When testing aggregates, ores, coal, and coke in geotechnical or construction materials testing laboratories, sample preparation often involves the reduction of particle sizes from the initial bulk or field sample. Many of these materials are hard, tough, or brittle, so crushing them to smaller sizes is an ideal application for robust, rugged, and durable jaw crushers.
All jaw crushers operate on the same straightforward principle; two hard-faced heavy plates or jaws crush large particles between them. One powered jaw reciprocates in an elliptical motion opposite a stationary jaw mounted in the frame.
During an operating cycle, the gap between the two jaws opens; a particle drops in, the jaws close in and crush the particle. Further crushing of the fractured pieces continues until particles are small enough to fall through the bottom opening by gravity. The jaws face each other at a slight vertical angle, so particles become smaller as they progress toward the bottom.
A simple adjustment of the distance between the two jaws regulates the final sample size. The term final size can be a little vague. It refers to the approximate maximum particle size at completion of crushing, but the size range and distribution can vary considerably based on the material properties of the sample.
The selection of the best jaw crusher for your application will naturally be governed by the particle size, volume, and properties of your bulk material, along with the desired particle size and quantity of the final sample. The size of the jaw plates limits the particle size capacity and determines the size of the feed opening. In general, maximum particle sizes are about 70-80% of the feed opening, but this can vary by manufacturers and models. Jaw materials are available in a variety of materials to adapt to the hardness and toughness properties of samples and to extend service life.
Small Crushers: For applications where reduced quantities of materials with smaller top sizes and final sizes are needed, these smaller jaw crushers fit the bill. Their compact size allows easy positioning anywhere in the lab, even on a benchtop.
Large Crushers: When size capacity and throughput are the most sought-after features, these units are the best choice. Options for power by gasoline or Diesel engines mean the crushers can work on-site at remote laboratories or pilot plants.