A 15% reduction in mill power consumption, a 10% increase in work roll life and a 20% reduction of mill load are the result of employing hot mill roll lubricants. The correct selection and method of application is essential in achieving such results.
Although the subject of hot roll lubrication has been around for a long time, recent experience has confirmed its value and benefit to the mill owner and their customers; the key is a professional approach and a commitment by all parties to make it work.
In an environment where supply exceeds demand and customers seek even higher quality, cost competitiveness is the essence of survival, supported by technical innovation and intensive customer focus. Suppliers who know their customers will understand these pressures and will come forward with ideas and proposals from which all can benefit, ultimately resulting in reduced cost per tonne of steel rolled. In the case of hot roll lubrication, reduced mill power consumption and lower loads, fewer roll changes with less regrinds, higher output and improved strip surface finish can all be achieved along the way.
With a growing number of success stories to support these claims and thus raise interest, the first step is to discuss the principles with a trusted supplier who can provide quantitative data on specific examples and, following a detailed survey of the candidate mill, make specific proposals and estimates of likely costs and benefits.
Factored into the discussions must be manpower resources, since in almost every case where such a project has failed or been aborted part-way through, the commitment of those involved has been short-lived. Success and access to the consequent benefits depend on maintaining this commitment.
Some suppliers will offer a trial on a single stand before committing to a larger installation. In such cases, 'portable' equipment is fitted and connected by experts, who, working with the mill personnel, optimize the trial to suit the mill characteristics and rolling programme. Comparison of pre- and post-installation data will confirm the viability of the principles and study of the quantitative results will determine whether a full installation is to be made.
During a successful one month trial of Shell Fenella Hot Rolling oil at a modern steel complex in India, a 15% reduction in power consumption, a 10% increase in work roll life and a 20% reduction of load were recorded. The customer has since requested a permanent installation on four of the six stands. This is now being commissioned. Furthermore, the mill management's confidence that theory could be translated into practice has been totally vindicated and has been an inspiration to the mill operators. The control system for the oil delivery equipment has been fully integrated into the mill, computers and now operates automatically according to the type of strip and its dimensions and many-other relevant parameters.
At an earlier installation in Western Europe, roll load reductions of 20% were observed, with a drop in power consumption of between 10% and 38% according to the material being rolled. The final conclusions were that, in addition to the major benefits, roll durability was increased, vibration during oil application was decreased and environmental limits on airborne emissions were not exceeded.
The lubricants are delivered to the roll bite as a dispersion, rather than as an emulsion and are volatilized as they contact the hot strip; any small quantities that find their way into the cooling water will rapidly separate into oil and water phases for easy disposal.