Grading Success: Why Putting a Round Object through a Square Hole Makes Sense

Grading Success: Why Putting a Round Object through a Square Hole Makes Sense

Mechanical sizing and grading equipment comes in many forms. For some products, it is easy to determine the best piece of equipment to accomplish the job. Rotary sizing and grading is great for large products that are in their whole form or after they have been cut. However, small roundish products such as blueberries, cranberries, raisins, and pistachios would seem to be easily graded by size, but can actually be quite tricky.

Key’s vibratory conveyors typically use punch plate screens with a round hole diameter to match the size grade desired. For the most part, this works relatively well, but when the product is just a little bigger than the hole, it can cause blinding (i.e. it fills the hole because it is not big enough to move across the hole and not small enough to drop thorough).

Key’s innovative engineers tackled this challenge and found that using square holes to size-grade round products provides less opportunity for the product to touch all sides of the hole and therefore easily drop through or pass, as desired. For some applications, an octagonal hole works even better and significantly reduces blinding.

Contact us today to learn about which type of screen equipment is best for your application. We are always here to help you meet your quality and efficiency goals!