Conveyor chains deliver savings

For a brewery in Europe, as for many manufacturers, efficient pallet transportation was crucial to maintain a cost effective production regime. When it started to develop problems which lead to increased maintenance costs and lost production time, a high quality chain offered a solution.

The brewery employs 18 conveyors to transport pallets from the production area to the warehouse. Any breakdown in the system has an immediate effect on the brewery's productivity as well as accruing unscheduled maintenance costs. Each conveyor is 9.75m in length and consists of three strands of standard conveyor chain which runs at a speed of 15m/min, powered by a 7.5kW drive motor.

There are eight pallet positions on each conveyor, which are designed to convey a stack of three pallets, each holding five barrels. This arrangement places a load of 1,620kg on each conveyor position, allowing each to transfer up to nearly 13 tonnes at any one time, meaning that a failure of just one conveyor has a significant impact on production efficiency.

To improve the durability of the storage system, the pallets were changed from a wooden construction to plastic, allowing them to be reused a greater number of times. However, while improving one aspect of production, this change also introduced an unexpected issue with the conveyor system. The new pallets became contaminated by the lubrication oil on the conveyor chain, which in turn was transferred to the barrels, increasing the number of barrels that had to be rejected.

The initial action by the brewery to address this issue was to stop the lubrication of the conveyor chains, however this resulted in rapid elongation and the rollers within the chain wore quickly and unevenly due to the stick-slip effect. These worsening conditions increased the load on the drive motor causing the thermal trip to cut power to the motor, which led to increased loss of production and maintenance costs.

With rising levels of frustration and cost, the brewery needed to make an improvement to the conveyor system. The brewery approached Tsubaki to inspect the system and offer a solution to improve its reliability. An initial inspection revealed the issues with the conveyor chain and it was suggested that it be replaced with a maintenance free alternative consisting of two strands of Tsubaki Bearing Roller Conveyor Chain Lube-free Series.

This particular chain uses special cylindrical bearings that provide self-lubricating properties between the bushes and the rollers. Tests have shown this design to provide 5 times the wear life of general use conveyor chain. The expected lifetime is now 15 years, compared to 4 years in the previous setup, saving cost of maintenance and reducing total cost of ownership.

The design of this chain allows the cost of lubrication to be eliminated as well as reducing the load on the drive motor to such an extent that the original 7.5kW motor could be replaced with a 1.5kW version. This additional benefit means that the annual energy consumption for the conveyor system is reduced from 27,000kWh to just 5,400kWh, which in turn has reduced the associated CO2 emissions to 20% of the original figures.

The completed installation has greatly improved the reliability of the production line and significantly reduced the amount of lost production. In addition, savings have also been made in maintenance costs by eliminating the need for lubrication as well as the reduction in energy costs.