Drilling Processes Hole quality

The kinematics of reaming is comparable to the drilling process that incorporates a rotational movement and a linear movement in axial direction of the tool (Fig. 1). Reaming is basically a counter bore operation with thin chips. The target is to produce high precise holes in diameter with excellent surface and form quality. 

Undercut drill bits generally provide better hole quality with these materials. Other drill process variables must also be examined, and include ... 

Effects. Excessive backup penetration depth increases drill wear and the occurrence of breakage of small-diameter drill bits, adversely affects hole quality, and increases process time per load. Insufficient backup penetration depth results in incompletely drilled holes. This impiies that thickness variations of the backup material are very important, meaning that minimai variations are a much desired characteristic of the backup and need to be considered when choosing a material suitable for your application. 

When tracked over time, this information can help alert the engineering team of any sudden changes in the drilling process. Although the used drill bit condition information is subjective, with properly trained personnel it can serve as a key indicator of the level of hole wall quality. 

External cylindrical lapping is used to process external surfaces of cylindrical parts. Therefore, the workpieces are moxmted radially on a workpiece holder on a two-face machine, whereby the parts scroll with an eccentric motion between the lapping disks. This process is used to reach very high shape precision, required, for instance, for jet needles in injection pumps. Cylindrical lapping of drilled holes is realized with cylindrical bushes, which describe rotating and lifting movements. Because of this kinematic, high surface qualities are reached, which are unable to be accomplished by other processes (Paulmann 1991). 

The quality of a hole drilled through a printed circuit board is measured by its ability to interface with the following processes plating, soldering, and forming a highly reliable, nondegrading electrical and mechanical connection. 

Costly deep-hole drillings as well as the complex milling operations should also be considered. All processing steps up to the mold contour can be obtained from the standard parts manufacturer. Through this extended workbench of the mold maker, optimum quality and precision can be achieved. 

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