Review of the Ergo Measurement Tools Jason Beardsley Bob Fox

New Force Measurement Gauges Mark – 10 Series 3 Hoggan Health ergoFET

ErgoFET Dual Function Push/Pull Force Gauge  Can measure push/pull forces up to 300 lb.  Comes with hardware and attachments for push and pull measurements.

ErgoFET Dual Function Push/Pull Force Gauge  Can set measures to lb., N or Kgf  Records peak force  Displays duration of measurement in seconds.

ErgoFET Dual Function Push/Pull Force Gauge  Variable threshold sensitivity.  Has wireless capability – with software and USB wireless receiver you can record time-force measurements on your computer. –Useful if taking measurements in positions where you can’t read the gauge. –Useful in staged insertions and/or where there is a tendency to “bottom out” and elevate the measurement.

ergoFET Threshold Settings  Adjust with the threshold button  Settings: –High Threshold – most commonly used, 3 lb. force must be exceeded before ergoFET starts to record force data. –Low Threshold – designed for sensitive forces. Threshold of 0.8 lb. before data is recorded.

ergoFET Hardware Accessories

Mark - 10  Tension and compression testing (pull/push).  Measurement range from 0.12 lb. to 500 lb., accuracy ± 0.3% of full scale.

Mark – 10 Keypad Power button Zero out reading Mode button – tension, compression Menu button – sets units, backlighting, data options Data button – for USB data downloads

Mark - 10  Rechargable battery with AC adapter/charger.  Charge good for about 7 hour with backlight turned on or 24 hours with backlight turned off.  Selectable units – lb, N, KgF.  USB connection for PC data download.  Attachments: extension rod; cone, chisel; v-groove; flat; hook and coupling.

Mark - 10 Attachments

ergoFET Vs. Mark - 10: When to Use Which One?  The ergoFET is best configured for hand/palm push force measurements and, with the attachments, for higher exertion or whole-body push pull exertions.  The Mark - 10 with its attachments is best configured for finger force exertions involving objects of relatively small surface area.

PG-30 Pinch Gauge  Measures 0-30 lb. in 1.0 lb. increments.  Accuracy = 0.3 lb.

JAMAR Hand Dynamometer Model J00105  Measures isometric grip force from 0 to 200 lb./90 kg.  Adjustable handle in five grip positions 1.275” to 3.375” in 0.5” increments.

Proper Use of the Pinch and Grip Strength Dynamometers  Remember that technically these gauges are strength gauges to measure isometric strength.  We can use them to estimate force demands by having operators: –Exert a simulated force against the gauge that approximates the exertion needed for a finger/grip task, or; –Insert the gauge into the part insertion process to capture the force exertion.  These uses should be considered only if a conventional force gauge cannot otherwise be used.

Gage Calibration  Be sure and follow the manufacturer’s instructions for having the gauges calibrated.  Some mechanical gauges can be calibrated in the plants if the necessary calibration equipment is available although most electronic gauges under warranty will likely have to be calibrated by the manufacturer (e.g., microFET).  Most manufacturers suggest an approximate yearly calibration, more if the unit has had heavy use or if damage is suspected.

Precision Vs. Accuracy What’s the Difference?  Accuracy refers to how close the measurement is to the actual value being measured.  Precision is the degree to which repeated measurements show the same results.

Reminders For Taking Reliable Force Measurements  Use the right gauge, interface and attachments for the measurement.  Make sure that the calibration is up to date.  Before you start be sure and anticipate anything that can affect the accuracy and precision of the measurement.  Make sure the direction of your push/pull with the gauge is the same as the direction of the force exertion by the operator.  Make the effort slow, steady and coordinated. DO NOT make an accelerated or abrupt push/pull – remember that this is a measurement of static effort.  Try to reduce any sources of variation.

Notes on How to Reduce Variation When Taking Measurements  Use the same measurement technique for each measurement.  Use the same force gage if you are taking a series of measurements.  Have the same person take the measurements. If multiple people take the same measurements, their measurements should largely agree. GM Global Ergonomics revised October

Notes on How to Reduce Variation When Taking Measurements  Make sure that the capacity of your gage is suitable for the magnitude of force measured.  Make sure that the end effecter of the gage is appropriate for the contact point on the part. Minimize the opportunity for slipping.  Identify any other factors that may influence the measurement and try to control for them. GM Global Ergonomics revised October

Reminders For Taking Reliable Force Measurements: Whole-Body Push/Pull  Be sure and keep the gauge level;  Be sure that the structure/surface that you are pushing on is not being deformed by the push;  Do not accelerate when measuring sustained push forces.  For repeated measures: (per Liberty Mutual practice) –Try to obtain at least three measurements that are within 15% or less of each other; –For initial force measurements, take the peak value of the number measurements. –For sustained force measurements take the average of the number of measurements.

Cautions on Repeated Measurements  If you are taking repeated measurements of the same part, consider if the repeated insertions will have any effects on the part that will change (increase or decrease) the measured force.  If measuring multiple parts, be sure and set up the measurement procedure to be identical for all parts measured.

Statistics  Some statistical procedures may be necessary if you need to do the following: –You need to measure multiple parts to compare them to a force specification or guideline; –You need to compare force measurements for two or more different conditions/parts in order to determine if one is higher/lower than the other(s).  If you have a statistics-related issue or question, CALL US.