Plastic Screw Conveyors: A Comprehensive Overview of Types, Uses, Benefits and Components

Overview of Plastic Screw Conveyors

Plastic screw conveyors, also sometimes referred to as auger conveyors, are material handling systems that transport bulk materials horizontally or at slight inclines. They transport a variety of materials including foods, chemicals, pharmaceuticals, grains, and many more. The conveying action works by rotating a helical screw within a fixed trough, effectively pushing material along the trough.

Benefits of Using Plastic Screw Conveyors

Plastic screw conveyors offer several advantages over traditional conveyor belt systems:

• They can transport almost any bulk material including those that are coarse, fragile, powdery, or fibrous.
• Their enclosed design contains dust and prevents spills.
• Plastic construction means they are corrosion resistant for use with chemicals and foods.
• They are able to meter or deliver precise amounts.
• Incline angles typically range from horizontal to 45 degrees allowing flexibility.
• They have no moving external parts, which enhances safety.
• Maintenance is relatively low compared to belt conveyors.

Key Components of Plastic Screw Conveyors

Plastic screw conveyors have several main components:

• Trough - The trough, or outer casing, houses and supports the conveying screw. Plastic troughs are typically made of polyethylene or polyurethane materials. They may have a U-shaped cross-section or be fully enclosed tubes.
• Conveying Screw - The helical screw rotates inside the trough to push material forward. Plastic screws can be made of polymers like acetal or nylon for smooth, non-stick, and corrosion resistant transport.
• Inlet/Outlet - Inlets control how material enters the conveyor while adjustable outlets meter flow rates. Various inlet designs exist for different material handling needs.
• Drive Unit - Gear reducers, motors, and bearings make up the drive unit to rotate the screw at the desired speed.

Types of Plastic Screw Conveyors

There are several common types of plastic screw conveyors suited to handle different material and process requirements:

Flexible Wall Conveyors

Flexible wall conveyors use a rotating screw inside a tube-like casing made of thick plastic. The flexible tube walls expand and contract allowing the system to temporarily hold more material. This start-and-stop conveyance works well with processes having variable output.

Trough Screw Conveyors

Trough screw conveyors consist of a U-shaped or V-shaped trough with a screw rotating inside. They efficiently move light, free-flowing material horizontally or up slight inclines up to 30 degrees. The shape makes them easy to clean and ideal for food applications.

Ribbon Screw Conveyors

Ribbon screw conveyors have helical screws made up of short, overlapping segments rather than continuous spiral flights. This limits pressure on the conveyed material for gentle handling. Plastic ribbon construction allow handling of sticky materials without build up.

Shaftless Spiral Conveyors

Shaftless spiral conveyors use a spiral screw strip or belt that loops around rotating drive wheels rather than an actual shaft. The means no central shaft contacts the transported material. They allow large items to pass through easily minimizing damage or jamming.

Key Industries Using Plastic Screw Conveyors

Plastic screw conveyors meet the demands of many industries. Some top examples include:

Food Processing

The food industry relies on plastic screw conveyors to hygienically move wet, dry, and uneven food items without contaminating product. Conveyors move food stuffs ranging from fruits and vegetables to grains, candies and chocolates, potatoes and fries, and baked goods.

Wastewater Treatment

Plastic conveyors equipped with drain holes transport wet sludge between holding tanks, concentrate thickeners, filter presses or belt filter systems. Plastic stands up to caustic and acidic materials while eliminating bacteria harboring locations.

Recycling Facilities

Recycling plants use plastic spiral conveyors within systems designed to transport, sort, separate and process various recycled goods. The conveyors withstand dirty conditions when moving materials like used glass, papers, metals, textiles and electronics.

Mining

Mining operations rely on plastic screw conveyors due to their heavy-duty construction and installation flexibility. Conveyors transport excavated ores, precious metals, copper, coal and other bulk materials often under harsh environmental conditions.

Buying Considerations for Plastic Screw Conveyors

When purchasing plastic screw conveyors, some important factors to consider include:

• Conveyed Material Properties – Factors like particle size, density, corrosiveness, abrasiveness, temperature, and tendency to pack, cake or smear impact conveyor selection.
• Capacity – Required throughput capacities depend on production volumes and space availability.
• Incline Angles – Incline angle impacts suitable screw design and horsepower needs.
• Speed Control – Conveying screws allow speed regulation for starting, stopping and pacing flows.
• Customization – Specialized designs accommodate challenging physical layouts and extreme working conditions.

Discussing application details with manufacturers ensures selecting high-performing plastic screw conveyors tailored to unique material handling needs.

FAQs

What types of materials can plastic screw conveyors transport?

Plastic screw conveyors can gently handle a wide variety of materials including powders, flakes, granules, pellets, chips, fibers, slurries, viscous pastes, fruits and vegetables, recycled goods and more. Plastic stands up well to acids, bases, fats, oils and solvents.

How are plastic screw conveyors powered?

An external drive source powers the rotation of the conveying screw. Common options include electric motors, hydraulic motors or manual drives. Gear reducers are often used to reduce output speeds to optimal conveying speeds.

What industries use plastic screw conveyors?

Top industries served include food and beverage processing, wastewater treatment, recycling facilities, manufacturing plants, mining, pulp and paper, chemical plants and agriculture. Their versatility supports many processing applications.

What maintenance is required on plastic screw conveyors?

Plastic screw conveyors are relatively low maintenance compared to belt conveyors because they have fewer moving parts. Typically just occasional motor, gearbox and bearing checks are needed along with cleaning when handling sticky materials. End seals or gaskets may also need periodic replacing.