Exera® 4C27A free-cutting medical wire Wire

Datasheet updated

2022-05-10 07:47
(supersedes all previous editions)

Exera® 4C27A is a hardenable stainless chromium steel alloyed with molybdenum. This grade is supplied in wire form.

It is characterized by:

  • Very good machinability
  • High wear resistance
  • Good toughness
  • Good corrosion resistance due to addition of molybdenum

Exera® 4C27A is used for the manufacture of precision components such as watch parts, measuring points, dental tools, precision instruments and drilled surgical needles.

Standards

  • ASTM: 420F Mod
  • DIN: X 22 CrMoNiS 13 1

Product standard

ASTM F899

Applications

Exera® 4C27A is a hardenable grade used for medical and dental tools as dental burrs, dental drills, bone drills, dental taps, reamers, screw drivers and drilled surgical needles.

Chemical composition (nominal) %

C Si Mn P S Cr Ni Mo
0.22 0.6 1.3 ≤0.030 0.2 13 0.8 1.2

Mechanical properties

Forms of supply/ finishes Diameter Tensile strength Proof strength Elongation
Rm1) Rp0.21) 2) 3) A1) 3)
mm MPa MPa %
Wire in coils:
Annealed 0.6-3.0 <800 450 25
Drawn 0.45-4.0 950 770 10
Straightened wire:
Annealed 0.6-10.0 <800 450 25
Drawn
0.6-3.0
>3.0-5.0
>5.0-10.0
950
950
850
770
770
650
10
10
11
Drawn/ground 0.6-3.0
>3.0-5.0
>5.0-10.0
950
950
850
770
770
650
10
10
11
Annealed/ground 0.6-10.0 <800 450 25

1) Nominal values. Other properties on request.
2) Corresponds to 0.2 % proof strength.
3) Rp0.2 and elongation values are given for information only.

Physical properties

Density (annealed) : 7.8 g/cm3, 0.28 lb/in3
Resistivity Cold drawn : 670 µΩm
Heat treated : 740 µΩm

Thermal expansion 1)

Temperature 20-100 20-200 20-300
Cold dawn 10.5 11.0 11.5
Heat treated 11.0 11.5 11.5

1) Mean values in temperature ranges (x10-6)

Exera® 4C27A is a magnetic material.

Heat treatment

Soft-annealing

When required, soft-annealing should be conducted for a period of one hour at a temperature of 650-680°C.

Hardening
Diameter Temperature Soaking time Quenching 1)
mm °C approx. min.
<6 1030-1050 3-6 in oil at 50 °C
>6 1030-1050 6-10 in oil at 50 °C

1) Diameter <2 mm may also be cooled in air or, to prevent oxidation, in a protective gas.

The smaller the dimensions, the shorter the soaking time. To prevent oxidation and decarburization, hardening should be carried out in a protective gas atmosphere using nitrogen, argon or vacuum.

Tempering

Temperature 100-350°C
Temperatures below 350°C are recommended for the retention of favorable corrosion resistance.
Tempering time 30-60 min.

The core of the material should have a tempering time of at least 30 min. To reduce the risk of cracking tempering should be conducted immediately after hardening. The heating rate should not be too high, particularly in the case of intricately shaped components.

Figure 1. Hardness after recommended hardening procedures, valid for all dimensions.
Soaking time 30 minutes.

Figure 2. Hardness after recommended hardening procedures, valid for all dimensions.
Soaking time 30 minutes. Standard Charpy V specimens at 20°C.

Machining

The recommended values, based on Sandvik Coromant cemented carbide cutting tools or high speed steel tools from Sandvik, are to be regarded as starting data. To obtain the optimal combination of finishes, tolerances and productivity the values should be adjusted for each individual operation.

The data assume the use of a suitable cutting fluid.

When machining without a cutting fluid, the values should be reduced by around 10%. Detailed recommendations can be obtained from your nearest Sandvik Coromant or Sandvik office.

Turning

The charts below give guidance of how speed and feed affects tolerances and surface roughness of turned components. The charts are based on longitudinal turning. The tolerances are given by using the ISO-system, i.e. IT7 could mean h7, k7 or js7. Brazed cemented carbide tools with the following data have been used: Sandvik Coromant tool 310 L197-1212-200 grade H10F, rake angle 0°, clearance angle 6° and entering angle 90°.

Figure 3. Wire diameter 1.00 mm, depth of cut between 0.15-0.25 mm. Brazed cemented carbide.

Figure 4. Wire diameter 2.00 mm, depth of cut between 0.30-0.50 mm. Brazed cemented carbide.

CNC lathes and similar

Indexable insert tools. For diameters d < approx. 20 mm lower cutting speeds should be used.

Feed mm/rev. Cutting speed m/min.
GT 4015 CT 525 GC 235
CT 5015 GC 4015 GC 4035
0.05 330 250 -
0.15 220 210 200
0.5 - - 165

Longitudinal turning automatics, plunging automatics and similar machines

Diameter < approx. 10 mm

Operation Cutting depth, Feed, mm/rev.
mm Finish turning (1) Medium Rough turning (2)
Single point turning
Forming
Plunge cutting and parting off
<1
1-3
>3
0.005-0.01
0.02
0.01
0.005
0.01
0.01-0.015
0.03
0.02
0.015
0.02
0.025
0.05
0.03
0.03
0.04

1) For parts requiring high precision.
2) For parts with moderate tolerance requirements and parts that must subsequently be machined finished

Parting off and grooving

Parting off in CNC lathes and similar
Tool Feed mm/rev. Cutting speed m/mm.
GC 235, 4025 0.05-0.15 80-160
HSS 0.02-0.05 30-40

Bar automatics

Diameter > approx. 2 mm

Tool Cutting speed m/min
CC 45-60
H2S 25-35

Single and multiple spindle automatic lathes

Diameter >approx. 10 mm

Operation Feed, mm/rev.
Finish turning Rough turning
Single point 0.05-0.10 0.10-0.25
Forming 0.01-0.03 0.03-0.08
Plunge cutting and parting off 0.02-0.05 0.05-0.10

Threading

Tool Grade Cutting speed m/mm.
Threading dies HSS 1.5-3
Self-opening die heads HSS 2-5
Thread chasers HSS
CC
15-30
90-150
Thread rolling HSS
CC
5-8
8-10
Thread turning GC1020 90-110

Drilling

Drill diameter, mm Feed mm/rev. Speed rpm
0.5 0.005 2500
1 0.01 2200
31) 0.03 1400
51) 0.05 1100
81) 0.07 800
101) 0.09 700

1) Cemented carbide drills of Delta type with the following data can also be used:
Grade GC1020, speed 70-110 m/min.

Face milling

Operation Grade Feed,
mm/tooth
Cutting speed
m/min.
Finish milling with high cutting speed under favorable working conditions 530 or
1025
0.1
0.2
170-210
150-190
Finish and medium-rough milling under normal to difficult working conditions 4030 or
4040
0.1
0.2
150-180
120-150
Medium-rough to rough milling under difficult conditions SM30 or
4040
0.1
0.2
110-130
100-110

Endmilling

Tool type Grade CC Cutting speed m/min.
Indexable insert tools 530 240
Solid carbide end mills 1025 220
Brazed helical fluted end mills 4040
GC1020
P40
160
140
55
Hobbing
Tool Cutting speed m/mm.
CC 25-50
HSS 20-40

Reaming

Cutting speed for diameters > about 2 mm

Reamer Grade Cutting speed m/min.
Straight/helical fluted HSS 10
Gun drill geometry CC
HSS
25
15

Feed

Diameter mm Feed mm/rev. Allowance mm
1-5 0.05-0.10 0.05-0.10
6-10 0.10-0.20 0.10-0.20
11-20 0.15-0.30 0.20-0.30

All data is nominal. Values refer to 20oC unless otherwise stated.

Further information

Material datasheets and in-depth technical information about Sandvik Bioline grades and products are available on the Sandvik website, www.sandvik.com/medical.

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.