Regular calibration is critical to quality manufacturing operations. Weighing equipment such as platform scales, laboratory balances, weighbridges and silos need to be calibrated at regular intervals to ensure accuracy. You can do this by using a third party calibration laboratory such as D Brash & Sons Ltd or conducting in-house calibration. 

At first thought, it might seem easier to calibrate on your own, but before you choose, there are 5 considerations for you to think through.

1 Meeting Quality Guidelines

Organisations must conduct calibration testing that meets documented calibration requirements. An internal QMS (quality management system) may contain requirements stipulating testing frequency and laboratory proficiency. Regulatory or accrediting bodies, such as ISO 9001 or AS 9100, have multiple quality management requirements. A manufacturer must consider if it is possible to meet all requirements when performing in-house calibration.

2 Time

A common misconception is that in-house calibration saves time!

We carry out 98% of all calibrations on customers sites, and equipment does not need to be returned to us for this service.

 Compare that to performing calibration in-house. In most cases, it will take an in-house technician longer to test the same items. An in-house technician is not required to perform testing on the same types of instruments continually versus a third party calibration lab technician. Often the person performing in-house calibration testing has other responsibilities, which may be put on hold while testing occurs. This effect is most common in small to midsize manufacturing environments.

3 Investment

One of the main considerations for in-house calibration testing is the initial investment. Standards require a considerable upfront expense. 

You will need to purchase and maintain suitable test weights for calibrating each scale.

Take for example a business with three scales of the following capacities

Scale 1 - 2000Kg x 0.5Kg Capacity

Scale 2 - 300Kg x 0.05 Kg Capacity

Scale 3 - 100g x 0.001g Capacity

Each scale will need its own set of test weights to carry out the calibration effectively. For the 1500Kg capacity scale to be effectively tested the you would need 50 x 20Kg Test Weights, or at least 50% of the capacity 1000Kg. 

For the second scale you could utilise the weights you have purchased for scale 1.

With scale 3 you will need a set of stainless steel E2 test weights to effectively calibrate the equipment, so again at least 6 weights to effectively test the range of this unit.

Total Test Weights required = 56 weights.

In addition these weights will also require annual calibration to ensure their accuracy to a relevant calibration standard. This also comes at a cost!

Third party calibration laboratories have an easier time recouping the costs involved, due to the volume of equipment that is tested with each standard. 

Anyone that is part of the in-house calibration team will need ongoing, formal training on calibration procedures to ensure their competency. 

4 Adjustment

In-house calibration staff are unlikely to have the technical ability and technical expertise to be able to adjust a weighing scale when it fails In-house calibration. Brash Calibration contracts includes adjustments both mechanical and electrical assuring you that the results you achieve from the weighing devices are accurate and reliable.

5 ISO 17025 Accreditation

ISO/IEC 17025 accreditation is given to laboratories that meet calibration testing competency requirements. Many quality guidelines require that calibration should be performed by an ISO 17025 accredited laboratory. As one of the main considerations for in-house calibration, this can be problematic. The accreditation process requires yearly expenses, and the laboratory must pass thorough audits and reviews. If you are required to have calibration testing performed by an ISO/IEC 17025 accredited laboratory, in-house calibration will most likely not work for your quality program.

Keep these considerations in mind as you make your decision.