Spinning Rifflers generate samples of particulates which reflect very closely the properties of the larger quantity from which they were derived.   They integrate appropriately into analytical, developmental, research, and control procedures to provide the representative samples of powders and granular solids upon which you can depend for accuracy, and reproducibility.   In fact, the composition of a sample produced by spin riffling usually approximates very closely to the theoretical limits imposed by the statistical functions by which that material is best described and in fact, more closely than all other methods for the preparation of samples of particulate matter.

Representative sampling is important !

Have you ever wondered why there is always dust at the bottom of a cereal packet ?   This would be due to settling of the contents, combined with a bit of crushing and abrasion.   It doesn't normally bother us since we just throw the dust out, but how would you measure the particle size distribution of ALL of the cereal box's contents ?

The answer would be to pass the entire box's contents through a Microscal Spinning Riffler so that you could obtain a representative sample of the cereal (dust and all) which is small enough to be run on an appropriate analyser but with a size distribution which represents the whole box closely.

Did you know that sixty–five percent of all goods employ powders at some point in their production cycle ?   The characteristics of these materials tend to change batch to batch and also with storage and preparation conditions.   These variables need to be known and evaluated, but without a truly representative sampling procedure being systematically applied, the errors can accumulate and hide the source(s) of the variances ultimately observed.

Unique incremental sampling technique.

The spin riffling technique relies on the concept of random sampling to build a set of fractions from a bulk of material so that each fraction contains all the characteristics, including particle size distribution, as the bulk from which they all came.

The technique builds each sample by a process of multiple addition so that a statistically representative image of the bulk exists in each of the newly created sample fractions.

A spinning riffler comprises three principal components: the Mass Flow Hopper which holds the bulk of particulate to be sampled; a controlled–rate Feeder which steadily transports the bulk from the Hopper to the Sample Collectors; a Dividing Head placed on a rotating platform above the Collectors or integral with them, which cuts the particulate stream from the Feeder into small incremental portions, repeatedly.   The Sample Collectors are glass or metal containers each designed to hold the appropriate fraction of the bulk particulate which is to be sampled.

Since the device is designed to allow many passes of the Dividing Head during the course of one sampling operation, each fraction is built up from multiple samples of the bulk.   So long as the Dividing Head rotation and the flow of particulates along the Feeder are both constant, the fractions which accumulate in the Sample Collectors during the riffle will be closely representative of the bulk.

Hopper capacity and overall collection capacity are matched to avoid overflows or bridging between sample fractions.   Typically, a spinning riffler with a sample collection capacity that exceeds the volume of the bulk to be sampled is employed.

What some people have said about Spin Riffling

"Spin riffling has been shown to be the most accurate and reliable technique for the representative sampling of particulates." Dr. Arthur Hawkins, 1996.

"The real benefit is repeatable test results that are reliable.   You save time, resources, material, and ultimately money." Alan Gibbon, Johnson Matthey, 1992.

"The spinning riffler is the best technique by far – it samples unmixed just as efficiently as mixed powders." T. Allen and A.A. Khan, The Chemical Engineer, 1970.

"Extensive studies have shown spin riffling to be a very efficient sampling method." Brian Kaye, Direct Characterization of Fine Powders, 1981.

"The table shows that spin riffling is a superior division method: the rotating tray removes all chance of operator error" L. A. Kressin, Powder and Bulk Engineering, July 1989.

A reliable method of extracting a representative sample from a bulk of particulate material that is both reproducible and operator–independent, is fundamental to the consistent processing of powders and granular materials.

Several conventional methods to extract a proportion from a bulk of particulates are used.   Many organizations rely on operators to perform exactly the same critical procedure, repeatedly.   Manual error introduced during these critical steps amplifies sampling error.    Introduced in 1970, spinning rifflers are designed to address this problem.   Spin riffling is the most reproducible and operator–independent method yet developed to extract representative samples from a bulk quantity of particles.

Microscal Spinning Rifflers offer the widest range of particulate samplers designed to provide the highest reproducibility and precision in representative sampling at an affordable cost.   In fact, the cost consequences of using un–representative samples are potentially much greater.

Spinning Rifflers offer a simple and dependable sampling method which approaches the best that is theoretically possible.   The technique overcomes segregation, heterogeneity, and stratification while virtually eliminating operator–introduced error.

Spinning rifflers produce the highest sampling accuracy

The high reliability of spin riffling compared to other methods of sample generation was published by T. Allen and A.A. Khan in The Chemical Engineer, 1970.   Their sampling test based on a 60%/40% mixture by weight of coarse and fine sands produced the following comparisons:

Thus spin riffling yields a sampling error far less than the other methods, which is also very close to genuine random variation (i.e. that which is theoretically possible).

L.A. Kressin in Powder and Bulk Engineering, July 1989, (in his article "How to use dry sieving tests") states "The table [shown above] shows that spin riffling is a superior division method: the rotating tray removes all chance of operator error".