Gear inspection is a critical aspect for producing a quality product. Jesse Garant of Jesse Garant Metrology Center recently sat down with Gear Solutions to discuss the importance of inspection and how it has grown to service the changing gear manufacturing industry.
Why is gear inspection important?
Gear inspection is important to validate not only the end product for dimensional requirements but the gear itself for internal structural integrity for identifying a minimum void size. As the gear industry further adopts lower density alloys and printed gears, the internal integrity further becomes a concern. In the past, this was less of a concern, as most gears were over engineered for strength due to the nature of the alloy being used.
Are different types of gears inspected differently?
Although gear inspection for external features has used several well-known and established techniques, internal inspection has typically been prone to destructive testing or validation with go/no go gauges. However, with light-weight gears and advancements for internal metrology, new methods have recently come to market such as Industrial CT Scanning.
Are there different phases of gear inspection? What are they?
As a metrology lab, we typically see four different phases of gear inspection: preproduction inspection of new gears, production validation for high-value, low-volume gears, intermediate production validation of high-volume gears, and failure investigation.
What makes each inspection phase necessary?
Each phase is necessary depending on where the manufacturer is within their build cycle.
How is reverse engineering important to inspection?
We typically see reverse engineering important for retooling of manufacturing lines or for relic gears where only limited quantities are currently available. The difficulty is that, even with inspection technologies available, accurate reverse engineering becomes a difficult process for large or high-density gears. The combination of various metrology methods and a hands-on CAD programmer allow for the most accurate model generation.
What is a high-energy industrial CT scanning service and what does it mean for gear inspection?
High-energy CT scanning becomes very applicable for the gear industry for internal validation of light weight alloy gears or 3D printed gears for internal porosity. The reason why this technology does not meet the metrology requirements for gears is that larger gears are still high precision products with tolerances of 0.001” or less. Due to X-ray spot sizes for high-energy accelerators, the technology currently has an accuracy of 0.015”. However, for smaller gears, micro focus CT scanning is directly in line with metrology requirements for gear inspection as the accuracy can fall under 0.001”.
What other recent developments in inspection have helped advance the field? How so?
With the advancements in vision systems and 3D scanning systems setup for production validation, the quality control methods for 100 percent external gear inspection have drastically improved over the years. Due to these technologies, manufacturers and OEMs are seeing a drastic reduction in out-of-tolerance gears. Acoustic inspection has also added to the validation of internal gear features as it measures the harmonic signature of a known good gear and compares it extremely quickly in a production setting to a manufactured gear.
Do you expect more advances in inspection to become a reality in the next 10 to 20 years? What kinds of advancements do you expect? What advancements are on your wishlist?
Over the next 10 to 20 years I expect to see an increase in the use of imaging systems and their ability to improve measurement accuracy on difficult features. On my wish list, I would like to see neutron imaging become more affordable with a drastic reduction in spot size to allow for useable metrology on large and high-density parts such as gears and castings.
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