a tool were to break at the beginning, the remaining parts would also be scrap.
Although the demand for these components is very high, Bahama always only manufactures batch sizes of a maximum of 500 pieces. The production relies on a continuous process to ensure the supply of parts for all umbrellas. Therefore, different components are almost daily on the machines. The in-house parts manufacturing also makes it possible to produce spare parts for older products if needed. Often, the company's sun umbrellas are used for decades.
It is quite possible that production will switch from profile to solid material at an appropriate time. Some other parts are already being milled from aluminum blocks today. The step drill could also continue to be used after a switch. Sven Altmann can imagine using even more special tools from INGERSOLL in production in the future – to further optimize the existing manufacturing or to start with optimal processing for newly developed products.
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