Why use a screw conveyor ?
When thinking about conveying bulk material, a number of options are available to you, the most commonly used are:
Aero mechanical conveyor
So why choose screw conveying over these solutions ?
First of all, lets start with a quick definition of what a screw conveyor is : a device for moving loose materials, consisting of a shaft with a broad, helically wound blade rotating in a tube or trough. It is also often referred as an auger conveyor or an helical conveyor.
The definition and images on Wikipedia can also be of help to get a better idea of the possible applications for such devices. It can also be called a worm conveyor in some cases.
There are a number of advantages for screw conveyors :
The possibility to handle from dry solids to semi fluid materials
The cost effectiveness of the solution
The possibility to have multiple inlets, outlets and discharge points in the conveyor
The possibility to build an enclosed conveyor for corrosive or hazardous requirements
On top of those advantages for traditional shafted screw conveyors, you can also add some specific advantages for shaftless screw conveyors:
Possibility to handle sticky and sluggish bulk material without the risk of material building up around the screw's shaft
The efficiency is higher due to the fact that the conveyor can work with a filling rate of up to 100%
Because the shaftless screw conveyors do not need hangers and bearings, layout is much easier, therefore saving space and money
Shaftless screw design and calculation (myth)
When designing a shaftless screw for use in various types of equipment i.e. (shaftless screw conveyor, shaftless screw feeder, grit classifier…) the most common assumption is the thickest part of the screw profile, should be the out-side peripheral edge of the screw, (in contact with the liner), because this is where the maximum stress is (commonly used flight profiles 1” 3/4 x 1/2” inner and 2” 1/4 x 3/4” outer for a 11” 1/2 OD screw).
After researching the best profiles for shaftless screws by manufacturing different profiles and then performing destructive testing (in both pulling and pushing modes), it turns out that the maximum amount of stress imposed on the screw, is in fact imposed by the gear drive along the inside center axis of the screw, justifying the fact that a thicker inside profile would allow for greater resistance over time.
Two solutions seem to be better suited to get the maximum out of your shaftless screw equipment, extending the life of the screw, reducing the cost of operation and maintenance downtimes:
Go with a shaftless screw with a thicker inner section and thinner outer section (for example 3” x 3/4” inner and 1” 1/4 x 1/2” outer for a 11” 1/2 OD screw)
Ask for a supplier that can manufacture your screws in one section only (4” x 3/4” for the same 11” 1/2 OD screw).
Feel free to contact us to get more information on our study or to find out how we could help you improve your screw's life expectancy by using one of the two above mentioned solutions.
S2S Industries is a Canadian company specialized in cold forming spirals for municipal, industrial and agricultural applications at competitive pricing. We manufacture every kind of conveyor screw.
Our screws can be designed and manufactured to fit all available screw conveyor replacement OEM parts.
S2S Industries meets and exceeds all standards of the industry. We manufacture a complete line of standard spirals and also design and manufacture custom spirals to meet our clients’ highest demands.
S2S Industries has developed its own software that allows us to design, engineer and manufacture improved spiral profiles and a combination of steel tailored to the specific needs of our clients.
With decades of experience in both Europe and North America manufacturing both shaftless and shafted spiral for screw conveyors, compactors and classifiers, S2S Industries’ team has a unique know-how and experience which enables us to produce the most demanding profiles using the hardest steel with a consistent outstanding quality.
S2S Industries’ technical team will be pleased to assist you in your selection of the type of spiral you need and when necessary will come to the site for installation.
S2S Industries is located in Laval, Province of Quebec, Canada.
Our 12 000 square feet facility is equipped to manufacture all types of spirals and conveyor parts.
Our exceptional quality, service and logistics programs ensure deliveries on time coast-to-coast for our North and South American clients.
Our machines enable us to produce stronger, heavier "cross sectional / profiles", wear resistant spirals resulting in major cost savings (lower maintenance) for our clients.
On the BLOG section of our website, you will find relevant news, as well as some of the projects we are working on at the moment.
This will give you a better idea of what we do.
As always, feel free to contact us, either by calling us at +1 (514) 228-1660 or using the Contact us page of this website if you have any question about our products, or any project you would like us to help you with.
When discussing screw conveyors, it is important to know the difference between shafted and shaftless screw conveyors and their respective applications. You will find a simple explanation below telling you a bit more about it.
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