Highly automated, specially programmed machining centers drastically reduce production times
With 24 million vehicles sold in 2015, China is now the largest automotive market in the world and has become a core business for many well-known automotive manufacturers and suppliers. In order to hold its own in this interesting but highly competitive environment, the German Schlote Group, a series supplier to the automotive and supplier industry, uses highly automated machine solutions that guarantee faster and thus more efficient production of quality products: For the production site founded in 2013 in Tianjin, China, the company, which specializes in the mechanical machining of complex engine, chassis and transmission components, purchased, among other things, 48 particularly precise machining centers from Schwäbische Werkzeugmaschinen GmbH (SW), which were able to cut machining times in half in some cases.Two different types are in use; in addition to the single-spindle BA one6also the multi-spindle BA W06-22, which with a feed rate of up to 100 m/min and an acceleration of 2 G is the fastest machine of this size on the market. Due to their design, the highly automated systems ensure a significant reduction in loading and clamping operations, which saves labor and reduces costs.
In 2013, the Schlote Group, a major supplier to renowned car manufacturers such as VW, BMW, Audi and Porsche, opened its own production facility in northern China in order to expand in the world’s largest automotive market and at the same time build closer ties with customers. The expected increase in order volume from existing as well as new Chinese customers required particularly high machining capacities, which were met, among other things, with the help of a highly automated and powerful machining and production line from SW: “Schlote stands out particularly in the manufacture of difficult automotive parts such as transmissions. We can ensure that quality products are manufactured more quickly, which gives us a major competitive advantage,” explains Heiko Thuene, project manager at Schlote Automobile Parts (Tianjin) Co. Ltd. In order to achieve the necessary high production output – VW alone purchases around 900,000 transmissions a year – while maintaining high quality and efficiency, machining equipment with outstanding performance must be used and the level of automation and production must be constantly increased.
High precision, lower costs
“We use a total of 48 SW machining centers in Tianjin,” Thuene said. “There are two different types in use, namely the BA W06-22 and the BAone6.” As a “two-spindle + two-position” type, the BA W06-22 belongs to the multi-spindle machining centers and, with a fast feed rate of up to 100 m/min and an acceleration of 2 G, is currently the fastest machine of this size on the market. “Unlike machines with only one spindle, it can always machine two workpieces in parallel,” says Thomas Mäntele, Key Account Manager at SW and the person responsible for the project. The clamping device can be mounted directly on the fourth or fifth axis, both driven by a torque motor. This is equipped with its own direct measuring system. In addition to high machining precision and the dynamic features, the BAW06-22 also offers the advantage that it can be loaded and unloaded without affecting machining time, which significantly reduces labor and costs.
“SW’s two-spindle machines improve efficiency considerably compared to single-spindle machines: Where a conventional machine produces a workpiece in 5 minutes, SW’s takes only 2.5 minutes. This efficiency equates to profit for us,” Thuene explains. The systems also save space and energy, reduce maintenance and labor costs, and significantly reduce the average manufacturing cost per workpiece through improved production flow and efficiency.
Automatic loading/unloading
The BA one6, SW’s high-precision new single-spindle machining center, has been specially adapted to Schlote’s requirements and is used to complement the BA W06-22. Since the design of the two machine types is identical, the BA one6 is ideally suited for joint interlinking. The spindle speed is up to 17,500 rpm and acceleration to maximum speed takes less than 0.7 s. Linear and torque motors in the feed axes also guarantee maximum workpiece accuracy with a position tolerance of less than 0.005 mm with maximum dynamics and very short non-productive times. The chip-to-chip time is only 2.5 s.
The BA one6 is equipped with a SW-typical double swivel beam. This design concept enables loading/unloading of a workpiece during the main time. The machine therefore does not have to wait when loading the blank, which allows uninterrupted machining of the workpiece and automatic loading/unloading. This ensures a high level of stability and reliability and improves production efficiency.
Development of integrated solutions
SW also supports Schlote in planning production: “In the automated parts manufacturing industry, it is becoming increasingly important to take advantage of short cycle times and thus land large projects. At the same time, however, the price per workpiece must be reduced,” explains Jiangang Gao, head of Schlote Automobile Parts (Tianjin) Co. Ltd. “SW therefore also works closely with Schlote in the area of cost calculation for parts.” Thus, the production time is already calculated the moment the customer informs Schlote of the quantity of parts needed for a year. “The corresponding calculation is very detailed,” Mäntele said. “For example, if 10,000 parts need to be made for a year, Schlote and SW calculate how many days this will take and how many minutes per day are required.” In order to carry out the production task in accordance with this calculation, the processes must be designed as automated production throughout, which is a major challenge for many suppliers of machining centers.
However, SW not only supplies high-performance machining centers but also automated integrated solutions: “In cooperation with our subsidiary SW Automation GmbH, we develop a comprehensive program for production processes through to the finished product for our customers,” explains Mäntele. For example, the loading door can remain closed and the robot gantry can load and unload the machine from above on the elevated seventh axis. This has the enormous advantage that the entire machine remains freely accessible. The special gripping technology developed for this project can also deposit and rotate the parts via the clipboard. Another separate line was set up to carry out the tasks of deburring, assembly, leak testing and fine washing, so that completely finished components are available at the end.
Shortening of the production cycle planned
In total, the solution installed by SW comprises eight highly automated production units, from picking up the blank to the final optical recognition of the finished part. In addition, only two stations along the entire production line currently require an employee. To ensure this smooth operation and the safety of the products, SW technicians are regularly on site in Tianjin to train employees, update programming or perform proactive maintenance on the equipment. “In part to provide this on-site service to our China-based customers, SW is opening a plant in Suzhou at the end of October 2016,” Mäntele explains. The company continues to work with Schlote to continuously improve production efficiency: “Our plan for the next project is to shorten the production cycle by 15 percent,” Thuene says. “We have set an ambitious goal to become the largest plant in the group and for the emerging Chinese market.”
The SCHLOTE GROUP is made up of eight companies that are active as development partners and series suppliers to the automotive and supplier industry, foundry technology and mechanical engineering. In addition to the mechanical processing of products and the assembly of ready-to-install components, the range of services also includes the design and manufacture of die casting molds, tools and fixtures. In the Group’s CNC machining centers and automated production lines, castings are made from a wide variety of material alloys – mainly aluminum and aluminum alloys,
Iron, steel and forged materials – machined. SCHLOTE’s products are primarily produced by machining processes and further processed by various manufacturing processes and technologies. The production lines are designed for small, medium and large series, but individual part production and prototypes are also offered. The Group currently employs a total of 1,500 people and 50 trainees.
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