3m™ Ground Pro® Ground Integrity Meter - Pick & place training

Let’s check for Ground Impedance on the chassis of a pick and place machine. First, turn on the machine as well as other parts of the manufacturing line that are connected to the machine. To obtain an accurate measurement, select a point on the machine that is conductive and is an integral part of the equipment. Also confirm that the measurement point on your unit will be in contact with the chip or the board. For this example, let’s connect to a screw on the Chassis of the Pick and Place Machine. Connect one lead to the screw and the other to “Electrical Ground”. Note that many customers use electrical ground as facility ground. Work with your manufacturing safety group and take appropriate caution when disabling any machine guards. Turn on Ground Pro and select the “Ohms” button. Move the “up” and “down” arrow buttons until you see a reading on your display. Select the lowest impedance scale for better resolution and accuracy. A low impedance value indicates a “Good conductivity of the unit to facility ground”. Press the “V” button to see if there is any voltage traveling through the ground. We will look for both a “DC” and an “AC” voltage signal. Remember to use the lowest possible scale. Finally, press the “EMI” button once. Ground Pro measures any “noise” coming through the ground as both a “Voltage” and “decibel micro volt ”. You will see two values… the top value is the PEAK Voltage and the bottom value is the AVERAGE Voltage. If the PEAK Voltage is fluctuating then press the “Hold” button twice in order to get the “Max Voltage” value for the connection you are testing. The Peak value is the most important measurement. The lower the peak value, the better the ground. You can gain a better understanding of the connection integrity to the facility ground by measuring the Impedance for the connectivity of the unit to the facility ground, the level of voltage in the unit, the ground connection, and the source of the voltage. This information will help you repair your ground connection, if necessary. Another potential source of poor grounding or bonding is the voltage difference that may be present between two pick and place machines connected by a conveyor. First, place one of the leads on the chassis of the first pick and place machine. Again, make sure that the connection point is making integral contact with the conductive chassis of the machine. Second, connect the other lead to the ground chassis corresponding to the second pick and place machine. Check for proper grounding or in this case bonding between the two pieces of equipment. Press the “V” button to check for any high voltage sources potentially running between the two units. Also check the “EMI” voltage potential between the two units. Yet another place to check conductivity to ground and EMI noise is between the metal bracket that the tape “rides on” before being picked up by the robotic head. Place one lead at this location. Place the second lead on the machine chassis that we have already determined to be properly grounded. You can also place the second lead on the facility ground. As you take measurements, please make sure that the operator is a safe distance from the moving equipment and follow your facilities safety practices while measuring the Ground Impedance, Voltage, and EMI noise. Finally, you can also use Ground Pro to measure the Ground Impedance on a moving piece of equipment. Attach one lead to the screw on the head of the pick and place machine. Next, attach the other lead to facilities ground or the chassis of the pick and place machine. Now we can take measurements of Ground Impedance, Voltage and EMI when the head is not moving. Make sure that the pick and place machine is powered up. Next, let’s make small movements with the head. As you take measurements, please make sure that the operator is a safe distance from the moving equipment and follow your facilities safety practices. Measure the Ground Impedance, Voltage and EMI and record the data. Change the location of the lead to check other parts of the moving head and take the corresponding measurements using Ground Pro.