PBR Columbia utilizes workcell concept to produce brake calipers.

When purchasing a vehicle with aluminum brake calipers, chances are those brakes carry the PBR brand. PBR Automotive is a subsidiary of the Pacifica Group, Melbourne, Australia, a designer and manufacturer of automobile components and friction materials.

When PBR began building its newest facility in Columbia, South Carolina (it also has foundries in Knoxville, Tennessee, and Melbourne, Australia), it chose CMH Manufacturing Co., Lubbock, Texas (along with its technology arm, Pacifica Group Technologies), to help design and build a total workcell concept for the casting of aluminum brake calipers. The workcell consists of three major CMH components--an eight station rotary permanent mold casting system, a casting cooling system, and a riser cut-off saw capable of automatic quality inspection, riser removal and sorting.

Rotary Table 

PBR Columbia's casting plant manufactures a range of aluminum caliper castings so equipment flexibility is important. The supplier started with its permanent mold casting rotary table capable of 400 castings/hr on a continuous basis then added new features required by PBR, such as continuous rotation, pouring and casting removal on the fly. The casting machines were designed to accommodate PBR's proprietary mold mounting system. Extra care was given to eliminating pinch points and shear points.

The casting process starts with the operator assigning a part number to a rotary table station number. The stored part number profile includes the proportional tilt rate, solidification time and shot size for that casting. The castings are ejected on the fly onto a moving casting catcher that is at a height that allows the operator to remove the castings safely and perform a visual inspection.

Rotary table rotation is controlled with an AC inverter powering an all-electric drive system. Exact position of the table is continuously tracked with an absolute encoder. All hydraulics are onboard the table, eliminating the need for a high-pressure rotary fluid coupling. A low-pressure rotary union is used to provide compressed air, natural gas, water in and water out to each station. Tilting and mold clamping are hydraulic and each casting device on the table has fully proportional tilt capabilities. There is an onboard operator control at each machine for all hydraulic functions. Each casting device has fork lift boots built into the base to facilitate device change out on the table.

Casting Cooling Tower

The machine is specifically designed to function in line with high volume casting rotary tables. The cooler loading station is positioned at an ergonomically friendly height relative to the casting catcher tray of the casting machine, thereby eliminating a lifting operation. Interfacing the casting catcher and cooler load position also minimizes twisting, pushing and pulling motions. Machine operator walk distances, which were often as high as two miles per shift, were reduced to approximately 600 yards.

By utilizing a unique method of racking the casting and balancing the cooling capabilities to the output of the casting carousel, all work in progress is carried within the walls of the machine. Of key importance is the ability to engineer the cooler to match the production rate of the casting cell with the appropriate heat removal rate. The novel combination of conveying, racking and internal machine chamber design ensures that hot castings are not damaged during the cooling cycle.

The use of a vertical tower design ensures the floor space required for the machine is minimized and that the loading and unloading positions are adjacent to one another.

Riser Cut Off

The riser cut off saw is a highly automated casting processing device. As noted earlier, PBR Columbia produces multiple part numbers. Saws are required to automatically identify, quality inspect, engrave, saw and sort any three types of castings and direct them to downstream processes.

The saw is based on an eight station rotary table. Stations one and two are operator-loading stations that are light curtain protected. At station three the casting is identified, checked for proper clamping and digitally inspected for key features. At station four, a CNC controlled engraver marks the casting with a unique tracking number. Station five is the sawing station. The saw is hydraulically controlled with a proportional valve that has digital feedback as to the saw head position. This control factor minimizes cycle time. Station six is used for other operations such as post sawing inspection, trimming and other finishing operations. At station seven, the casting is ejected and automatically sorted for further processing. The final step is carried out at station eight where the fixture is cleaned and made ready for the cycle to recommence.

The PBR Columbia project is an example of how a successful team effort can meet the ever increasing expectations demanded by global competition.

Select No. 032 at www.moderncasting.com/info