Question:
We are looking into replacing the quench oil in our integral-quench furnaces and were hoping you could provide us with some thoughts on what we need to look at?  

Answer:
Here are some factors to consider that I’ve found useful when selecting quench oil.

1. Oil type (quench characteristics, cooling-curve data)

2. Oil speed: fast (9-11 seconds), medium (12-14 seconds), slow (15-18 seconds) or marquench (>20 seconds)

3. Oil temperature

4. (Effective) quench-tank volume

5. Height of oil over load

6. Agitation – agitators or pumps

7. Quench-tank design factors
a. Number of agitators or pumps
b. Location of agitators
c. Size of agitators
d. Propeller size (diameter, clearance in draft tube)
e. Internal tank baffling (draft tubes, directional flow vanes, etc.)
f. Flow direction
g. Quench elevator design (flow restrictions)
h. Volume of oil
i. Type of agitators – fixed, two-speed, variable speed
j. Maximum (design) temperature rise
k. Heat exchanger – type, size, heat removal rate (BTU/hr & instantaneous BTU/minute)

8. Part geometry (thin, thick, combination on some parts)

9. Flow velocity through load

10. Prior (manufacturing) operations/stress state

11. Post-heat-treat operations (if any)

12. Part mass

13. Grids, baskets and fixture – material & design

14. Part spacing

15. Material – chemistry & hardenability