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SAE J2605: Non-Contact Laser Measurement for Hose Dimensions – A Round-Robin Study
SAE J2605 presents the findings of a collaborative round-robin study carried out by the Hose Measurement Task Force. The study evaluated the measuring capability of a non-contact, laser-based system—the LOTIS QC-20—for simultaneously measuring inside diameter (ID), outside diameter (OD), wall thickness, and wall thickness variation of automotive hoses. By replicating the methodology of SAE J1759, this report allows direct comparison between traditional contact methods and modern non-contact laser gauging.
Study Overview
Three end-user companies participated in the study, each using their own QC-20 device. Three sets of hoses were measured: two straight sections (parts X and Y) and one curved section (part Z). Each set contained ten black rubber samples. The measurements were performed at a consistent location—19 mm (0.75 in) from a uniquely marked end of each hose—after a 24-hour equilibration period at 23 °C and 50 % relative humidity. Three operators at each plant took three repeated measurements per hose, and the data were recorded on standardized forms before being sent to Plant A for GR&R analysis.
| Parameter | Description |
|---|---|
| Participants | 3 end-user companies (Plants A, B, C) |
| Hose Sets | Three sets: two straight (X, Y) and one curved (Z); all black |
| Measured Attributes | Inside Diameter (ID), Outside Diameter (OD), Wall Thickness (WT), Wall Variation (WV) |
| Measurement Device | LOTIS QC-20 non-contact laser gauging system (12 mm size) |
| Measurement Location | 19 mm (0.75 in) from the marked end of each hose |
| Environmental Conditioning | 24 hours at 23 °C ± 1 °C, target 50 % RH |
| Replicates per Hose | 3 operators × 3 repetitions per plant |
| GR&R Standard | Based on AIAG Measurement Systems Analysis (MSA) manual |
Key Findings and Design Insights
The study produced two separate GR&R calculations for each hose set, evaluating both the device’s repeatability and reproducibility across plants and operators. The non-contact, laser-based approach offers distinct advantages: it eliminates physical deformation of the hose, captures 1,600 radius measurements per revolution for both ID and OD, and computes wall thickness and variation from the same scan. However, consistent procedure proved to be the largest factor in achieving reliable results.
🛠️ Best Practice Tip: Equilibration
All hose samples and measuring devices must be conditioned for at least 24 hours at 23 °C and 50 % RH before any measurement. This small step minimizes material expansion or contraction and reduces environmental noise in your GR&R data.
⚠️ Common Mistake to Avoid
Inconsistent positioning along the hose length or failure to mark the measurement end can introduce significant variability. Always measure at the specified distance (19 mm) from a clearly marked end, and use three repetitions per operator to capture true process variation.
The study also confirmed that operator-to-operator variability is low when the QC-20 is used according to the prescribed protocol. For curved hoses, careful fixturing is needed to prevent the laser beam from skewing relative to the hose axis. These insights directly support the design of robust measurement systems for production and quality control.
Frequently Asked Questions
Why are non-contact methods like laser gauging preferred for hose measurement?
Non-contact systems eliminate deformation of the hose during measurement, allow simultaneous capture of ID and OD, and produce wall thickness results without separate steps. This reduces measurement error and cycle time compared to plug gauges, tapes, or calipers.
What is the recommended measurement distance from the hose end?
The study used a distance of 19 mm (0.75 in) from the marked end. This consistent reference point reduces variability and is now a standard practice for non-contact hose gauging.
How many measurements are needed for a reliable GR&R study?
SAE J2605 used three operators performing three repetitions each at every plant. For a robust GR&R, at least three operators and three replicates per part are recommended, with parts covering the expected range of variation.
How does SAE J2605 relate to the earlier SAE J1759 study?
SAE J2605 intentionally mirrors the methodology of SAE J1759, which evaluated contact methods (plug gauges, tapes, calipers). This enables direct comparison of measurement capability between contact and non-contact techniques.
