Hot Roll Lubrication - A Cost-Cutting Measure

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Hot roll lubrication has been known about for a long time and the latest research has demonstrated the advantage and value of this method to mill owners and their customers. The key lies in the commitment and professional approach by all concerned parties to make this method work.

Increasing the Competitiveness of Hot Rolling

Cost-competitiveness is the key to survival, specifically in a setting where customers look for even higher quality, and supply exceeds demand. Such competitiveness is supported by intensive customer focus and technical breakthroughs. Suppliers who understand their customers will be aware of these pressures and will recommend proposals and ideas that can benefit everyone.

This would eventually result in reduced cost for each ton of rolled steel. Where hot roll lubrication is concerned, benefits like lower loads, reduced mill power consumption, higher output, fewer roll changes with less regrinds, and better strip surface finish can be realized along the way.

Where to Start?

Such claims are supported by an increasing number of success stories, gaining considerable attention. Therefore, the initial step is to discuss the principles with a reliable supplier who can offer quantitative data on particular examples. After surveying the candidate mill thoroughly, the supplier can make certain proposals and estimates of potential benefits and costs.

Factors to Consider

Manpower resources should be considered in the discussions because, in almost all the cases, such projects either have failed or have been abandoned half-way through. Hence, the commitment of those involved in the projects has been rather short-lived. Maintaining this commitment is important to achieve success and to avail the resulting benefits.

Trials

There are a few suppliers providing a trial on a single stand before agreeing to a larger installation. In such situations, “portable” equipment is installed and linked by experts. In association with the mill personnel, these experts will improve the trial to suit the rolling program and mill characteristics.

The viability of the principles can be confirmed by comparing both pre- and post-installation data. Furthermore, an analysis of the quantitative results will help establish whether a complete installation has to be made.

Case Study—India

A one-month trial of Shell Fenella Hot Rolling oil was successfully carried out at a contemporary steel complex in India. During that trial, a 20% reduction of load, a 10% increase in work roll life, and a 15% reduction in power consumption were recorded. Since then, the customer has wished for a permanent installation on four of the six stands, and this request is currently being commissioned.

In addition, the confidence of the mill management that theory can be converted into practice has been fully justified and has served as an inspiration to the mill operators. The control system meant for the oil delivery equipment has been completely incorporated into the mill computers and currently works automatically based on the type of strip and its dimensions, and also several other applicable parameters.

Case Study—Western Europe

At a previous installation in Western Europe, a 20% reduction in roll load was noticed, with a reduced power consumption of 10% to 38% based on the material being rolled. The concluding results were that, apart from the significant advantages, vibration during oil application was decreased, roll durability was increased, and environmental limits on airborne emissions were not surpassed.

Lubricant Delivery

Lubricants are sent to the roll bite in a dispersion form and not as an emulsion. These lubricants are volatilized as they come into contact with the hot strip; any negligible amounts that end up in the cooling water will quickly separate into water and oil phases, to facilitate easy disposal.

Optimizing Variables

It takes time and dedication to set up a hot roll lubrication system for a specific mill, especially when many variables have to be optimized and the system needs to be customized to suit the conditions. However, those who are serious about the total cost reduction obtained by lower operating costs, greater uptime, and better quality will find that time spent in doing this task is useful. Once the lubrication system is optimized, hundreds and thousands of dollars can be saved.

Cold Rolling

The cold rolling mill requires different parameters. Here, the choice of a powerful product will pay for itself with respect to maximizing strip quality and speeds, extending emulsion life, and increasing roll life. Here, emulsions are more sensitive to mistreatment or lack of care.

Since housekeeping is significantly contributing to the total cost-efficiency of a mill, good cellar management should be followed. Even the best cold rolling oils will not stand the test of time if subjected to ineffective filtration, excessive contamination, or contamination by other debris and lubricants.

Infrastructure Management

Routine inspection of the mechanical systems to make sure that leaks are detected and fixed immediately, and that mechanical equipment, including filtration, is in good working condition is important for efficient operation.

Case Study

A two-month trial was conducted on a 5-stand tandem mill located in the Far East by making use of Shell Fenella CR grades. This resulted in better productivity with less material rejection, increased rolling speed, and excellent oil recovery.

A package of products and services was also purchased by another Indian steelworks. This package includes cellar management, Shell Fenella rolling oils, and on-site analysis to make sure that the fluid is kept in excellent condition, and that the quantity and quality of the mill output are maximized. With regard to disposal, easy methods can be used to separate the fluid phases, and suitable routines can be used for ultimate disposal.

Post-Rolling Coating Oils

Following the rolling processes, a range of protectives and coating oils are available for a variety of purposes. These include tinplate coatings, sheet coating oils, temporary protectives, and pickle rinse inhibitors—some complex, some simple, some solvent-containing, some solvent-free, short-term through to long-term, and dual purpose. In a few cases, the end-user will specify certain technology where certain choices will be governed by local legislation.