Wet machining is still carried out in the metal cutting industry today; machining experts continue to work to reduce the use of coolant so that benefits for the environment, economy and operator safety can be obtained. The research aims to obtain cutting conditions which have a good chance of realizing the concept of dry machining on S45C steel regarding surface roughness. The research was carried out using 9 specimens by statics method with a normal distribution curve where S45C steel turning using uncoated carbide chisels was carried out on dry machining and wet machining. Machine spindle rotation of 700 rpm, 1000 rpm and 1300 rpm can be converted in the amount of cutting speed, then for infeed 0.15 mm/r, 0.2 mm/r, 0.25 mm/r and the depth of cut remains 1 mm. Machining S45C steel is selected for optimum cutting conditions on wet and dry machining. Machined surface roughness was tested using the Surface Test measuring instrument. The surface roughness obtained for dry machining was 1.602 µm, 1.667 µm and 2.041 µm for dry machining while for wet machining the results were 1.521 µm, 1.593 µm respectively and 1.915 µm. So, the most optimum cutting is obtained in cutting conditions with a cutting speed of 87.92 m/min at 700 rpm machine spindle rotation with Ra = 1.602 µm for dry machining while wet machining obtains a surface roughness value of Ra = 1.521 µm on wet machining. Comparison of the results of dry machining (Ra= 1.602 µm) and wet machining (Ra= 1.521 µm) to obtain the optimum surface roughness value Ra is not significant, so it is a good opportunity for the possibility of a dry machining technology to be applied to the metal cutting industry even though today many still use the wet machining method of turning using a cutting fluid to cut metal. Keywords: S45C steel, cutting parameters, surface roughness, dry turning

The aim of this research is to know the fiber laminate adding effect to tensile strength, SEM photo, and hardness of teki grass (cyperus rotundus) composite specimen. Tensile and hardness test specimens were prepared by hand lay-up method with variations of 1, 2, and 3 fiber layers. Test results showed the highest tensile strength occurred in 1 layer fiber of 21.83 MPa and decreased in 2 layers of fiber and 3 layers of fiber of 17.95 MPa and 16.17 MPa. This is caused by random fibers that spread in all directions so that many fibers are not aligned with the tensile force. Addition of the fiber layer results in reduced resin volume so that the bond between fiber and matrix also decreases, which in turn will make the fiber cannot withstand tensile well. Analysis of SEM photographs also proves that the reduced volume of resin causes the bond between fiber and matrix to decrease resulting in cavities in 2 layer and 3 layers of composite. The results of the hardness test show that the addition of fiber layer decreases the hardness value. This is due to the soft grass fiber that is softer than the resin polyester, so that the added layer of fiber will reduce the hardness value.

Drilling is the process of making holes by pressing a rotating drill bit on the workpiece. During the machining process there is interaction between the drilling bit and the workpiece in the drill bit of the workpiece with a hole while the drill bit undergoes friction. Such a friction comes from the chipped surface that flows on the surface of the workpiece that has been cut; as a result, the tool wears out. The wear of the drill bit that occurs due to friction between the drill bit and the workpiece needs to be examined so that the extent of the wear and tear is known. The purpose of this study was to determine wear on the Dormer A100 Brazil drill bit with size (8 mm), rotation speed (260 rpm, 375 rpm and 710 rpm). Tool wear data was collected using a microscope with a magnification of 20x. Tool wear is seen three times during the drilling and the machining process. The result obtained is that the higher the cutting speed, the bigger the wear occurs. Keywords: Dormer A100, gray cast iron, drilling process

No abstract

Shape and surface roughness of a product, when it is produced by a lathe, plays an important role because of its friction, wear, lubrication systems, and others. In each workpiece, the result of the machining process has a certain shape and surface roughness such as shiny, smooth, and rough surfaces. The machining process determines the surface roughness at a certain level, where the surface roughness is used as a reference for product evaluation. Machining the surface roughness of a product does not have a small value, but sometimes a product requires a large surface roughness value according to its function. Keywords: Feeding, surface roughness, AISI 1045, diamond chisel.