Vacuum Sintering & Ageing Furnace

Selection criteria

Temperature uniformity, vacuum level, cooling rate.

Supply chain

Vacuum sintering and ageing furnaces for magnets come from Japanese makers and from Shenyang-area Chinese manufacturers. Temperature uniformity and cooling control drive batch-to-batch consistency of Br and Hcj.

Buyer FAQ

What does a typical sintering and ageing cycle look like?

NdFeB is typically sintered at about 1030–1100 °C under vacuum, then gas-quenched with argon. Two-stage ageing follows, commonly near 900 °C and then about 480–600 °C, to develop coercivity. A full cycle often runs 20 h or more, so furnace count and load size set plant capacity.

What temperature uniformity and vacuum should I require?

Look for temperature uniformity of about ±3–5 °C across the working zone, proven by a multi-thermocouple survey on a loaded furnace, plus a specified leak rate and ultimate vacuum. Non-uniformity shows up as Br and Hcj differences between load positions. Ask suppliers for recent uniformity surveys and per-position test results.

How should I verify magnet lots from a sintering batch?

Require hysteresisgraph tests to IEC 60404-5 for Br, Hcj, HcB and (BH)max on samples from several furnace positions, plus density (about 7.5 g/cm³ for sintered NdFeB). Check demagnetisation-curve squareness, with Hk/Hcj of about 0.9 or higher as a common target. Large spread between positions points to furnace or loading problems.

Where it is used