Chinese Industry 4.0 production line increases quality

November 2016

Thanks to an Industry 4.0 production line, the Chinese machine tool manufacturer QCMT&T has increased the quality of its robot gear production and can handle small batches with large variety.

Future-oriented thinking lies in the DNA of the Qinchuan Machine Tool Group (QCMT&T), which is based in Baoji in the northwestern Chinese province of Shaanxi. An important goal for this leading company in the Chinese machine tool industry is to significantly increase the level of automation and proportion of smart technologies in its production. QCMT&T has been working closely with Bosch Rexroth since the early 1980s. Their latest project saw the two companies jointly developing a fully connected production line for the manufacturing of robot gear boxes. “We opted for the partnership with Bosch Rexroth because we not only wanted to buy individual components, but also implement the complete project together with a partner,” explains Xingyuan Long, Chairman of the Executive Board of QCMT&T.

Keeping an eye on the value stream

In joint workshops, the partners first defined the value streams of the planned production line. This step was particularly important because QCMT&T previously assembled the robot gears manually and therefore could not draw on past experiences in the field of connected production. The ambitious goal of the project for the next years: to increase the capacity of the line to 60,000 robot gears per year.

The process has resulted in a two-part production line, which can accomplish precisely that. In the first section, gear cutting and non-circular grinding machines from QCMT&T produce eccentric shafts for the gear boxes. In the second section, the assembly line, a whole range of Rexroth technologies contribute their strengths.

35 variants, high quality

The most important requirements of QCMT&T were quality assurance and the handling of small batches with large variety: seven different gear types in five gear ratios are produced on the line. To ensure that nothing goes wrong, a Pick-to-Light system supports the production staff by making sure they use the correct components each time. A green light indicates from which material shelf compartment a component should be taken. Small glass doors in front of each material compartment provide an additional safeguard, as only those with the required part can be opened. In addition, all eight assembly work stations are equipped with personalized identification. This ensures that only those employees qualified for a work step are actually able to perform it.

During the actual assembly, the intelligent Nexo cordless nutrunner assists employees at two work stations. It is directly connected to the Manufacturing Execution System (MES) and thus knows – depending on the variant at hand – with which torque the screws or nuts need to be tightened. The individual work stations are connected via transfer systems from Rexroth. These transfer the workpieces through the assembly line on workpiece carriers equipped with RFID tags. Thanks to the tags, all of the components find their own way to the next station and the employees can detect on their station display whether they ought to perform a work step on a component or not.

Convenient overview

Those in charge can keep track of production thanks to the interactive ActiveCockpit communication platform from Rexroth. The software presents important production data such as processing times, utilization, and the current order situation on a large display in real time. Thanks to the individual user profiles, the system shows each user exactly the information that is relevant to him. During meetings at the shop floor level, ActiveCockpit also provides a glimpse of possible weaknesses or production problems, which are then immediately discussed. Each decision on how to proceed further is documented in the system and an e-mail with tasks is sent to the persons responsible. To ensure people outside the production facility also get an insight into the current production status, they can access ActiveCockpit using mobile end devices such as tablets or smartphones.

With the Industry 4.0 line, QCMT&T is also optimally equipped for future growth. Thanks to its modular design, it can be easily scaled. If additional gear variants are to be produced at the plant, further work stations can be integrated into the process without any problems. And networking with suppliers or another production line is also easily possible via the MES.