Optimization of extrusion process parameter in manufacture of ilmenite TiO₂ reinforced pencil lead

The production of pencil lead with the inclusion of ilmenite for strength improvement and product wear control especially during production was investigated. A Response Surface Methodology (RSM) based on three numeric factors and two center points thus generating sixteen runs was used as tool for the optimization of production process parameters. The major raw materials which are graphite clay and ilmenite were characterized using X-ray fluorescence technique while the surface morphology was studied using scanning Electronic microscopy. The studied input variables were ram pressure, moisture content and die dead angle. Also, an experimental investigation of fracture force and wear rate of pencil lead were carried out. To obtain the optimum values of the properties being investigated, a tribometer and Micro Universal Testing Machine (MUTEM 4) were used for measurements, and response table was generated. The response surface plots showed that all three input variable had considerable impact on the responses. Results showed that the graphite used is made up majorly of carbon and ilmenite (TiO₂). The control factor levels were applied to optimize the desired mechanical properties of reengineered pencil lead using the RSM. Results also showed that with a die angle of 55.3850^oram pressure of 5.716Mpa and moisture content of 22.735, the optimal fracture force is 2.6055N, and optimal wear rate is 0.445 mm/l. These results were validated with those of industrially manufactured ones whose values are 2.95N and 0.35 mm/l respectively. It was concluded that ilmenite can serve as a good additive to pencil lead production.