NON-CONTACT MEASUREMENT & INSPECTION FEATURE trip at 4.400 VDC
• 4.300VDC x . 05% = .00215 VDC change per degree C. Hence a 10˚C change in ambient temperature could result in an untapped hole voltage of 4.3215 VDC, now only .0785Vdc from the switch point instead of the original 0.100 VDC. • At wider gaps, the voltage value is higher, resulting in a higher voltage shift, getting even closer to the switch point. Cut vs. cold form threads –Cut threads are easier to detect. Formed threads requires tighter insertion repeatability: • Hole diameter for cold form threads is larger than cut threads • The difference between the hole diameter and average (basically pitch) diameter is much less with cold formed threads
• Cold working can change the properties of the material somewhat, affecting the sensor output. This is more of a concern with ferrous materials • Cold form threads typically can be 60% of full depth vs. 75 % of full depth for the same strength in cut threads. This can reduce the drill diameter to average diameter distance even more. Base material – As this is an eddy current device, the base material must
be electrically conductive: • The most influential difference is seen between ferrous and non-ferrous material
• The second major influence is conductivity
• Within ferrous and non-ferrous categories, ‘teaching’ the sensor the new material is sufficient to accommodate the variation in conductivity. Sensor damage potential:
Teach LED Power on LED
Spring-loaded sensor mounts minimise damage potential during operation: • The coil in the sensor is only ~0.010” from the OD of the PEEK sensor tip just below the conical section. Exercise care to avoid the sensor tip rubbing on the inside of the hole. • Plunging the sensor into a broken tap is obviously going to cause irreparable damage. Using a spring loaded sensor mount will help minimise this potential. • The sensor and electronics are rated IP67. The cabling is PUR jacketed, and the sensor is made of PEEK and stainless steel. This combination holds up very well to a wide variety of coolants and lubricants.
TEACHING THE THREADCHECKER 1. Push the teach button once to put the microprocessor in ‘teach’ mode. The ‘Thread’ LED will be yellow and flash rapidly. 2. Insert the sensor into a threaded hole, and push the teach button once. The ‘Thread’ LED will be yellow and flash slowly. 3. Insert the sensor into an unthreaded hole, and push the teach button once. The ‘Thread’ LED will be red indicating no thread. 4. Alternate between threaded and unthreaded holes and verify the ‘Thread’ LED is green when the sensor is in the threaded hole and red when the sensor is in the unthreaded hole (or not in a hole at all). 5. If desired, the
Teach pushbutton
polarity of the switched output can be inverted by holding the teach button for 10 seconds.
Ixthus Instrumentation T: 01327 353437
www.ixthus.co.uk
INSTRUMENTATION | MARCH 2016
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