Milling Possibilities of Material Inconel 718

Manuf. and Ind. Eng., 11(4), 2012, ISSN 1338-6549
© Faculty of Manuf. Tech. TUKE
Milling Possibilities of Material Inconel 718
Miroslav Janos, Ivan Mrkvica
Abstract
In this document I am describing milling possibilities of nickel alloy Inconel 718. In the beginning is described use of
nickel alloys in industry and division of nickel alloys. Further is described nickel alloy what I used – Inconel 718, on this
material I make all my tests of machinability. Further chapters describe recommended cutting materials for nickel alloys
milling. Cutters with exchangeable sintered carbide blade plates were used as cutting tools company Pramet Tools s.r.o.
Main goal was investigate durability and wear of indexable cutting inserts for different cutting procedures. It was mainly
about different combinations of used cutting speeds and feeds. The final part includes a summary of the results. The results
are ones from first steps to definition of effective nickel alloy machining.
Keywords: Machinability, milling, Inconel 718
1 Introduction
Reliability and long lifetime are most important properties of new machinery parts in the present. By this are growing requirements for construction and technology of manufacturing of these parts. These requirements could be
fixed by different ways, e.g. by changing of dimensions,
shape, improvement of surface layer and finally what is important by use of superior materials.
In the present as well as in the future will grow a demand for parts made from so called super-alloys. To superalloy materials belong Inconel, Hastelloy, Waspaloy,
Nimonic or Titan. Benefits of these materials are mainly
used for manufacturing of turbine engine, engines in energy
sector, air-industry, cosmonautics, mining and for medical
equipments. In 90’s were these super-alloys used in less
than 1%, in last few year this use grew up to present 2-3%.
Unique and wanted properties of super-alloys make their
machinability more complicated, especially because of extremely high temperature created on the edge of a tooling.
This leads to deformations within machinability and faster
wear of a tooling this is assigned with process economics
[1].
2 Inconel 718 – Milled material
It is high-strength, corrosion-resistive, precipitation hardened alloy, being used in the temperature range from 252°C to +700°C. Thanks to its wide temperature range
usability is Inconel 718 used for a lot of applications (acc. to
Introduction). Chemical composition is in Table No.1 Mechanical properties: Rm = 1240 MPa, HRC=36 [3].
machining of Inconel 718 is recommended use of very
positive millers. I used miller made by Pramet Tools s.r.o.,
marked as 100A10R-S45SE09F-C (fig. No.1). Miller parameters are: external diameter 100mm, number of milling
tooth 10, adjusted angle κr = 45°, angle of front part in back
plane γp = 20°, angle of front part in side plane γf = -5°.
Fig.1 Sintered-carbide-tipped cutter
100A10R-S45SE09F-C
For experiment were used indexable cutting inserts made by Pramet Tools, s.r.o. from sintered carbide 8240 marked SEMT 09T3AFSN (fig. No.2). Manufacturer recommends material 8240 for machining of nickel alloys. Manufacturer recommends cutting conditions: cutting speed vc =
35-75m.min-1, feed per teeth fz = 0,12-0,21 mm.teeth-1, cutting depth ap = 0,5-2,7mm.
Tab. 1 Inconel 718 Chemical composition
3 Experiment
Target of this experiment if find the most optimal cutting conditions for planar milling of Inconel 718, experiment was made on stock of size 70 x 115 x 320mm. Stock
was clamped to milling machine type FNG 32 CNC. For
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Fig.2 Indexable cutting inserts (ICI) SEMT 09T3AFSN
In Table No. 2 are used cutting parameters. The experiment was made by combination of feeds and cutting speeds.
All tests were made with use of process liquids – cooling.
Tab. 2 Used cutting conditions
4 Results
Fig.7 Flank area of cutting inserts
4.1.2 Wear of cutting inserts in operation no.3 (vc =
45m.min-1; fot = 0,12mm)
Fig.8 Face area of cutting inserts
Fig.4 Comparsion of machined material when different
cutting conditions used
Fig.5 Inconel 718 chips
4.1 Pictures wear of cutting inserts
4.1.1 Wear of cutting inserts in operation no.1 (vc =
35m.min-1; fot = 0,12mm)
Fig.6 Face area of cutting inserts
Fig.9 Flank area of cutting inserts
4.1.3 Wear of cutting inserts in operation no.6 (vc =
55m.min-1; fot = 0,16mm)
Fig.10 Face area of cutting inserts
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ns about 0.8 - 2 μm. Summarizing all results I can state that
if there are used correct cutting parameters, cutting material and geometry of a tool then also machining of alloys
as Inconel 718 is economical and effective.
Acknowledgments
Article has been done in connection with project Increasing of Professional Skills by Practical Acquirements and
Knowledge, reg. no. CZ.1.07/2.4.00/17.0082 supported by
Education for Competitiveness Operational Programme
financed by Structural Founds of Europe Union and from
the means of state budget of the Czech Republic.
Fig.11 Flank area of cutting inserts
Janos Miroslav, M.Sc.,
Assoc. Prof. Mrkvica Ivan, M.Sc., PhD.,
VSB - Technical University of Ostrava,
Department of Machining and Assembly,
Street 17. Listopadu 15/2172, 708 33 Ostrava,
Czech Republic,
E-mail: [email protected],
[email protected]
5 Experiment summary
Identification of the most optimal cutting conditions for
used Indexable cutting inserts was done by measuring of
milling time until critical wear was reached when inserts
were already unable to keep machining. Experiment was
made on one type of Indexable cutting inserts which were
cutting under three different cutting speeds and two feeds.
Cutting depth was during experiment constant ap = 1mm.
According to figure No. 3 was defined a machining time to
reach of critical inserts wear.
Figure No. 3 shows that indexable cutting inserts SEMT
09T3 AFSN machined longest time when cutting speed vc =
35 m.min-1 and feed fot = 0,12mm – 1113s. These parameters were chosen as the most optimal for this type of indexable cutting inserts. The worst cutting parameters were
reached in combination of cutting speed vc = 55m.min-1 and
feed fot = 0,16mm – 178s.
6 Conclusions
This article shows milling possibilities for nickel alloy
Inconel 718 by indexable cutting inserts made by Pramet
Tools, s.r.o. from sintered carbide. For inserts SEMT
09T3AFSN were found (from the point of durability) the
most optimal cutting parameters vc = 35m.min-1 and feed fot
= 0,12mm, when inserts were able to keep machining for
approx. 18,5 minutes and remove Q = 147.2 cm3 of material. From the point of reached surface roughness were these
parameters found as the most optimal. Average arithmetic
deviation of surface roughness Ra was under these condicio-
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