Precise size requirements are achieved using the simple micro-adjustment within the burnish tool. This allows size to be controlled during long production runs with minimal interruption and low skill levels being necessary.
Burnish tools can be used on any driven machine spindle so eliminating the need for expensive honing, grinding or polishing operations.
There are no waste by-product sludge deposits produced as in grinding and honing.
TO ADJUST THE TOOL, release the lock nut and pull back the spring-loaded adjustment housing. Turn the housing to the left to increase the diameter or to the right to decrease the diameter. Once the desired size is found, lightly tighten the locknut to prevent accidental adjustment of the diameter.
To set the diameter of the tool, slide it into (or onto) the work-piece and gradually increase the diameter until the rolls contact the work-piece and a resistance is felt, like a tight plug gauge fit.
Now increase the diameter of the tool to apply the burnishing pressure. This is going to relate to the stock displacement expected but as a starting point add 0.010 to 0.015mm (each division on the tool is 0.0025mm).
Check the work-piece diameter and finish compared to the pre-machined part and adjust the tool until the desired results are achieved. It may take several attempts to reach the desired result and each should be conducted on a pre-machined part as burnishing is a 1-pass operation.
If the achieved part size needs changing, adjust the pre-machined size and the burnish tool by the same amount.
LUBRICATION – a continuous stream of lubricant, in sufficient volume to flush and clean the tool and work piece, should be provided during operation. Use any standard lightweight, low viscosity oil or mineral oil based soluble on the majority of materials. For aluminium or magnesium alloys, a highly refined oil based coolant of low viscosity is suggested.
All lubricants should be filtered. Without filtration, chip particles flushed into the area to be burnished can distort the bore and mar the fine finish.
For long tool life and optimum performance the tool should be kept clear of metallic particles and any other foreign matter that could prematurely damage the tool.
MAINTENANCE – when properly used the roller burnishing tool requires only routine maintenance. Rolls, mandrels and cages should be examined at regular intervals and replaced when the required size and finish are no longer obtainable. Always replace a complete set of rolls since there will be some sacrifice of tolerance and finish quality if new and used rolls are run simultaneously.
TOOL ALIGNMENT – A minimal misalignment of up to 0.1mm should not adversely affect the performance of the burnish tool. However, if the alignment deviates more than this it will cause fatigue failure of the mandrel tip, especially where the tool is rotating.