Cellasto®

A cellular polyurethane elastomer

Cellasto automobile auxi l iary springs

Cellasto seals, dampingcomponents and buffers

Cellasto crane buffers

Cellasto bearings to isolatenoise and vibration

Technical information

T h e c h a r a c t e r i s t i c s

2 Cellasto – a cellular polyurethane elastomer

Quasistatic progressive pressure-compression behaviourCellasto components are based on a cel lular polyurethane elastomer. The moulded components are produced ina closed-mould foaming process. Depending on the amount of the materialused the moulded components have densit ies of 350 to 650 kg/m3. The porevolume accounts for 50 – 63 % of themoulded volume.

The pore diameters l ie in the tenth of amil l imetre range and are mainly closed.

The graphs show experimental data thathave been generated with standardizedtest specimen. When applying this data forproduct development it should be notedthat the material propert ies further dependon instal lat ion condit ions, dimensional factors and others.

During compression loading, f irst the porevolume and then the material i tself is compressed. I t therefore gains r igidity withincreasing compression. The material ischaracterized by progressive pressure-compression behaviour.The maximum compression of Cellastomoulded components depends on theirdensity. The real izable spring excursion increases with decreasing density and canreach up to 80 % of the original length ofthe component.Large spring excursion and low block dimension characterize moulded components made of this material.For Cellasto components a compressivestrain of 4 N/mm2 represents the dynamiccontinuous load l imit. However, the materialis not destroyed by single impacts generating stresses of up to 20 N/mm2.

Low transverse expansion and high volume compressibilityCompact elastomers show large transverseexpansion when compressed. However, thisis not the case with cel lular polyurethaneelastomers. They are characterized by lowtransverse expansion. Cellasto spring elements are therefore suitable for applications where the sourrounding structural space is confined.Cellasto components also act as springs inenclosed structural space.

� Quasistatic progressive pressure-compression behaviour

� Low transverse expansion and high volume compressibi l i ty

0 10 20 30 40 50 60 70 800

1

2

3

4

Compression [%]

Com

pres

sive

str

ess[

N/m

m2 ]

normal climatic conditions

0.650.600.550.500.450.400.35

bulk density g/cm3

rubberCellasto

P

100%

0%

63%

Compression in enclosed space

P

Cellastorubber

Compression between two plates

Com

pres

sive

str

ess

20 60 100

rubber in a cylinder

Cellasto ina cylinder

Compression [%]

20 40 60 80 100

20

40

60

80

100

120

Compression [%]

Incr

ease

in d

iam

eter

[%] (45 Shore A)

rubber

Cellasto350 kg/m3

Material grades: Cellasto and rubber in the initial compression range (rubber 45 Shore A.1.18 g/cm3; Cellasto: 350 kg/m3)

Scale representation of the compression(compressive deformation of Cellasto andrubber between two plates)

T h e c h a r a c t e r i s t i c s

Cellasto – a cellular polyurethane elastomer 3

Characteristic curves as a function oftemperatureThe mechanical propert ies of plastics aretemperature dependent. They are subjectto temperature l imits.

Moulded Cellasto components graduallyharden with decreasing temperature. Theyare suitable for applications down to about-30°C.

Moulded Cellasto components that also have to maintain their elasticity at lowtemperatures can be manufactured fromspecial cryo-flexible Cellasto types. Theyare then suitable for applications down toabout -40°C.

Moulded Cellasto components graduallysoften with increasing temperature. Thecharacterist ic curve for Cellasto onlychanges sl ightly up to a temperature ofapprox. 80°C, so that moulded Cellastocomponents can be used in ambient temperatures of up to 80°C without lossesin elasticity behaviour.

Temperature increase caused by dampingThe material damps a port ion of the mechanical energy input and converts i t toheat. The dissipating heat thereby increases the temperature in the stressedmoulded component. This temperatureshould not exceed 110°C.

For moulded components subject tostresses of constant frequency andconstant spring deflection an equil ibriumtemperature, which has been determinedon the basis of standardized form components, is reached. The resultant family of curves – the f igure on the right isan example – enables, already in the moulded component development phase, a prediction as to whether the crit ical thermal damage temperature would be reached in the foreseen application.

Cellasto components which have hardenedat low temperatures regain their elasticproperties in the course of mechanicalstresses and associated warming up.

� Characterist ic curves as a function of temperature

� Temperature increase caused by damping

Spring deflection [%]

Tem

pera

ture

[°C

]

Freq

uenc

y [Hz]

Krit. � 110 ˚C�

60

40

20

10

1.0

2.0

3.0

0.63

180

160

140

120

100

80

60

40

20

0

60

50

MH 24–50

0 10 20 30 40 50 60 70 800

Compression [%]

bulk density 0,50 g/cm3

-30 °C

-20 °C

0–80 °C

00

1

2

3

4

Com

pres

sive

str

ess

[N/m

m2 ]

T h e c h a r a c t e r i s t i c s

Cellasto – a cellular polyurethane elastomer 4

Static load-related creepWhen dimensioning moulded Cellasto components the increased compressionover t ime at constant load – creep – mustbe considered from the outset. The scaleof creep, in comparison with reversiblecompression, is extremely sl ight and cangeneral ly be neglected in standard applications.

The measurements performed on test specimens – the diagram is but oneexample of many – are carried out over aperiod of years. Moreover, extrapolationbeyond the t ime of the measurements ispossible due to the l inearity of the creepcurves.

Dynamic load-related creepUnder dynamic loading, in addit ion to theinit ial load and load amplitude, the frequency and number of load alternationscrucial ly determine deformation. For otherwise identical loads, compression increases with increasing load frequency.The diagrams above indicate the reasonfor this. Increasing frequency raises thetemperature of the Cellasto specimen; thematerial becomes softer.

The curve in the diagram showing deformation as a function of load alternations f lattens out in the force-control led test. The low increase in deformation accords with the remainingcompression set. Hence the specimen approximately returns to i ts original heightat the end of the test.

� Dynamic load-related creep

� Static load-related creep

0

10

20

30

40

50

60

70

80

100 2 5 101 2 5 102 2 5 103 2 5 104 2

Time [h]

Com

pres

sion

[%]

20

2020

MH 24-60

0

10

20

30

40

50

60

70

80

102 2 5 103 2 5 104 2 5 105 2 5 106 2

Alternating load

Com

pres

sion

[%]

MH 24-6520

207

f=15 Hz

f=3 1/3 Hz

f=3 1/3 Hz

f=15 Hz

Material characteristics

Property Tested in Material designation: Cellasto MH24 Dimensionaccordance with -35 -40 -45 -50 -55 -60 -65

Bulk density DIN 53 240 350 400 450 500 550 600 650 kg/m3

Tensile strength DIN 53 571 3.0 3.5 4.0 4.5 5.5 6.5 7.0 N/mm2

Specimen A

Breaking strength DIN 53 571 350 350 400 400 400 400 400 %Specimen A

Tear growth resistance DIN 53 515 8.0 10.0 12.0 14.0 16.0 18.0 20.0 N/mm

Residual compressivedeformation at 50%/70h/20°C DIN 53 572 3.5 3.5 3.5 3.5 3.5 3.5 3.5 %deformation at 50%/22h/70°C DIN 53 572 5.0 5.0 5.0 5.0 5.0 5.5 5.5 %

T h e c h a r a c t e r i s t i c s

5 Cellasto – a cellular polyurethane elastomer

Amplitude selective dampingFor many applications in the f ield Noise,Vibration and Harshness (NVH) a smalldamping at low amplitudes of high frequencies is necessary for a good isolation. This is the opposite to large movements where the requirement is rapiddamping for dynamic and safe driving purposes. These seemingly contrasting requirements are met equally well with theuse of Cellasto.

The diagram clearly shows the steep rise in “loss angle” (a measurement of dam-ping), with the increasing amplitudes for all material densities.

Dynamic stiffeningCellasto demonstrates a very low stiffeningup to high frequencies. The diagram showsthe dynamic st iffening values at high frequencies in comparison to 1 Hz. Thesevalues are measured at a precompressionof 30 % and an amplitude of 0,1 mm deflection. The stiffening wil l reduce withthe increase of material density.

These qualit ies show Cellasto as the idealmaterial for use against vibration and toimprove noise isolation when used in theconstruction of many load carrying bearings.

� Amplitude selective damping

� Very low dynamic stiffening

10

8

6

4

2

0

Precompression: 30%Frequency: 10 Hz

0 1 2 3 4 5

Amplitude [mm]

Loss

ang

le [°

]

MH 24-35

MH 24-45

MH 24-55

MH 24-65

ø 30 mm

30 mm

1.4

1.35

1.3

1.25

1.2

1.15

1.1

1.05

1.0

MH 24-35MH 24-45MH 24-55

MH 24-65

1 20 40 60 80 100 120 140 160 180 200

Dyn

amic

stif

feni

ng [i

n co

mpa

rison

to 1

Hz]

Frequency [Hz]

ø 30 mm

30 mm

Precompression: 30%Amplitude: 0.1 mm

The semifinished products and components division processes cel lularpolyurethane elastomers to Cellasto semifinished products and mouldedcomponents. This starts with processing the reactive base materials,through the foaming process, to themoulded Cellasto components. Sophist icated process assurance guarantees a high quality standard.

The semifinished products and components division develops themoulded components to customer specif ications. Moreover, the companyhas the backup of wide-ranging experience, up-to-date vibration simulation, CAD technology, tr ied andtested inspection methods and practice-oriented component testingfaci l i t ies.

In product development the companyhas access to the whole research anddevelopment potential of the parentcompany.

BASF Polyurethanes GmbHEuropean Business ManagementMicrocellular Elastomers (Cellasto®)P.O. Box 1140 49440 Lemfoerde Germany Phone +49/54 43/12-23 02Fax +49/54 43/12-21 05E-mail cel lasto-eu@basf.comwww.pu.basf.eu K

U/W

M,

180-

10-1

0/G

B

® reg is te red t rademark o f BASF Po lyure thanes GmbH

The in fo rmat ion prov ided here i s cons is tent w i th the cur rent s ta te o f our techn ica l knowledge and exper ienceand rep laces the in fo rmat ion conta ined in prev ious vers ions . Because o f the mul t i tude o f in f luences in theprocess ing and app l ica t ion or our products they do notre lease the buyers o f our products f rom implement ingthe i r own tes ts and t r ia ls . The in fo rmat ion mere ly ser vesas genera l in fo rmat ion and does in no way const i tu te aguarantee o f any spec i f i c p roduct cond i t ions or proper t ies(product spec i f i ca t ion ) . The deta i l s do not descr ibe thesu i tab i l i t y o f the product fo r spec i f i c app l ica t ions andpurposes. In fo rmat ion regard ing qua l i t y and usefu l l i fe o ro ther fea tures do not represent guarantees . Any ex is t ingcommerc ia l r igh ts and ex is t ing laws and regu la t ions mustbe obser ved under the respons ib i l i t y o f the rec ip ien t o four products . P lease contac t our headquar ters or our sa les out le t w i th regard to the ava i lab i l i t y o f p roducts .(10/10)

B A S F Po l y u r e t h a n e s G m b H