الفهرس 
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Abstract
Quality and productivity are major objectives of any manufacturing facility. To compete internationally, it is not enough to build just a good product. Manufacturers are racing to produce products that satisfy or exceed customers’ needs and expectations.
In hot rolling, physical and metallurgical properties together with dimensional and surface quality of the finished product will affect rolled sheet performance. Building a product is usually completed in three main phases: process design (planning), parameters design and tolerance design.
In the present work a parameters design approach is implemented to study the factors affecting the product quality and equipment performance in hot rolling plants. Four empirical models were developed to predict and explain the relationship between the main critical process parameters and the type and range of product defects together with the equipment disorders. The study is mainly devoted to the improvement of product quality through optimization and control of process parameters.
Experimental work based on the design of experiments method is used to study the influence of operating variables (process parameters) for the rolling process on Product quality and equipment performance.
The most critical process parameters were set at specified values (levels) and the effect of the change in these parameters on produced sheets quality together with equipment performance is evaluated. The four process parameters considered in the investigation are the reduction ratio at the considered stand (Rd), the slab temperature (Ts), the exit strip speed (Sp) and the oil flow quantity that sprayed upon top and bottom rolls surface (Ot and Ob). The product quality characteristics considered include; distance between batches of chatter marks, sheet profile and flatness. The performance indicators considered include; value of rolling force and vibration level at considered stands.
The investigation proved that through optimization of process parameters using the design of experiments approach it is possible to improve both product quality and equipment performance in hot rolling plants. It was possible to reduce chatter with no change in equipment components or management. Consequently, chatter marks were eliminated and roll wear greatly reduced. Plant down time and production scrap was considerably reduced. Problems associated with inefficient roll lubrication (e.g.: cobble formation, strip waviness, roll crack ... etc) were also reduced through optimization of the lubrication strategy.