|
Machinability
Ratings and Material Selection |
MATERIAL
Dura-Bar Grades |
TOOL
LIFE COMPARISON
at 450 SFM |
RECOMMENDED
SFM |
Best
for Applications Requiring: |
Gray
Iron,
Alloyed Gray Iron |
100% |
1100 |
High
noise damping, moderate strength and wear,
relatively low contact stresses. |
65-45-12
Ferritic Ductile |
260% |
1400 |
Excellent
machinability, predictable growth after
heat-treat, responds well to quench and
tempering and austempering |
| 80-55-06
Partially Pearlitic Ductile |
35% |
900 |
Good
machinability, responds well to induction
hardening, good noise damping. |
| 80-55-06
Modified for Enhanced Machinability |
80% |
1200 |
| 100-70-02
Pearliltic Ductile |
25% |
750 |
Used
when elimination of heat-treat is a
possibility, good strength and wear in the
as-cast condition, good damping. |
| Machinability
Ratings for Steel |
N/A |
| 8620
Steel |
60% |
350-800 |
| 4140
Steel |
65% |
350-800 |
| 1144
Steel |
85% |
600-1000 |
Cost
Comparison
Dura-Bar's cost
advantage over steel is made possible because of
its ability to be machined faster, often 2 to 3
times faster than alloyed steel, which translates
to more piece production per hour. Dramatic
reduction in the cost of the finished part can
occur by taking advantage of the free machining
characteristics of the material. Deburring
costs can also be reduced or eliminated.
Strength
Dura-Bar is
available in gray and ductile iron with tensile
strengths ranging from 35,000 psi to 100,000 psi
in the as-cast condition and strengths up to
230,000 when heat treated. Mechanical
properties are better than those in conventionally
cast parts because of the continuous casting
process and strict metallurgical controls.
The highly
engineered process produces the best graphite
nodularity, with control over nodule size, nodule
count and distribution. This means optimal
strengths in tension, compression and fatigue.
Selecting the right heat-treat method will produce
strengths to 90% of those in 8620 carburized and
hardened steel and up to 80% of those in 4140
through hardened steel.
| Fatigue
Data for Heat-Treated Steel & Gray and
Ductile Iron |
| Material |
Single
Tooth Bending Fatigue Strength (psi) |
Rotating
Beam Fatigue Strength (psi) |
Contact
Fatigue Stress (psi) |
Overall
Relative Strength* |
| G2,
as-cast |
25,000 |
20,000 |
75,000 |
N/A |
G2,
Q & T
Rc 45 |
30,000 |
25,000 |
80,000 |
N/A |
| 65-45-12
ductile iron, as-cast |
35,000 |
40,000 |
60,000 |
N/A |
80-55-06
ductile iron,
as cast |
40,000 |
40,000 |
65,000 |
N/A |
100-70-02
ductile iron,
as cast |
50,000 |
35,000 |
115,000 |
N/A |
| Ductile
Iron, quenched and tempered 50Rc |
60,000 |
45,000 |
225,000 |
90% |
| Grade
1 ADI |
85,000 |
80,000 |
130,000 |
N/A |
| Grade
2 ADI |
80,000 |
75,000 |
140,000 |
N/A |
| Grade
3 ADI |
75,000 |
73,000 |
180,000 |
85% |
| Grade
4 ADI |
72,000 |
70,000 |
220,000 |
80% |
| Grade
5 ADI |
67m,000 |
65,000 |
250,000 |
75% |
NOTE:
*1).
Based on study conducted at the University
of Dayton Research Institute on spur test
gears using a specially designed fixture
to test the strength in a test gear
machined to specific standards.
2). All values listed are
typical and not for specific design
purposes.
3). Shot peening will increase
fatigue strength properties up to 50%. |
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