Gravity roller conveyor is referred to as such, because it uses gravity to move goods. The basic design is that of an outer framework made from steel or plastic and fitted with a series of steel or plastic rollers that are fixed within that frame, over which the goods can then be rolled from point to point. The movement of the goods can be completed by gravity, pushed manually, or by electrical power. Manual power obviously needs a member of the workforce to gently encourage the goods along the conveyor; complete independent gravity requires some specific design work to achieve this, whilst electric conveyors will cost more money! There are several options of conveyors that can be considered, but it is always best to consult the experts first. Many of our customers just use a simple straight line of conveyor whilst others ask us to design more complicated systems that integrate with production and assembly processes already used on site.
Roller conveyor can be set out on the floor, on top of workbenches or mounted on legs. Assembly lines often use them in production areas, where staff assemble goods, then move those goods by hand down a roller conveyor line to another point. To move goods along a conveyor line by gravity, you will need leg supports that are set at a variety of heights to promote the 'gravity effect'. Usually an initial ‘push’ is required to start them on their way. Electrically powered roller conveyor can obviously take out this manual effort and control the rate of timing and speed of operation more precisely. Combinations of electric and gravity conveyor systems can be employed to provide the optimum system required. It is always important to employ safety stops and guarding mechanisms to prevent accidents or damage occurring.
Roller conveyor frames can be supplied in these materials:
- Mild steel
- Aluminium
- Plastic
- Stainless steel
Conveyor rollers can be manufactured from:
- Mild steel
- Stainless steel
- Plastic
Integrated steel roller conveyor system
The type of conveyor that is best suited to an application is usually established by assessing weight/size capacity, operating environment and the available budget. Mild steel gravity conveyor is the most popular, although the final choice is usually dependant on the weight/size of the goods to be conveyed. Plastic conveyors come in two distinct designs - roller or skate-wheel. The skate-wheel system is the lighter of the two in terms of capacity and they offer the ability to turn goods through a tighter radius around corners or bends. Sometimes a combination of the two types working in tandem can provide the best result.
Steel frame and rollers
Steel frame and plastic rollers
Aluminium frame and plastic skatewheels
The roller capacity is worked out by dividing the overall weight of a product to be conveyed by any three rollers. Three rollers being the minimum 'under product' requirement at any one time supporting the load. As an example, if the product weighs 150Kg then each roller will need to have a minimum capacity of 50Kg.
The higher the weight capacity, the larger the diameter and wall thickness of roller will be required. The 'fitting of three rollers' at any one time under your product load will require some working out, as goods often differ in size and weight, so you must consider all the different product ranges that you wish to convey. Should you require it, assistance is readily available from our sales team to help determine the correct configuration.
The point of contact between the product load and the top of the rollers also needs to be carefully considered as uneven, ribbed or non-uniform product bases may prevent smoothly movement of goods down the conveyor line. Often, we find that awkward shaped goods will have to be mounted on a pallet base or in a container to ensure that they roll easily and safely.
Regular maintenance or replacement of damaged rollers also needs to be considered. The cost-effective way of mounting rollers within a framework is by securing them in place with a length of rod that runs through the roller spindles outside of the framework on both sides of the conveyor. This however means that replacement of a single roller requires all of the rollers to be removed from the framework to access any one individual roller. However, spring loaded roller systems allows for access to individual rollers making this faster and easier. This also allows for quicker cleaning of the rollers as well.
Conveyor systems can be designed with bends, corners, transfer sections and specialised accessories to suit the application, so it’s advisable to seek guidance when purchasing a conveyor system.