Tham khảo tài liệu 'newnes sensor technology handbook 2005 yyepg lotb part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 15 Sr Sn .10 X Sn Temperature drift tolerances must be also calculated. Over a range of -25 to 70 C a sensing distance drift of 10 can be expected. Over -25 to 85 C the tolerance increases to 15 . Su Sr .10 X Sr -25 to 70 C Su Sr .15 X Sr -25 to 85 C Usable sensing distance Su of any sensor can now be estimated. Su is the distance at which the sensor will always operate. If the target-to-sensor range is greater the sensor may or may not operate reliably. See Figure . Sn .10Sn Figure Nominal sensing distance Sn versus usable sensing distance Su . Once the usable sensing distance is determined you need to figure in the actual application conditions. There are three factors to take into account Target material Target size and Target presentation mode. The nominal sensing distance given in inductive proximity sensor specifications is determined with a target made of mild steel in accordance with EN 60947-5-2 . Whenever a target is a different metal a correction needs to be made to the usable sensing distance Su . The formula is New Su Old Su X M M material correction factor 350 Position and Motion Sensors The standard target is a square of steel 1mm .04 in. thick with sides equal to sensor diameter. To determine the sensing distances for materials other than standard a corresponding correction factor is used. Some common materials and their correction factors are listed in Table . Table Correction factors for non-standard target materials. Correction Factor 400 series stainless steel Cast iron Mild steel Din 1623 Aluminum foil 0 300 series stainless steel Brass MS63F38 Aluminum ALMG3F23 Copper CCUF3O Mild steel targets of standard sizes are used to establish published sensing distances. The standard size for each size and style of sensor usually is given in the manufacturer s order guides. If your desired target is the same size or larger than the standard target no correction factor is .
