How can an efficient production process be created at a new location in minimal time?
Chinese automotive company opts for all-vertical shaft machining
25.07.2012 - Oliver Hagenlocher
Long-term forecasts for the Chinese automotive industry have and continue to look outstanding. PricewaterhouseCoopers, estimates that within five years, the production of cars in China will nearly double from the current rate of around 14.5 million to 27 million units. Achieving this boost in capacity requires new production facilities, which translate into an enormous task for planners. How can an efficient production process be created at a new location in minimal time, and when complex components are needed? A mechanical engineering company that specializes in a wide range of production technologies can provide the answer, in this case the turning and grinding specialists at EMAG, who have partnered with Chinese customer Changan Automobile. The main focus is the camshaft machining, a highly skilled discipline in the metalworking industry. In the future, the comprehensive turning, drilling, and grinding work required for this critical engine part will be handled using a multi-stage production line from EMAG. All machining processes will also be done vertically, a process that has never been used at Changan before and contains many benefits.
Based in Salach, Germany, EMAG has designed a large number of machining centers that operate according to the vertical principle. During the machining process, the tool is located adjacent to the vertically positioned workpiece. This ensures that chips and shavings are removed when the workpiece is turned or ground, guaranteeing stable and reliable machining. To meet the requirements for Changan Automobile, EMAG had to take the technology a step further by using vertical machining to handle all aspects of soft and hard machining a camshaft within a multi-stage production line. "We really did enter new territory with this all-in-one solution," explains Dr. Guido Hegner, Managing Director at EMAG Salach Maschinenfabrik GmbH. "It goes without saying that we have a lot of experience with horizontal grinding and drilling processes. The accompanying step of deep-drilling a shaft in the vertical direction is in itself unusual, since the bit must drill 320 millimeters into the component. Our goal from the very beginning was to apply the principle of vertical machining to the entire line to exploit the benefits it provides."
EMAG technology in action
The camshaft production line began in Chongqing, China in May at the production headquarters of Chnagan. This solution features two almost identical production lines, installed parallel to each other, for the intake and exhaust camshaft. Interlinked shaft machining is initiated with two VTC 250 DUO turning centers from EMAG. While one VTC 250 DUO is used to mill the shaft and machine its ends, the other carries out deep drilling, drills radial oil holes, and mills a marking surface. Two VTC 315 DS grinding centers from EMAG then perform all necessary grinding steps, where the first center grinds the shaft bearings and the second executes out-of-round grinding on the cams. What really sets these machines apart, however, is that they integrate two grinding disks, which contact the camshaft on both sides and run in different directions. Feed forces are counteracted by the opposing arrangement of the grinding disks. This design is beneficial in more than one way: First, the rigid bracing facilitates extreme grinding feed rates for a camshaft. The time saved here is then complemented by the two disks, which further reduce machining time.
Intelligent automation, efficient cooling
The EMAG technology is also the key to enabling the distinct automation efficiency of the entire line for all turning and grinding processes. Integrated pick-up conveyors for the turning centers remove the components from a shuttle and place them on a different shuttle. Transport then continues. Inside the grinding centers are robots that secure transfer of the workpieces from shuttle to shuttle. "Coolant is also supplied throughout the entire plant in a very efficient manner," adds Hegener. "The fact that the two lines for the intake and exhaust camshaft are close to each other and are almost identical in design made it possible to combine the cooling supply for their machining centers. Only two systems are used to clean the coolant.“ One system supplies coolant to the turning centers of both production lines, while the other cools all grinding centers – an effective solution that also decreases investment costs. The downstream production sequence for machining the camshaft also includes a series of systems which safeguard component quality by crack testing and measuring as well as finish components so that they can be installed by washing them and applying a protective coating.
Short cycle times guaranteed
Two turning centers, two grinding machines, a deburring and finishing process, an additional machine for mounting gear wheels, and quality assurance measures – no camshaft takes more than 69 seconds to complete each of these steps during production. How can such short cycle times be maintained? "Several factors come into play. The synchronous support grinder, for example, has two grinding disks to expedite rotary grinding. The same applies to the 4-axis turning assembly. Non-productive time is also minimized, since parts are loaded and unloaded simultaneously," explains Hegener.
Changan will profit from an efficient solution that ensures very high component quality. The all-vertical machining helps safeguard process reliability as well. "There are many reasons why this solution is attractive," Hegener summarizes. "A key aspect that persuaded our Chinese partners to commission us for the project, however, was the great deal of know-how we possess when it comes to machining shafts. We designed and assembled the entire production line, including all interlinks and peripheral equipment required. This all-in-one solution then made it much easier to develop the new production facility."