Advancements in Single-Pass Bore Finishing - Systems Approach (pag. 7 of 10)

Advancements Manufacturers are continually pushing the envelope in regards to what can be accomplished with the singlepass Processo. Improved tool, fixture, and machine designs have allowed for increased production rates as well as improved bore precision. The following are some of the latest advancements that have been made.. Cross Hatch Patterns: Another recent development that has been made in the singlepass style of bore finishing includes creating various “cross hatch” or “sine curve” scratch patterns on the finished bores. (The depth and angle of the scratch pattern can vary depending upon the size of the superabrasive grit; material to be finished, and operating speeds and feeds). These patterns are thought to be beneficial in the retaining of oil in engine cylinder bores. This pattern is achieved by feeding a proprietary designed Rodatura style tool through a bore at a higher than normal feed rate, (which only removes a portion of the parts material) then reciprocate the tool through the bore a number of times at a set spindle speed and feed rate. The spindle speed and feed rate will determine the crosshatch angle. With this method, many of the advantages of the Rodatura method are obtained, as well as the desired crosshatch pattern.

Gears being finished with single-pass Processo

Adding a controlled peck method to the Processo may also produce a similar pattern (sine curve). This method allows for the finishing of long uninterrupted bores in even the most gummy of materials b allowing the chip that is produced to be broken up, and a fresh supply of lubricating fluid to enter the work area. This method is also advantageous on Applicazionis where it is important to keep the cutting stresses down to an absolute minimum, such as in the finishing of thin walled components. The following case histories illustrate examples of Applicazionis where either the “cross hatch” or “sine curve” patterns are produced.

Diameter:	68mm	Length/Clearance:	102mm
Material:	Cast Iron	Hardness:
Bore Type:	Thru	Stock Removal:	0.035mm
Tool Pass #1:	67.992mm	Diamond Size:	140/170
Tool Pass #2:	68.002mm	Diamond Size:	325/400
Tool Pass #3:	Brush

Bore Quality	Required	Achieved
Size:	.010mm	0.005mm
Roundness:	.006mm	.002mm
Straightness:	.006mm	.002mm
Surface Finish:	1.6Rz	1.4Rz

Machine Type:	Engis Model # 9425-14S (4 Spindle Machine)
Production:	60 Parts Per Hour