Do you need to convey fragile materials? You can successfully convey your material with minimal material breakage with careful selection of the conveyor. There are several conveyors available in today’s market place that allow for gentle conveying of fragile materials. In order to select the most appropriate conveyor, the following material characteristics and equipment related application requirements must be determined:
What are the characteristics of your material?
- Bulk density
- Volume or units to be conveyed
- Drop testing data
- Angle of repose
- Angle of slide
- Particle distribution analysis
- Particle shape
- Moisture content
- Sensitivity to temperature and humidity
- Temperature of operating environment
What are your application requirements?
- Convey capacity of equipment
- Conveyor layout/routing
- Desired conveying rate
- Site constraints
- Power requirements
- Sanitary requirements and ease of cleaning
- Material of construction
- Wear properties
- Enclosed vs. open conveyor design
It is always in the end user’s best interest to select a supplier that has several conveying options available and a testing facility to test the material in a controlled environment. These specialty equipment suppliers will have experience handling fragile materials and quite likely the actual material that you need to convey.
Cable Drag Conveyors: These conveyors are among the gentlest available for applications requiring complex circuits as well as multiple inlets and outlets. A single cable drag conveyor can operate in three planes, often making it the low cost choice for many fragile conveying applications. Intelligent design of these complex circuits keeps fragile materials from passing through drive or idler housings, which would degrade the product. The speed that the cable and disks travel through the system is also an important design consideration. Another key advantage of cable drag conveyors are their ability to transition grades, both up and down, in a controlled and enclosed fashion. Cable drag conveyors are often used to convey foods such as coffee (green coffee beans, roasted coffee beans, ground coffee), tea, nuts (peanuts, almonds, walnuts, pecans, pistachios), dried beans, dried peas, seeds, grains, rices, and cereals as well as frozen fruits and vegetables.
Wrap/Tube Conveyors: This is a hybrid belt conveyor where product is initially fed onto a flat belt that is then rolled into a tube by forming rollers to create a totally enclosed moving tube. This type of conveyor accommodates multiple inlets and outlets, and can curve, incline and decline without discharging to another conveyor. The wrap conveyor is very easy to clean and is perhaps the gentlest commercially available option today.
Vibratory Conveyors: These are some of the simplest conveyors to operate and maintain on the market. They are also incredibly gentle on product. Vibratory conveyors can have a totally enclosed design and break down for easy cleaning. Limiting factors are typically distance and changes in direction, which often require additional conveyors and elevation transitions.
Belt Conveyors: The old standard workhorse in the mining and minerals industry also happens to be a very gentle conveying option. Belt conveyors easily move fragile materials because product being conveyed remains stationary as the belt tracks its course. Options such as cleated belts allow for traversing steep inclines and declines are also possible. Changes in direction or layouts with multiple discharge points are difficult to accomplish. Often special transitions, that limit the distance material falls between two independent conveyors, are required to prevent damage to the product. Standard belt conveyors are often open to the environment leaving material vulnerable to contamination. This is a major concern for any hygienic application within the food industry. Although enclosures are available, they can prove difficult to clean and pose contamination issues if not properly maintained.
Written by Mathias Lee, VP of Sales & Marketing
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