The fracture-split technology will provide better alignment for rodbolts.
Click picture above for specs on 4340 vs. ASTM 4260 Metallurgy
With a definite model in place, the process of determining material composition (a proprietary secret) is underway. A base powder is combined with selected alloying elements, and in some cases, lubrication materials or graphite is added. The newly formed combination is placed into a mixing apparatus for blending the components. This blending process points out one advantage of the powder metal. Custom blends can be accommodated, though GKN has standardized thousands of combinations for components. Physical characteristics can be enhanced with a slight change in the blended material. The process of mixing also allows for closer elemental interaction. Metal-forming alternatives like die-casting molten metals face limitations in alloy choices because of the behavior of the raw material when melted and processed.
After mixing, the material is fed into a compaction machine. The material is placed into a die cavity with two punches. A press squeezes the powder into the shape of the component. The compounds in the existing powder serve as an adhesive to form the part.
(above & below left) GKN's aggressive testing program was a key selling point in itsrelati
The next step is sintering. This is the process of forming a cohesive mass by the use of heat without melting the part. During the sin- tering process, parameters such as temperature, atmosphere, belt speed, and environmental factors are monitored and registered. Lubricants and binding agents are driven from the part. The heat of the sintering process forces the alloying agents to diffuse throughout the part. After the sintering operation, parts are maintained in a controlled atmosphere to prevent decarburization. At this stage, the rods are known as pre-forms. The pre-form is quickly heated to above 1,500 degrees, and a mechanical screw press is used for final forging. Force, speed, timing, tool temperature uniformity, and tool lubrication are controlled. The rods are now complete to near net shape and are forged to full density.
The rods also involve a practice known as fracture notching, which falls into the classification of "secondary operation." There are advantages to the fracture split technology that serve the part better than the standard saw cut. Superior alignment is assured with the processing. The fracture split surface will also eliminate fretting, thus there's no need for guide bushings with this procedure.
The parts require other secondary operations. These could include honing, boring, grinding, and drilling. If a chamfered or beveled face is needed for a product, this can also be implemented at this step.
The rods are the product of an evolution. They start in the briquetteform (left), go throu
The finished product is thoroughly tested to determine its ability to withstand the demands of the application. After satisfactory completion of the testing phase, mass production of the pieces can be ordered.
Precision powder forging has several advantages over the conventional forging process:
1. Greater material flexibility
2. Fewer burrs that require additional work to remove
3. Minimal weight fluctuation between pieces--allowing easy replacement of a single rod
4. No material textures
(above & right) Powder production utilizes melting and atomizing with annealing muchlike t
In the blending process, the important elements are mixed. GKN has theability to create cu