TABLE OF CONTENTS Designers require countersinking for many reasons, which are described below. Similarly, while designers may not require countersinking the manufacturing engineer may need it to facilitate manufacturing. Normally, this requirement is determined after the manufacturing engineer and the designer talk, but in some companies countersinking is simply a standard manufacturing practice that is not expressed on drawings.
remove burrs
remove uneven edges
prevent burrs from forming
allow screw heads to seat below flush
allow rivets to seat flush with top surface
allow rivet nuts to seat flush with top surface
provide starting feature for drills
enhance location accuracy of tapped holes
prevent tapping swell at top of hole
provide accurate centers for lathe parts (combined drill and countersink tools)
prevent sharp edge from interfering with radii under pin heads or mating parts
eliminate sharp edges that affect microwave frequencies
eliminate sharp edges that cut wires
reduce edge cratering, flaking or crumbling
reduce turbulence and nonlaminar flow
increase volumetric efficiency of air compressors
increase sheet metal formability
change stress or fatigue patterns
provide more stress effective castings (chamfer mold features to eliminate sharp internal corners)
reduce subsequent plating build up
change electromagnetic fields
reduce pressure drops across orifices
provide aesthetic appearance
enhance heat transfer rates while keeping orifice pressure drop constant
minimize side leakage in journal bearings
facilitate assembly of mating parts (less insertion force and energy required with chamfers)
provide flexible joint (spherical chamfers to simulate spine joints).
Burrs cause 19 different problems in...
