Selecting an induction quenching and tempering line for steel bars with a wide diameter range – from 14mm to 80mm – is not a one-size-fits-all decision. Using the same power and frequency for small and large bars leads to overheating on small diameters or core under-heating on large diameters.

Engineering explanation

The heating depth (electrical penetration depth) is inversely proportional to the square root of frequency. For small-diameter bars (14-28mm), higher frequencies (6000-8000Hz) concentrate heat near the surface, enabling rapid austenitization. For larger bars (65-80mm), lower frequencies (1000-1500Hz) provide deeper heat penetration to ensure core heating. Power also scales with cross-sectional area: a φ80mm bar requires approximately three times the power of a φ28mm bar to achieve the same throughput.

Real order case (based on Yuantuo engineering standard)

– Workpiece: Steel bars φ14-80mm, length 6000mm
– Configuration: Three independent lines – φ14-28mm: IGBT 350kW quench + 200kW temper; φ30-60mm: KGPS 700kW quench + 450kW temper; φ65-80mm: KGPS 1000kW quench + 600kW temper
– Customer pain point: Single-line solution caused surface melting on φ14 bars and core under-heating on φ65 bars
– Solution: Yuantuo proposed segmented lines with dedicated frequency and power per diameter range
– Result: Each diameter group achieves target hardness (±2 HRC) at 1-3 tons/hour respectively

Complete system solution

Yuantuo’s steel bar Q&T line includes: IGBT or KGPS power supplies, induction heating coils (quench + temper), inclined U-shaped roller conveyor (self-rotating), infrared pyrometers (Raytek), Siemens PLC with closed-loop temperature control, quenching spray system with water pressure/temperature monitoring, oxide scale filter, closed cooling tower, and automatic material handling.

Call to action

Provide your steel bar diameter range, length, target hardness, and hourly output. Yuantuo engineers will recommend the optimal diameter segmentation and power configuration within 24 hours.

Website：yuantuoinduction.com
WhatsApp：+86-15226757228
Email：yuantuo38@gmail.com