The Situation
A global manufacturer of plastic piping was experiencing a number of recurring issues with their critical extrusion processes. The screw being driven by the extruder gearbox had broken on a number of occasions, causing production stoppages. Several gearbox failures had also happened, costing up to £30,000 each time to replace with considerable lead times (3-4 weeks) associated with these units. As a registered MRO supplier for the customer, HAYLEY DEXIS had already resolved the issues in one gearbox, and was now invited to look at seven further gearboxes on-site.
The Solution
The original gearboxes in question were 30kW Nord units, all operating at 140rpm. The customer needed to reduce the speed to 40rpm, and had previously attempted to do this with an inverter. However, the inverter was set at 13hz and was causing serious heat build-up at the core of the motor, resulting in frequent burn outs and breakdowns. The challenge was to get down to the 40rpm speed with limited space of the design envelope of the gear reducer. Increasing the ratio to the maximum allowable within the same frame size of reducer allowed for the frequency to be increased to 33Hz. This vastly improved the cooling effect of the motor, with the increase in ratio improving output torque and enabling the motor size to be reduced to 11kW. Upon completion, the system was refilled with new oil and production restarted.
"REDUCING THE POWER OF THE GEARBOXES HAS ENABLED THE CUSTOMER TO REDUCE ELECTRICITY COSTS BY £209,869 PER ANNUM.
The Result
Thanks to the technical expertise of the team involved with the project, a solution was arrived at that has halted costly mechanical failures as a result. In terms of time savings, each failure would previously have involved a 3-4 hour replacement process and a 3-4 day repair turnaround (if viable), or a 3-4 week leadtime on a new gearbox. The downtime costs associated with these durations is now no longer a concern for the maintenance team.
Reducing the power of the gearboxes has enabled the customer to reduce electricity costs by £209,869.66 per annum, enabling a payback period of <1 month. This calculation is based on a generous negotiated cost of 22p per kWh that the customer currently has in-place. As a result of the ongoing benefits that HAYLEY DEXIS has enabled the customer to achieve, HAYLEY DEXIS has been invited to replicate the process again with four additional gearboxes on site. This is estimated to save the customer a further £119,926 per year on their energy costs.