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Flexible Screw Conveyors

Flexible Screw Conveyor

Applied Engineering: The Requirement of Process Conveying Performance

The principle of helicoid motion as a processing and production conveying method is widely used. Yet, National Bulk Equipment has advanced this science by combining our application-specific bulk material handling expertise with market-dominant build specifications and materials of construction. NBE flexible screw conveying systems provide sustained conveying performance, at designed capacities, of the most demanding materials and bulk densities.

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Features and Integration:

Standard Build Details

NBE flexible screw conveyor systems are engineered, constructed, and applied to processing and packaging operations based on the specific performance requirements of each application, such as: conveying rate, angle, distance, material flow characteristics, upstream and downstream equipment integration, and automation. NBE flexible screw conveying systems leverage the resources of NBE engineered-to-application project delivery to ensure fast response and optimal effectiveness are not mutually exclusive. Avoid the risks of force-fit stock, avoid the delays of assembling and wiring a delivery of parts and pieces. NBE flexible screw conveying systems improve run time performance while reducing maintenance and repair.

Application Selections

NBE flexible screw conveyor systems are built to protect the valuable uptime, costly process materials, and vital production yield of dry bulk material handling lines. The market-dominant materials of construction and build specifications of NBE flexible screw conveying equipment ensure reliable, long-term process performance. Eliminate the negative effects of off-the-shelf engineering or garage-shop construction. Convey with confidence in the equipment and expertise provided in each NBE flexible screw conveyor system.


The performance-proven materials of construction of every National Bulk Equipment flexible conveyor screw; together with its process-specific flight design, pitch, and finished machining, ensure sustained conveying accuracy, at designed capacities, of even the most demanding materials and bulk densities. NBE flexible conveyor screws provide the balance of precision and power that is key to efficient performance.

  • Flat Wire Flexible Screw Conveyor Auger for Free Flowing Bulk Material ConveyingFlat Wire: For applications where material flow is typically free-flowing to semi free-flowing, and material characteristics are lightweight, highly aerated, powdered, or fluidizing; the National Bulk Equipment flat wire screw is available in a wide-face design for conveying of materials such as: flour, talc, calcium carbonate, starch, seasonings, fumed silica, and ground coffee.
  • Beveled Wire Flexible Screw Conveyor Auger for Semi-Free Flowing Bulk Material ConveyingBeveled Wire: For applications where material flow is typically semi-free flowing to sluggish flowing, and material characteristics are sticky, with tendencies to pack, smear, cake, or crumble; the National Bulk Equipment beveled wire screw is available in a wide-face design for conveying of materials such as: iron oxide, zinc oxide, cocoa powder, and carbon black.
  • Round Wire Flexible Screw Conveyor Auger for Sluggish Flowing Bulk Material ConveyingRound Wire: For applications where material flow is typically semi-free flowing to sluggish flowing, and material characteristics are highly abrasive, granular, flake, pellet, or irregular shape; the National Bulk Equipment round bar wire screw provides excellent conveying of materials such as: salt, sugar, rice, coffee beans, corn, and plastic regrind.
  • Square Bar Flexible Screw Conveyor Auger for Abrasive Bulk Material ConveyingSquare Wire: For applications where material flow can be free-flowing, semi-free flowing, or sluggish, and material characteristics are highly abrasive, with high bulk density; the National Bulk Equipment square bar wire screw provides highly efficient conveying of materials such as: sand, metal powder, steel shot, and large salt.


Double the thickness of typical flexible conveyor outer tubes, National Bulk Equipment outer tube is available in up to half-inch wall thickness; in either UHMWPE or polypropylene construction. The extremely smooth interior surface of UHMWPE adds additional protection from cross contamination. For applications requiring even greater resistance to material contamination, and long-term wear resistance, NBE Type 304 stainless steel outer tubes, and NBE carbon steel outer tubes ensure reliable performance, regardless of demanding process materials, duty cycles, or both.

  • Flexible Screw Conveyor Polypropylene TubePolypropylene: For applications requiring high-volume conveying, or conveying of larger materials, National Bulk Equipment polypropylene outer tubes provide large-diameter tube construction to accommodate the application-appropriate flexible conveyor screw outside diameter and flight design. NBE polypropylene tube is non-bending, and is available in lengths up to 30 feet.
  • Flexible Screw Conveyor UHMWPE TubeUHMWPE: For applications requiring exceptional operating durability and performance, National Bulk Equipment provides flexible screw conveyor outer tubes constructed of ultra-high molecular weight polyethylene (UHMWPE). These NBE UHMWPE outer tubes have the highest impact strength and tensile strength of any thermoplastic outer tube; and are FDA and USDA approved, non-corrosive, and temperature resistant. NBE UHMWPE outer tubes can bend to a radius as tight as 6 feet; enabling conveying tube to run around layout obstacles. NBE UHMWPE outer tubes are available in lengths up to 40 feet.
  • Stainless Steel: For applications requiring excellent corrosion resistance and cross-contamination resistance, National Bulk Equipment Type 304 stainless steel outer tubes are nearly impervious to most all conveyable materials; while also aiding in FDA and USDA regulatory compliance. NBE stainless steel outer tubes also have an inherent rigidity that enables longer runs between supports than UHMWPE.
  • Carbon Steel: For applications requiring very high tube strength, beyond even that of UHMWPE; but where the exceptional corrosion resistance and regulatory compliance of stainless steel tube are not required, National Bulk Equipment carbon steel outer tubes provide a dependable, high-performance alternative.

Optional Features

When process materials are unpredictable, harsh operating environments are inhospitable, and production rates seem unattainable, NBE will leverage extensive expertise and resources in application analysis, material sciences, and R&D to design and manufacture a process-specific flexible screw conveyor system for the application. NBE engineered-to-application flexible screw conveying systems turn material issues, facility limitations, and run time factors from problems to production.

  • Flexible Screw Conveyor with Right Angle GearboxRight Angle Gearbox: In facilities with height restrictions or where other equipment is blocking access, a right angle gearbox is a common solution in a compact package, and available for all NBE flexible screw conveyor sizes.
  • Washdown: Where sanitary or hygienic requirements exist, NBE flexible screw conveyor drive systems can utilize washdown drive systems, with gasketed motors and compliant epoxy coatings on drive components.
  • Explosion-Proof: NBE flexible screw conveyors are commonly built to meet Class I customer specification for explosive or ignitable mixtures. In addition to selecting the correct drive system, NBE engineers can also integrate bearing temperature sensors, where applicable, with the standard control packages for additional monitoring.
  • Flexible Screw Conveyor with Portable CartCarts Without Raise/Lower: Fixed-position portable carts enable operators to quickly reposition the flexible screw conveyor and hopper to meet process requirements, or to remove the conveyor from the process area for cleaning. Locking casters and construction in both carbon steel and 304 stainless steel are available options.
  • Carts With Raise/Lower: The raise / lower mechanism allows the discharge head and screw to be tilted down for easy access during cleaning or changeover, without the need for ladders or platforms. This also enables easier transport within the facility. Depending on hopper size, some models will also fit through standard door opening.
  • Class II Div II: Dry bulk solids often create hazardous dusting conditions that must be addressed through compliance accommodations. NBE Class II Div II drive systems can easily be specified from the factory, or upgraded later, to meet these requirements.
  • Quick Clean: NBE quick-clean drive heads eliminate bolts and allow operators to access the internal drive system via a hinged access door secured by two, tool-less clamps. These design features represent a leap forward from traditional cleanout systems that may utilize multiple T-handles, or leave the operator to manage a loose panels while conducting cleanout procedures. Also standard on NBE quick-clean discharge heads is a magnetic cutoff switch in the door to ensure that easy access doesn't compromise safety.
  • Vibrators: With pneumatic, electric, and hydraulic options, hopper vibrators are a flexible and effective method to combat ratholing or bridging in certain materials. However, vibrators are often specified incorrectly, leading to unnecessary stress on components and in some cases, more compaction of material. NBE process engineers will ensure proper size and placement for optimal flow control.
  • Airpads: Airpads are specified for fine dry bulk materials that tend to pack and cling together, or in situations where either the hopper or screw configuration is limited by external constraints. Introducing low-pressure air to the hopper via airpad helps separate material and encourages even, consistent flow to the screw inlet.
  • Flexible Screw Conveyor with Z-Paddle AgitatorZ-Paddle: The NBE Z-paddle flow aid mechanically agitates material in the hopper, promoting flow from the sides of the hopper. With over 740 ft-lbs of torque at 7 rpm, the heavy duty construction of the Z-paddle agitator ensures materials are reliably conveyed to the center screw inlet.
  • Flexible Screw Conveyor with Ribbon AgitatorRibbon: For challenging materials, helical ribbon blenders ensure thorough agitation and infeed. Heavy-duty opposing ribbons are placed along a horizontal shaft, moving material both axially and radially throughout the hopper. Speed, flight angle, and any additional agitation aids can be specified through material testing.
  • Flexible Screw Conveyor Replacement Parts for Multiple Makes and ModelsReplacement Parts: Get the dependable uptime, throughput, and quality finished product that comes from specifying National Bulk Equipment original equipment parts for your flexible conveyor system. Processing payback quickly disappears when adding-up the costs of those all-too-frequent replacements of under-built parts on under-built flexible screw conveying systems. Whether your current system is red, orange, blue, or shop-made, specify National Bulk Equipment flexible screw conveyor parts and components and bring optimal performance and process efficiency to any flexible screw conveying operation.
  • Upgrade Kits: Improving total process performance is possible without a total system replacement. When original equipment specifications are not enough. When application requirements have changed. Or, when unplanned downtime caused by under-built equipment is too frequent; specify the flexible screw conveyor performance upgrade kit from National Bulk Equipment. This performance upgrade kit includes an application-specific drive system and discharge head, the flexible screw, and outer tube; and is designed to easily interface with most any process hopper or material supply source.
  • Manual / Automatic Controls: National Bulk Equipment sets a new benchmark in standard equipment with the flexible screw conveyors controls package. With fully functioning, pre-programmed touchscreen PLC and HMI, NBE flexible screw conveyors ship from the factory with more available features than any other system of their kind. As appropriate, operators have access to automatic and manual function of the system, and can adjust screw speed, flow aids, and other integrated equipment from the touchscreen. The standard PLC also has the ability to accept any digital signal, making it easy to integrate with other systems that utilize independent level sensing for infeed, or downstream process feedback for discharge.
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