POLMAX CALDIE NIMAX   UNIMAX



 

  


General

Unimax is a chromium - molybdenum - vanadium alloyed tool steel.Unimax is suitable for long run production moulds, moulds for reinforced plastics and compression moulding.

Characteristics found in UNIMAX:

Excellent toughness and ductility in all directions.

Good wear resistance

Good dimensional stability in heat treatment and in    service
Excellent through - hardning properties

Good resistance to tempering back.

Excellent polishability

Good thermal fatigue resistance.

Good hot strength.

Good hot strength.
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Typical Analysis %
C 0,5
Si 0,2
Mn 0,5
Cr 5.0
Mo
2,3
V
0,5
Standard Specification
None
Delivery
Condition
Soft annealed to approx
185HB
Colour Code
Brown/Grey

   

Applications

Unimax is suitable for long run products moulds,moulds for reinforced plastics and    compression moulding.

Unimax is a problem solver in severe cold work tooling applications such as heavy    duty blanking, cold forging and thread rolling , where high chipping resistance is    required.

Engineering and hot work applications requiring high hardness and toughness are     also an option.


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Properties

The properties below are representative of samples which have been taken from the centre of bars with dimensions 396 x 136 mm.(15.6" x 5.35" ),Ø 125mm( 4.93") and Ø 220mm(8.67").Unless otherwise indicatedall apecimens have been hardened at 1025ºC (1875ºF), gas quenchedin a vacuum furnace and tmpered twice at 525ºC(975ºF) for two hours;yielding a working hardness of 56 -58 HRC

PHYSICAL PROPERTIES.
Hardened and tempered to 56-58 HRC.

Temparature
20º C
(68º F)
200º C
(390º F)
400º C
(750º F)
Density, Kg/m³
Ibs/in³
7 790
0,281
Coefficient of thermal expansion
Per º C from 20º
Per º F from 68ºF

-

-

11,5 x 10-6
6,3 x 10-6

12,3 x 10-6
6,8 x 10-6
Thermal conductivity
W/m º C
Btu in/( ft2h º F)



25
174

28
195
Modulus of elasticity
MPa
Psi

213 000
31.2 x 106

192 000
27,8 x 106

180 000
26,1 x 106
Specific heat
J/kg º C
Btu/Ib º F

460
0,11
-
-

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Mechanical Properties

Approximately strength and ductility at room temperature at tensile testing.

Hardness
HRC
53HRC
 56HRC 58HRC
Yield srength , Rp0.2
1720MPa
1720MPa
1780MPa
Tensile strength,Rm
2050MPa
2150Mpa
2510Mpa
Elongation, A5
9%
8%
8%
Reduction of area ,Z
40%
32%
28%

Approximate strength at elevated temperatures Longitudinal direction.
The speciman were hardened from 1025ºc(1875ºF) and tempered twice at 525ºC(975ºF) to 58 HRC.

Effect of time at high temperatures on hardness intial hardness 57 HRC.

Effect of testing temperature on impact energy.
Charpy-V specimens, longitudinal and short transverse direction.Approximate values for specimens fromØ25mm(4.9")bar.

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Heat treatment

SOFT ANNEALING

Protect the steel and heat through to 850ºC (1560ºF).  Then cool in the furnace at 10ºC (20ºF) per hour to 600ºC (1110ºF), then freely in air.

STRESS-RELIEVING

After rough machining the tool should be heated through to 650ºC (1200ºF), holding time 2 hours.  Cool slowly to 500ºC (930ºF), then freely in air.

HARDENING

Preheating temperature    : 600-650ºC (1100-1200ºF) and 850-900ºC(1560-1650ºCF).
Austenitizing temperature : 1000-1025ºC (1830-1875ºF)
Holding time                    : 30 Min

Temperature
Soaking time
minutes
Hardness before
tempering
ºC ºF    
1000
1830
 30 61HRC
1025
1875
 30 63HRC

Soaking time = time at hardening temperature after the tool is fully heated throug.


Protect the part against decarburization and oxidation during Austenitizing.


Quenching Media

 High speed gas / circulating atmosphere.
 Vacuum furnace (high speed gas with sufficient overpressure).
Martempering bath ,salt bath or fluidized bed at 500-550ºC(930-1020ºF)
 Martempering bath at 200 -350ºC (390-660ºF)

Note: Temper the tool as soon as its temperature reaches 50-70ºC(120-160ºF).

Cooling Curve No
 Hardness HV 10

T800-500
(Sec)
1 835 1
2 819 5
3 798 33
4 782 140
5 724 630
6 712 1064
7 525 2900
8 476 6250
9 476 13850
 
 

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 Tempering
Hardness,HRC
Choose the tempering temperature according to the hardness required by reference to the tempering graph below.Temper at least twice with intermittent cooling temperature.the lowest tempering temperature which should be used is 525ºC(980ºF).The minimum holding time at temperature is 2 hours.

Tempering Graph


 
 
Hardness, grain size and retained austenite as a function of austenitizing temperature.



Dimensional Changes During Hardening and Tempering
The dimensional changes have been measured after austenitizing at 1020ºc(1870ºf)/30 minutes followed by gas quenching in N2 at a cooling rate of 1,1ºC/s between 800-50ºC (1470 -930ºF) in a cold chamber vacuum furnace.
Specimen size : 100 x 100 x 100 mm (3.9" x3.9" x 3.9" )
Values for all directions are within the marked areas.

 



SURFACE TREATMENTS

Tool steels may be given a surface treatment in order to reduce friction and increase wear resistance.The most commonly used treatments are nitriding and surface coating with wear resistant layers produced via PVD or CVD.

The high hardness and toughness together with agood dimenional stability makes Caldie suitable as a substrate for various surface coatings.


NITRIDING AND NITROCARBURZING

Nitriding and nitrocarburizing result in a hard surfce layer which is very resistant to wear and galling.
The surface hardness after nitriding is approximately 1000-1200HV0.2kg.The thickness of the layer should be chosen to suit the application in question.

PVD
Physical vapour deposition ,PVD, is a method of applying a wear - resistant coating at temperatures between 200-500ºc(390-930ºF) .

CVD

Chemical vapour deposition , CVD, is used for applying wear- resistant surface coatings at a temperature of around 1000ºc.
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Cutting data recommendations

The cutting data beow are to be considered as guiding values, which must be adapted to existing local conditions.
Conditions: Soft annealed to ~185HB

TURNING

 Cutting Data parameters Turning with Carbide
Turning with high speed steel
Fine tuning tuning
 
Rough Turning Fine turning
 Cutting speed(vc)m/min   f.p.m
150-200
490-655
200-250
655-820
15-20
50-65

 Feed(f) mm/r i.p.r
0.2-0.4
0.008-0.016
0.05-0.2
0.002-0.008
0.05-0.3
0.002-0.012  

 Depth of cut (ap)mm inch

 
2-4
0.08-0.16
0.5-2
0.02-0.08
0.5-2
0.02-0.08
 Carbide designation
ISo
US
P20-P30
C6-C5
Coated Carbide
P10
C7
Coated Carbide or Cement
-
-


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Milling
Face - and square shoulder milling

 
Milling with carbide
Cutting Data Parameters Rough milling Fine milling
Cutting speed(vc)
120-170
394-558
170-210
558-690
Feed(fz)
mm/tooth
inch/toth
0.2-0.4
0.008-0.016
0.1-0.2
0.004-0.008
Depth of cut (ap)
mm
inch
2-4
0.08-0.16
0.5-2
0.02-0.08
Carbide designation
ISO
US
P20-P40
C6-C5
Coated carbide
P10-20
C7-C6
Coated carbide or cement

End milling
 
Type of milling
Cutting data Parameters Solid carbide Carbide indexable inser
High speed steel
Cutting Speed(Vc)
     m/mm
     f.p.m
120-150
390-490
110-150
360-490
20-25¹
66-80¹
Feed (fz)
     mm/tooth
     inch/tooth
0.01-0.20²
0.0003-0.008²
0.06-0.20²
0.02-0.008²
0.01-0.30²
0.0003-0.012²
Carbide designation
     ISo
     US
-
P20-P30
C6-C5
-
¹) For coated HSS end mill Vc =35-40 /min.(115-130 f.p.m).
² ) Depending on radial depth of cut and cutter diameter.

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Drilling
High speed steel twist drill

Drill diameter
Cutting Speed(Vc)
Feed (f)
mm
inch
m/min
f.p.m
mm/r
i.p.r
-5
-3/16
15-20*
49-66*
0.05-0.10
0.002-0.004
5-10
3/16-3/8
15-20*
49-66*
0.10-0.20
0.004-0.008
10-15
3/8-5/8
15-20*
49-66*
0.20-0.30
0.008-0.012
15-20
5/8-3/4
15-20*
49-66*
0.30-0.35
0.012-0.014

For coated HSS drill Vc=35-40 m/min(110-130 f.p.m).

Carbide drill
 
Type of drill
Cutting data parameters Indexable insert solid carbide Brazes Carbide¹
Cutting Speed (Vc)
m/min
f.p.m
160-220590-720
120-150390-490
60-90195-295
Feed (f)
m/r
i.p.r

0.03-0.10²

0.001-0.004²
0.10-0.25²
0.004-0.01²
0.15-0.25²
0.006-0.01²

¹) Drill with internal cooling channels and brazed carbide tip
²) Depending on drill diameter.
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Grinding
A general grinding wheel recommendation is given below.

Wheel Recommendation

Type of grinding
Soft annealed condation
Hardened condition
Face grinding stright wheel
A46HV
A46HV
Face grinding segments
A24GV
A36GV
Cylindrical grinding
A46LV
A60KV
Internal grinding
A46JV
A60IV
Profile grinding
A100LV
A120KV

Electrical Discharge Machining

Following the EDM process, the applicable die surfaces are covered with a resolidified layer(White layer) and a rehardened and untempered layer,both of which are very brittle and hence detrimental to die performance.
If EDM is used the white layer must be completely removed mechanically by grinding or stoning.After finish -machining the tool should be given an additional temper at approx.25ºC(50ºF) below the highest previous tempering temperature.


Welding
Welding of die components can be performed , with acceptable results, as long as the proper precautions are taken during the presentation of the joint, the filler material selection ,the preheating of the die,the controlled cooling of the die and the post weld heat tretment processes.The following guidelines summerize the most importent welding process parameters.

Welding method
TIG
MMA
Preheating temperature
200-250ºC
(390-485ºF)
200-250ºc
(390-485ºF)
Filler material

UTP ADUR600
UTPA73G2

UTP675
UTP73G2
Maximum interpass temperature
350ºC
(660ºF)
350ºC
(660ºF)
Post weld cooling 20-40ºc/h(40-50ºF/h)for the first 2 hours and then freely in air.
Hardness after Welding      54-60HRC               55-58HRC
Post weld treatment
Hardened condition Tempere at 510ºC(950ºF) for 2 hours.
Soft annealed condition Soft - anneal according to the "Heat treatment recommenditions".


Further Information

Please contact your local uddeholm office for further information on the selection, heat treatment, application and availability of Uddeholm tool steels.
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