Repeatability and reproducibility (R&R) testing is an excellent strategy for monitoring and proving the consistency of laboratory instrumentation and rheology testing machines. Regular R&R testing grants frequent insight into instrument performance, so quality personnel can catch and address potential issues quickly and minimize downtime or other losses.
- Run the exact same test, on the exact same material, on a set schedule
- Three components: a consistent test method, a frozen control stock and a regular schedule
- Weekly testing is considered by many to be best practice
- Frequent R&R limits how much product must be investigated when drift is detected
What Is R&R Testing?
R&R testing is consistent, repetitive testing conducted at a prescribed interval in order to monitor the performance of a laboratory instrument. The exact same test is performed, using the exact same material, on a set schedule, and lab managers review the data after every test and over time to ensure consistent performance. An R&R test has three major components:
Test method
Regular R&R testing should use the same test spec every time to ensure consistent data. Common examples include ASTM D5289 and ISO 6502, both of which are designed for quality control.
Control stock
R&R testing should be conducted with the same rubber compound every time. Many laboratories opt for a standard compound, such as peroxide cure EPDM rubber or Alpha Technologies’ Alpha Quality Compound (AQC), a soapbox cure EPDM compound. Some laboratories make their own control stock, based on compounds frequently tested in their machines. Ideally, this is a compound the lab has mixed for years and knows well, so operators know what results to expect and can spot anomalies easily.
Schedule
R&R testing should be conducted at a prescribed, regular interval. Weekly testing is considered by many to be best practice, giving frequent insight into instrument performance without erring on the side of excess. Some facilities may choose to test every two weeks or once a month, depending on their resources and needs.
Regardless of what material is chosen, control stock should be kept frozen to prevent chemical reactions before testing. It is important to note that even in the freezer most rubber compounds only have a shelf life of 6–24 months.
Why Conduct R&R Testing?
There are three primary reasons to conduct regular R&R testing on laboratory and rheology instruments:
Prove an instrument’s capability
Regular R&R testing creates a data record of an instrument’s compliance and performance. This record can be used to demonstrate consistency for an audit, customer communications, internal quality assurance, or other purposes.
Reduce investigation time
When drift is detected, the first step is to identify when the issue may have first occurred. If the instrument hasn’t been R&R tested in a few weeks or more, any work completed since must be investigated. If the last test was less than a week ago, the investigation goes much faster, and far fewer products are at risk of going to waste.
Detect drift in an older instrument
Alpha Technologies lab instruments are designed for many years of reliable performance, but aging is inevitable. Regular R&R testing reveals patterns that may signal the end of service life, giving a longer time horizon for planning an upgrade, budgets and potential downtime.
An example response plan
When R&R testing does detect an anomaly in instrument performance, there are several steps or strategies to consider.
- Tag the instrument and take it out of service temporarily.
- Recalibrate the instrument.
- Call the instrument’s manufacturer to schedule a repair or, depending on the age of the machine, discuss an upgrade.
Once steps have been taken to address the drift, any material that has passed through the instrument since the last R&R test can be investigated for possible issues.
The Alpha Technologies Approach to R&R Testing
The team at Alpha Technologies understands that reliable, consistent performance of laboratory instruments is critical. We’ve designed our laboratory instruments and our service strategy around supporting R&R testing, so we can help our customers ensure consistency in their labs.
Alpha Technologies is proud to offer accredited calibration services based on popular ASTM and ISO quality assurance specifications through AlphaCare. We also offer long-term planning support for customers who need to schedule instrument upgrades around budgetary considerations, downtime, and other variables.
Designing an R&R protocol or planning an upgrade?
Whether you’re seeking support for designing an R&R testing protocol or planning a large-scale laboratory upgrade, talk to a member of our team about your goals.