What Is a PCD Insert?

A PCD insert looks like a standard indexable insert from a distance, but the cutting edge itself is different: instead of solid carbide, a small tip of polycrystalline diamond (PCD) is brazed onto the insert body at the cutting edge. That tip is what gives PCD inserts their defining characteristic — very long tool life on the right material.

Why PCD, and why only for non-ferrous materials

Diamond is extremely hard and wear-resistant, but it reacts chemically with iron at the temperatures generated in machining, which causes rapid tool wear on ferrous materials like steel and cast iron. PCD is therefore used almost exclusively on non-ferrous, abrasive materials — aluminium (especially high-silicon casting alloys), other non-ferrous metals, and some composites — where that chemical reaction isn't a problem and diamond's wear resistance becomes a major advantage.

PCD vs carbide for aluminium machining

Standard carbide inserts, even ground and polished ones intended for aluminium, will wear measurably faster than a PCD insert on abrasive, high-silicon aluminium alloys — the kind commonly used in die-cast automotive and EV components. For lower-volume or less abrasive aluminium work, a precision-ground positive carbide insert is often sufficient and considerably cheaper per insert. For high-volume production runs on abrasive aluminium, the longer tool life of a PCD insert can offset its higher upfront cost through fewer changeovers and more consistent surface finish over a longer run.

Choosing between the two

As a general rule: consider PCD when you're running high volumes of abrasive aluminium (particularly high-silicon die-cast alloys) and tool-change downtime or finish consistency is a real cost factor. Consider a precision-ground carbide insert for lower-volume aluminium work or where the alloy is less abrasive. Tell us your aluminium alloy, expected volume and current insert (if any), and we'll help you weigh the two options.