An Elevator feeder as well as Stock feeder is used to hold extra parts for replenishing the supply in a vibratory bowl feeder. They are set to operate automatically by a signal from a level control switch, thus eliminating either a deficiency or an over-supply of parts in the bowl.
The number of components which can be loaded in a vibratory bowl feeder is limited either due to the volume or weight of the components. Volume is especially important in case of rubber or plastic components and weight when the components are metallic. In case extra loading capacity is required, then the choice is to either use a bigger bowl feeder or else to use an auxiliary feeding unit like a flat vibratory hopper or elevator, silo etc. These auxiliary equipments can increase the loading quantity tremendously and the bowl feeder can become a totally man-less operation requiring refilling at longer intervals.
Thus an elevator and a stock feeder are competing products and while deciding on which one to opt for, the following points require consideration –
- Weight of the parts / components – The loading height of a stock feeder is usually around 400 mm to 700 mm above that of the vibratory bowl feeder and that of a elevator is between 500 mm to 700 mm from the ground level. Hence, in case of heavier parts, it is preferable to opt for an elevator so that operator fatigue is reduced and the parts can be easily loaded at a lower height. In case of small plastic parts or other light weight parts, a stock feeder is ideal.
- Volume / loading capacity required – Volume in case of stock feeders or hoppers can range between 15 litres to 50 litres while that of elevators range between 50 litres to 200 litres.
- Running cost – Elevators work on 0.25 HP to 1 HP motors (depending upon their size and component weight while stock feeders or hoppers have a linear vibrator drawing power of just 10 VA to 400 VA (depending upon its size).
- Replacement parts – The only parts which need be replaced in case of stock feeders are coil, controller and spring plates of the linear vibrator. The prices of these spares are very less. In case of an elevator, belt, gear box (or its components), bearings etc. might require replacement over time.
- Space required – Stock feeders / hoppers use much less space and additionally are kept at a height, thus reducing the total foot print. Vis a vis elevators require much more space.
- Life – Life of both are usually the same and they last for many years.
- Cost – Obviously, the cost of a stock hopper is much less than that of an elevator
Thus, an elevator feeder has obvious advantages over that of a stock feeder or hopper but its initial cost, space required and running cost is much more than that of a stock feeder. Hence, the decision whether to opt for a stock feeder or a elevator depends upon the loading capacity required and weight of the parts to be fed.