Gearboxes turn the screw on nylon production

Edited by the Engineeringtalk editorial team Nov 5, 2002

The compact nature and high reliability of Brevini's planetary gearboxes have been instrumental in their specification for use in the production of nylon at Du Pont's facility in Gloucestershire.

The compact nature and high reliability of Brevini's planetary gearboxes have been instrumental factors in their specification for use in the production of nylon at Du Pont's manufacturing facility in Gloucestershire.

The planetary units are currently being installed by engineering contractor BSL as part of an order for a total of 450 Brevini gearboxes worth GBP 0.33 million.

The large order resulted from a maintenance contract, which BSL was awarded at Du Pont's Gloucestershire facility.

As part of this contract, BSL was asked to overhaul several planetary gearboxes that played a key role in the manufacturing of nylon.

The gearboxes turned screws that controlled the delivery and mixing of raw materials used in the process.

Their importance to production meant that any maintenance work carried out on them had to ensure the longest meantime before failure to avoid costly downtime in what is a complex continuous process.

After the initial inspection, it was found that the cost of overhauling the old planetary gearboxes exceeded that of supplying completely new units.

This fact, coupled with BSL's experience in the power transmission market, led to the specification of over-sized Brevini planetary gearboxes, due to their proven operation in similar applications and their compact, lightweight design.

The Brevini units easily fitted Du Pont's existing drive system plinths and were supplied with custom shafts that ensured compatibility with the original delivery screws.

Despite this modification the cost of replacement was still below that of an overhauled unit.

Initially, Brevini three- and four-stage gearboxes were provided and put through 5 months of intensive trials, which involved continuous use with as many as three start/start operations per minute.

The performance of the Brevini gearboxes in the trials was successful enough for BSL to place an order for the custom gearboxes in preparation to replace all of the 450 planetary gearboxes being used at the plant.

The programme for gearbox replacement represents BSL's largest order of gearboxes to date at GBP 338,000 in a deal worth a total of GBP 0.5 million.

The Du Pont order is typical of the increasing acceptance of Brevini's planetary gearboxes for use in industrial applications.

The reasons for this are many.

Firstly, planetary gear trains are able to deliver high reduction ratios in small packages, and transmit several times the torque of comparably sized, conventional gear units.

Secondly, the planetary drive is up to 98% efficient and, critically, is able to provide extremely low speeds without any loss of efficiency.

Finally, high levels of reliability are a feature of the planetary design, thanks to the distribution of stress among several load-bearing components.

Added to these features is the facility for modular design, based upon the epicyclic cell, to provide ultra-compact multiple reduction units.

The advantages of this arrangement to the designer are twofold; the planetary stages can be combined to match the increasing torque being transmitted through a gearbox and be assembled to provide reduction ratios to a value of 15,000:1 if required.