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A part's-eye view of a boring bar. Hole types: Blind hole (left), through hole (middle), interrupted hole (right). In machining, boring is the process of enlarging a hole that has already been drilled (or cast) by means of a single-point cutting tool (or of a boring head containing several such tools), such as in boring a gun barrel or an engine cylinder.
Honing uses a special tool, called a honing stone or a hone, to achieve a precision surface. The hone is composed of abrasive grains that are bound together with an adhesive. Generally, honing grains are irregularly shaped and about 10 to 50 micrometers in diameter (300 to 1500 mesh grit). Smaller grain sizes produce a smoother surface on the ...
The thinner bore surface also allows for more compact bore spacing, and can potentially provide better heat transfer. Automotive engines that use PTWA include Nissan VR38DETT, [3] and Ford Coyote. [4] [5] Caterpillar and Ford also use PTWA to remanufacture engines. [6]
Superfinishing, also known as microfinishing [1] and short-stroke honing, is a metalworking process that improves surface finish and workpiece geometry. This is achieved by removing just the thin amorphous surface layer of fragmented or smeared metal left by the last process with an abrasive stone or tape; this layer is usually about 1 μm in magnitude.
The part is then transferred to the next station or a larger tool is mounted and a larger bore machined, and the process repeated until the desired bore geometry is reached. The number of tools required to achieve the desired bore size is dependent on the workpiece material, the amount of stock to be removed and geometrical requirements, with ...
The key is to find the optimum balance of all the factors for the engine requirements. Further complicating the system is the fact that the piston dome, the signal source, continually moves. First moving down the cylinder, thus increasing the distance the signal must travel.
The advantage is that the engine block will be reduced in size, or the bore can be increased in size. The disadvantage is a higher temperature between two cylinders, requiring a stronger engine block to avoid distortion of the metal, and better gasket sealing between the two bores.
Although successfully used by many European manufacturers, there are potentially issues associated with engines that use Alusil blocks, namely cylinder bore scoring which occurs when there is a breakdown of the exposed silicon particles in the cylinder bore, resulting in increased oil consumption and excessive piston noise.