Back to the Basics:
Time to Calibrate?
So when should I calibrate inspection equipment?
Ideally, calibration should occur before every use, but that is not always practical or required. However, there are no hard and fast rules.
Technically, calibration is required when there is a historical change in accuracy. Beyond that, determining regular interval periods is usually customized to a specific quality system. Many large manufacturers have in-house specifications and guidelines relying on product inspection results, an instrument's drift, historical records, and some scheduled intervals.
Some points to keep in mind when determining your calibration schedule:
- Quality and stability of the measuring equipment
- Frequency of use (instruments used more often get calibrated more often)
- Extent of stress during use
- Industry standards or regulations
- Initial accuracy specification
- Importance of the instrument's absolute measurement accuracy
- Calibration frequency of similar models
- Existence of a secondary back-up device
- Manufacturer's recommendations
Nevertheless, a good rule of thumb for many instruments is to calibrate at least once per year. However, there are specific instances where calibration should occur immediately or the interval should be adjusted. Some of the more common instances are:
- Inspection Disputes
- Different readings from different instruments of the same model
- Repeatability issues with the same gage (i.e. the gage gives different readings on the same part)
- Products that are increasingly out of specification could be attributed to an inaccurate gage
- Any instrument suffering any form of damage should be calibrated
- Gauge blocks or frame standards should be calibrated before the next use after any damage is inflicted, especially if dropped.
- If dropped less than two feet, some less accurate gages may only require checking against a known standard instead of requiring immediate calibration
- Heavy use/increased workload
- Inspecting an increased workload increases the chances that an instrument will no longer be properly calibrated.
- Gages (or parts of gages) that fully engage in interference contact with the object to be measured can wear down over time (i.e. tapered thread plug gages, thread rolls), especially in high volume inspections.
- After any repair is made, equipment should be calibrated.
- Auditors may have their own calibration requirements and request more frequent intervals
- Calibration may coincide around the audit interval
- Industry Standards and Industry Association Regulations
- API recommends calibrating indicators once per quarter.
- Standardization Organization Guidelines
- ISO 9001 requires calibration for gage blocks, micrometers, pin gages, calipers, thread gauges, mechanical gauges, transducers, other measurement tools, and a variety of digital measurement devices (e.g. voltmeters, oscilloscopes, etc.) on a regular interval or before usage.
- ISO 9001 also requires a reassesment every 3 years which may cause additional calibrations or changes to a schedule.
- Manufacturer Recommendation
- Interval times provided along with acceptable tolerances over that period
- Ex.: Gagemaker recommends calibrating an MRP gage undergoing normal usage at least once a quarter
- Not following the recommendations may affect warranties
- May have specific reasons for the time period/use level/etc.
Gagemaker provides full service calibration and repair on all Gagemaker manufactured products. We can also help in establishing in-house calibration which grants greater control over the calibration process while saving time and money. The Gagemaker In-House MIC TRAC 4000 Series Precision Gage Calibration System enables you to inspect parts, calibrate and track a wide variety of gage styles, including ring and plugs. If you need to only measure parts, calibrate hand held gages, and preset indicator style gages, the Gagemaker Shop Floor MIC TRAC 3000 Series Gage Setting and Part Measurement System may be a better option.
Look for more Gagemaker's Back to the Basics in the months ahead!
Strengthening the Gagemaker Network
Meeting for the Future
Gagemaker hosted its first distributor and reseller meeting at the Crowne Plaza River Oaks Hotel in Houston last week. Over 60 representatives traveled from China, Russia, UK, Singapore, Canada, and Mexico, as well as all over the United States to attend this event which featured product demonstrations, plant tour, information sessions and annual awards.
The first day of the meeting was filled with informational sessions that covered a variety of different topics including sales techniques, product development and hands-on training workshops. The day was capped off with a little fun with a welcome reception followed by an evening dinner banquet where many prizes were won and outstanding distributors and resellers were awarded for outstanding achievements in sales and service.
The second day of the meeting featured a morning tour of the Gagemaker campus followed by sessions on quoting, ordering and marketing. The meeting closed with a roundtable discussion where Gagemaker management and attendees had open conversation regarding products, service and procedures which generated many great ideas for the future.
The Gagemaker team enjoyed their guests from all over the world and plans for the 2013 meeting are already in motion!
Locate your local Gagemaker authorized distributor/reseller