Conveying Misconceptions

Cable and Disc Systems Gently Convey Coffee Blends

For specialty coffee roasters, dispelling misconceptions about coffee conveying can result in optimal preservation of delicate or precise blends. This assessment will address two widely held industry misconceptions about tubular drag cable and disc conveyors.   

These conveyors gently move the product through a sealed tube using a coated, flexible stainless-steel drag cable pulled through on a loop. Solid circular discs (flights) are attached to the cable, pushing the product through the tube without air. The tubular drag conveyors excel in transporting delicate, precise coffee blends in versatile layouts and configurations.

Misconception #1:

Conveyors Are Not Designed to Protect Coffee Blends

When transporting a coffee blend with a conveyor system, maintaining a consistent mix ratio is essential, whether fine or coarse. However, conventional conveyor systems are not specifically designed to precisely transport coffee blends without changing the mix ratio. Various product material weights, sizes, and shapes can shift and disperse in open systems like bucket conveyors, and vibration can cause the blended product to shift throughout transport. Vacuum and pneumatic systems can cause smaller lightweight particles in a blend to move at different speeds than heavier or larger particulates, resulting in significant blend restructuring when the product reaches its discharge point.

In contrast, tubular drag cable conveyors are engineered to maintain precise coffee blend ratios. As an example, engineers from Cablevey Conveyors, a mechanical conveyor manufacturer that serves the specialty coffee and food markets, have resolved the issue with a completely enclosed, compartmentalized tubular conveyor system. The company has designed, engineered, and serviced enclosed cable and disc tube conveyors for 50 years in over 66 countries.  

Not unlike an endless succession of train cars, each space between solid circular discs holds a predefined volume of product. Based on the manufacturer’s specifications and requirements, engineers can calculate the optimal speed of the system, the most appropriate tube angles, and the proper construction design to guarantee their blended coffee product remains consistent from input to discharge, even at high volumes.

Misconception #2:

These Conveyors are the Same as a Screw System

Another common misconception is that tubular drag cable and screw conveyors are identical, which is far from the case. Screw systems, also known as auger conveyors, typically utilize a helical blade that moves granular materials within a tube. However, augurs can cause product damage and compromise blends. So, the units tend to be an option when material integrity is not critical, such as when conveying food waste products. The key difference to look for is that augurs convey material with a helical screw. The transfer speed is directly proportional to the rotation speed of the screw.  

On the other hand, tubular drag cable conveyors transfer material between two discs pulled by a sealed cable and are specifically designed to reliably protect delicate coffee products and blends. This capability not only reduces potential product damage but also enhances the value of the coffee and brand.

by Karl Seidel, Marketing Director, Cablevey Conveyors

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