PRODUCT DATA
■ Guaranteed Range of Shaft–diameter Precision
■ Guaranteed Range of Nitriding and Surface Hardness Straight Ejector Pins
Surface hardness
Head thickness (T)
● Details of part A
M Material
x 3 max.
As shown in the figure on the left, smooth step R processing is performed on the junction section between the shaft diameter (P) area and the relief area. ※ Size of step R: approximately 100R (reference value)
①
② (Guaranteed range of nitrided surface hardness)
※ Cross–sectional view
(Range of guaranteed shaft diameter precision)
x 1
b 1
x 1
b 1
b 3 (Guaranteed range of nitrided surface hardness)
x 3
T4 (4mm)
※ Step R
40
SKD61 + Nitrid- ing
Base material hardness
–
900HV–
JIS (4/6/8mm)
A
40
900HV–
L
①
②
(without nitrided layer) (with nitrided layer)
b 1 ≧ L− x 1 max.
T10 (10mm)
L
40
b 3 ≧ L −x 3 max. ● Nitriding
x 1 max.
T Shaft Diameter (P) Tolerance
Nitriding is one of the steel surface treatment methods.
p 1 Precision
Shaft diameter 0.01mm increments
Head thickness (T)
Shaft diameter fixed side
M Material
The steel is placed in a furnace that is then filled with nitrogen gas, and at high temperatures (around 500 ℃ ) a hardened layer combined with the nitrogen is formed on the surface of the steel.
(Nitrided)
L150.00 or less
L150.01 –200.00
L200.01 –250.00
L250.01 –300.00
L300.01 or more
T4 (Extra Precision P < 0.8) EPV–L EPV–G EPVB T4 (Extra Precision P ≧ 0.8) EPV–L EPV–G EPVB
10
10
● Nitrided
This refers to the depth of the hardened layer formed on the surface of the steel by nitriding treatment.
0 –0.002
Depth
The nitrided depth of MISUMI's Hardness of 900HV– plastic mold ejector pin is 0.003–0.008mm (reference value) and the depth at which the hardness of steel increases due to the combination with nitrogen is 0.1mm from (reference value) than the surface. The nitrided depth of straight ejector pin is controlled by adjusting nitriding temperature and treatment time in accordance with shaft diameter size. In the case of stepped ejector pins, nitrided depth is controlled by adjusting nitriding temperature and treatment time in accordance with tip diameter (P) size. For this reason, the surface hardness of the retention diameter (D) of stepped ejector pins becomes slightly lower at around 500HV (reference value).
30
30
–
–
–
–
p 1 ＝ P
0 –0.1
T4 (Small diameter) EPY–L EPY–G EPYB
SKH51
10
10
0 –0.005
30 35 30 35
30 35 30 35
30 35 30 35
T4 (4mm)
60
100
150
■ Hardness of ejector pins
JIS (6/8mm)
T4 (4mm)
p 1 ＝ P
Normally, it is quite easy to file down an ejector pin using a regular file (metalworking file). The nitriding treatment applied to the surface of SKD61 + Nitriding makes it difficult to file down because the file does not bite as easily into the surface. The nitrided layer is several microns thick, so a little pressure should be applied to the file. ※ Most regular metalworking files have a hardness of 68–70HRC. How to measure the hardness of the ejector pin: 1) If you want to check the hardness quickly and easily, use a simple hardness check file. 2) When you want to measure hardness accurately, we recommend using a Vickers hardness tester or micro–Vickers hardness tester. Since Vickers hardness testers can change the test load during hardness measurement, they are useful for measuring objects that are small, thin, or have curved surfaces. It is suitable for hardness testing of thin cylindrical parts such as ejector pins.
–0.01 –0.1
–0.01 –0.02
60
100
150
JIS (6/8mm)
Metalworking le
T4 (4mm)
Ejector Pin
See attached table 1
40
40
40
40
40
40
JIS (6/8mm) T10 (10mm) T ＊＊ (4/5/6/8/10/12mm)
SKD61 + Nitriding
p 1 ＝ P p 1 ＝ P p 1 ＝ P
–0.01 –0.1
–0.02 –0.04
40
40
40
40
40
40
Load
0 –0.1
0 –0.005
SKD61
40
40
40
40
40
40
T4 (4mm)
–0.01 –0.1
–0.01 –0.02
Hardness tester
SKD61 Pre–hardened
See attached table 1
35 30 35
35 30 35
35 30 35
35
35
35
JIS (4/6/8mm)
Ejector Pin
T4 (4mm)
V block
p 1 ＝ P
0 –0.1
0 –0.005
–
–
–
SUS440C
JIS (6/8mm)
E Check each product page as well.
■ Attached Table 1 L P
■ Guaranteed Range of Base Material Hardness
One point advice Rockwell hardness tester (C scale) is generally not suitable for measuring the hardness of thin cylindrical parts such as ejector pins.
L ≦ 500 L ＞ 500 p 1 Precision
x 2
b 2 (Guaranteed Range of Base Material Hardness)
The Rockwell hardness tester (C scale) applies a large load (150 kgf) to the object to be measured with a diamond conical indenter when measuring hardness. If the object to be measured is not flat (curved surface), the conical indenter will slip and measurement error will occur, causing the meter to display a lower hardness than the actual hardness. The measurement error of this curved surface shape requires correction of the values according to the manual supplied with the hardness tester. (The thinner it is, the larger the measurement error.) In order to keep the measurement error of the Rockwell hardness tester (C scale) low, it is necessary to cut the object, make a flat part, and measure that part. Not suitable for measurement of thin plates. (Generally speaking, a thickness of at least 1.2mm is required for hardness measurement.) General guideline (reference value) for measuring cylindrical objects (curved surface) with a Rockwell hardness tester (C scale): –Approximately φ 6mm............Not suitable for measurement because of large error and difficulty in measurement. φ 6.5–9mm..............................needs to be corrected according to the manual provided with but it is said to be unsuitable due to large measurement errors. φ 10–25mm.............................Correction is required according to the supplied manual. Approximately φ 30mm............No need for numerical correction after measurement. ＊ There are models that can be changed from C scale (HRC) to A scale (HRA) or D scale (HRD) of Rockwell hardness testers, but the load applied during measurement is as high as 60 kgf for A scale and 100 kgf for D scale, so they are not suitable for measuring thin objects or objects with curved surfaces as well as C scale. ※ For details, check the manual that comes with the hardness tester.
T ＋ 2
–0.01 –0.02 –0.01 –0.03 –0.01 –0.04
–0.01 –0.03 –0.01 –0.03 –0.01 –0.05
1–13
p 1 = P
–0.01 –0.1
13.01–20
Head annealing
b 2 ≧ L− x 2 max.
① ②
③
L
p 1 = P
–0.01 –0.15
20.01–25
Base material hardness
Head thickness (T) x 2 max.
M Material
①
②
③ (Guaranteed range of base material hardness)
T4 ( EPY–L EPV–L EPVB EPY–G EPV–G EPYB EVSL EVSG EVSF EHYF ERVYF )
58–60HRC Overall quenching (no annealing)
58–60HRC Overall quenching (no annealing)
0
58–60HRC
※ SKH51
■ MISUMI Ejector Pin Tempered Hardness and General Tempered Hardness M Material SKH51 (JIS high–speed steel)
T4 (4mm)
30 35
M Material SKD61 (JIS die steel) pre–hardened, and nitrided
28–35HRC (reference value)
28–60HRC (reference value)
58–60HRC
JIS (4/6/8mm)
70HRC
70HRC
About 68–70HRC
T4 (4mm)
Metalworking le (Reference value)
Metalworking le (Reference value)
28–45HRC (reference value) (Excluding nitrided surface) 28–43HRC (reference value) (Excluding nitrided surface) 28–45HRC (reference value) (Excluding nitrided surface) 28–45HRC (reference value)
28–45HRC (reference value) (Excluding nitrided surface) 28–43HRC (reference value) (Excluding nitrided surface) 28–45HRC (reference value) (Excluding nitrided surface) 28–55HRC (reference value)
40–45HRC (Excluding nitrided surface) 40–43HRC (Excluding nitrided surface) 40–45HRC (Excluding nitrided surface)
About 68–70HRC
65HRC
68HRC
JIS (4/6/8mm) T10 (10mm) T ＊＊ (4/5/6/8/10/12mm)
Cutting Tool (Reference value)
SKD61 + Nitriding
SKH51
60HRC
66HRC
40
About 64–67HRC
55HRC
64HRC
Press Die Punch (Reference value)
(General completely quenched) (Ex.) Plate, etc.
About 61–64HRC
SKH51
SKD61
About 48–52HRC
50HRC
62HRC
SKD61
T4 (4mm)
40
50–55HRC
45HRC
60HRC
Ejector pin for plastic mold
Ejector pin for plastic mold
SKD61 Pre–hardened
SKD61
About 40–45HRC
SKH51
About 58–60HRC
JIS (4/6/8mm)
35
28–45HRC (reference value)
28–45HRC (reference value)
40–45HRC
40HRC
58HRC
■ Finishing of tips and edges
T4 (4mm)
30 35
SUS440C
26–35HRC (reference value)
26–60HRC (reference value)
56–60HRC
When ejector pins are processed to determine the total length, fine, processing burring about 0.02–0.05mm (reference values) in length occurs at the edge of the tip. When this burring is removed, a slight sag results. MISUMI does not deburr the tip in order to prevent sagging. The allowable sag R at the tip of the pin depends on a variety of conditions such as precision of individual mold, characteristics of the formed object, various shape and resin type. For this reason, the sag R caused by deburring may be an issue. Use an oilstone, sandpaper, cloth, etc. to remove the burring according the precision control standards on your design drawing of the mold being used.
JIS (4/6mm)
※ The following products are fully hardened. Straight ejector pin EPH P ≦ 0.2
• Annealing is performed on the heads of SKH51 SUS440C SKD61 to achieve a level of 30HRC. Annealing is performed on heads of SKD61 + Nitriding SKD61 Pre–hardened to achieve a level of 40HRC.
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