For more than 45 years, Spiroflow has been building flexible screw conveyors for processors around the world. In fact, the flexible screw conveyor is the product that launched the company! These conveyors are dust free, easy to clean, hygienic, gentle, and maintain mixtures.
One of the most common questions we get is, “how much does a flexible screw conveyor cost?” When comparing mechanical conveyors, a flexible screw conveyor is the most economical option out there. Determining the cost depends on several application-specific factors. This article will lay out all of the variables that can affect the final cost.
What conveying capacity do you require?
Flexible screw conveyors are offered in different diameters depending on the capacity you require. As a general rule, our largest screw conveyor can achieve capacities of up to 29 ft3/min (0.82m3/min). An experienced supplier can recommend the right sized conveyor for our needs.
What is your required conveying distance?
Flexible screw conveyors can be up to 40 ft long (12m) and multiple conveyors can be ‘daisy chained’ to achieve longer distances.
What type of spiral will most effectively convey your material?
No matter whether you call it a spiral or a screw, the type you need depends on the material you need to convey.
Round Spirals
The standard round spiral works for most applications. This style of screw forces solids outward, which reduces friction and lowers load.
Flat Spirals
Flat spirals are recommended for light, aerated, or very fine products. The flat spiral directs more force in the direction of flow and increases capacity slightly.
Beveled Spirals
Beveled spirals work well with difficult materials like iron oxide, chocolate, pigments, or any smearing or cohesive products. This setup is semi-rigid and bends are not recommended, but up to 45˚ conveying angles are possible.
Heavy-duty & Double Spirals
Heavy-duty spirals are also available for certain high density or aggressive materials. We sometimes recommend a double spiral for high-density products.
Polished Spirals
Polished spirals are always available for hygienic food applications.
Center Cores
Sometimes a spiral may not be enough. You might need a center core. This is a solid plastic rod that sits inside the spiral. It keeps material from falling back through the middle when working with light material and material that fluidizes easily. It’s also an option for conveyors that end up inclined more than 60˚.
What type of conveying tube is best?
Your material and application requirements will determine the best materials of construction for the tube. There are plenty of choices.
Food Grade Ultra High Molecular Weight Polyethylene (UHMWPE) tubes work for the majority of applications.
Tubes made from antistatic polymers are an option for volatile environments.
Are you working with minerals or abrasive materials? If so, tubes made from abrasion resistant rubber are for you.
Tubes can also be made from carbon steel or 304/316 stainless steel. Steel tubes are needed for products that are abrasive and have high temperatures.
What are your layout requirements?
There are a vast number of possible layouts and site constraints within your plant must be accounted for.Here are some common ways processors use flex screw conveyors:
- Are you conveying from a hopper to a process?
- Do you need a horizontal outlet for restricted headroom?
- Are you feeding or dosing from bulk bags?
- Do you require more than one inlet or outlet?
- Are you filling a silo or bulk bags?
- Do you require a mobile conveyor?
And, by the way, did you know that these conveyors are easily installed through interior AND exterior plant walls?
What components will you need?
An electric motor for your screw conveyor can be designed to deliver as much voltage as you need. An experienced supplier can determine proper motor for you. Depending on your specifications, spiral speed can be fixed or variable.
Level probes are an option as well. They identify high and low solid levels in the hopper feeding the screw or the hopper the screw is delivering material to.
Optional interlocked, quick release connectors enhance rapid dismantling and reassembly for cleaning.
Other Options Worth Considering
- Access panels
- Integral bag dump/sack dump stations
- Feed hopper agitators
- Mobile base
- Control panel or purged control panel
- Drive motor wash down
- Sanitary seal standoff
- Quick-release tube connections
- USDA/3A Design
- Right angle gear reducer
- Flexible discharge hose
- Static grounding
- Explosion proof motor
- NEMA 4 or 7/ATEX compliance
What are the maintenance costs?
We consider flexible screw conveyors to be low maintenance because they only have one moving part, the inner spiral. When installed correctly these conveyors are reliable and hassle-free. We recommend spirals that are heat treated and tempered for maximum working life. We also recommend that processors keep a spare spiral on hand. If by chance, your material changes or you incur any unexpected issue (see our article on Problems with Flexible Screw Conveyors), keeping a spare spiral on hand will minimize downtime.
How much will it cost?
Flexible screw conveyors are popular due to their relatively low cost but, as you can see, there are many variables that determine the price. You can expect the cost of a good quality flexible screw conveyor from a respected supplier to range from $4,000 (£1,800) at the low end and up to $20,000 (£18,000) at the high end.
