How to Regrind and Reuse Carbide Inserts (When Possible)

Why regrinding matters

Regrinding (or reconditioning) of cutting tools can extend tool life, reduce waste and lower tooling cost-per-part — but it’s not always appropriate for every carbide insert. Knowing which inserts can be safely and economically regrind, what the process involves, and what risks you accept (loss of coating, changes to chipbreaker geometry, tolerance drift, warranty issues) helps shops make the right call. Leading toolmakers and reconditioning services offer regrind programs for certain tool types; however, manufacturer guidance and ISO tolerances must be respected. 

What “regrind” means in everyday terms

Think of a regrind like a dentist filing a tooth to restore its shape. For cutting tools, regrinding removes the worn material (flank, nose or crater) on the cutting edge and re-establishes the original geometry (nose radius, clearance angle). After grinding, tools may be recoated (PVD/CVD) or left bare depending on the tool type and economics.

Important distinction: indexable inserts (small, often-coated, replaceable inserts like CNMG, SNMG) are different from solid carbide drills/endmills and brazed/tipped tools in how regrindable and recoat-friendly they are. Many solid-carbide tools are routinely regrindable; indexable inserts are sometimes regrindable but have additional constraints (coating, chipbreaker geometry, tolerance). 

Is it technically possible to regrind carbide inserts?

Yes — technically most cemented carbide substrates can be ground and reshaped using diamond wheels, provided the process controls heat, avoids cobalt leaching and restores the critical geometry. But practical viability depends on:

• Insert type (solid carbide vs indexable vs tipped).
• Coating type & thickness (PVD coatings are thin but can be difficult to strip cleanly; CVD coatings are thicker).
• Presence of chipbreakers and ground features (regrinding may remove these).
• Whether the final geometry can meet the required tolerances for seating/clamping (ISO 1832 tolerances).
• Cost vs buying new inserts (shipping, grinding, recoating costs). 

Regrind-friendly: typical candidates

• Solid carbide endmills, drills and special cutters — commonly reconditioned by OEMs and regrind houses (Sandvik and Kennametal offer reconditioning services for solid carbide tools). 
• Certain indexable inserts — possible when geometry allows (large nose radii, simple corner shapes) and when chipbreaker/clamping features aren’t essential or can be re-established. Many shops regrind inserts for hobby or low-volume production, and specialist service companies can regrind or refurbish certain insert families. 

Less practical / higher risk

• Very small or heavily chipbreaker-dependent inserts (e.g., multi-feature chipbreaker faces on many CNMG/CNGN types). Regrinding may destroy the chipbreaker and make the insert unpredictable.
• Inserts whose coating or manufacturer marking must remain intact for traceability or warranty. Regrinding/coating removal can void warranty or factory support. Always check manufacturer policy.

ISO 1832 standardizes indexable insert designations (shape, clearance angle, tolerance, size) so you can match geometry across brands. If you want to know whether a specific insert can be reground and still meet dimensional requirements, use the ISO code and dimensional tables as your reference. For example:

ISO code example: CNMG120408 — decode simply:

• C = 80° rhombic shape (shape).
• N = 0° clearance / relief angle (clearance).
• M = manufacturer tolerance/series code (check ISO/brand key).
• G = ground / chipbreaker / clamping modifier (manufacturer-specific extra symbol).
• 12 = inscribed circle (IC) size (~12.7 mm).
• 04 = thickness (≈ 4.76 mm).
• 08 = corner radius 0.8 mm.

ISO tables and supplier designation keys let you confirm original dimensions and permissible tolerances — critical when deciding whether a reground insert will still seat/clamp correctly.

1.Inspect the failure mode

• Flank wear only (VB) → often suitable for regrind.
• Major chipping/broken corner → may be recoverable depending on size; small chips sometimes ground away; large loss often not economical.
• Crater wear on rake face → may be reground but beware of coating removal.

2. Identify insert type & features

• Does the insert have a critical chipbreaker, ground face, or special geometry that regrinding will destroy? If yes, regrind is less attractive. Use ISO code to confirm geometry. 

3. Check coating & substrate

• Is it PVD or CVD coated? Can the coating be stripped / retained without damaging the substrate? PVD coatings are thin, but coating removal or removal of coating from rake/clearance can reduce performance significantly. Kennametal’s guidance notes that removing coating from the rake face can reduce tool life substantially. 

4. Estimate economics

• Cost to regrind + (possible) recoating + shipping vs. new insert cost. For expensive, large or specialty inserts, regrind often makes sense. For cheap commodity inserts, buying new is usually cheaper. Third-party regrind shops offer quotes and volume discounts. 

5. Decide on recoat

• If regrind removes the coating from critical faces, re-coating may restore performance — but re-coating is a specialist operation, not always cost-effective on small inserts. Stripping & re-coating PVD/CVD layers requires careful process control to avoid substrate damage. 

6. Confirm tolerances

• Make sure the reground geometry will meet the seating/clamping tolerances from ISO 1832 (insert thickness, hole position, corner radius). If not, the insert may not fit or may produce runout.

7. Choose a qualified reconditioning partner (or in-house setup)

• Use reputable services for recoating or fine diamond grinding. Many OEMs and specialist shops recondition tools to OEM tolerances. Examples: OEM reconditioning pages and specialist reconditioning houses offer service options.

• High-value custom inserts / large milling tips: If the original insert is expensive (special geometry, expensive grade) and the worn area is minor, regrind + recoat can be economical. 
• Solid carbide tools: drills and endmills are commonly reground 2–5 times by service centers and OEMs (Sandvik and Kennametal document reconditioning services for solid carbide tools). 
• Sustainable/low-volume shops: small shops with many identical parts sometimes regrind inserts to squeeze more life from existing inventory — but must control quality and inspect carefully to avoid scrapped parts.

• Inspect before you decide — the failure mode determines feasibility.
• Use ISO 1832 & manufacturer keys to confirm whether reground geometry will still meet seating/clamping tolerances.
• Expect coating & chipbreaker tradeoffs — regrinds can reduce coating protection and destroy chipbreaker function; plan for possible recoating if performance must match original.
• Do the math — compare regrind + recoat + shipping to new insert cost; for expensive or specialty inserts, regrind often wins; for commodity inserts, buying new usually does. 
• When in doubt, use OEM / certified reconditioning to keep tolerances and performance predictable.