Understanding Accuracy with the FaroArm and ScanArm
Overview
The FaroArm® is a precision electronic measurement device that is designed for use in industrial environments. Although it is made to withstand every-day use in varying manufacturing environments, you must still take care when operating the FaroArm.
The FaroArm encoders are in the articulating joints. These encoders convert position information to an electronic signal that is interpreted by the onboard or external measurement software used with the FaroArm. To ensure the accuracy of your measurements and avoid encoder defects that can only be fixed by the FARO factory, make sure you protect the FaroArm against these conditions that may occur in your work environment.
- Fluctuations in the power supplied to the FaroArm
- Electrostatic discharges around or brought to the FaroArm
- Electrical current on the ground of the power network that is connected to the FaroArm
- Defective USB port on the computer sending electrical current to the FaroArm
- Abuse, such as dropping or twisting the FaroArm at the joint end stops
- Strong vibrations from large machinery or traffic in the vicinity of the FaroArm
- Excessive temperature changes without the appropriate adjustment time
As protection against power related problems, use power surge protection and connect the FaroArm to its own electrical circuit. Machines that have high energy demands, such as welders and milling machines, can affect the FaroArm if they are on the same circuit.
CAUTION: Using a third party power supply with your FARO equipment can void the warranty.
Below are some more issues that can degrade accuracy while measuring with the FaroArm.
Mounting
- Mounting to any type of wooden surface.
- Mounting to an optical table (e.g. Vibraplanes), because the steel sheet on top of the tables is thin and deflects.
- Folding tripods using the stabilizing struts.
- Heavy-duty stands with wheels down.
- Excessive clamping force.
Compensation
With Probes
- Measuring with Point Probes.
- Measuring with chipped, loose, or cracked ball probes.
- Measuring with probe extensions. The extensions will deflect.
With the Laser Line Probe
- Dragging the probe over the FARO Compensation Plate during the plane measurement. Ensure to lift the probe in between points to avoid scratching the surface of the plate.
- Poor probe compensation technique. Tip: Do not do short sweeps with the FARO Laser Line Probe during compensation.
- Having a dirty lens. Make sure to clean the top and bottom lenses with the cloth from the FARO Laser Line. Dirt and grease on either lens can cause poor results.
Measurement Environment
- Measuring close to an end stop can induce unwanted stress.
- Extending the arm out as far as it can go can cause unnecessary stress.
- Having excessive vibration in the surrounding area that can produce unwanted results.
- Rapid changes in ambient temperature can cause errors in the arm’s automatic temperature compensation.
- Measuring using poor techniques; minimum number of measured points per feature, moving while recording individual points and small coverage area.
Special Note: If the arm is mounted on granite table or cart, do not measure objects that are not mounted to the granite table or cart.
Lastly, note plane-to-plane dimensions are only acceptable on certified artifacts. These artifacts are precision machined to have near perfect parallel surfaces. When measuring the distance between two sides of a regular plate or block, a plane to plane measurement is NOT recommended.