Flexible Screw Conveyors

Benefits Of Flexible Screw Conveyors

Simple, reliable, and all-around versatile, Flexible Screw Conveyors are a common choice for transporting powders and dry bulk solids.

Consisting of one moving part, the flexible spiral, also known as a pigtail screw, process engineers around the globe opt for their low-maintenance requirements and overall reliability.

Flexible Screw Conveyors are designed to be precisely what their name suggests… flexible!

Trantec flexible spiral conveyors are available in various configurations and directions, including vertical, horizontal, at an angle, around fixed equipment, through to another room, with multiple discharge points, fit in a tight spot, or a fully mobile unit.

The spiral auger is designed to self-centralise inside the ultra-high molecular weight polyethene (UHMWPE) conveying tube, which maintains dust-tights conditions, preventing cross-contamination. The spiral uses the material being handled to keep itself rigid, which is maintained through consistent mixing of the contained powders.

A single motor drives the spiral, gently transporting powders without the risk of product degradation before dropping out of the material outlet at a constant pre-determined rate.

Trantec specialises in designing and manufacturing Flexible Screw Conveyors, providing material transfer solutions to processing manufacturers and machinery suppliers for over two decades.

Well known for their simplistic design, Flexible Screw Conveyors, also called Flexi Screws or spiral conveyors, consist of one moving part, the (spiral) helical auger. The spiral self-centres itself inside of the hollow outer tube using the conveyed material to do so.

Manufactured in stainless steel or powder-coated mild steel, Trantec Flexible Screw Conveyors have throughput ranging from a few kilos to many tonnes per hour. We manufacture most of our conveyor parts in-house using our laser cutting and fabrication department combined with CNC press forming and CAD sheet metal design. We have invested heavily in our machining department with state-of-the-art CNC milling and turning capacity. We pass on our economies to our customers, giving Trantec a highly competitive edge in the flexible screw marketplace without compromising quality. Over the past two decades, our evolution has put Trantec in a commanding position to challenge existing flexible screw manufacturers and bring a fresh, customer-centred approach to the marketplace.

Please send us details of your application by clicking here, and our experienced sales team will be in contact with you immediately.

Here are some other common names for Flexible Screw Conveyors:

  • Flexible Auger Conveyor
  • Spiral Screw Conveyor
  • Flexible Spiral Conveyor
  • Flex Screw Conveyor
  • Helical Screw Conveyor / Helix Conveyor / Flexible Helix Conveyor
  • Shaft-less Screw Conveyor
  • Centreless Screw Conveyor

Trantec Flexible Screw Conveyors

Trantec Flexible Screw Conveyors offer efficient, low-cost transport of powders and dry bulk solids.

Suitable materials include fine powders, granules, large pellets, flakes, and pills. We have considerable knowledge and experience in the solids handling industry, working alongside some of the best-known brands and OEMs spanning over twenty years.


Trantec’s Flexible Screw Conveyors are constructed in mild steel, 304, or 316 stainless steel, with various polish finishes. These include welds as laid, standard, crevice-free, and mirror (0.2Ra). These materials include the construction of any inlets, outlets, hopper, lids, agitators, connection flanges, and drive shafts.

  • Mild steel (or low-carbon steel): A composition of iron, carbon, and manganese, it is a low-cost construction material. Known for its ease in shaping, making manufacturing this steel alloy cost-effective and easy to manipulate. Not suitable for food contact or pharmaceutical processes.
  • 304 stainless steel: An alloy composition containing 18% chromium and 8% nickel, 304 stainless steel is the most common construction material worldwide due to its resistance to acidic and caustic solutions, combined with reduced risk of intergranular corrosion and high ease of fabrication.
  • 316 stainless steel: Greater resistance than 304 stainless steel. Easier fabrication, welding, and cleaning properties. Increased resistance to sodium chloride (NaCl) based substances. Typically used for the construction of food and pharmaceutical solutions.

Easy-clean features are provided, including quick-release, to assist in reducing downtime. Trantec works closely with all USDA, EC, FDA, and 3-A dairy food contact legislation and can advise the most suitable construction and finish required by current legislation.

UHMWPE is an approved material for extrusion and is the number one choice for conveying tubes for to its excellent low friction, chemical resistance, and overall high wear resistance properties.

Many of our components are now produced in-house from specifically selected materials. Trantec can advise on the pros and cons of all, with full traceability available upon request.

Regardless of the manufacturer, all Flexible Screw Conveyors will have the same components. These include:

  1. Inlet (where materials are deposited) and corresponding connection flanges.
  2. Spiral auger – cut to length, spiral section profile dependant on material properties and requirements.
  3. UHMWPE outer tube – dust-tight, cut to length and size to match the spiral auger.
  4. Outlet (where materials are dispensed from) and connection flanges.
  5. Drive shaft with a motor adapter.
  6. Three-phase electric motor, 50/60hz – typically AC or DC (AC for higher RPMs).
  7. Can be fed directly from a storage hopper, sack tip station, FIBC Discharger or alternate materials handling the equipment.

The above is an example of a base model powder transfer conveyor and will not include additional features such as agitation or quick release.

Agitation Devices For Poor Flowing Materials

An agitation device may be required for poor-flowing materials. To prevent material build-up, an agitator will be added to condition and break apart the powder constantly.

A blade mechanism is a typical agitation method, with the type of agitation specially selected for the application to suit the material flow properties.

Vibratory agitation is occasionally used for certain powders and granular materials that cannot flow with traditional techniques but are not commonly required.

Trantec’s agitation devices are independently driven, providing precise control of rotation speed and product conditioning levels.

Below are examples of common issues faced with poor-flowing materials.

Rat-holing: The term given to materials that form a hole above the spiral auger or the hop

Bridging (or arching): When powders form a bridge or arch above the spiral or discharge point in the hopper, causing similar issues to rat-holing, preventing material from dropping and entering the inlet for conveying.

The full term given to this is Bridging and Rat-Holing.

Both of these will affect your product flow rates, so your equipment must be able to handle the application. After all, you can’t design your powders flow properties to suit your machine!

Trantec’s Flexible Screw Conveyors or Flexible screw augers are available in various designs and configurations whilst staying true to their fundamental operating principles. We offer tailored solutions based solely on your application, ensuring the most efficient means of transport whilst producing accurate rates as desired. Whether horizontal, vertical or at a 45° angle, through to a different room in your process plant or multiple discharge points, Flexible Screw Conveyors can be adapted to suit almost any application without compromise. Our flexible UHMWPE tubing and spiral augers allow for construction around bends and obstacles, meaning our Flexi Screws can fit into the tightest of spots – hence the name Flexible!

Flexi spiro conveyor by Trantec

Key Features

  • Low cost
  • Low maintenance
  • Dust-free
  • Quick, easy dismantling and cleanability
  • Gentle handling
  • Wide capacity options
  • Sanitary & Easy-Clean options
  • Complete containment of product
  • Custom, bespoke options available
  • Multi-directional
  • Stationary or mobile options

Two Decades of Experience Across a Variety of Industries

Flexible Screw Conveyors are carefully engineered and can be configured for both batching and continuous conveying, giving them further popularity in the solids handling industry for their versatility. Common materials conveyed include powders, pellets, crystals, brittle materials, granules, and flakes.

Their ability to distribute a wide range of dry bulk solids and powders, from free-flowing to non-free-flowing, is renowned. Trantec has supplied conveying solutions to the following industries for the last two decades:

Trantec has the manufacturing, and innovative technology that has enabled the UK and EU-based OEMs to incorporate our products into their industries. Some of the products that are used are Flexible Screw Conveyors, Gravimetric and Volumetric screw feeders, FIBC dischargers, sack tip stations and storage hoppers/silos. Sometimes larger custom-built machinery is added – such as Rigid Auger conveyors and dosing systems.