Possible Causes – Unequal chamfers, Incorrect margins, Excessive spindle runout, Chatter
Possible Solutions – Regrind reamer with equal chamfer angle. Regrind reamer with narrow margins for reaming lower tensile materials. Increase reamer back taper (will lose size faster). Reduce speed and increase feed rate. Use power feed unless material is hard. Use right or left spiral fluted reamer. Grind secondary lead angle immediately back of 45° chamfer.
Possible Causes – Misalignment, Insufficient, cutting action
Possible Solutions – Use bushing – .0002″/.0003″ over reamer diameter. If hole location varies, use floating reamer holder. Increase reamer back taper (will lose size faster). Specify reamer with positive radial rake to reduce cutting pressure – may produce slightly larger diameter holes.
Possible Causes – Insufficient stock for removal, Excessive reaming pressure, Misalignment
Possible Solutions – Decrease previous operation drill size to allow more material for removal by reamer – leave about 3% of hole diameter for cast iron and more stock for non-ferrous materials. Increase feed rate. Reduce stock to be removed by increasing previous operation drill size – leave about 3% of the hole diameter. See Problem #2
Possible Causes – Not drilled straight
Possible Solutions – Correct previous drilling operation – reamer will follow the drilled hole. Increase reamer attack angle (chamfer) to 120°/180° included angle.
Possible Causes – Excessive reaming pressure, Misalignment
Possible Solutions – Reduce stock to be removed – See Problem #3 – See Problem #2
Possible Causes – Excessive feed, Excessive lip relief, Vibration, Thermal cracking carbide
Possible Solutions – Reduce feed. Reduce lip relief to provide smaller chisel angle. Frequently a worn drill bushing – REPLACE. Maintain adequate coolant flow at all times to avoid thermal shocking carbide.
Possible Causes – Drill Dwelling, Only one lip cutting
Possible Solutions – Maintain adequate feed at all times. Regrind with equal lip heights and chisel in center.
Possible Causes – Unequal lip heights, Worn drill bushing
Possible Solutions – Regrind with equal lip heights and chisel in center. Replace drill bushing.
Possible Causes – Unequal lip heights, Excessive lip relief, Worn drill bushing
Possible Solutions – Regrind with equal lip heights and chisel in center. Reduce lip relief to provide smaller chisel angle. Replace drill bushing.
Possible Causes – Dull cutting edge, Inadequate coolant
Possible Solutions – Regrind with fine grit diamond wheel. Review type of coolant and maintain adequate flow.
Possible Causes – Dull cutting edge, Wrong feeds & speeds
Possible Solutions – Resharpen to original tool geometry. Increase speed – also try reduced feed.
Possible Causes – Wrong feeds & speeds, Rough cutting edge, Insufficient coolant
Possible Solutions – Increase feed (should always be over .001″ per tooth) – especially when machining ductile or free machining materials. Also try reduced speed. Lightly hone cutting edge with fine grit diamond hone. Increase coolant flow – review type of coolant.
Possible Causes – Poor chip removal, Recutting work hardened chips, Vibration, Incorrect carbide grade
Possible Solutions – Use tool with larger flute space – larger diameter or fewer flutes. Increase coolant flow. Increase rigidity of set-up, especially worn tool holders. Change to tougher carbide grade.
Possible Causes – Insufficient machine horsepower, Vibration
Possible Solutions – Use tool with fewer flutes as correct speeds & feeds must be maintained. Consider climb milling. Use larger diameter cutter. Resharpen tool with more clearance.
Possible Causes – Feed too light, Dull cutting edge, Insufficient clearance
Possible Solutions – Increase feed. Resharpen tool to original geometry. Resharpen tool with more clearance.
Possible Causes – Excessive cratering, Milling abrasive material, Milling hard material, Insufficient chip room, Milling surface scale, Delayed resharpening, Thermal cracked carbide
Possible Solutions – Increase speed or decrease feed. Change to harder grade of carbide. Decrease speed and increase feed. Increase coolant flow. Climb milling better than conventional milling. Reduced speed – rigidity very important. Use larger diameter tool. Conventional milling better than climb milling. Prompt resharpening to original geometry will increase total tool life. Increase coolant flow at all times. Climb milling is cooler than conventional milling.