| 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. Increasing the Competitiveness of Hot Rolling 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. Where to Start? 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. Factors to Consider 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. Trials 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, optimise 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. Case Study – India 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. Case Study – Western Europe 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. Lubricant Delivery The lubricants are delivered to the roll bite as a dispersion, rather than as an emulsion and are volatilised 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. Optimising Variables Setting up a hot roll lubrication system for a particular mill takes time and dedication in order to optimise the many variables and tailor it for the circumstances. But for those serious about overall cost reduction achieved by greater uptime, lower operating costs and improved quality, then time spent in doing this time is well spent. Saving of hundreds of thousands of dollars are being made once the lubrication system is optimised. Cold Rolling Different parameters are required for the cold rolling mill, where the selection of a robust product will pay for itself in terms of maximising speeds and strip quality, increasing roll life and extending emulsion life. Emulsions here are more sensitive to a lack of care or mistreatment. With housekeeping playing such an important role in the overall cost efficiency of a mill, it is critical that good cellar management is in operation. Even the best cold rolling oils will suffer if subjected to excessive contamination, ineffective filtration or contamination by other lubricants and debris. Infrastructure Management Regular inspection of the mechanical systems, to ensure that leaks are found and fixed as soon as possible, and that filtration and other mechanical equipment is in good operating condition, is essential to efficient operation. Case Study A two month trial on a 5-stand tandem mill in the Far East using Shell Fenella CR grades, resulted in increased rolling speed, improved productivity with less reject material and good oil recovery. Another Indian steelworks has purchased a package of products and services that includes Shell Fenella rolling oils, cellar management and on-site analysis to ensure that the fluid is maintained in tip-top condition and mill output quality and quantity is maximised. When it comes to disposal, simple techniques can be applied to the separation of the fluid phases and appropriate routines employed for final disposal. Post Rolling Coating Oils After the rolling processes, a variety of coating oils and protectives are available for many different purposes, including temporary protectives, sheet coating oils, tinplate coatings and pickle rinse inhibitors; some simple, some complex, some solvent containing some not, dual purpose and short through to long term. In some cases the end customer will specify particular technology and local legislation may dictate certain choices. | 
DMG World Media
