One assignee leads with 30 of the 191 records in this dataset, noticeably ahead of the fifth-ranked filer at 21. The five most active assignees combined account for 64.4% of all records, and the top ten reach 79.6%. This is a concentrated field: a small group of integrated steelmakers and equipment suppliers controls most of the documented claim space, and the remaining activity is spread thinly across 59 ranked companies in total.

Filings peaked at 10 in 2018 and have since pulled back, falling from 6 in 2021 to 2 in 2024 -- a 67% decline over that three-year window. That said, publication typically lags filing by around 18 months, so figures for 2025 and 2026 are still incomplete and should not be read as confirmation of a continued slowdown. The safest read is that the field cooled through the early 2020s relative to its 2018 peak, with the very latest trend still unresolved.

US8210238B2, assigned to POSCO, covers a continuous casting machine and method that delivers molten mould flux directly into the mould through a heated injection tube, rather than adding solid flux that melts in place. Key elements include a mould cover, a separate flux-melting unit, and an injection tube with its own heater. For anyone designing a flux-delivery system, the claims are most relevant if your design also melts flux externally and delivers it through a covered, heated conduit into the mould cavity; delivery mechanisms that add flux in solid form at the meniscus sit outside this specific claim structure.

Relative to the dominant B22D metal-casting classification, which touches 93.7% of the 191 records, classes like heat treatment (C21D, 3.7%), material analysis and testing (G01N, 2.6%), and metal extraction and refining (C22B, 2.1%) are comparatively thin. Practically, this points to under-claimed territory around post-cast heat treatment coupled to mould conditions, in-mould sensing and diagnostics, and flux-alloy interaction claims -- areas adjacent to the core casting mechanics but not yet heavily occupied.

Highly concentrated at the top and long-tailed below it. The leading assignee holds 30 records, the top five combined hold 64.4% of all 191 records in scope, and the top ten hold 79.6%. Below that, the ranking extends to 59 companies, many with only a handful of filings each, which is typical of a process technology area where the foundational mechanics were established early and later filers patent narrower refinements.