Application of Vacuum Heat Treatment Technology in High Speed Steel Tools

---

The application of vacuum heat treatment technology in high-speed steel tools is traditionally believed to encounter problems in two aspects: one is the heat treatment of shank tools with different shank and blade materials; the other is the large and complex tool. For this reason, the vacuum heat treatment test of the adapter tap and the vacuum heat treatment test of the hob were carried out.

1. Vacuum Heat Treatment Test of Adapter Tap

The blade part of the adapter tap material is general-purpose M2 material, and the handle part is 45 steel.

(1) Tensile strength test: The tensile strength in each state is shown in Table 1.

From the analysis in Table 1, it can be seen that for the adapter taps, the tensile strength of vacuum quenching and salt bath quenching is equivalent.

Salt bath quenching 20t drawing machine (MPa)	579	611	675	668
Vacuum quenching 20t drawing machine (MPa)	694	872	636	630

Table 1 Vacuum and salt bath quenching tensile strength

(2) Cutting performance test: This test was carried out in accordance with the national cutting test specifications, and its wear failure index judgment basis is shown in the table 2.

Specification	First grade	Premium	Maximum wear of flank surface (mm)
12	2.5	4	0.5

Table 2 Failure Judgment Index

The test blank material is 40Cr, quenched and tempered, the hardness is HB220 ~ HB229, the depth of cut is 2D, and the cutting results are shown in Table 3. It can be seen from Table 3 that the salt bath quenching and vacuum quenching cutting conditions can meet the national-equivalent product requirements, but the vacuum quenching cutting conditions are clear.

Significantly better than the salt bath quenching situation.

2. Vacuum Heat Treatment Test of Hob

Quenching method	Serial number	Cutting amount	Number of machining holes	Processing length (m)	Maximum wear of flank surface (mm)
Salt bath quenching	1 2 3	H=24mm，V=4.7m/min H=24mm，V=4.7m/min H=24mm，V=4.7m/min	97 99 94	2.33 2.38 2.26	0.270 0.258 0.249
Vacuum hardening	1 2 3	H=24mm，V=6m/min H=24mm，V=6m/min H=24mm，V=6m/min	95 100 98	2.28 2.40 2.35	0.208 0.179 0.184

Table 3 Cutting situation of M12x 1.75 adapter tap

Figure 1 Shows the hob after vacuum heat treatment.

Figure 1 Hob after vacuum heat treatment

Our company has conducted a lot of experiments to explore the vacuum heat treatment of hobs. Examples of successful cases are shown in Table 4.

It can be seen from Table 4 that the hobbing life of the vacuum quenching hob has reached the requirements of the first-class product.

Product name	Gear hob (M2)	Machine model	Y3180F Gear Hobbing Machine
Coolant flow	20# engine oil	Test requirements	Vacuum quenching durability test
Material hardness of test blank	40Cr quenched and tempered 200-220HB	Specification accuracy	80 Class A in M3
Test specification	Standard requirement	Actual adoption
Cutting speed (m/min)	V=30~50	V=31.41
Feeding amount (mm/min)	f=2.5mm/r	f-2.5mm/r
Depth of cut or number of feeds	6.75mm/time	6.75mm/time
Cutting length	21m for high-class products, 14m for first-class products
Actual cutting situation	The cutting life is 22.5m, which meets the requirements of superior products

Table 4 Hob cutting experiment situation

Through the adapter tap test and the hob test, it is proved that the vacuum quenching is completely suitable for the heat treatment of the adapter tool and the large complex tool.

Learn more:

Vacuum Heat Treatment Furnace

High Temperature Vacuum Brazing Furnace

Copyright: SIMUWU Vacuum Furnace