Heat and pressure. That is what formed the earth we live on. The same two principles also are the origins of powder metal parts used in the automobiles we drive.

GKN Sinter Metals makes a range of these products for leading automakers, from clutch plates to power steering components. Last year, the company upgraded the manufacturing line in Salem, Ind. that produces six sizes of transmission clutch plates for light commercial trucks. The new design has provided a continuous flow throughout the pressing and sintering processes. It has also more than doubled throughput (from three pieces a minute to seven), improved quality, reduced line operators (from six to one), and eliminated the need for overtime.

Before the upgrade, most materials were moved manually from one station to another using wire baskets. Parts were wheeled from the compacting press to drilling operations and then to the sintering furnace. But that needed to change to reduce handling and meet new throughput targets. Today, conveyors and gentle transfer units (Shuttleworth, Inc., www.shuttleworth.com) combine with robotic systems to do just that.

'Now we have a continuous flow operation,' says Gale Wiseman, electrical engineering supervisor. 'We are able to run on this one line what three presses were doing before. We took out handling steps that did not add value to the product.'

The powders that will be used as the basis of the parts arrive at the facility's receiving area in bulk packs resting on wooden pallets. Lift trucks pick up the pallets and take them to racks in a materials storage area. The powders, which have a consistency similar to sugar, are primarily stored in dedicated areas. Drivers note the location of each pallet upon deposit.

When ready for processing, lift trucks are directed by pick tickets to collect the required powder and take it to a machine that inverts the bulk pack for use within a compacting press. A die within the compacting press provides the shape the powder will assume as pressure is added.

Formed parts are then ejected from the die onto a low-pressure accumulating conveyor that carries them to a weigh station. There, parts are raised slightly above the conveyor surface and checked against a known weight. Parts that do not match up are diverted down a reject spur.

Parts passing the weight test are conveyed to an automated robot using a vision system that allows the robot to pick the parts in the required orientation.

The robot sees the part and uses electro-magnets on its gripper to lift the part to a drilling station. The robot then turns to pick up another part exiting the drilling operations. It next stacks parts up to four high onto a ceramic disc that acts as a pallet for conveying the parts through the sintering furnace. The discs, each about 101/2 inches in diameter, are placed three across on the conveyor. The discs then enter a specially designed right-angle transfer that gently lifts and redirects them around the sharp turn needed to reach the furnace opening.

Temperatures within the 300-foot furnace can reach 2,200 degrees F. It takes over two hours for the parts to be slowly conveyed at about 7 inches per minute through various heating and cooling processes. In one area, they pass through a protective atmosphere of hydrogen and nitrogen that keeps out harmful oxides as the powder bonds.

Upon exiting, another right angle lift and transfer places the discs and their loads onto a conveyor for transport to a second robot station. This robot lifts all four stacked parts at once and dips them into a rust-inhibiting solution. The robot then places the parts in the correct orientation and stacking height into wire baskets staged at two stations. The robot signals a worker when the first basket is filled, then it begins filling the basket at the second station. Meanwhile, the ceramic discs are conveyed back to the beginning of the line.

The next stop is the sizing and machining processes, where much of the handling is still manual. However, GKN is currently in the design phase of extending automation to these areas for improved efficiencies.

Wire baskets on carts are manually moved to the sizing operation that flattens the part and ensures it has the proper dimensions and densities. After sizing, parts are manually loaded onto other carts for transport to machining.

Once machining is completed, parts are automatically discharged onto a conveyor that carries them to a tumbler machine. An operator there manually places the parts onto a lift that feeds them into the tumbler. The machine uses ceramic pellets and fluids to remove any burrs that remain from the earlier operations. Completed parts are manually placed into returnable dunnage containers, most of which are owned by the automakers. These containers are stacked upon pallets and manually wrapped to secure them for shipping.

Lift trucks pick up the container loads and stage them temporarily in racks within the shipping department until ready for loading onto trucks. Some just-in-time items ship immediately, though GKN tries to keep about two day's worth of inventory within the racks.

'We are moving toward a pull system, so we want a couple of days inventory on hand,' adds Wiseman.

Click icon to read how automation helped engine component manufacturer Hayes increase efficiences.