On the day of a customer audit, the finding often starts not with a complex process but with the calibration label on a single vernier caliper. The due date expired three weeks ago. Nobody can say where the certificate is. This pattern repeats itself in Japanese-owned factories across Thailand, and it is not a problem of calibration technique. It is a problem of the management structure around calibration. This article walks through what ISO 9001 actually requires for measurement traceability, where to send instruments for calibration in Thailand, and how far a calibration management system takes you, in the order the work actually happens on the shop floor.
Why calibration management breaks down in Thai factories
The plant calibrates, and still gets written up
Among Japanese manufacturers with production sites in Thailand, almost none skip instrument calibration altogether. The budget is allocated. A contract with an external calibration laboratory is in place. Yet calibration-related findings keep appearing in customer audits and ISO surveillance visits, because what the auditor evaluates is not whether calibration was performed. It is whether the plant knows the calibration status of every instrument at all times and can prove it.
Here is the kind of thing an auditor actually does. Pull three instruments at random from a shelf on the floor, read their identification numbers, look those numbers up in the register, ask for the most recent calibration certificate for each, and compare the next due date against today’s date. Any factory where that sequence takes more than five minutes is already carrying risk. There were two versions of the register. Certificates were kept both as PDFs and on paper. The person who filed them has left the company and nobody knows where the originals are. That is what the findings almost always come down to.
Gaps come from dispersion, not from volume
While the plant has a few dozen instruments, an Excel sheet plus one person’s memory is enough. Trouble starts when the count reaches several hundred, storage is split across the inspection room, the individual lines, outgoing inspection and the maintenance store, ownership is split between Thai staff and Japanese expatriate managers, and certificates start arriving in a mix of Thai, English and Japanese.
Doubling the number of instruments doubles the administrative load. But when location, owner and language multiply against each other, the number of exchanges needed to confirm a single fact grows far faster than the instrument count. That dispersion is an inevitable consequence of organisational growth, so reformatting the Excel register does not solve it. A calibration management system becomes necessary at exactly the point where dispersion exceeds what manual coordination can absorb.
What ISO 9001 requires for instrument calibration
7.1.5.2 Measurement traceability
Clause 7.1.5.2 of ISO 9001 (2015 edition) applies when measurement traceability is a requirement, or when the organisation considers it essential in order to have confidence in the validity of measurement results. In those cases, measuring equipment must be calibrated or verified, or both, at specified intervals or prior to use, against measurement standards traceable to international or national measurement standards. Where no such standards exist, the basis used for calibration or verification must be retained as documented information. The equipment must be identified in order to determine its calibration status. And it must be safeguarded from adjustments, damage or deterioration that would invalidate the calibration status and subsequent measurement results.
The phrase that most plants read past is “specified intervals”, and specifically who specifies them. The standard names no number of days or months. The organisation itself decides the interval, and the organisation must be able to explain the basis for that decision. Plenty of factories apply the manufacturer’s recommended twelve months uniformly to every model. If the auditor asks why twelve months, and nobody can answer, that is an interval set without justification and it is fair game for a finding.
The real test is what happens when an instrument fails calibration
The second requirement, and the one most often missing in practice, covers what the organisation does when measuring equipment is found to be unfit for its intended purpose. ISO 9001 requires the organisation to determine whether the validity of previous measurement results has been adversely affected, and to take appropriate action as necessary.
In practical terms that is a requirement for retrospective investigation. If a coordinate measuring machine is found outside tolerance at its annual calibration, the plant must assess every product that machine judged as pass or fail between the last successful calibration and today, and decide whether any of those judgements could have flipped. What that assessment needs is a link between the instrument and the inspection record. Which instrument measured which lot, and when. A factory that has not retained this cannot narrow the scope of the investigation at all, and ends up having to suspect every lot in the window. On the inspection record side, combining the register with the approach covered in the cost and payback of automated inspection data collection lets you carve out the affected scope mechanically, instrument by instrument.
On the next revision of ISO 9001, certification bodies have announced an expected publication date within 2026, but as of the time of writing it has not been issued. Nothing published so far suggests that the backbone of the requirements for measuring equipment will change substantially, so the operating discipline you should be building now is unaffected.
IATF 16949 stacks additional requirements on top
In automotive component plants, the IATF 16949 requirements sit on top of ISO 9001. For calibration and verification records, the items to be included are listed explicitly. Two representative examples are a statement on the validity of previous measurement results when the equipment is found to be out of specification, and a statement of conformance to specification. On top of that, measurement systems that appear in the control plan require measurement systems analysis (MSA), not just a calibration certificate.
For an automotive supplier, in other words, “we have the certificate” is only the starting line. The content of the certificate has to be readable in a form that supports a judgement, the impact assessment for out-of-specification findings has to survive as a record, and all of it has to be presentable within a few minutes in the audit room. The full picture of traceability requirements for automotive parts is covered in automotive parts traceability for IATF 16949.
Where to send instruments for calibration in Thailand
Understand the traceability chain correctly
The first thing to grasp when arranging calibration in Thailand is the structure of the chain that gives a certificate its international standing. It runs in this order.
The plant’s instrument is calibrated by a calibration laboratory accredited to ISO/IEC 17025. The reference standards that laboratory uses are traceable to NIMT (National Institute of Metrology Thailand), the national metrology institute of Thailand. NIMT’s standards have their international equivalence underwritten through the CIPM MRA, the mutual recognition arrangement of the International Committee for Weights and Measures, and are ultimately connected to the SI units.
NIMT was established on 1 June 1998 under the National Metrology System Development Act of B.E. 2540, with the mandate to establish and maintain Thailand’s national measurement standards and to disseminate those standards within the country. In any discussion of calibration inside Thailand, this is the ultimate point of reference.
If any single link in that chain is broken, the certificate means nothing beyond an internal record. Conversely, when the chain holds, a certificate issued by a laboratory in Thailand stands up in an audit by the Japanese parent company and in a customer audit from Europe or North America alike.
The CIPM MRA and the ILAC MRA are separate frameworks
This is where the most common misunderstanding in daily practice lives, and getting it wrong makes the statement factually incorrect. The CIPM MRA and the ILAC MRA are not the same thing.
The CIPM MRA is a framework whose participants are national metrology institutes (NMIs), their designated institutes, and a small number of international organisations invited by the CIPM. According to the published figures from the International Bureau of Weights and Measures (BIPM), there are 260 participants, made up of 98 NMIs, 158 designated institutes and 4 international organisations. A commercial calibration laboratory, however high its technical capability, is not a participant in the CIPM MRA. The explanation “the certificates from the commercial lab we use are listed under the CIPM MRA, so they are internationally accepted” is simply wrong.
The basis on which a certificate from a commercial ISO/IEC 17025 accredited laboratory is accepted internationally is the ILAC MRA instead, that is, the mutual recognition arrangement between accreditation bodies. If the accreditation body has signed the ILAC arrangement, calibration results from the laboratories it accredits are accepted in the other signatory economies. In Thailand, the accreditation body for calibration laboratories is TISI (Thai Industrial Standards Institute), which participates in the ILAC mutual recognition arrangement.
ILAC-G24 / OIML D 10:2022 makes the same separation. When it sets out the conditions under which calibration records can be used to determine recalibration intervals, it lists calibration by national metrology institutes and designated institutes that have been peer reviewed under the CIPM MRA, and calibration by laboratories accredited by a signatory to the ILAC arrangement, as clearly distinct items. At the level of international documents as well, these are treated as two parallel routes.
One institutional change is worth noting. On 1 January 2026, ILAC and IAF (the International Accreditation Forum) merged into Global Accreditation Cooperation Incorporated (Global ACI), and the ILAC MRA and the IAF MLA were succeeded by the Global ACI mutual recognition arrangement. The name and the operating body have changed, but the underlying structure, in which mutual recognition between accreditation bodies is what makes certificates from accredited commercial laboratories internationally acceptable, has not. If your internal documents use the term ILAC MRA, adding a note at the next revision will make the explanation smoother during an audit.
How to find an accredited calibration laboratory in Thailand
TISI publishes a list of calibration laboratories accredited against มอก. 17025, the Thai national adoption of ISO/IEC 17025. The scope of calibration is divided into three groups.
| Group | Fields covered | Typical instruments sent out from a factory |
|---|---|---|
| Group 1 | Electrical, frequency, temperature, relative humidity and related fields | Testers, thermometers, thermostatic chambers, data loggers |
| Group 2 | Force, mass, dimension, pressure and related mechanical fields | Vernier calipers, micrometers, weighing scales, torque wrenches, pressure gauges |
| Group 3 | Volume, chemical testing instruments and related chemical fields | Pipettes, volumetric flasks, pH meters |
This grouping is also useful when you collect quotations. Few laboratories cover all three fields on their own, so contracting with several laboratories by field is the realistic approach. Note that the English version of the TISI list is dated. It shows 170 calibration laboratories, but that page was last updated in December 2016. To confirm the current accreditation status, and whether an accreditation has been suspended or withdrawn, check the accreditation number against the Thai-language search database. Before signing a contract, always obtain the accreditation scope and confirm that the measurand and measuring range you want calibrated fall inside it. Even at an accredited laboratory, work outside the scope does not produce a certificate carrying the accreditation symbol.
When the JCSS certificate on an instrument brought from Japan runs out
When equipment is relocated or a new plant is commissioned, instruments often arrive from Japan with a JCSS calibration certificate attached. JCSS is Japan’s registration scheme for calibration service providers under the Measurement Act, and a certificate issued by an accredited provider under the international MRA arrangement, carrying the ILAC MRA accreditation symbol, is accepted in the participating economies. JCSS joined the APLAC mutual recognition arrangement in 1999 and the ILAC arrangement in 2000, and Thailand sits inside that framework.
That holds only for as long as the certificate the instrument arrived with is still within its validity period. Where to recalibrate the instrument after that date is a separate question, and there are three options.
- Ship it back to Japan for JCSS calibration. Continuity of the certificate is preserved, but you have to absorb transit time, export and import formalities, and the cost of a substitute instrument while it is away
- Calibrate at a TISI-accredited laboratory in Thailand. Lead time and cost drop sharply, but the certificate format and language change, so you need a revised internal procedure and an explanation prepared for the customer
- Calibrate at the manufacturer’s Thai subsidiary or service centre. Whether this counts as accredited calibration varies by manufacturer, so always confirm whether the accreditation symbol is present
This is not a decision to make in a hurry after the instruments have landed. The correct approach is to build the list of incoming instruments during the relocation planning phase and decide, for each one, where its next calibration will go. The first calibration due date after a move very often lands in the busiest period, just as the equipment enters volume production, and postponing it is a reliable way to end up with an expired instrument.
The limits of running calibration due dates on Excel and paper
Scanning a feature list will not convince anyone that a calibration management system is necessary. It is faster to look at the shape of the failures that actually occur, so here are four scenarios that come up repeatedly in Japanese-owned plants in Thailand.
Scenario 1 – The missed due date
The Excel register has a next calibration date column, and conditional formatting turns rows yellow as the date approaches. The problem is that nobody sees the colour unless somebody opens the file. The owner takes extended leave, or transfers to another department. Over those two months three instruments pass their due date, and the fact surfaces at the next customer audit.
What the plant carries at that point is not the expiry itself but the burden of retrospective investigation. Identify every lot judged with that instrument between the last calibration date and today, assess whether any judgement could have changed, compile a report and present it to the customer. It costs people, it costs time, and it costs credibility.
Scenario 2 – The certificate that cannot be found
Certificates arrive as PDFs and the practice is to save them to a shared folder. But whoever receives the certificate does the saving, and everyone names files differently. Some by instrument identification number, some by the laboratory’s document number, some by date only. On the day of the audit somebody searches for the certificate of one specific instrument, full-text search across the folder finds nothing, and the usual ending is that this one arrived on paper and was never scanned.
A certificate only means something once it is linked to the master record of the instrument. A file share is not a register. The same thinking applies well beyond measuring instruments, and the principle set out in quality data management systems in 2026, that a record must always be held against the identifier of the object it describes, applies here without modification.
Scenario 3 – The register does not match the floor
The register says 420 instruments. Counting the shelves and the floor turns up 403. The missing 17 are a mixture of items scrapped after failure but never removed from the register, items lent to another line and never returned, and items purchased but never registered.
What makes this state dangerous is that instruments not on the register are in use on the floor. Making pass or fail judgements with an uncalibrated instrument is the kind of finding that gets classified as major. An annual stocktake cannot keep up, and without a mechanism that updates the record at the moment an item physically moves, the drift will always come back.
Scenario 4 – The language and site barrier
Calibration certificates come in Thai or English, internal work instructions are in Thai, and reporting to the parent company is in Japanese. The comment field in the register says “รอผลสอบเทียบ” and the Japanese quality assurance manager cannot read it. Or it says something in Japanese that the Thai staff cannot read.
Companies with two or more sites face a further layer. The Rayong plant and the Chonburi plant use different register formats and different numbering rules for instrument identification. Simply answering how many instruments the group owns, and how many of them are overdue, becomes a consolidation exercise that takes the responsible person several days.
What a calibration management system actually needs to do
To close out the four scenarios above, here is what a calibration management system has to provide. You do not need to satisfy every line of a vendor’s feature list. What matters is working down from the features that address your own failure scenarios first.
Master data for the instrument register
Everything else rests on this. For each instrument, hold the identification number, name, manufacturer, model, serial number, measuring range, resolution, tolerance, location, owning department, purchase date and status (in use, on loan, under repair, scrapped). The identification number must match the number on the physical label attached to the instrument, and that match is where everything else begins.
Risk-based calibration intervals
ILAC-G24 / OIML D 10:2022 states that the determination of the initial recalibration interval is based mainly on a risk assessment, and lists the factors to consider. These include the required measurement uncertainty, the type of measuring equipment, the risk of exceeding the maximum permissible error, manufacturer recommendations, trends in wear and drift, the extent and severity of use, environmental conditions, the frequency and results of intermediate checks, risks associated with transport, and legal requirements.
What the system side needs is to hold a criticality class per instrument reflecting those factors, and to hold the mapping from class to interval as a rule. It typically looks like this.
| Criticality class | Definition | Guideline interval | Intermediate check |
|---|---|---|---|
| A | Used directly for pass or fail judgement against customer specification. An out-of-tolerance result triggers retrospective work on shipped product | 6 months | Monthly |
| B | Used to judge in-process control values. An out-of-tolerance result requires process readjustment | 12 months | Quarterly |
| C | Used only for reference measurement or setup confirmation, never for pass or fail judgement | 24 months or excluded from calibration | None |
The point of holding a criticality class is not to shorten intervals. It is to concentrate a limited calibration budget on class A while lowering cost by removing class C from external calibration altogether. A blanket twelve months for every instrument is easy to administer, but it leaves the dangerous items thinly covered while spending money on items that do not need it.
Expiry alerts
This is the feature that stops due dates from being missed. Three points matter in the design. First, the notification has to go out without anyone opening a screen, which means push to email or chat. Second, the recipient has to be a role rather than an individual, so that the message still reaches a supervisor or backup when the usual owner is away. Third, it has to be staged. Ninety days out, a heads-up for budget and arrangement. Thirty days out, an instruction to arrange the work. Seven days out, a chase. On the due date and afterwards, a warning that the instrument must be taken out of service. Different lead times deserve different notifications.
Calibration laboratories in Thailand can run lead times over a month in their busy season, and for some models a thirty-day notice is already too late. Large fixed measuring machines, and instruments that need protective packing for transport, only get arranged in time if the ninety-day heads-up exists.
Electronic storage and retrieval of certificates
Attach the certificate PDF directly to the instrument record so that it opens in one click from the identification number. On top of that, carrying the key values written on the certificate as fields in the register changes how fast you can respond in an audit. At minimum, the calibration date, next due date, laboratory name and accreditation number, the judgement result, whether any out-of-specification condition was found, and the measurement uncertainty are worth holding as structured fields.
If someone still has to open the PDF and read the numbers inside it, that data is not really digital yet. The dividing line is whether the register’s list view lets you filter down to only the instruments flagged as out of specification.
Out-of-tolerance records and support for retrospective investigation
Ideally, when a calibration result falls outside tolerance, the record itself launches the impact assessment process. The system pulls the last passing calibration date automatically, offers that window as the assessment period, and keeps the identification of affected lots, the judgement and the record of action taken together as a single case. The statement of conformance and the statement on validity that IATF 16949 requires both fit inside that record.
Multilingual support and access control
Two things matter in practice. Users must be able to switch the display language individually, and register comments and statuses must be held as selectable values rather than free text. If status is a fixed list of choices, such as in use, calibration requested, at the calibration laboratory, under repair and scrapped, then switching the display language is enough for Japanese and Thai staff to read the same information. Keep the free-text field, but every field used for aggregation or search must be a selection. That is the iron rule in a multilingual environment.
Access rights work well at roughly four levels, being read only, register update, interval change, and scrap approval. Interval changes and scrapping in particular bear directly on the integrity of the records, so restrict the approvers and configure the system to retain a change history.
How to roll out a calibration management system
There is work to do before you choose a system. Get the order wrong and you migrate dirty data into a new tool, which digitises the confusion and nothing else.
Stage 1 – Stocktake the instrument register
Start by counting physical items. Inspection room, each line, outgoing inspection, the maintenance store, and individual toolboxes as well. Physically confirm every measuring and weighing instrument and record whether it carries an identification label and what the number is. This exercise will always surface instruments absent from the register and register entries with no physical item behind them. Resolve each difference into a definite answer, whether the item was scrapped, is on loan, or was never registered.
At a scale of several hundred instruments, budget roughly one week with two people. Many factories skip this and go straight to system selection, but migrating without a stocktake always means doing it again later.
Stage 2 – Criticality classification
Assign an A, B or C criticality to every instrument confirmed in the stocktake. The axis for the decision is whether the values from that instrument feed directly into a pass or fail judgement presented to the customer. Do not decide this inside the quality assurance department alone. Bring in production and engineering, because there is always a way the instrument is actually used that only the floor knows about.
It is normal to find that twenty to thirty percent of the total can be moved into class C at this stage. Vernier calipers used only for setup confirmation, thermometers read only as reference values. Removing these from external calibration and switching them to internal checks brings a visible drop in calibration spend. That said, the instruments you remove need a marking on the physical item showing that they are not to be used for pass or fail judgement, and the procedure must say so as well. Without the marking, somebody will eventually use one for a judgement.
Stage 3 – Set intervals and document the basis
Decide the mapping rule from criticality class to interval, and decide the conditions under which an exception is allowed. Then write up, on a single page, why you chose those intervals. List the factors from ILAC-G24 / OIML D 10 that you considered, and if the initial value came from the manufacturer’s recommendation, say so. That alone lets you answer the audit question about the basis for the interval on the spot.
The same document should carry the rules for reviewing intervals. For example, if the last three calibration results all fell within fifty percent of the tolerance the instrument becomes a candidate for extension, and a single out-of-specification result halves the interval. Of the review methods ILAC-G24 describes, the automatic adjustment and control chart methods only become feasible once calibration history is accumulated electronically.
Stage 4 – System implementation and data migration
Only now does the system itself come into play. The data to migrate is the register confirmed by the stocktake, the criticality classes, the intervals, and the most recent calibration certificates. There is no need to load every historical certificate. The latest one for each instrument, plus anything that came back out of specification, is enough to start operating.
The one thing to settle during migration is the numbering rule for identification numbers. With multiple sites, unify to a group-wide rule that includes a site code. Miss this opportunity and the per-site numbering becomes entrenched, and the cost of consolidating later rises steeply.
Stage 5 – Making the new way stick
The three months right after go-live decide the outcome. Two things make it stick. Fix a date on which parallel operation with paper and Excel stops, and make it explicit who responds to alerts. If parallel operation continues, one of the two will stop being updated, without exception.
Review with indicators after three months. Is the count of expired instruments zero? Is the average number of days from alert to calibration arrangement within expectation? Has the time taken to present a certificate in an audit come down? If those three are moving, the new way has taken hold.
Model case – Cost estimate for an automotive parts plant with 420 instruments
To show the effect concretely, here is an estimate for a fictional model plant. Every assumption behind the numbers is stated, so substitute your own figures as appropriate.
Assumptions
A Japanese-owned automotive parts manufacturer located in Chonburi Province, 380 employees, with 420 measuring and weighing instruments in total. The breakdown is as follows.
| Category | Units | External calibration frequency | External calibrations per year |
|---|---|---|---|
| General measuring tools such as vernier calipers and micrometers | 260 | 130 units annually, the remaining 130 on internal check | 130 |
| Dial gauges, height gauges and similar | 60 | Annually | 60 |
| Fixed measuring machines such as CMMs and contour measuring machines | 8 | Annually | 8 |
| Torque wrenches | 34 | Twice a year | 68 |
| Thermometers, thermostatic chambers, weighing scales and similar | 58 | Annually | 58 |
| Total | 420 | — | 324 |
For the 130 general measuring tools moved to internal check, this plant performs intermediate checks twice a year, giving 260 internal check events per year.
Current annual administrative workload
Building up the workload of the current operation, run on an Excel register and a shared folder.
| Task | Unit time | Events per year | Hours per year |
|---|---|---|---|
| Administration per external calibration. Request form, pickup arrangement, receiving check, scanning and filing the certificate, register update, label replacement | 25 min | 324 | 135 hours |
| Recording per internal check | 10 min | 260 | 43 hours |
| Due date monitoring. Visual check of the Excel register and chasing other departments | 2 h per week | 48 weeks | 96 hours |
| Searching for and preparing certificates for customer audits and ISO surveillance | 8 h | 6 per year | 48 hours |
| Total | — | — | 322 hours |
That is roughly 320 hours a year. Taking 2,000 hours as the annual working time of one quality assurance staff member, 16 percent of that person’s year disappears into calibration administration.
Projected workload after implementation
The projected workload once a calibration management system is in place, with automatic due date alerts, electronic storage and search of certificates, and a single consolidated register.
| Task | Unit time | Events per year | Hours per year |
|---|---|---|---|
| Administration per external calibration. Request and receiving become standard entries, and the certificate is linked simply by selecting the file | 12 min | 324 | 65 hours |
| Recording per internal check. Entered directly from a tablet | 5 min | 260 | 22 hours |
| Due date monitoring. Reviewing alerts and issuing arrangement instructions only | 15 min per week | 48 weeks | 12 hours |
| Presenting certificates in customer audits and ISO surveillance. Displayed instantly from the identification number | 2 h | 6 per year | 12 hours |
| Total | — | — | 111 hours |
The difference is 211 hours a year, a reduction of about 65 percent. If a Thai quality assurance staff member is paid 35,000 baht a month, with a monthly cost of 42,000 baht including social security and other overheads, the annual cost is 504,000 baht. Divided by 2,000 annual working hours, the hourly rate is 252 baht. Converting the 211 hours saved gives roughly 53,000 baht a year.
The real benefit is not the labour saving
A figure of 53,000 baht a year is not what decides an implementation. The real benefit is never having a single retrospective investigation caused by an expired instrument.
Here is an estimate, for the same model plant, of what one retrospective investigation costs when product has been judged with an expired instrument.
| Item | Basis | Amount |
|---|---|---|
| Lot reconciliation and re-inspection covering a three month window | 2 QA staff × 5 days = 80 hours × 252 baht | 20,160 baht |
| Preparing the report for the customer and visiting to explain | 2 QA staff × 2 days = 32 hours × 252 baht | 8,064 baht |
| Sorting work on shipped product (assuming a shop floor operator rate of 95 baht per hour) | 6 operators × 3 days = 144 hours × 95 baht | 13,680 baht |
| Total | — | 41,904 baht |
One retrospective investigation runs to roughly 42,000 baht, about the same order of magnitude as the annual labour saving from the system. And there are losses this table does not price at all. A downgrade in the customer’s supplier rating, an increase in audit frequency, and the delay to everything else the quality assurance department should have been doing while it spent several weeks on this. Those effects are hard to quantify, and in reality they weigh more.
Three hundred and twenty hours a year of administration, and the standing risk of a retrospective investigation that could happen at any time. Weigh those two together when deciding whether the investment in a calibration management system pays back.
Frequently asked questions
What is a calibration management system
It is a mechanism that consolidates the register of measuring and weighing instruments held by a plant, together with calibration intervals, due dates, calibration certificates and calibration results, and automatically notifies the responsible people when an instrument approaches its due date. Besides dedicated packaged software, the capability is sometimes delivered as a function inside a production management system or a maintenance management system. The essential difference from an Excel register is twofold. Due dates continue to be managed whether or not anyone opens a screen, and you can reach a certificate and its history immediately from the instrument identifier.
How should we decide calibration due intervals
ISO 9001 specifies no number of days and requires the organisation to determine intervals for itself. ILAC-G24 / OIML D 10:2022 states that the initial interval is determined on the basis of a risk assessment, and lists the required measurement uncertainty, the type of equipment, the risk of exceeding the maximum permissible error, manufacturer recommendations, trends in wear and drift, the extent and severity of use, environmental conditions, and the frequency and results of intermediate checks as factors to weigh. In practice, take the manufacturer’s recommendation as the initial value, adjust by criticality class, and decide on extension or shortening once about three calibration cycles of history have accumulated. Always retain the basis for the decision in a document.
Where should we send instruments for calibration in Thailand
The default is an ISO/IEC 17025 calibration laboratory accredited by TISI. TISI publishes a list of accredited calibration laboratories, divided into three groups covering electrical and temperature, force, mass and dimension, and volume and chemistry. Always obtain the accreditation scope before signing, and confirm that the measurand and measuring range you need fall inside it. Even at an accredited laboratory, calibration outside the scope does not produce a certificate carrying the accreditation symbol. The traceability of a certificate issued by a calibration laboratory connects to the SI units by way of NIMT.
Are certificates from commercial calibration laboratories internationally accepted under the CIPM MRA
No, that understanding is incorrect. Participation in the CIPM MRA is limited to national metrology institutes, their designated institutes and international organisations invited by the CIPM. Commercial calibration laboratories are not participants. The basis on which certificates from accredited commercial laboratories are accepted internationally is the ILAC MRA, the mutual recognition arrangement between accreditation bodies, and from 1 January 2026 the Global ACI mutual recognition arrangement that succeeded it. Confusing the two in internal explanatory material invites doubts about your technical credibility in an audit.
Is in-house calibration acceptable
Yes, provided the conditions are met. Even when calibration is performed internally, the reference standards used must be traceable to national measurement standards, the calibration procedure must be documented, the competence of the person performing it must be confirmed, and the measurement uncertainty must be evaluated. Checking general measuring tools internally against gauge blocks is widely practised, but if those gauge blocks are not themselves calibrated at an accredited laboratory, the chain is broken. Manage in-house calibration records in the same register as external calibration.
How many years should calibration certificates be retained
The standard sets no specific number of years. In practice the baseline is to match the retention period for quality records defined by your customer. The automotive industry often requires long retention aligned to the product lifecycle, and ten years or more is not unusual. What matters more than the number of years is being able to retrieve the certificates covering the relevant window when a retrospective investigation becomes necessary. Retaining paper certificates only carries a risk of fading and loss, so parallel electronic storage is recommended.
Summary
What trips up Japanese-owned plants in Thailand on instrument calibration management is not calibration technique. It is the structure for knowing and proving calibration status at all times. Clause 7.1.5.2 of ISO 9001 asks for more than periodic calibration. It covers calibration against traceable standards, identification of calibration status, and retrospective assessment when an instrument is found out of specification.
When choosing where to send instruments in Thailand, the prerequisite is understanding the chain that runs from the plant’s instrument through an ISO/IEC 17025 accredited laboratory to NIMT and on to the SI units. The basis on which certificates from accredited commercial laboratories are internationally accepted is the ILAC MRA, and from 1 January 2026 the Global ACI mutual recognition arrangement, while the CIPM MRA is the framework of national metrology institutes and their designated institutes. Getting this distinction right at the stage of internal explanatory material keeps your account steady during an audit.
Excel and paper reach their limit the moment instrument count, storage location and working language disperse. What a calibration management system has to provide is master data for the register, risk-based interval setting, staged expiry alerts, electronic storage and structured fields for certificates, support for out-of-specification retrospective investigation, and multilingual operation. Start the implementation only after the stocktake of the instrument register, the criticality classification, and the interval setting with its documented basis are complete. Keep that order and, as the model case shows, roughly 200 hours a year of administration disappears, and more importantly the heavy incident of a retrospective investigation never happens in the first place.
Where to begin the stocktake of your instrument register, how to split your instruments by criticality, how to connect calibration management to the production management system you already run. Circumstances differ from plant to plant, so general principles alone will not answer these. TOMAS TECH supports Japanese manufacturers in Thailand in building production and quality management structures, and we are happy to talk even while you are still exploring options and the requirements are not yet fixed. Looking at your current register together and sorting out where it is realistic to start is a perfectly good place to begin. Feel free to reach us through the contact page.
References
- BIPM CIPM MRA Participation — Eligibility for the CIPM MRA and the breakdown of participating institutes
- NIMT About Us — Legal basis and role of the National Institute of Metrology Thailand
- TISI List of Accredited Calibration Laboratories — English list of TISI accredited calibration laboratories and the field groups
- TISI Accredited Laboratory Search Database — Database for checking current accreditation status
- ILAC-G24 / OIML D 10:2022 Guidelines for the determination of recalibration intervals of measuring equipment — Methods and factors for determining recalibration intervals
- ILAC MRA and Signatories — Explanation of the mutual recognition arrangement between accreditation bodies
- Global Accreditation Cooperation Incorporated — The organisation succeeding ILAC and IAF and the status of the mutual recognition arrangement
- APAC Global Accreditation Cooperation Incorporated to replace IAF and ILAC — Announcement of the start of operations on 1 January 2026
- NITE Outline of JCSS — Position of JCSS and the international MRA accreditation symbol
- BSI ISO 9001 2026 Key Changes and Guidance — Expected publication of the next revision of ISO 9001 and the transition period
