Materials and Manufacturing: Surface Roughness in Turning - Lab Report Example

Name Course Task: report Tittle: Materials and manufactureing 2 – surface roughness in turning lab report Date Materials and manufactureing 2 – surface roughness in turning lab report Introduction Machining is a manufacturing process that determines the final dimension and geometry, as well as the surface tecture. The machine surface roughness depends on the work material, the geometry, machine tool and vibrations. The nose radius and the feed rate are the most important factors that affect the surafce finish. Their effect can be combined to form an equation that can be used to predict the surface roughness produced by single point tool. The equation is shown below. Where Ri is the theoretical surface roughness, NR is nose radius of the tool point and f is feed rate. The figure below shows the nose radius and the feed on the surface finish Figure 1: (a) a nose radius (b) the feed on the surface Objective The objectives of this experiment are: To analyse the effects of depth of the cut, the cutting speed and the feed on the machining a work piece using cutting tool. To compare the surface roughness between the values obtained from the experimental and those obtained from books. The lathe machine used in the experiment is like as shown below. Lathe machine Methodology Lathe machine was used to perform the experiment while ensuring that the depth of cut was kept at a maximum of 2mm. the work piece with a length of 50mm and diameter of 45 mm was clamped on the chuck such that the two sections on the other end could be machined. One of the sections was turned using a cutting tool with a nose radius of 0.2 mm with a low cutting speed, but other section was turn with a high cutting speed. A spindle speed of 350 rpm and 1500 rpm was used. Similar procedure was followed in section 3 but with a different cutting tool nose radius of 1.2 mm. Results Exp Depth of cut (mm) Feed (mm/rev) Spindle speed (rpm) Cutting speed (rpm) Surface roughness (µm) 1 (low) (High) 3.044 3.143 0.22 350 1500 49.5 212.143 3.143 1.3314 2 3.394 3.027 0.22 350 1500 49.5 212.143 3.112 1.33 3 3.231 3.112 0.22 350 1500 49.5 212.143 3.027 1.3231 Ave 3.223 3.094 0.22 350 1500 49.5 212.143 3.071 1.302 Sample of calculation V= (N π D)/1000 Cutting speed, N =350 rpm, 1500 rpm D0=45 V = 350 x π x 45/1000 = 49.5 rpm VTn = C T = (L+A)/fr Ra = C x V-0.539 x Nr-0.271 x f0.707x d0.184 Ra = 36.53 x 49.5-0.539 x 1.2-0.271 x 0.220.707 x 3.0440.184 = 10.09 µm A graph representing changes of surface roughness (Ra) obtained from the instrument against cutting speed (v) when smaller cutting nose radius used. A graph with a nose radius of 0.2mm Exp Depth of cut (mm) Feed (mm/rev) Spindle speed (rpm) Cutting speed (rpm) Surface roughness (µm) 1 (low) (High) 3.290 1.738 0.22 350 1500 49.5 212.143 1.83884 0.7402 2 3.565 1.802 0.22 350 1500 49.5 212.143 1.8117 0.7353 3 3.089 1.793 0.22 350 1500 49.5 212.143 1.7907 0.7393 Ave 3.298 1.778 0.22 350 1500 49.5 212.143 1.8122 0.7370 A graph representing changes of surface roughness (Ra) obtained from the instrument against cutting speed (v) when larger cutting nose radius used A graph with a nose radius of 0.2mm The graphs shows that the cutting speed affect the surface finish. The surface finish is improved with an increase in the cutting speed. It has has also been shown that the machinability is improved by increasing the cutting speed. The is because as the cutting speed increase, there is a continous decline of the edge formation. It has also been shown that as depth of the cut increases, the surface finish is improved. The rough surface is affected by the interaction that involves the feed rate and depth of cut. This shows that in order to obtain a quality or good surface finish as well as highest surface removal, it is advisable to apply high feed rate that is related to the depth of the cut. It has aso been shown that an increase in cutting speed will result in an increase in quality of the surface finish a, but the feed rate reduce. This confirm the discussion regarding the effct on the surface roughnes which is as a result of an increase in the cutting speed on the workpiece. The relationship between the depth of cut and cutting speed shows that as the depth of the cut and the cutting speed increases, the surface roughness is deteriorated (Groover, 2011). Application In most production processes, turning is used to produce components with crucial features that require quality surface finish. There should be adequate knowledge on the factors affecting the surface finish, as the improper choices may result in large production, but with low quality. In the medical and aerospace fields, the components surface finish is very vital. The fuel injection system in the aerospace and the hydraulic systems requires accurately defined features and with high quality, like O-ring grooves if the integrity of the systems is to last. The manufacturers of pharmaceutical products and medical equipment should give information about the surface finish. The quality of the machine component is critical if lives have to be saved (Bhatnagar & Srivatsan, 2009; Groover, 2011). Some medical equipment like orthoscopic instruments need to have less fine surface so that it does not reflect fiber optic light on the eyes of the surgeons, making it hard to operate. The shafts of the golf club have rough surface to assist in crib. Surface of bicycle frames are also of low quality because high quality surfaces are not necessary and costly. There is less concern about the quality of surfaces finish in some market products like in automobile industry. Rough surface can also be used to provide aesthetic properties (Bhatnagar & Srivatsan, 2009). Conclusion It has been shown that as the nose radius decreases, the surface roughness decreases, hence the surface finish increases. The depth of cut and the cutting speed also affect the quality of the surface finish. The optimal combination of parameters for the manufacturing process of the work piece as related to the maximum surface finish or minimum surface roughness can be obtained with a cutting speed of 212.143 rpm, depth of cut of 1.778 mm, nose radius 1.2 mm, and cutting feed of 0.22 mm/rev. References Groover, M. P. (2011). Principles of modern manufacturing. Hoboken, N.J: J. Wiley & Sons. International Symposium on Processing and Fabrication of Advanced Materials XVII, Bhatnagar, N., & Srivatsan, T. S. (2009). Processing and fabrication of advanced materials, XVII. New Delhi: I.K. International Pub. House. Read More