Point angle

AZ Azimuth point angle measured between the plane of the array (generally also the SBR velocity vector) and the elevation plane... 

For the unequivocal characterization of a low-molecular-weight compound, it is sufficient to specify a few physical or chemical properties, for example, boiling point, melting point, angle of optical rotation, refractive index, elemental analysis, IR and NMR spectra. If two low-molecular-weight samples have the same characteristic properties, they may be considered as identical. 

Although a more sharply pointed emitter tip was expected to yield better electrospray performance, no difference was observed between point angles of 30 ° and 60 (Figure 4.7) for PDMS emitters prepared by the trimming method. However, the 60 ° angle was found to be preferable for tips prepared by other... 

Figures Figures that accompany questions are intended to provide information useful in answering the questions. Unless otherwise indicated, positions of points, angles, regions, etc. are in the order shown angle measures are positive lines shown as straight are straight and figures lie in a plane.

Drills with a helbc angle of 20 - known as slow-helix drills - are available with a point angle of 118 for cutting brass and bronze, Fig. 7.13(b), and with a point angle of 90 for cutting plastics materials,... 

Quick-helbc drills, with a helix angle of 40 and a point angle of 100 , are suitable for drilling the softer materials such as aluminium alloys and copper. Fig. 7.13(c). 

Although usually made from HSS or HSCo, drills are also available in solid carbide from 3 to 20 mm with a point angle of 140° suitable for cutting a wide range of materials including carbon and alloy steels, stainless steels, cast iron and non-ferrous metals. 

To produce holes quickly, accurately and with a good surface finish, a correctly ground drill is required. In grinding the correct drill point, three important items must be controlled the point angle, the lip length and the lip clearance angle. 

When a great deal of drilling is done, it is economical to use a drill-point grinding machine, which ensures correct point angle and lip clearance and equal lip lengths. However, it is often necessary to regrind a drill by hand, and you should be able to do this so tbat the drill cuts correcdy. 

A simple gauge as shown in Fig. 7.15(a) can be used as a guide to the correct point angle. Correct Up length can be checked using the simple gauge shown in Fig. 7.15(b). With the shank of the drill supported, a line is scratched with each Up. When the lines coincide, the Up lengths are equal. 

In drilling thin plastics sheet, a point angle as great as 150 is used on fhe larger diameter drills, so that the point is still in contact with the material when the drill starts cutting its full diameter. Alternatively, the sheet can be clamped to a piece of waste material as with thin sheet metal. 

The test samples were M7 hardened tool steel drill bar, cylindrical shaped, with an average length Lave = 98.425 mm and 118° point angle. 

Drills are available with parabolic flutes where the heel of the flutes is rolled over, which provides additional flute space for chip evacuation and produces a thinner land. This is advantageous particularly with deep hole drilling on CNC machines where constant withdrawl of the tool to clear chips can be minimised thus reducing cycle times. They have a 130° point angle and a quick helix around 38°. These are available with a nitride coating to increase wear resistance and improve tool life. 

Drills are also available ground with a split point and a point angle of 135°. The chisel edge is removed and results in a single central point. 

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