Search Results

Compacted-graphite iron (CGI) has been promoted as the material of choice for diesel engines as popular alternatives to conventional gray cast iron. CGI has higher strength and elastic modulus than gray iron but retains the damping properties, thermal conductivity, and castability of gray iron. But for all the advantages of higher strength and wear resistance offered by CGI, it is precisely these properties that make it difficult to machine. Rotary-insert tooling is a patented boring tool that shows promise for reducing the machine horsepower needed for cylinder boring operations. Holes with large diameters are usually bored with boring heads having multiple inserts. The boring heads are used as alternatives to single point boring bars. The diameter of the boring head is equal to the finish diameter of the hole, and inserts are symmetrically distributed around the circumference of the boring head in order to provide force cancellations in the plane perpendicular to hole axis.

Mechanical properties of porous materials such as bones for example are controlled by the geometry and structure of the pore space. Traditionally, most attempts to understand the effect of pore structure on mechanical properties have assumed that the pores can be modeled as ellipsoids Eshelby [9] etc. Nevertheless pictures taken by SEM show that pore shapes are never as simple as circles or ellipses. But the use of real pore shapes in the modeling process has been hindered by the lack of analytical solutions for these shapes. Zimmermann [24] suggested that the pore compressibility Cpc scales approximately with where A is the area of the pore space and P is the perimeter surrounding the pore space. Forcing this scaling law to be exact for a circular hole leads to the approximation . Zimmerman [25] showed that this approximation has an error of less than 8% for all hypotrochoids and an error of about 23% for thin, crack-like pores, which he suggested might be the "worst-case" shape.

Drilling compound hole is very common material processing operation in engineering industry. In this special machining process before drilling the hole the part is rotated about an auxiliary axis parallel to one of the reference axes. Accuracy of the drilled hole is paramount in several applications such as in cylinder head and some other applications of bone surgery. Inaccuracy in hole axis may result in the loss of engine efficiency in the case of Cylinder Head or unsuccessful bone surgery. In the previous papers Murty et al. [8], [9] the algorithms developed had restricted application. In the first paper the tool was restricted to move in vertical plane and WY-plane was considered as reference plane. In the second paper the tool movement was unrestricted in space but the WY-plane was considered as reference plane and the skew error was assumed only in WY-plane.