Test sieves are a vital component of your quality control program. Unfortunately, sieve calibration or examination can be a complex process that requires the crunching of intimidating numbers. Premium providers of test sieve calibration services, however, come to the rescue by performing the complicated calculations for you and from there making the right test sieve recommendation.
Be advised. Test sieves can not be adjusted and be returned to specification standards as with many other instruments. They can only be examined and collect data to be analyzed to determine if the sieve meets the known standard.
You can rest assured that these recommendations are based on the ASTM E 11-09 and ISO 3310-1 standards for test sieves. When choosing a sieve calibration service provider, it’s a major bonus to uncover one that maintains an active role on the committees that write and oversee these standards.
The main governing body behind the traceability of all sieve calibration is the National Institute of Standards and Technology, more commonly recognized by its acronym, N.I.S.T. Your service provider should therefore offer some degree of traceability directly to the institute through the regular examination of the measuring device. N.I.S.T. traceable histograms of the test sieve ensure proper adherence to known standards, affording a 99.73% level of confidence that results from measuring the amount of mesh openings of the ASTM Calibration Grade. The use of an automatic, non-contact dimensional measurement system can attain sieve calibration accuracy within one-tenth of a micron.
But what if you decide to undertake the task yourself? How exactly are test sieves calibrated or examined? One of two methods is typically employed: the glass microsphere method or one of four various sieve shaking methods.
The microsphere process entails a series of tedious weigh-ins. There are also four different sieve shaking methods that can be employed. By vigorously swirling the pan, you can perform the sieve calibration by hand. This manual process works for sieves of 45 um or greater. Mechanical devices can also be used to aid in the process, but be aware that their feasibility is dependent on the sieve’s size, with minimum and maximum um guidelines being set.
Air jet sieves and sonic sieves can also be examined using a sophisticated optical imaging devise. The same traceable documents can be provided.
Regardless of the method you choose, it is unlikely you will achieve the same one-tenth of a micron accuracy that a proven automatic sieve calibration measurement system can. As a result, entrusting your sieve calibration needs to an expert can save you precious time and aggravation. Automated high speed calibration generally has a one to two week delivery and is modestly priced. In addition, there is no question about their accuracy or the accuracy of the calculations being performed.
