ISO9001 System Document Package (33) | Work Instruction for Calibration and Periodic Verification of Measuring Instruments

Document Description: This work instruction is a lower-level supporting document for the "Control of Monitoring and Measuring Resources Procedure" (the 10th document in the package). It belongs to the third-level documents of the quality management system (QMS) and is used to implement the requirements of clause 7.1.5.2 "Measurement Traceability" at the operational level of measuring instruments. The difference between this work instruction and the second-level procedure document is that the procedure document answers "who manages, what is managed, and according to what process," while this work instruction answers "how to number, how to record in the ledger, how to determine the calibration cycle, how to confirm the calibration certificate, and how to use periodic verification to control measurement values between two calibrations." It is applicable to all enterprises that conduct inspections and tests using tools such as calipers, micrometers, plug gauges, gauge blocks, thermometers, pressure gauges, balances, hardness testers, electrical parameter measuring instruments, and specialized inspection tools. For instruments fixed on equipment and used only for process monitoring without product conformity determination, they can be simplified according to the classification criteria in section 4.1 of this work instruction. This document can be directly published and used as a third-level document of the enterprise. When using it, replace the organization name, department code, and tool category with the actual ones.

1. Purpose

To standardize the entire process management of measuring instruments (including gauges, inspection tools, testing equipment, standard devices, and other measuring instruments, hereinafter collectively referred to as measuring instruments) in terms of numbering, ledger management, calibration, metrological confirmation, labeling, periodic verification, traceability of inaccuracies, and disposal, ensuring:

1. The measurement values of measuring instruments can be traced back to national or international metrological standards through an unbroken chain of comparisons, ensuring the comparability and legal validity of measurement results;
2. Measuring instruments used for product conformity verification are in a calibrated and effective state before and during use, with their maximum permissible errors meeting the tolerance requirements of the measured characteristics (sufficient measurement capability);
3. The risk of measurement value drift between two calibrations is identified and controlled to prevent missed inspections, incorrect judgments, and wrong releases due to instrument inaccuracies;
4. Calibration and verification records are traceable, accessible, and reproducible, meeting the requirements of ISO 9001:2015 clause 7.1.5 and clause 7.5.3.

2. Scope of Application

2.1 This work instruction applies to the entire process management of all measuring devices listed in the measuring instrument ledger of the company, including:

a) General gauges: vernier calipers, micrometers, height gauges, depth gauges, internal diameter gauges, feeler gauges, plug gauges, thread gauges, radius gauges, square gauges, levels; b) Standard devices: gauge blocks, standard ring gauges, standard spheres, weights, standard resistors, standard batteries, standard platinum resistors, torque calibrators, specialized calibration fixtures; c) Testing and inspection equipment: tensile testing machines, hardness testers, impact testing machines, insulation and dielectric strength testers, dielectric strength testers, insulation resistance testers, ground continuity testers, multimeters, clamp meters, oscilloscopes, power supplies, temperature recorders, temperature and humidity chambers, electronic balances, pressure gauges and transmitters, flow meters, tachometers, noise meters, illuminance meters; d) Specialized inspection tools and fixtures: positionality gauges, coaxiality gauges, plug gauges, height gauges, spline gauges, pneumatic gauges, and their standard components.

2.2 The following instruments are classified according to the criteria in section 4.1 of this work instruction. If they are not used for product conformity determination, they can be subject to initial acceptance and functional confirmation only, and not included in periodic calibration. However, they must be noted in the ledger as category C with a justification:

a) Indicating instruments used only for monitoring the operating status of equipment (e.g., oil pressure gauges, water pressure gauges, cylinder pressure gauges without accuracy requirements); b) Simple templates and marking tools used only for tool setting, positioning, or process reference; c) Instruments used only for qualitative judgment (e.g., magnets, magnifying glasses, leak detection liquids).

2.3 When the calibration requirements for specific instruments are stricter than those in this work instruction, the stricter requirements shall be followed. Measuring instruments provided, lent, or designated by customers shall be registered according to the "Control of Customer Property Procedure" and managed according to this work instruction.

3. Responsibilities

3.1 The Quality Department (Metrology Management Position) is the principal department responsible for this work instruction, tasked with: establishing and maintaining the company's measuring instrument ledger; formulating numbering rules and category criteria; preparing the annual calibration plan and monthly implementation details; selecting and evaluating external calibration institutions; organizing internal calibration personnel qualification certification and internal calibration implementation; reviewing calibration certificates and completing metrological confirmation; preparing periodic verification plans and organizing verifications; managing instrument status labels; organizing traceability and handling of inaccuracies; and preserving all metrological records.

3.2 The using departments are responsible for: proposing the purchase requirements and technical parameters (range, resolution, maximum permissible error) of measuring instruments; using the instruments according to labels and valid periods; immediately stopping use and isolating for repair if the instruments are found to be overdue, damaged, or showing abnormal readings; cooperating with periodic verification and traceability of inaccuracies; and being responsible for the daily storage, cleaning, and protection of the instruments in their departments.

3.3 The Purchasing Department is responsible for: selecting qualified external calibration service providers and instrument suppliers according to technical requirements; signing procurement and calibration service contracts, obtaining qualification certificates and calibration certificates; and tracking the delivery and invoice settlement of calibration services.

3.4 The Equipment Department (or Technical Department) is responsible for: participating in the technical scheme review of specialized inspection tools and online measurement devices; being responsible for the installation, modification, and fault repair of online measurement devices; and cooperating with corrective actions involving the equipment side in measurement system analysis (MSA).

3.5 The Management Representative is responsible for: approving the annual calibration plan and periodic verification plan; approving temporary calibration plans for instruments without qualifications; and organizing the review of recall or recovery decisions if inaccuracies lead to product risks.

3.6 Internal calibration personnel must be trained, evaluated, and authorized for internal calibration (see the "Employee Training Work Instruction"). Each internal calibration task must involve at least two authorized personnel to avoid single-point failures in critical positions.

4. Work Procedures

4.1 Classification and Ledger Management of Measuring Instruments

4.1.1 Classification criteria (based on the impact on product conformity):

4.1.2 The Quality Department determines and registers the classification during the factory acceptance of the instruments. Any change in classification must be documented in the "Instrument Category Change Explanation" and approved by the Management Representative.

4.1.3 Numbering rule: Category Code-Department Code-Serial Number, for example, JC-PZ-001 represents the 001st general gauge of the Quality Department; BZ-JS-002 represents the 002nd standard device of the Technical Department. Once a serial number is assigned, it cannot be reused. The number of a scrapped instrument is permanently retired and not reassigned to another instrument.

4.1.4 The measuring instrument ledger (QR-7.1.5-01 "Measuring Instrument Ledger") should be reviewed annually and compared with the physical instruments quarterly. The comparison results should be recorded in the "Comparison Record" column of the ledger. The ledger must include the fields listed in the form list in section 4.10.

4.2 Determination of Calibration Methods and Cycles

4.2.1 Calibration methods are divided into external calibration, internal calibration, and no calibration:

a) External Calibration: Applicable to A Class instruments; projects where the company lacks standard devices or the required environment; legally mandated instruments (such as pressure gauges, electronic scales, balances, torque wrenches, etc., which are listed in the mandatory inspection directory and should be sent to legal metrological technical institutions or approved institutions for calibration according to the "Metrology Law"); projects where customers or the system require third-party certificates. b) Internal Calibration: Applicable to projects where the company is equipped with the corresponding standard devices, has a temperature/humidity/vibration environment that meets requirements, and has authorized internal calibration personnel, such as general gauges (calipers, micrometers), plug gauges, and simple inspection tools. Internal calibration must be performed according to a specialized internal calibration specification (which can be simplified based on JJG/JJF regulations), clearly defining the standard devices, environmental conditions, calibration points, data recording format, and judgment criteria. c) No Calibration: Applicable only to C Class instruments, which must be noted in the ledger as "no calibration (not used for product conformity determination)."

4.2.2 Selection and evaluation of external calibration institutions: The legal qualifications (CMA/CNAS accreditation certificate or legal metrological institution qualification), recognized capability range (whether the calibration projects and ranges cover the company's instruments), validity period of the accreditation certificate, service response and delivery capability, and historical error records must be verified. The evaluation conclusions should be filled in the "External Calibration Institution Evaluation Form," and qualified institutions should be listed in the "Qualified Calibration Institution Directory," which is reviewed annually. If false data, range coverage issues, or certificate information errors are found, the institution should be immediately suspended and re-evaluated.

4.2.3 The calibration cycle is determined based on the following factors: instrument category and impact on the product; usage frequency and environment (temperature, humidity, dust, vibration, corrosion); manufacturer's recommendations; historical calibration data drift trends; frequency of inaccuracies in similar instruments; and customer and regulatory requirements. The initial cycle can be set at 6-12 months for A Class, 12 months for B Class, and no calibration for C Class.

4.2.4 Adjustment of the calibration cycle: If the results of two consecutive calibrations are both qualified and the measurement error is stable within one-third of the maximum permissible error, an application can be made to extend the cycle (each extension should not exceed 50% of the original cycle). If any of the following situations occur, the cycle must be shortened: the results of two consecutive calibrations are close to the maximum permissible error; periodic verification shows abnormalities; a traceability of inaccuracies has occurred; the usage environment is harsh or the instrument is used frequently. Any changes in the cycle should be proposed by the Quality Department, approved by the Management Representative, and recorded in the ledger with the change date and reason.

4.3 Preparation and Implementation of Calibration Plans

4.3.1 The Quality Department compiles the "Annual Calibration Plan for Measuring Instruments" (QR-7.1.5-02) by December each year, which includes: instrument number, name, model and specifications, measurement range, accuracy class or maximum permissible error, using department, calibration method, calibration institution, last calibration date and validity period, and planned calibration month.

4.3.2 The plan must allow sufficient buffer time: External calibration instruments should be sent for calibration 30 working days before the validity period expires, and internal calibration instruments should be arranged 10 working days before the validity period expires. For critical instruments that need continuous use, backup instruments should be prepared in advance or calibration should be scheduled during maintenance periods.

4.3.3 Monthly implementation: The Quality Department compiles the "Monthly Calibration Implementation Details" by the 25th of each month, specifying the list of instruments to be sent for calibration, the send and return dates, the responsible person, and notifying the using departments to transfer the instruments by the specified date.

4.3.4 Pre-calibration handling: Clean the surface and measurement faces of the instruments; check the appearance, moving parts, and zero position; fill out the "Calibration Commission Form," noting the commission project (calibration or verification), calibration points or range, judgment criteria, and certificate requirements (whether uncertainty needs to be provided, whether a conformity conclusion is required); package for shock protection, and if necessary, include standard components or specialized fixtures. Upon retrieval, verify that the certificate information matches the instrument number to prevent misallocation.

4.3.5 Internal calibration implementation: Follow the specialized internal calibration specification, with at least two people involved in the entire process (one operator, one verifier). Environmental conditions (temperature, humidity, isothermal time of standard and calibrated items) must be accurately recorded in the calibration record. The accuracy class of the standard device should be at least three times higher than that of the calibrated instrument, or the uncertainty should not exceed one-third of the maximum permissible error of the calibrated instrument.

4.4 Confirmation of Calibration Results (Metrological Confirmation)

4.4.1 After receiving the calibration certificate, the Quality Department must complete metrological confirmation within 5 working days, not just based on the "Conclusion" section of the certificate. The confirmation content includes:

a) Consistency of certificate information: whether the instrument name, number, model and specifications, and factory number match the ledger; b) Traceability effectiveness: whether the issuing institution is on the qualified list, whether the recognized projects cover the calibrated projects and ranges, and whether the standard device traceability information is complete; c) Technical conformity: whether the measurement errors or correction values at each calibration point are within the maximum permissible error (MPEV); and whether the measurement capability meets the tolerance requirements of the measured characteristics (recommended that the maximum permissible error of the measuring device is no more than one-third to one-tenth of the tolerance band); d) Specification conformity: whether there are stricter requirements from customers or internal norms.

4.4.2 Judgment rules: Single-item judgment is based on |Measurement Error| ≤ MPEV for qualification. If the calibration certificate provides uncertainty and the impact of uncertainty is considered, handle it according to the judgment rules in JJF 1094. If necessary, use the "Qualified Judgment Zone" and "Unqualified Judgment Zone" to handle pending situations, which are determined by the Quality Department and the Technical Department.

4.4.3 The confirmation conclusion has three types: Qualified (can be used directly); Qualified but with restrictions (e.g., limited to a specific range, requiring the use of correction values, with a restriction notice posted in the using department and noted in the ledger); Unqualified (enter the disposal process in section 4.7). The confirmation results are recorded in the "Metrological Confirmation Record" (QR-7.1.5-03) and signed by the confirmatory person.

4.4.4 Use of correction values: If the instrument needs to be used according to correction values after calibration, the using department must keep a correction value table and train the operators. The correction value table is compiled by the Quality Department. If the instrument has an adjustable device that has been adjusted during calibration, the change in measurement values before and after adjustment must be recorded to determine if previous measurement results were affected.

4.5 Periodic Verification

4.5.1 Purpose of periodic verification: To confirm that the measurement values of the instruments have not significantly drifted between two calibrations, especially for A Class instruments, frequently used or harsh environment instruments, instruments with longer calibration cycles, and instruments that have previously been inaccurate.

4.5.2 Determination of verification objects: The Quality Department compiles the "Periodic Verification Plan" annually, including: all A Class instruments; instruments that showed abnormalities in the previous year's periodic verification or calibration; general gauges used more than once daily (selected); instruments that have been reactivated after long-term disuse; instruments that have been moved, transported over long distances, or repaired; and instruments specified by customers.

4.5.3 Verification timing: Before the first use after calibration; at the midpoint before the next calibration (between two calibrations); when a significantly abnormal measurement result occurs; after the instrument has fallen, been hit, overloaded, or exposed to moisture; and before reactivation after long-term disuse (more than 3 months).

4.5.4 Verification methods (choose one or a combination based on the instrument):

a) Verification Standard Method: Use a verification standard item with stable measurement values, sealed by the Quality Department (e.g., standard gauge blocks, standard ring gauges, standard weights) to repeatedly measure the instrument n times (n ≥ 5), calculate the average value and standard deviation, and compare with the historical assigned value of the verification standard; b) Transfer Comparison Method: Use a higher-accuracy standard device or another instrument of the same grade to compare measurements, and judge the results based on the En value; c) Retest Sample Method: Repeatedly measure a stable performance sample and compare the results with previous measurements; d) Characteristic Inspection Method: Check the zero position, repeatability, stability, appearance, and functionality of moving parts, suitable for simple instruments without a verification standard.

4.5.5 Judgment criteria:

a) When using the verification standard method or transfer comparison method, calculate En = (Instrument Reading - Standard Value) / sqrt(U1² + U2²), and |En| ≤ 1 is judged as controlled; b) When using the retest sample method, if the deviation of the current average value from the previous average value is no more than half of the instrument's maximum permissible error, it is judged as controlled; c) When using the characteristic inspection method, if the zero position deviation, repeatability, and stability all meet the requirements of the instrument manual or internal calibration specification, it is judged as controlled.

4.5.6 Handling of verification results: Controlled—continue using, and record in the "Periodic Verification Record" (QR-7.1.5-04); Uncontrolled—immediately stop using, affix a "Out of Service for Handling" label, and the Quality Department organizes a cause analysis. Follow the traceability process in section 4.7 and open a corrective action according to the "Corrective Action Implementation and Verification Work Instruction." The inspection data produced during the uncontrolled period must be re-evaluated.

4.5.7 Periodic verification records must retain the original observation data, environmental conditions, verification standard information, and judgment calculation process, not just the conclusion.

4.6 Management of Status Labels

4.6.1 All in-use measuring instruments must have status labels affixed, which should at least include: instrument number, calibration validity period, calibration method and institution, and status (qualified/limited use/out of service/reference use).

4.6.2 Suggested label colors and styles: green for "Qualified"; yellow for "Limited Use"; red for "Out of Service" (including pending repair and pending disposal); white for "Reference Use." The labels should be made of non-detachable materials and affixed to a prominent and wear-resistant location on the instrument. For small instruments that cannot be labeled, tags can be hung or placed in the box.

4.6.3 The using department should confirm the integrity and validity of the labels before daily use. If the labels are lost or blurred, the Quality Department should issue new ones, and the using department should not write their own. The use of instruments without labels, expired labels, or in an "Out of Service" status for inspection is prohibited.

4.7 Traceability and Disposal of Inaccurate Instruments

4.7.1 When any of the following situations occur, the Quality Department should initiate traceability: the calibration is judged as unqualified; the periodic verification is uncontrolled; the instrument is found to have been adjusted beyond the normal range during calibration; a significant error in the reading is discovered; or abnormal measurement data is reported by customers or external sources.

4.7.2 Traceability scope: Determine the time interval from the last qualified calibration (or last controlled verification) to the discovery of the inaccuracy, and review all batches, product numbers, and inspection records within that interval.

4.7.3 Traceability assessment method: Measure the degree of inaccuracy (measurement error) of the instrument and compare it with the tolerance of the measured characteristics:

a) If the error is much smaller than the tolerance band (e.g., less than one-fifth of the tolerance) and the actual measurement values are sufficiently far from the judgment boundary, the previous measurement results are judged as unaffected, and a statement is issued and archived; b) If the impact cannot be ruled out, the related products should be re-measured or subjected to more stringent inspection. For delivered products, the impact range should be assessed according to the "Nonconforming Product Control Procedure" and the "Customer Satisfaction Monitoring and Measurement Procedure." If necessary, notify the customer and initiate a recall or recovery.

4.7.4 Disposal methods for unqualified instruments: send for repair and re-calibrate; downgrade for limited use; convert to reference use or teaching use (remove inspection use labels); or scrap. Disposal must be recorded in the "Instrument Disposal Record," confirmed by the Quality Department and the using department, and approved by the Management Representative for scrapping.

4.7.5 The entire traceability process forms the "Inaccuracy Traceability Record," which serves as input for corrective actions. Analyze the root cause (e.g., too long calibration cycle, improper use, insufficient protection) and implement improvements.

4.8 Use, Handling, Storage, and Disposal

4.8.1 Pre-use inspection: no rust, no dents, no bends; clean measurement faces with no burrs; flexible moving parts; correct zero position; and valid labels. If the inspection is不合格, immediately hand it over to the Quality Department for handling.

4.8.2 Usage requirements: Use the instruments according to the methods and ranges specified in the instrument manual, and do not exceed the range or temperature limits. For general gauges, the measurement force should be uniform, and do not strike or forcefully pull. For electronic instruments, preheat after turning on and zero according to the manual. For specialized inspection tools, use them according to the operation diagrams and do not substitute or modify them.

4.8.3 Daily maintenance: After use, wipe clean, apply rust preventive oil, and store in a dedicated box or rack. Do not mix with workpieces or tools. For battery-powered instruments, replace batteries periodically and prevent leakage and corrosion.

4.8.4 Handling and storage: For long-distance transportation, use the original packaging or equivalent shockproof packaging. The storage environment should be clean, dry, and free of corrosive gases, with temperature and humidity within the ranges specified in the instrument manual. Long-term stored instruments should be checked quarterly and recorded. If the storage period exceeds the calibration validity period, re-calibration is required before use. If the storage period is less than 3 months but the validity period has not expired, periodic verification should be conducted.

4.8.5 Disposal conditions: irreparable; repair costs exceeding 50% of the price of a new instrument of the same type; precision cannot be restored to the specified requirements; the manufacturer has discontinued production and no spare parts are available; or legal requirements for mandatory disposal. Scrapped instruments must have their labels removed, adjustable components dismantled or destroyed, and be stored separately to prevent misuse.

4.9 Flowchart (Text Version)

Instrument purchase and selection → Factory acceptance (appearance, function, and accompanying certificate verification) → Classification determination (A/B/C) → Numbering and ledger registration → Determination of calibration method and cycle → Affixing status labels → Putting into use → Sending for calibration (external) or arranging internal calibration before expiration → Review of calibration certificate/internal calibration record → Metrological confirmation (qualified/limited use/unqualified) → Updating ledger and labels → Periodic verification (according to plan and timing) → Continue using if controlled, stop and trace inaccuracy if uncontrolled → Disposal (continue using/limited use/repair/downgrade/scrap) → Archiving records.

Abnormal loop: If any step identifies unqualified or uncontrolled instruments, immediately isolate and stop use, and enter the inaccuracy traceability and corrective action process.

4.10 Form List, Fields, and Filling Instructions

（1）QR-7.1.5-01 Measuring Instrument Ledger

Fields: Serial Number | Instrument Number | Name | Model and Specifications | Measurement Range | Resolution | Accuracy Class/Maximum Permissible Error | Manufacturer | Factory Number | Purchase Date | Activation Date | Using Department | Storage Location | Category (A/B/C) | Calibration Method (External/Internal/No Calibration) | Calibration Institution | Calibration Cycle (Months) | Last Calibration Date | Valid Until | Status | Remarks.

Filling Instructions: One row per instrument; the instrument number must be unique and not repeated; any change in "Category" must be noted in the remarks with the change date and approver; after each quarterly physical verification, the verification date and verifier should be recorded in the "Status" column or a separate verification record.

Example row: 1 | JC-PZ-001 | Vernier Caliper | 0～150mm | 0～150mm | 0.02mm | ±0.02mm | Some Gauge Factory | 12345678 | 2024-03-10 | 2024-03-15 | Quality Department | Metrology Room | B | External | XX City Metrology Institute | 12 | 2026-03-15 | 2027-03-14 | Qualified | —.

（2）QR-7.1.5-02 Annual Calibration Plan / Monthly Calibration Implementation Details

Fields: Serial Number | Instrument Number | Name | Using Department | Calibration Method | Calibration Institution | Last Calibration Date | Valid Until | Planned Calibration Month | Send Date | Return Date | Responsible Person | Completion Status | Remarks.

Filling Instructions: Schedule months based on the validity period, with external calibration 30 working days in advance and internal calibration 10 working days in advance; completion status should be "Completed/Delayed/Cancelled" with reasons noted; any plan adjustments must retain the original plan traces.

Example row: 12 | JC-PZ-001 | Vernier Caliper | Quality Department | External | XX City Metrology Institute | 2026-03-15 | 2027-03-14 | 2027-02 | 2027-02-20 | 2027-02-28 | Zhang | Completed | —.

（3）QR-7.1.5-03 Metrological Confirmation Record

Fields: Instrument Number | Name | Calibration Certificate Number | Calibration Institution | Calibration Date | Standard Device and Traceability Information | Calibration Points (Nominal Value) | Reading | Measurement Error | Correction Value | Uncertainty | Maximum Permissible Error | Single Item Judgment | Comprehensive Conclusion (Qualified/Limited Use/Unqualified) | Limited Use Explanation | Confirmer | Confirmation Date.

Filling Instructions: Fill in each calibration point individually, do not just copy the certificate conclusion; if uncertainty is provided, specify the judgment rule; for limited use, clearly state the restricted range or the use method requiring correction values; sign by the Quality Department confirmer, and if necessary, co-sign by the Technical Department.

Example row: JC-PZ-001 | Vernier Caliper | JL2026-0088 | XX City Metrology Institute | 2026-03-15 | Gauge Block Class 3, traceable to national standard | 50.00mm | 50.01mm | +0.01mm | -0.01mm | U=0.01mm (k=2) | ±0.02mm | Qualified | Qualified | — | Wang | 2026-03-18.

（4）QR-7.1.5-04 Periodic Verification Record

Fields: Instrument Number | Name | Verification Date | Verification Method (Verification Standard Method/Transfer Comparison Method/Retest Sample Method/Characteristic Inspection Method) | Verification Standard Number and Assigned Value | Environmental Conditions (Temperature, Humidity) | Measurement Times | Each Observation Value | Average Value | Standard Deviation | Instrument Reading | Deviation | U1 | U2 | En Value | Judgment Criteria | Conclusion (Controlled/Uncontrolled) | Uncontrolled Handling Measures | Verifier | Reviewer.

Filling Instructions: Retain original observation data; accurately record environmental conditions; include the judgment calculation process in the record; for uncontrolled instruments, specify isolation, traceability, and corrective action numbers in the same record.

Example row: JC-PZ-001 | Vernier Caliper | 2026-09-10 | Verification Standard Method | HZ-001, assigned value 50.000mm | 22.5℃/55%RH | 5 | 50.01/50.01/50.02/50.01/50.01 | 50.012mm | 0.004mm | 50.012mm | 0.012mm | 0.005mm | 0.008mm | 1.27 | |En|≤1 | Uncontrolled | Isolated and traced, see ZJ-2026-003 | Li | Zhang.

（5）QR-7.1.5-05 Inaccuracy Traceability Record

Fields: Instrument Number | Discovery Date | Discovery Method (Calibration/Verification/In Use) | Degree of Inaccuracy | Last Controlled Date | Traceability Time Interval | Involved Batches/Product Numbers | Inspection Record Numbers | Error and Tolerance Comparison | Impact Judgment (Yes/No/Pending) | Disposal Measures | Traceability Conclusion | Compiler | Approver.

Filling Instructions: The starting point of the traceability interval is the last qualified calibration or controlled verification date; if the impact judgment is "No," specify the quantitative comparison basis of the error and tolerance; if involving customers, note the notification date and customer response.

（6）QR-7.1.5-06 Instrument Disposal Record

Fields: Instrument Number | Name | Disposal Date | Disposal Reason | Disposal Method (Re-calibration after repair/Downgrade for limited use/Convert to reference use/Scrap) | Repair Unit | Repair Content | Re-calibration Result | Scrap Confirmation (Dismantle adjustable components, remove labels) | Applicant | Approver.

Filling Instructions: Scraping must be confirmed by at least two people and handled to prevent misuse; for downgrading or converting to reference use, update the ledger, labels, and usage instructions.

（7）QR-7.1.5-07 External Calibration Institution Evaluation Form / Qualified Calibration Institution Directory

Fields (Evaluation Form): Institution Name | Qualification Type and Certificate Number | Recognized Capability Range (Projects, Ranges) | Certificate Validity Period | Service Response Time | Delivery Performance | Historical Error Records | Evaluation Conclusion | Evaluator | Evaluation Date | Review Date.

Fields (Directory): Serial Number | Institution Name | Qualification Number | Recognized Project Range | Contact Person | Contact Information | Valid Until | Status.

（8）QR-7.1.5-08 Internal Calibration Record / Internal Calibration Specification Registration Form

Fields (Internal Calibration Record): Internal Calibration Date | Instrument Number | Name | Standard Device Number and Validity Period | Environmental Conditions | Calibration Points | Standard Device Reading | Instrument Reading | Measurement Error | Judgment | Conclusion | Operator | Reviewer.

Fields (Specification Registration Form): Specification Number | Applicable Instrument Category | Basis Regulations | Calibration Points and Methods | Standard Device Requirements | Judgment Criteria | Compiler | Approver | Effective Date.

5. Related Records

• QR-7.1.5-01 Measuring Instrument Ledger
• QR-7.1.5-02 Annual Calibration Plan / Monthly Calibration Implementation Details
• QR-7.1.5-03 Metrological Confirmation Record
• QR-7.1.5-04 Periodic Verification Record
• QR-7.1.5-05 Inaccuracy Traceability Record
• QR-7.1.5-06 Instrument Disposal Record
• QR-7.1.5-07 External Calibration Institution Evaluation Form / Qualified Calibration Institution Directory
• External calibration certificates and verification certificates (originals or scanned copies, archived)
• Calibration commission forms, internal calibration personnel qualification authorization records

Record retention period: Calibration certificates, metrological confirmation records, periodic verification records, and inaccuracy traceability records should be retained for no less than three calibration cycles and no less than three years. Records involving product traceability should be retained according to the longest retention period specified in the "Record Control Procedure."

6. Related Documents

• Chapter 7.1.5 of the Quality Manual: Monitoring and Measuring Resources
• "Control of Monitoring and Measuring Resources Procedure" (the 10th document in the package)
• "Infrastructure and Equipment Management Procedure" (the 9th document in the package)
• "Record Control Procedure" (the 4th document in the package)
• "Document Control Procedure" (the 3rd document in the package)
• "Nonconforming Product Control Procedure" (the 22nd document in the package)
• "Nonconformity and Corrective Action Procedure" (the 27th document in the package)
• "Corrective Action Implementation and Verification Work Instruction" (the 45th document in the package)
• "Employee Training Work Instruction" (the 31st document in the package)
• "Process Inspection Work Instruction" and "Finished Product Inspection Work Instruction" (the 35th and 36th documents in the package)
• Relevant metrological verification regulations and calibration specifications (JJG, JJF series, referenced according to the instrument)

Usage Instructions

1. How to Modify According to Actual Enterprise Conditions

1. Replace the Instrument List According to Product Type: The instrument enumeration in section 2.1 covers common types in machining, assembly, electrical, food, and chemical industries. The enterprise should retain only the categories it actually uses and delete the rest. When adding new categories, supplement the corresponding internal calibration basis or external calibration requirements.
2. Adjust Responsibilities According to Organizational Structure: If there is no independent metrology room, the responsibilities in section 3.1 can be merged into the Quality Department's comprehensive position, but must be clearly assigned to specific positions rather than departments. If there is no Equipment Department, the technical responsibilities for online measurement devices can be assigned to the Technical Department or Production Department. Responsibilities not assigned to specific positions are the most common reason for "written but not used" in this document.
3. Set Judgment Criteria According to Measurement Capability: The specific values for A/B/C classification and calibration cycles should be set based on the tolerance of the measured characteristics, the drift trend of the instruments, and actual inaccuracy records. Do not copy the example cycles from this document. If the measurement capability is insufficient (the maximum permissible error of the instrument is greater than one-third of the tolerance band), prioritize replacing the instrument or introducing correction values, rather than relaxing the judgment criteria.
4. Choose Calibration Methods According to Resource Conditions: The prerequisite for internal calibration is the availability of standard devices, the environment, and personnel. If resources are insufficient, it is better to send all instruments for external calibration rather than use untraceable standard devices for internal calibration, which is one of the most serious defects in audits.
5. Verify According to the Mandatory Inspection Directory: The enterprise must verify whether its instruments are within the national mandatory inspection directory. If they are, they must be sent to legal institutions for calibration and obtain a calibration certificate, and cannot be replaced by internal calibration or third-party calibration reports.

2. Audit Focus Points

1. Whether the ledger and physical instruments correspond one-to-one, and whether there are any unregistered instruments in use; whether the numbers are unique and whether scrapped numbers are sealed.
2. Whether the calibration certificates are valid and cover the usage period; whether the calibration institutions are on the qualified list and whether their recognized ranges cover the calibrated ranges.
3. Whether there are independent metrological confirmation records, and not just based on the "Conclusion" section of the certificate; whether uncertainty is considered.
4. Whether there is a basis and adjustment record for the calibration cycle, and whether there is a formal approach of "12 months every year without adjustment."
5. Whether periodic verification is truly implemented, and whether the records include original observation data and calculation processes; whether the traceability and corrective actions for uncontrolled verification are closed-loop.
6. Whether the status labels are consistent with the ledger and certificates; whether the using departments of limited-use instruments are aware of the restrictions.
7. Whether there is a basis for defining the traceability interval when inaccuracy occurs, and whether delivered products have been assessed.
8. Whether the reasons for classifying C Class instruments are clearly stated in the ledger to prevent instruments that should be managed from being avoided under the guise of "reference use."

3. Common Errors

1. Treating Calibration as Verification: Calibration only provides measurement errors and does not give a qualification judgment. If the enterprise does not perform its own metrological confirmation, it will result in a compliance loophole of "having a certificate but no conclusion."
2. Using Certificate Validity as Confirmation Date: The issuance date of the certificate and the confirmation date are different, leading to delayed confirmation and the inability to self-verify the effectiveness of measurement data used during the period.
3. Unreasonable Selection of Calibration Points: Calibrating only the mid-range or a few points, not covering the actual range used by the enterprise; calibration points should be selected based on the actual usage range and additional points should be added near the range endpoints.
4. Ignoring Pre-Adjustment Measurement Changes: The certificate shows that the instrument has been adjusted but does not record the adjustment amount, making it impossible to determine if previous measurement results were affected, and preventing the closure of traceability.
5. Periodic Verification Becomes "Copying Previous Data": Verification without a verification standard, original data, or judgment calculation, which is a typical risk of record forgery in audits.
6. Omission in Standard Device Management: Standard gauge blocks and weights used for internal calibration are not included in the ledger or not regularly sent for calibration, leading to a broken traceability chain.
7. Only Replacing Instruments Without Traceability: Scrapping and replacing instruments without assessing previous batches of products, leaving risks with customers.
8. Disconnection Between Labels and Ledger: Instruments have expired but the labels have not been updated, and the ledger has not been revised, leading to different validity periods indicated by the physical instruments and records.

The essence of managing measuring instruments is to ensure that the evidence of measurement is reliable.

Knowledge code: 2.3.1

Version: v20260809

Author: QTank QTank is dedicated to providing systematic knowledge, methodologies, and practical tools for quality management professionals to continuously enhance the quality capabilities of enterprises.