Polyurethane Elastomer (Springs/Bushes)

        

* Particular safety under working conditions. No sudden breaking up. Capable of running in damaged condition & hence no damage to tooling through over loading. 
* No servicing required & thus very economical under continuous working conditions. 
* Nonresonant & shock absorbent, reduce air noise, metal resonance is immediately suppressed. 
* Very advantageous "price versus performance" ratio as compared with other spring types. 

                      Load Bearing Chart 90 shore A Elastomer   

                 

 

                       
  

Sr.           

Sizes in mm 
     Load in Kg. for Deflection of
 
 
D
I
10%
20%
30%
Catalogue No.
01
22
8
80
165
245
90 JPE 22 - L
02
25
10
100
205
305
90 JPE 25 - L
03
30
10
155
315
470
90 JPE 30 - L
04
32
10
180
360
540
90 JPE 32 - L
05
35
10
220
440
660
90 JPE 35 - L
06
40
10
290
580
880
90 JPE 40 - L
07
45
13
360
725
1090
90 JPE 45 - L
08
50
15
445
890
1335
90 JPE 50 - L
09
55
15
540
1095
1645
90 JPE 55 - L
10
60
17
645
1300
1950
90 JPE 60 - L
11
70 
21
875
1750
2625
90 JPE 70 - L
12
80
21
1150
2330
3500
90 JPE 80 - L
13
100
21
1870
3750
5620
90 JPE 100 - L
         
     
 
Specification 
 
Properties
Unit
ASTM test  
Method
Polyurethane  
Elastomer Spring
Hardnesss
Shore A
D-676
90+2
Tensile Strength
Kg / mm2
D-412
3.2
% Elongation
%
D-412
550
Compression Set
%
D-395-B
27
Compression Moulus
Kg / mm2
--
2.5
Rebound Resilience
%
D-2632
45
Colour
Orange
Conversion (Approx.) 1 kg/mm2 = 10 N/mm2 = 100 Kg/mm2 = 1450 1b/in2
 
 
Application - Hints / Installation of Springs 

Space requirements 
Elastomer springs cannot be compressed & therefore ample space should be left to accomodate their natural bulging action. The volume of deformation of length equals the volume of the bulge. Add to this figure a safety margin .  

Stacking 
 To obtain extended stroke lengths the springs can be used in series (stacking) 
The individual springs used in the stack has to be separated by spring washers. If all in the stack are equal the individual stroke, lengths are cumulative. Springs stacks have to be guided.  
 
  

Application hints : 

Elastomer :  
Springs :
Shore Hardness  
90
Stroke (S) max.
30 %
Creep of Original (Ss) height
5 -  8 %
  

  
  

 
  
  
  
  
  
  
Spring Stroke (S)  
The maximum stroke in relation to the original height depends on the stroke frequency & it can be inferred from the graph.  

Creep Factor (Ss)  
The creep factor of the height of the spring is determined by the ambient temperature and also by the spring material. The values given are based on practical results which have been reached up to 90% success under dynamic conditions after 10 cycles.  

Preload (Sv)  
In order to ensure a positive spring response the spring will have to be preloaded by an amount > than the creep factor.  

Application of springs  
All elastomer springs tend to show variation caused by stifness & as a result should be subjected to about 10 compression cycles before final use. The following graph represents values at 10 compression cycles under static conditions. This conforms to DIN 9835, Page 1, Part 1.  

    1.  : 1st Compression stroke
    2.  : 10th Compression stroke
    3.  : Return stroke for 1 & 2

The comparison between steel springs & Polyurethane elastomer bushes used in sheet metal dies for reference see the Steel Specification chart .



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