PCD and CBN cutting tools represent a significant upfront investment. When a worn insert is removed from the machine, the question arises: should it be discarded and replaced with a new one, or sent for regrinding to restore the cutting edge? The answer has direct implications for tooling cost per part, production scheduling, and overall manufacturing efficiency.
Regrinding — the process of re-sharpening a worn cutting edge to restore usable geometry — is a well-established practice for superhard tools. When applied correctly, it can reduce total tooling expenditure substantially. But regrinding is not universally beneficial. This guide provides a practical framework for deciding when regrinding PCD and CBN inserts makes economic and technical sense, and when replacement is the better choice.
For high-value superhard tools, the regrinding cost is typically 20% to 30% of the price of a new tool, depending on the tool type and complexity. Most PCD and CBN inserts can be reground 3 to 5 times before the superhard layer is consumed. This means the total cost of ownership over the tool's full service life can be dramatically reduced through regrinding.
Example calculation: A PCD insert costs $300 new. Regrinding costs $75 per cycle (25% of new). If the insert can be reground 4 times, the total cost for 5 life cycles is $300 + (4 x $75) = $600, producing 5 cutting edges. The average cost per edge is $120 — a 60% reduction compared to buying 5 new inserts at $1,500 total.
The simpler the tool geometry, the more economical regrinding becomes. Standard turning inserts, flat-top milling inserts, and simple profiling tools are excellent candidates for regrinding. Complex form tools with intricate profiles require more sophisticated and expensive regrinding operations, which may narrow the cost advantage.
Regrinding is the preferred option when the following conditions are met:
● Sufficient superhard layer remains: The PCD or CBN layer must have enough thickness remaining after regrinding to provide adequate cutting performance for the next service cycle.
● Tool geometry is regrindable: Simple geometries (standard turning inserts, flat milling inserts, simple grooving tools) are straightforward to regrind. The cost savings are most significant for these tool types.
● Production scheduling allows lead time: Regrinding requires sending tools off-site (or to an in-house regrinding department) and waiting for return. If production requires immediate tool replacement, new tools may be necessary regardless of cost considerations.
● Consistent quality requirements: If the application does not demand the absolute maximum precision that only a fresh, factory-ground edge can provide, regrind quality is typically sufficient for most industrial applications.
There are situations where buying a new tool is more practical and cost-effective than regrinding:
● Catastrophic damage: Edge chipping, thermal cracking, or sub-surface damage that extends beyond the regrindable allowance. Attempting to regrind a severely damaged tool may not restore usable edge quality.
● Superhard layer nearly consumed: When the PCD or CBN layer has been worn down to near the bond interface, further regrinding would expose the carbide substrate, which cannot perform the same cutting function.
● Complex tool geometries: Form tools with intricate profiles may require regrinding costs that approach or exceed the price of a new tool. In these cases, replacement is often more economical.
● Process-critical precision requirements: Some applications — such as optical mold finishing or semiconductor component machining — may require the geometric accuracy and edge quality that only a factory-new tool can guarantee.
● Inventory and logistics considerations: Maintaining a regrindable tool pool requires tracking, inspection, and coordination. For operations with limited tool management resources, the simplicity of new-tool replacement may outweigh the per-unit cost savings.
| Factor | Favors Regrinding | Favors Replacement |
| Wear type | Gradual flank/crater wear | Chipping, thermal cracking |
| Remaining layer thickness | Adequate for 1+ more cycles | Near minimum or unknown |
| Tool geometry | Simple (standard inserts, flat tools) | Complex (intricate form profiles) |
| Regrind cost vs. new cost | Below 30% of new tool price | Above 50% of new tool price |
| Production urgency | Planned replacement, lead time available | Immediate tool needed |
| Precision requirement | Standard industrial tolerances | Ultra-precision or optical-grade |
| Number of remaining regrinds | 2+ cycles possible | Last usable cycle |
A well-executed regrind should restore the cutting edge to near-original condition. However, there are practical differences between a reground edge and a factory-new edge:
● Edge radius: Regrinding may produce a slightly larger edge radius than the original factory grind, depending on the grinding wheel grit and process control. This can affect surface finish in finishing applications.
● Dimensional consistency: Each regrind cycle may introduce small dimensional variations. For applications with tight tolerances, these variations must be tracked and compensated.
● Coating implications: If the original tool had a surface treatment or coating, regrinding removes it from the re-ground surfaces. The performance impact depends on the specific coating and application.
For most production machining applications, these differences are manageable and do not affect part quality. The key is working with a regrinding service provider who understands superhard tool requirements and maintains consistent process control.
We supply a full range of PCD and CBN cutting tools for turning, milling, drilling, and grooving applications. For customers seeking to maximize tooling value, we also offer regrinding services for our PCD and CBN products, restoring worn tools to precise geometric specifications at a fraction of the new-tool cost.
Our technical team can help you evaluate whether regrinding or replacement is the better option for each tool in your inventory, based on wear condition, remaining layer thickness, and application requirements. Contact us to discuss your tooling management needs.
For the majority of standard PCD and CBN inserts in normal wear conditions, regrinding delivers substantial cost savings — typically reducing the cost per cutting edge by 50% to 75% over the tool's service life. The decision to regrind or replace should be based on a practical assessment of wear condition, tool geometry, remaining superhard layer thickness, and application precision requirements.
Regrinding is not a universal solution — it requires appropriate wear patterns, sufficient remaining material, and reasonable regrinding costs relative to new-tool price. But when these conditions are met, a structured regrinding program is one of the most effective ways to reduce superhard tooling costs without sacrificing machining quality or productivity.
Yes, for most standard PCD and CBN inserts, regrinding is worth it. Regrinding typically costs 20-30% of a new tool, and most tools can be reground 3-5 times. This can reduce total tooling cost by 50-75% over the tool's service life. The simpler the tool geometry, the more economical regrinding becomes.
Most PCD and CBN inserts can be reground 3 to 5 times, depending on the original PCD layer thickness, the insert geometry, and the amount of material removed per regrind. Each regrind cycle consumes a portion of the superhard layer, so the number of possible regrinds is finite.
Replace rather than regrind when the tool has edge chipping or catastrophic damage beyond the regrindable allowance, when the superhard layer is nearly consumed, when the tool geometry is so complex that regrinding cost approaches the new-tool price, or when the application demands the absolute maximum precision that only a fresh tool can guarantee.
A properly executed regrind restores cutting performance to near-original levels. There may be minor differences in edge radius and dimensional consistency compared to a factory-new tool, but for most production applications these differences do not affect part quality. Working with an experienced regrinding service provider is key to maintaining consistent quality across regrind cycles.
Regrinding removes any surface coating or treatment from the re-ground surfaces. If the original tool had a coating designed to reduce friction or improve wear resistance, those benefits are lost on the re-ground edge. For most PCD and CBN tools, however, the superhard material itself provides the primary cutting performance, so the impact of coating loss is generally minimal.
