Accredited DAkkS balance calibrations
ESSMANN | Waagen & Automation arranges calibrations in cooperation with the DAkkS-accredited calibration laboratory of KERN & SOHN GmbH.
DAkkS calibration for scales is a procedure in which the measurement results of scales are documented and evaluated to ensure that they meet the increasing quality requirements of demanding quality management systems. The DAkkS calibration certificate is a Europe-wide recognized document that meets the highest auditor and customer requirements. It offers the possibility of optimally evaluating the measurement results by containing a formula for calculating the measurement uncertainty. In this way, the user knows exactly what deviations to expect at each point of the linearity curve of his balance. In addition, so-called minimum weights can be calculated to check whether any tolerance specifications are being adhered to.
DAkkS calibration is carried out by accredited laboratories on the basis of the recognized DIN EN ISO 17025 standard. In contrast to a factory calibration certificate (ISO calibration), it is more meaningful as it includes a measurement uncertainty calculation for the respective scale. In addition, a calculation of a so-called minimum initial weight and, if applicable, a statement of conformity can also be documented.
In summary, DAkkS calibration of scales is an important procedure for ensuring the quality and accuracy of measurement results. It is carried out by accredited laboratories and offers the user the opportunity to optimally evaluate the measurement results.
If you want your scales to be calibrated, book an appointment directly. We will either come to you with test weights or you can send your scales to us.
Calibrating the scales – that’s why it’s important!
Precision is everything: How a scale works properly and why regular calibration is essential. Find out how you can determine the accuracy of your scales by calibrating them.
When should you calibrate a scale?
There are various reasons why a scale should be calibrated. In principle, a balance is calibrated to determine the accuracy of the measurements. A balance can be calibrated according to ISO or DAkkS. A DAkkS calibration is always carried out if the test equipment (scale or test weight) is used in a quality management process (e.g. according to ISO 9000ff, TS 16949, VDA 6.1, FDA, GLP, GMP, …).
In this article, you will learn everything you need to know about calibrating a scale. We’ll go step by step and explain exactly what you need to do. So, let’s get started!
Definition of calibration
Before we look at the actual calibration process, let us briefly explain what calibration means. Calibrating a scale basically means loading the scale with traceable standards (weights) and recording the displayed measurement results. Every scale has a certain measurement uncertainty, which means that it is not always 100% accurate. If the weight you read on the scale differs slightly from the actual weight, this is normal.
Test weight for calibrating a scale
One of the most important aspects of calibrating a scale is using the right test weights for calibration. A test weight, also known as a traceable standard, is itself also calibrated. For this purpose, it is weighed and adjusted on a very precise balance. This means that the test weight is processed until the value displayed on the very precise scale is within a permissible tolerance.
Example: A 100 g test weight of class OIML F1 has a permissible tolerance of only +/- 50 mg.
Each test weight we use for calibration has a serial number and its own calibration certificate. The test weights are calibrated by us at least once a year.
For this reason, our service staff will ask you for the manufacturer and type of scale before preparing a quotation. Based on this data, we can select the appropriate test weights. If you are already our customer, we already have all the data on your scales in our ESSMANN scale management software tool. Here we maintain the technical data of your scales, the service history and have also saved all specific dates and can thus remind you conveniently and in good time of dates for calibration or maintenance.
How to have your scales calibrated
You can either have your scales conveniently calibrated at your premises or you can send us your scales by parcel service. Especially if you have several scales, on-site calibration is more cost-effective and downtimes are minimized due to the elimination of the shipping route. The actual calibration process of a scale takes up to two hours, depending on the maximum load.
Our service includes preparation for adjustment, i.e. we check the scales for damage and clean them superficially. We also update the data in our scale management system.
The technician then begins with the actual metrological calibration of the scales. To do this, the test weights are placed on the scale according to a specific pattern. During DAkkS calibration, three different tests are carried out, among others. These are the repeatability test, the accuracy test and the off-center load test. With these tests, the balance is fully metrologically tested.
Adjustment and repair of the scales
If, after calibrating the scales, we determine that the measurement deviations are very high, we can adjust the scales. This will reduce the deviations. If a metrological adjustment does not result in an improvement, there may be damage (load cell defective, measuring cable kinked/broken, plug with too much play, …). In this case, we will contact you and carry out a repair of the scale after approval. After adjustment and/or repair, we will then recalibrate the scale.
If several calibration processes (“as found/as received” and “as left/as returned”) have been performed on the balance due to a repair or adjustment of the balance, the DAkkS calibration certificate contains a separate section for all these states with the corresponding measured values and results. Please note that this is only done at the customer’s request. As a rule, you will receive the calibration certificate with the values “as left”. If the values are also required before any adjustment or repair, please let us know in your order. As this is an optional service, it will be charged separately.
How often should a scale be calibrated?
The interval for calibration depends on the specifications of your QM system, the intended use and the location of the scale. Most customers have their scales calibrated by us once or twice a year. This is because the greater the deviation from the standard values, the less accurately the weight is displayed. For professional users, a tolerance limit that is too large can quickly threaten their existence.
Why is calibration important?
Accurate and reliable measurement is crucial for the smooth running of businesses. To ensure that you get consistent values for internal checkweighing for years to come, it is essential to calibrate your scales regularly.
