Ultra-Hard Cutting Tool Solutions In deep-hole machining, issues such as workpiece dimensional accuracy, surface quality, and tool life frequently arise. How to reduce or prevent these problems has become an urgent challenge that needs to be addressed. Let’s now explore the common problems associated with superhard cutting-tool solutions and the corresponding mitigation measures.

　　1. Ultra-hard cutting tool solutions suffer from increased hole diameter and greater dimensional errors.

　　1) Causes

　　The design value of the reamer’s outer diameter is excessively large, or burrs are present on the reamer’s cutting edge; built-up edge has adhered to the reamer’s cutting edge; during grinding, the runout of the reamer’s cutting tip is unacceptably high; when installing a reamer with an improperly selected cutting fluid, oil and other contaminants on the taper shank surface have not been thoroughly removed, or the taper surface exhibits scratches; the cutting speed is too high; the feed rate is inappropriate or the machining allowance is excessive; excessive principal rake angle causes bending of the reamed hole; after the flat tail of the taper shank is misaligned during installation on the machine tool spindle, interference occurs between the taper surfaces; the spindle is bent, or the spindle bearings are loose or damaged; the reamer is loosely mounted; when using a shaft or hand-held reaming tool that differs from the workpiece, uneven force application by both hands leads to lateral oscillation of the reamer.

　　2) Solution

　　Appropriately reduce the reamer’s outer diameter based on the specific conditions; decrease the cutting speed; carefully dress the reamer with an oilstone until it meets specifications; select a cutting fluid with good cooling performance that keeps runout within the allowable range. Before installing the reamer, thoroughly wipe away any oil or contaminants from the reamer’s tapered shank and the machine tool spindle’s tapered bore. Adjust the feed rate as appropriate, or straighten the reamer if it is bent, or discard it if necessary to reduce the machining allowance; also consider using a reamer with a reduced principal rake angle. Re-adjust the floating chuck, and if there are marks on the taper surface, use an oilstone to polish it smooth. Grind the reamer’s flat tail. Adjust or replace the spindle bearings. Realign the coaxiality. Pay close attention to proper operating procedures.

　　2 . Ultra-Hard Cutting Tool Solutions Existing problem: Aperture reduction

　　1) Causes

　　The design value for the reamer’s outer diameter is small; elastic recovery reduces the hole diameter; during reaming, excessive stock allowance or a dull reamer can easily lead to elastic recovery, as can excessively low cutting speeds, excessive feed rates, or an insufficient principal rake angle; improper selection of cutting fluid; failure to remove worn portions during regrinding, resulting in reduced hole diameter or lack of internal fillets and nonconforming hole dimensions.

　　2) Solution

　　Replace the reamer with one of a different outer diameter; appropriately increase the cutting speed and ensure proper grinding of the cutting edges of the reamer; when designing the reamer dimensions, moderately reduce the feed rate; regularly replace the reamer with one that has an appropriately increased principal rake angle and uses a high-performance oil-based cutting fluid; the above factors should be taken into account, or values should be selected based on actual conditions; conduct trial cutting to leave an appropriate machining allowance, and ensure the reamer is sharpened to a keen edge.

　　3. Problem with the superhard cutting tool solution: the hinge’s internal bore is out of round.

　　1) Causes

　　The reamer is excessively long and lacks sufficient rigidity, leading to vibration during reaming; the hole surface exhibits sand holes and porosity; the spindle is loose, there is no guide bushing, or the clearance between the reamer and the guide bushing is too large, resulting in an insufficient principal rake angle and a narrow cutting edge; excessive stock removal causes surface damage in the reamed hole, including cross-drilled holes; and overly tight clamping of thin-walled workpieces leads to deformation upon removal.

　　2) Solution

　　For reamers with insufficient rigidity, unequal-spacing reamers may be used. When using unequal-spacing reamers, employ long, precision guide sleeves; select qualified stock; when reaming holes with high precision using equal-spacing reamers, adjust the machine tool spindle clearance, increase the fit clearance of the guide bushing, and ensure rigid mounting of the reamer to increase the principal rake angle; select qualified reamers and control hole-position tolerances in preceding machining operations; or adopt appropriate clamping methods to reduce clamping force.

　　4. Issues with the superhard cutting tool solution: obvious sharp edges are present on the inner surface of the hole.

　　1) Causes

　　The reaming allowance is too large; the back rake angle of the reamer’s cutting portion is excessively large; the reamer’s cutting edge width is too wide; the workpiece surface has holes or porosity; and the spindle runout is excessive.

　　2) Solution

　　Reduce the reaming allowance and decrease the back rake angle of the cutting portion; grind the width of the cutting edge; select qualified stock; and adjust the machine tool spindle.

　　5. The ultra-hard cutting tool solution suffers from high surface roughness values on the inner bore.

　　1) Causes

　　Excessive cutting speed; improper selection of cutting fluid; excessively large principal rake angle of the reamer; severe runout of the reaming portion of the tool; dull cutting edges resulting in a rough surface finish; excessive width of the reamer’s cutting edge leading to poor chip evacuation and accelerated tool wear; scratching caused by impact on the reamer, with the cutting tips not lying on the same circular arc; excessive reaming allowance; uneven or insufficient reaming allowance, causing some areas to remain unreamed; burrs and chips remaining on the cutting edges; built-up edge formation at the cutting tip; and, due to material characteristics, unsuitability for reamers with zero or negative rake angles.

　　2) Solution

　　Reduce the cutting speed; select an appropriate cutting fluid based on the workpiece material, and either decrease the principal rake angle or increase the reaming allowance; use a qualified reamer; ensure proper grinding of the land width; depending on the situation, reduce the number of reamer teeth, enlarge the chip evacuation space, or employ a reamer with a negative clearance angle, and grind the cutting edge to form a sharp cutting tip; appropriately reduce the reaming allowance to improve the positional accuracy and quality of the pilot hole prior to reaming, while taking protective measures to prevent impact damage; for damaged reamers, repair them using ultra-fine oil shale or replace them entirely; ensure smooth chip evacuation; replace the reamer regularly and, during dressing, focus on grinding only the cutting zone; during dressing, use oil shale to restore the reamer to acceptable condition, and employ a reamer with a positive rake angle of 5–10 degrees.

　　The foregoing sections have outlined the common issues and corresponding solutions for superhard cutting tool applications. For more information, please feel free to contact us at any time!