Sandvik Intellectual Property AB v Kennametal UK Ltd & Anor

An invention is insufficient where the skilled person cannot perform it across the claimed scope without undue burden or inventive skill. Ordinary trial and error is permissible, but the specification and common general knowledge must provide reliable guidance towards success; a research programme is not enough.

A measurement claim is also insufficient where undisclosed choices produce materially different results and leave the skilled reader in a real quandary. A claim may be obvious as an arbitrary selection lacking plausible technical significance, regardless of technical field. A process claim remains non-obvious where its required sequence is not shown to produce the claimed product and obviousness depends on hindsight.

Sandvik claimed that Kennametal infringed a European patent concerning fine-grained, textured α-alumina coatings. Kennametal denied infringement and counterclaimed for revocation for lack of novelty, obviousness and insufficiency. Sandvik also sought conditional amendment of claim 1.

The court considered construction of the claims, whether the specification enabled the invention and its full claimed breadth, whether the claimed texture was an arbitrary selection, and whether the tested products infringed. The central issues included the choice of X-ray diffraction reference data and corrections, and whether the process instructions enabled production of the required texture.

The patent was invalid for insufficiency. Claims 1–6 were also invalid for obviousness, although claim 7 was not obvious. If the patent had been valid, infringement was established only for inserts made by process combinations 2 and 4.

1. Construction. Claims were construed purposively in context, applying the principles summarised in Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd [2009] EWCA Civ 1062, [2010] RPC 8. The claim required single-phase α-alumina. The absence of instructions identifying the relevant PDF card, or requiring Kα2 stripping, left the measurement feature genuinely ambiguous. A thin-film correction was not required because it was not common general knowledge.
2. Insufficiency. Under section 72(1)(c) of the Patents Act 1977, the skilled person had to perform the invention without undue burden or inventive skill. Ordinary trial and error was permissible, but the specification had to guide the skilled person towards success. Example 1 did not do so, and claim 6 covered a broad range of substrates, process conditions and products without teaching how to obtain the required texture. The specification therefore invited a research programme. The measurement ambiguity independently rendered the patent insufficient.
3. Novelty and obviousness. Applying Synthon BV v SmithKline Beecham plc [2005] UKHL 59, [2006] RPC 10, the prior uses were not enabling and did not destroy novelty. Applying the structured approach in Pozzoli v BDMO SA [2007] EWCA Civ 588, [2007] FSR 37, claim 6 was an arbitrary selection lacking plausible technical significance. Claim 7, however, was not shown to be obvious: its gas sequence could not be ignored merely because individual process features were known.
4. Infringement. Kennametal bore the burden of establishing its positive case that amorphous alumina was present, and failed to do so. Sandvik nevertheless failed to prove infringement for the eleven untested process combinations, since differences in coating layers and thickness could affect texture.