Our testing Journey
“At Motus Labs, we test our gears to validate specifications while also stressing the gearing beyond their intended capabilities, providing our customers a transparent view into the performance of our products.”
– VP, Product Technology Robert james
Testing gearing requires test benches, benches with the capabilities of collecting data, stressing the gearing to specification and beyond, and to determine life. Motus Lab engineers went to work, collaborating with motor and robotic experts, to design state of the art test benches which mimic and exceed the demands they will see in the field.
Stryker Test Bench
- Positional accuracy (arcmin)
- Backlash (arcsec)
- Transmission Error (Repeatability)
- No Load (Nm)
- Efficiency at Average Input Speed
- Max Input Speed Greased (rpm)
- Peak Noise at Max Input Speed (db)
- Peak Temperature at Max Input Speed no load (degrees C)
The business plan for the Orbital Flex™ gear design focused on developing a high-torque, zero backlash gearing solution which would enable a maintenance free, long-life gearbox.
The testing plan for the ML2000-86-60, the first gear available as part of the Orbital Flex™ enabled ML2000 gear series, encompassed testing the performance of each assembled gearbox to define specifications and then to begin life testing with an initial target of 10,000 hours.
Gearbox life testing is a critical process in introducing new gearing to the market. The initiative for Motus Labs’ life testing is to determine the characteristics the gearbox exhibits at failure, which component causes the failure in the gearbox, and how many hours of operation does the gearbox deliver at rated torque before it fails.
Our life testing journey is composed of two approaches, Accelerated Life and Standard Life Testing, executed in parallel. For both approaches, we are capturing data points at specific intervals to track and document degradation of the gear specifications over time. We have also partnered with a third party company, Stress Engineering Services INC., to confirm our approach and validate our results.
Standard Life testing involves running a series of gears at a desired torque and speed to confirm the results of the Accelerated Life testing. These tests require a lot of time to complete as 10,000 hours is more than 416 days.
Accelerated Life testing encompasses running a series of gearboxes involving higher, unsupported, torque levels at high speeds to simulate the rigors of operating at a predetermined set of hours. Our initial target being 10,000 hours. As the name suggests, the intent of this test is to fail gears quickly, to identify the gearboxes characteristics before failure and cause of failure.
While analyzing the data from the Accelerated Life testing, we noticed the gears were exceeding the initial life targeted specification of 10,000 hours. Not only did the gears continue to perform, but the key specifications had also not degraded. For example, backlash did not exceed the 17 arcsec threshold. There were zero gear failures during this testing.
This is where our focus shifted as, with oversight from Stress Engineering Services, we introduced Degradation Testing to our testing strategy. Motus’s Degradation Testing is a subcomponent of our Life Testing strategy. In Life Testing, gears would continue to be tested on the Accelerated Life and Standard Life benches until failure. With our Degradation Testing approach, Motus’s testing engineers are replacing gears on test stands once they exhibit more than 17 arcsec of backlash.
Life Testing will continue once we substantiate ML2000 maintains zero backlash for 10,000 hours and Stress Engineering Services validates our data. When we resume our efforts, we will use the same gears used in Degradation Testing to resume their testing profile until the gearbox breaks or stops performing as gearbox. Examples of these failures include:
- Excessive Vibration
- Change in Noise (consistency & loudness)
- Grease Leakage
- Velocity loss
- Mechanical Failure
We know our gears will fail at some number of hours, we just do not know how far beyond 10,000 hours that will be for ML2000 and Orbital Flex™, yet!