회사 소식 Can Turning Inserts and Milling Inserts Be Reground?

Turning inserts and milling inserts (mainly made of tungsten carbide cemented carbide) can both be reground. Proper regrinding is a practical solution to reduce tool costs and improve resource utilization. For issues such as minor wear, edge dullness, and small-area chip adhesion during machining, professional regrinding can restore their cutting performance, eliminating the need for immediate replacement with new inserts. However, regrinding requires the prerequisites of "no cracks in the insert body, damage within acceptable limits, and sufficient allowance". Additionally, due to differences in structure and application, turning inserts and milling inserts have distinct regrinding focuses. This article will answer core questions from four dimensions—"whether regrinding is possible", "prerequisites for regrinding", "regrinding differences between the two", and "advantages and precautions"—using plain language and clear tables, helping industry practitioners quickly grasp practical knowledge about regrinding these two types of inserts.

Not all turning or milling inserts are suitable for regrinding. The key depends on tool material and damage condition. Tungsten carbide inserts have the highest regrinding value, while coated inserts require a recoating process.

Key Judgment Criteria: Regrinding is only worthwhile when damage is concentrated on the cutting edge (no through cracks or severe chipping). Replace directly if:

• Chipping area exceeds 0.5mm (turning inserts) or 1mm (milling inserts);
• The insert body has cracks or severe edge defects;
• Thickness/diameter reduction exceeds 5% of the original size (insufficient allowance);
• The connection part of the shank/seat is deformed.

Regrinding of turning and milling inserts must meet the following unified prerequisites; otherwise, post-regrinding precision cannot be guaranteed, and machining quality may be affected:

1. Damage type is repairable: Only edge dullness, minor wear (wear ≤0.3mm), small-area chip adhesion or built-up edge, with no large-scale chipping or gaps;
2. Insert body structure is intact: No cracks or bending deformation, no severe depressions on the cutting surface, and no collapse or blockage in the flutes (milling inserts);
3. Sufficient regrinding allowance: New inserts leave regrinding allowance at the factory (usually ≥0.2mm for carbide inserts). Size reduction after multiple regrindings must not exceed the upper limit to avoid affecting machining tolerances.

Counterexample: If a milling insert has 1.5mm edge chipping due to high-speed collision, or a turning insert has through cracks, even regrinding cannot restore rigidity. Vibration and chipping are likely during machining, potentially damaging workpieces and equipment.

Due to differences in application and structure, turning inserts and milling inserts have distinct core focuses and requirements during regrinding, as detailed below:

Simple Explanation:

• Turning inserts focus on "linear cutting", so regrinding prioritizes ensuring the straightness of cutting edges and nose radius precision to avoid scratches on workpiece surfaces;
• Milling inserts focus on "rotary cutting", requiring consistent height across all peripheral and end edges. Otherwise, vibration during high-speed rotation will affect machining flatness.

• Cost reduction: Regrinding costs are only 10%-25% of new inserts. A carbide insert reground 2-3 times can save over 40% in total tool expenses;
• Efficiency improvement: The regrinding cycle is usually 1-2 days, faster than purchasing new inserts (especially custom specifications), reducing production downtime;
• Waste reduction: Full utilization of remaining insert value avoids direct scrapping of slightly worn inserts, aligning with energy-saving and consumption-reducing needs.

1. Professional operation is mandatory: Avoid manual grinding. Use dedicated CNC tool grinders to ensure regrinding precision (e.g., edge angle, arc radius);
2. Coated inserts need recoating: Regrinding removes the original coating. After repair, re-spray coatings like TiN or TiAlN; otherwise, wear resistance will drop significantly;
3. Control regrinding times: Exceeding recommended times leads to insufficient insert allowance, failing to meet cutting precision and rigidity requirements, easily causing machining errors;
4. Inspect after regrinding: Use calipers to check dimensions, angle rulers to verify edge angles, and conduct test cuts (on waste materials) if necessary. Confirm smooth cutting and no vibration before formal production.

Regrinding of turning and milling inserts (especially carbide ones) is entirely feasible. The core lies in "judging if damage is repairable, ensuring regrinding precision, and controlling regrinding times". Turning inserts focus on nose and cutting edge angles during regrinding, while milling inserts need to balance multi-edge consistency and flute smoothness. Coated inserts must be recoated after regrinding.

As a tungsten carbide industry practitioner, when recommending tools to customers, it is advisable to share regrinding-related knowledge (e.g., regrinding cycles, allowance requirements). For customers' old inserts, help judge if regrinding is worthwhile. A reasonable regrinding strategy can reduce costs for customers and improve tool utilization—a win-win choice.

Would you like me to sort out a regrinding parameter comparison table for turning and milling inserts, including recommended regrinding times, precision requirements, and suitable equipment for different specifications and materials, to facilitate your quick reference and customer recommendations?