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Machining automotive components with cbn inserts

CBN and PCD inserts are advanced cutting tools used for milling, drilling, turning and reaming of various automotive components in the vehicle manufacturing industry. They provide extremely high quality and economic efficiency in the mass production of complex automotive parts such as cylinder block, cylinder head, crankshaft, camshaft, connecting rod, transmission case, gearbox shaft, clutch housing, brake disc and drum, aluminum wheel, and pressure plate. CBN, polycrystalline cubic boron nitride, is well suited for machining of composite ferrous materials and superalloys that are commonly used in today's automobiles to reduce weight and increase fuel efficiency.

Cylinder Block
The cylinder block plays one of the most important functions in the entire engine. It is the central component that connects the cylinder head, piston, connecting rod, and crankshaft. The cylinder block is designed to withstand rigorous forces, vibration and friction. Therefore it is usually made of cast iron, compacted graphite iron (CGI), aluminum or super-alloys. In order to meet the new requirements for corporate average fuel economy, most engine blocks are now being re-designed to reduce weight. They are also machined with high precision to prevent leaking valves. To meet these new demands, many new machining tools with PCD and CBN inserts have been manufactured. For instance, reamers with custom pcd inserts of 26mm. Another example is the square shoulder milling cutter which has a double-sided cbn insert that provides very aggressive removal of material on cast iron. It maintains high productivity and reliability.

Cylinder Head
Above the cylinder block, the cylinder head sits and provides a portion of the internal combustion chamber. In particular, it has holes that house the spark plugs and valves. Performance of the engine is determined by the quality of the cylinder head. The shape of its ports, inlet passages and combustion chamber influence the compression ratio and efficiency of the engine. Since the cylinder head of most vehicles is usually made of more than 80% aluminum, tooling with pcd inserts are needed for high quality, high speed, repetitive machining. Inserts are available for face milling including specially designed cutting tools for initial rough milling and the fine surface finish. Other machining operations that are accomplished with PCD or CBN inserts include boring of the valve seat and guide, reaming, boring of the tappet and spark plug holes as well as the cam and oil control valves.

Crankshaft
This is the engine component that is responsible for translating the reciprocating motion of the piston into the rotational motion required to turn the flywheel, rotate the wheels of the vehicle, as well as the alternator and other parts of the engine. Traditionally, crankshafts were manufactured by casting ductile steel. But now most auto manufacturers prefer to forge the crankshaft from a steel bar through a process known as roll forging. Crankshafts produced by roll forging are lighter and offer better vibration dampening features. Hence, due to its intricate details, the machining of the crankshaft usually requires various inserts for face milling, pin journal and main journal milling, drilling, turn-turn broaching and external turning.

Camshaft
The camshaft is the part of the engine that regulates the movement of the poppet valves. On the cylindrical rod that extends throughout the length of the shaft, there are pairs of oblong lobes (as known as cams) that stick out of the shaft. One cam controls a single valve and causes it to open as it presses against it during the rotation of the shaft. Various kinds of standard and custom built tools have been developed with pcd inserts to make the production of the camshaft, faster, cheaper, more accurate, with great improvement in productivity. For example, machining operations such as double-sided face milling, center drilling, lug end milling, external cam milling, and external turning and grooving have their own specialized tools and inserts.

Connecting Rod
An automobile engine block has at least 4 pistons and one crankshaft. A connecting rod (also called con-rod) connects a piston to the crankshaft. For typical production engines used in mass produced automobiles, connecting rods are usually made of steel. But for high performance vehicles, they are made with other materials. Aluminum is used to reduce weight and absorb high impact while titanium provides greater strength at a much higher cost. Specialized cutting tools with CBN and PCD inserts are used to handle face milling, pin bore drilling, bolt hole machining, balance weight milling and boring of the crank core.

Transmission Case
This is the component that shields the transmission system (speed conversion system or gearbox) and helps to circulate the lubricant for the entire system. It is usually produced with a lightweight aluminum alloy. Most transmission cases have intricate designs and they often require the use of custom made tools with special inserts that can perform their operations efficiently. The machining operations that require these specialized tools include: boring of bearing holes, face milling, drilling, tapping and reaming.

Clutch Housing
Today, most new cars come with automatic transmission systems, but a few vehicles are still produced with manual transmission systems that are cheaper to maintain. Manual transmission systems have a flywheel and clutch plate that help to control the gearbox. A clutch housing is used to protect these components and it is usually assembled directly infront of the transmission case. Like the transmission case, special insert tooling is available for reaming, face milling, special boring, milling and tapping.

Brake Disc and Drum
A disc brake makes use of calipers to press a set of pads against a disc so that the friction created can slow down or stop the vehicle. In most cases, the disc is made of cast iron. But it may also be produced from ceramic matrix or reinforced carbon-carbon composites. The ceramic discs are manufactured for heavy vehicle and high performance cars. Therefore, they require special tooling and inserts due to their abrasive nature. cbn inserts are available to machine the differential case and the brake disc.

Aluminum Wheels
These wheels are produced from alloys of aluminum. They offer greater strength than wheels made of a single metal. Wheels made from aluminum alloys are lighter and provide greater heat dissipation with better aesthetics than steel wheels. Hence they improve braking performance. Their light weight also gives an opportunity for lower fuel consumption. But due to the brittle nature of aluminum when compared to iron or steel, they usually benefit from the use of pcd inserts during machining, especially for internal and external turning.

Conclusion
Those are some of the samples of automotive components that can be produced with high efficiency, lower production cost, shorter turnaround times, and more accurate surface finish. This is achieved through the use of both custom built and standard PCD and CBN inserts.

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