| Among the significant differences between the original BMW Group Mini and the new model is the use of a front end module (FEM). Supplied by HBPO’s new facility in Banbury only 50km from the Cowley plant, the modules incorporate lighting, the cooling system and fenders are supplied just in sequence at a rate of 46 per hour.
Just four hours separate order and delivery – little wonder BMW delegated all development and purchasing for the module to HBPO. Banbury employs 85 staff, assembling modules at a rate of 46 per hour. The module has 300,000 permutations of up to 170 parts from 31 suppliers. This makes the project unique to HBPO in terms of the scope of responsibility, and its success will be repeated in the future.
“We have discussions with OEMs worldwide,” said Massimo Graziano, marketing and communications, HBPO. “This FEM philosophy is accepted by other OEMs because of the benefits in giving responsibility to a supplier such as HBPO.”
The module is built around a one piece front wall designed by HBPO in Germany and moulded by Plastic Omnium in 30 per cent glass-filled nylon weighing less than 3kg. The steel bumper beam, lock bridge, lights, heat exchangers, washer reservoir and other components are all fixed to the moulding.
One front end, 300 000 permutations
The module also stiffens the Mini's shell by 2Hz
(click for exploded view)
Better cooling system packaging meant the bumper brackets could be moved further away from the radiator, creating extra space for impact energy absorption.
“The radiator is made wholly in aluminium because clamped-on plastic tanks waste space,” said Dirk Kersting, HBPO engineering design manager on the R56/57 project. “And it is the first time we’ve used 12mm tubing for the A/C condenser – the smallest size normally used by BMW is 16mm.”
The Mini doesn’t have traditional fenders so the module is attached to the longitudinal members, suspension domes and axle carrier using M8 bolts, contributing to the Mini’s rigidity. “BMW requested that we increase torsional stiffness of the body in white by 2Hz with the complete FEM.” said Kersting. “This was a target: total stiffness of the BIW was calculated by BMW using FEA.”
Other performance criteria were arrester hook forces of 4kN and pull/push latch forces of 2kN.
The original model incorporated the headlamps into the bonnet assembly but these have been relocated to the FEM for the new model. With headlamp apertures in the bonnet, correct fit-up on the production line must be assured. “We have a cubing at our plant with a nominal bonnet. Headlamps are pre-adjusted in the FEM with a jig,” said Kersting. “If the bonnet comes in a different tolerance on the BIW, it is possible to adjust the headlamps on the finish line.”
One clever feature is that the FEM can be raised 100mm from the car on conical pins and repositioned exactly: this aids tool access to the ancillary belt. Another is that the washer reservoir is shaped to leave space behind the foglamps or sidelights, allowing access through the wheel arch liner for bulb changing.
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