Browsing by Author "Muhammad Riza"

In mold and die industry, surface roughness is one of the important responses in defining the quality of a removed surface by machining including milling processes. Tool path has been considered to have influence on cutting force, tool wear, cutting temperature and subsequently the respected surface finish. Therefore, appropriate tool path strategies need to be investigated to achieve the expected quality. This study aims to investigate the effect of tool path strategies on surface roughness while pocket milling of AISI H13. Metal cutting was performed at cutting speeds 150, 200 and 250 m/min with feed rate were set at 0.05, 0.1 and 0.15 mm/tooth. Depths of cut were 0.1, 0.15 and 0.2 mm for every cutting process. Response Surface Method with a standard called Central Composite Design (CCD) was employed. The responses were evaluated by examining tool wear, surface roughness, cutting force and cutting temperature. It was found that the zigzag and contour-in tool path strategies have shortened the tool path by 26% and 36% respectively when compared to inclined strategy. Consequently, this brought down the cutting time for zigzag and contour-in strategy by about 30% and 46% respectively when compared to that of inclined strategy. It was also found that contour-in and zigzag strategy has also decreased cutting force by 46% and 36% respectively when compared to inclined strategy. From cutting temperature viewpoint, contour-in and zigzag strategy produced lower cutting temperature than inclined strategy by 23% and 12%, respectively. Contour-in and zigzag tool path strategy resulted 49% and 31% lower cutting force respectively when compared to inclined strategy. Ultimately, the result obtained from experimental work reveals that contour-in and zigzag strategy produced better surface finish indicated by lower surface roughness than inclined strategy by 31% and 22%, respectively. This is due to the fact that increases in cutting temperatures and cutting forces occurred in the corners of pocket and the turning points. Tool engagement angle also plays an important role in order to increase the cutting force and cutting temperature. By examining the empirical model analysis, it was clear that the cutting speed (Vc), feed per tooth (Fz) and depth of cut (DoC) have a positive effect to machining performance. However, feed per tooth (Fz) was identified as the most significant factor influencing tool wear, surface roughness, cutting force and cutting temperature for all tool path strategies. Overall, feed per tooth gives a significant impact to almost all responses. Twelve models were developed for tool wear, surface roughness, cutting force and cutting temperature that can be reliably used for prediction of the responses for tool path strategies. The quadratic model was found to be best fits for tool wear, surface roughness, cutting force and cutting temperature. It was found that the optimization value produced by Response Surface Methodology (RSM) is very close to the one produced by Genetic Algorithm (GA). This condition was pertinent for all tool path strategies. It was found that among the three different tool path strategies studied, the contour-in is considered as the best tool path in undertaking pocket milling within the range of cutting parameters specified. By taking into account all the advantages associated with contour-in strategy, its application is recommended in practice.

The development of cutting tool materials has been achieved mostly through practical machining operations. Cermets have been used as cutting tools materials for many years. This is due to improvement made on the cermet grades, its stability, speeds and conditions as well as the trend towards near-to-finish workpiece blanks. This research is to investigate performance of cermet insert under different rake angles and different cutting speed. Experiments were carried out by using cermet (CT5015). Different rake angles have been applied in the experiments which are 0o, -3o, -6o, -9o and -12o respectively. Cutting speeds 1000 m/min and 300 m/min with feed rate 800 mm/min and 240 mm/min have been applied. Depths of cut were kept constant throughout the experiments. Data were collected from measurement of every single pass of cutting, surface roughness, tool wear, cutting force and cutting temperature. The experimental results showed that increasing negative rake angles causes higher wear, shorter duration of tool life and poor surface finish. Temperature trend increases by increasing the negative rake angle. The different between high speed and conventional speed was also observed in this experiment. High speed turning gives shorter tool life, high wear rate but finer surface finish than conventional one.