Calibration Process and Equipment Requirements...
Information & Training. | Quality Assurance. Quality Management.The importance of Calibration. A well managed calibration system is essential in all manufacturing and monitoring operations. It provides confidence in the measured data and consistency in the measuring, test, manufacturing process. It is a requirement of ISO 9000, plus other regulatory standards and is often a customer requirement.
What is Calibration?• Calibration is checking the lack of certainty (uncertainty in measurement) of a measuring instrument.
• Is achieved by checking something that has a know value (traceable standard) and noting the output of our measuring instrument.
• The difference between both is the error.
Calibration requirements include the need to…• Establish and maintain documented procedures.
• Determine measurements to be made and accuracy required.
• Select an appropriate measurement instrument capable of measurement accuracy and precision.
• Identify and define measurement instrument for calibration.
• Calibrate to prescribed intervals and to national and international standards. (ILAB, NAMAS, NIST).
• Where no standards exist, document the basis used for calibration. (e.g. Test Fixtures, Autocollimators, etc.)
• Define the calibration process and specify the acceptance criteria.
• Label measurement instruments with a suitable indicator to show calibration status.
• Publish calibration status reports on defined intervals.
• When measurement instruments are not conforming, take appropriate action on same and product affected.
• Maintain calibration records.
• Protect measurement instruments from damage, misuse and deterioration. (Use suitable packaging when not in use)
• Safeguard measurement instruments, including software and hardware, from adjustments which would invalidate the calibration setting.
Calibration terms and definitions:• Measurement Instrument – Any instrument which monitors or controls a critical parameter of a manufacturing process, controlled environment or used to measure a product or component specification.
• Standard – A defined reference tool with traceability to a national standard.
• National standard – A reference tool utilized by an internationally recognized standards laboratory representing the country which operates that laboratory.
• Calibration – Verification of a measurement instrument’s performance against a traceable standard.
• Precision – Or repeatability. Variation in readings obtained when repeating the exact same measurement(s).
• Traceability – Documented reference of calibration results to a recognized standard.
• Accuracy – The relative agreement of a measured value with an accepted standard.
• Loop Calibration – The calibration of measurement instruments “as installed” in a total system and represents calibration of the instruments “as used”.
• Resolution – The power of discrimination of an instrument.
• Range – The breadth or span of an instruments capability of measurement.
Typical calibration user responsibilities in an organization…• Equipment user shall forward equipment to the calibration coordinator if (say) new batteries are required.
• Equipment user shall forward equipment to the calibration coordinator if there is a damaged or non-functional or missing or unreadable calibration label.
• Equipment user shall check equipment calibration due date prior to use to ensure it has not expired.
• Non-portable equipment, equipment user shall inform calibration coordinator if there is a damaged or non-functional or missing or an unreadable calibration label.
• Equipment user shall ensure proper use, handling and storage for assigned test equipment.
Typical calibration representative responsibilities in an organization…• Department calibration representatives shall attend regular calibration status meetings.
• Department calibration representatives shall perform monthly calibration equipment stock check with status reports provided by calibration coordinator.
• Department calibration representatives shall complete & return status reports to the calibration coordinator.
• Department calibration representative shall coordinate search for missing equipment within their respective department.
Identification requirements for calibration…• Identify and list all measuring instruments including personal measuring devices.
• Include all equipment involved with quality control measurements, including test fixtures and software based measuring applications.
• Clearly identify all equipment not to be calibrated with a suitable indicator.
• Quarantine measuring instruments that are not calibrated. If unable to remove, label the item “Do Not Use” and make inoperable if possible.
Selection of suitable equipment…• Criteria for selection of measuring instruments include appropriate accuracy, precision and resolution.
• Test uncertainty ratio of 4:1 or better must apply to accuracy. Documented rational required if (say) a test uncertainty ration of 4:1 cannot be achieved.
• Ease of use – portable, reliable, industry standard.
• Digital display preferred as analogue tends to lend itself to more interpretation during reading results.
Calibration database…• Must list all calibrated measuring instruments and standards.
• Update immediately as new equipment is purchased.
• Indexed by instrument serial number.
Equipment coding system and control…• Measuring instruments are tracked by original serial number.
• Calibration records must identify this unique serial number.
• Code number must be unique and not re-used when instrument is discontinued.
• Should be permanently marked, etched on the equipment.
• Battery replacement must be performed by the calibration department.
• Security seals, anti-tamper labels should be replaced by the calibration department.
• Software used for testing is validated, controlled and protected.
• Manufacture’s user manual, specification and calibration records archived in central area.
Setting calibration intervals…• A calibration interval is the maximum period between successive calibrations.
• Not possible to construct a list of intervals which can be universally applied.
• Based on manufacturers recommendation, extent and severity of use.
• Documented engineering rationale based on usage.
• If none of the above available, interval not greater than 6 months would be a good starting point.
• Apply trend data obtained from previous calibrations.
• Need to consider any tendency to wear and drift with equipment ageing.
• Need to consider the risk and potential impact of an incorrect measured value being accepted.
External calibration…• Performed by quality assured and approved subcontractors with accreditation for the relevant measuring instrument.
• Calibration to be performed to the manufacturers specification across the full instrument range.
• Calibration coordinator should approve calibration certificates.
• Have traceability to a national standard, e.g. NIST, ILAB, NMAS.
Internal calibration…• Calibration personnel must use application specific procedure.
• Fully trained personnel only.
• Environmental conditions must be considered and established.
• Provide instruction on calibration points, required accuracy and precision.
Calibration records & certificates…• Include measurement instrument ID.
• Calibration date and due date.
• Signature of person performing the calibration.
• Identity of standards used and due date.
• Identity of procedure and revision ID.
• Before and after data (if adjusted) for each calibration point.
• Statement of acceptability (pass or fail).
• Tolerances for accuracy and precision.
Misc…• Measuring instrument owner is responsible for submitting new equipment, equipment due and non-conforming equipment to calibration department.
• All measuring instruments require ID and status label.
• Traceability required for internal and external calibration.
Information & Training. | Quality Assurance. Quality Management.
- The Principles of Quality Management
- The Quality Manual
- Quality Standards and Specifications
- The Quality Management System
- Revised requirements of ISO 9001: 2015
- Design Quality – Products & Processes
- Good Manufacturing Practice (GMP)
- CAPA – Corrective And Preventative Action
- Calibration Certification
- Change Management and Control
- Quality Management Training
- Product and Process Validation
- Supplier Quality Assurance
- Audits & Auditing
- Ensuring the Quality Management System is Risk based
- Etc. …. Etc. …. Etc. …
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