Parker Hannifin mx80l precision grade Manual De Usuario

 

36 

 

 

• 

Ambient Temperature   

 
This is the air temperature that surrounds the MX80L  
 

• 

Application or Environment Sources  

 
These are mounting surfaces or other items which produce a thermal change that affect the 
temperature of the MX80L carriage (i.e. X/Y configurations with motors or other heat generating 
devices that heat the mounting surface and thus thermally affect the MX80L carriage). 
 

• 

Motor heating from MX80L   

 
Since the MX80L uses a servo motor as its drive, it produces no heat unless there is motion, or a 
force being generated. In low duty cycle applications heat generation is low, however as duty 
cycles increase, temperature of the MX80L will increase, causing thermal expansion of the base. 
With very high duty cycles these temperatures can reach temperatures as high as 30

° C above 

ambient. 
 

If the application requires high accuracy, the thermal effects must either be removed by regulating 
carriage temperature or compensated for with a correction factor added to the commanded 
position. Controlling the carriage temperature is the best method. However, this means controlling 
the ambient temperature by removing all heat/cold generators from the area and operating at very 
low duty cycles. Compensation is the other way of achieving accuracy without sacrificing 
performance. In this case the system must be exercised through its normal operating cycle. The 
temperature of the carriage should be measured and recorded from the beginning (cold) until the 
carriage becomes thermally stable. This carriage temperature should be used in a compensation 
equation. Below is the fundamental thermal compensation equation:  
 

∆T)) 

 

C

d

 = Corrected displacement (mm) 

I

d

  =  Incremental displacement (mm) 

T

e

 = Thermal Expansion (0.000022 mm/mm/

° C) 

∆T = Temperature Differential from 20° C  

 
Example: 

• 

Carriage Temperature of 32

° C required move of 100mm 

 
Cd = 100mm  -  (100mm * Te * 12

° C)  = 99.9736mm 

 
In this example the commanded move should be 26.4 microns less (100mm – 99.9736mm) than 
the desired move. This will compensate for the thermal expansion of the scale.  This is a simple 
linear correction factor and can be programmed in to most servo controllers using variables for the 
position commands. 

Daedal Division 
Irwin, Pennsylvania