Walter Grade Chart & ISO Equivalents

Walter splits its grades by coating edition, not just ISO class. Gold and Silver are not a hierarchy — they are two answers to different thermal problems. Here is when each one is the right buy.

How a Walter grade code is built

Walter's turning grades carry a WPP prefix — Walter PVD P-class. The structure is short and the suffix letter carries real information:

• The number is the ISO class position: WPP10, WPP20, WPP30.
• The suffix letter names the coating edition. G is the Tiger·tec Gold line; S is Tiger·tec Silver, which uses an AlCrN-based layer. So WPP10G and WPP10S are the same ISO class with different coating technology.
• WCB prefix is CBN for hardened steel.

The Gold/Silver distinction is the part worth understanding, because it is not a hierarchy — it is a different balance for different operating conditions.

Common Walter grades and their ISO classes

Walter grade sets and coating editions change between catalogue generations. The WPP family and its ISO positioning above follow published Walter turning grade listings; confirm the current edition of a specific code before specifying it on a drawing.

AlCrN vs AlTiN: when the Silver edition is the right buy

Most PVD inserts in this class use an AlTiN or TiAlN layer. Walter's Silver edition uses aluminium-chromium nitride, layered at nano scale. The practical difference in three points:

• Thermal stability. AlCrN holds its hardness to a higher temperature before it starts to break down. That matters where the cutting edge genuinely runs hot — high speed, long time in cut, dry or minimum-coolant operation, or a material with poor thermal conductivity.
• Wear progression. The claim to value here is a smoother, more gradual flank wear curve rather than a long flat period followed by sudden failure. In production that means fewer surprises and a change interval you can actually schedule.
• Friction and built-up edge. Lower friction on the rake face reduces the tendency to weld workpiece material to the edge, which is one of the ways a finishing operation drifts out of tolerance.

When AlTiN is still the better choice: a stable, continuous, well-cooled cut at moderate speed in plain carbon steel. You will not use the extra thermal headroom, so you are paying for a property the operation never reaches. Which edition is right depends on the job, and we would rather quote both than guess.

Where coating editions and ISO class interact

A useful rule when reading any PVD grade chart: the ISO class tells you the substrate, and the coating edition tells you the thermal envelope. Two grades can share a class and differ by a coating that extends the speed window. If a quote matches your ISO class but drops the coating edition, the substrate is right and the speed limit is not.