Reamers: Substrate Grades and Coating Selection

August 14, 2026 · Exactalloy Technical Team

Coating and substrate decide how a carbide reamer fails: abrasive wear, chipping, built-up edge or thermal cracking.

Quick answer: For carbide reamers use TiAlN, TiN, uncoated (polished). Higher aluminium content in the coating raises oxidation temperature — the right choice for dry or high-speed cutting of steel.

PVD or CVD?

PVD coatings are thinner (2–5 µm) and keep a sharp edge — best for small diameters and finishing. CVD coatings are thicker (8–20 µm) and suit heavy turning and interrupted cuts.

Coating comparison

TiAlN, TiN, uncoated (polished). Each trades sharpness, oxidation resistance and cost differently.

Substrate grain size

Ultra-fine grain substrates raise transverse rupture strength, letting you run harder grades without chipping.

When to run uncoated

Uncoated polished tools win on aluminium, copper and plastics where coating adhesion causes built-up edge.

Specifications at a glance

Coating	Max working temp	Best for
TiAlN	800 °C	General steel, dry machining
AlTiN	900 °C	Hardened steel, high speed
AlCrN	1100 °C	Inconel, titanium, stainless
DLC	400 °C	Aluminium, graphite, composites
TiN	600 °C	General purpose, low cost

Frequently asked questions

Does a thicker coating last longer?

Not always — thickness helps abrasive wear but blunts the edge and can spall on small tools.

Can I recoat a reground tool?

Yes, carbide reamers tools are commonly recoated after regrinding at a fraction of new-tool cost.

Get a quote and technical support

Exactalloy supplies carbide reamers from stock, made-to-order and reground. Send your drawing or specification for a quotation and lead time within 24 hours. Contact us or browse all products.