Effects of Cutting Parameters on Surface Roughness during End Milling of Aluminium under Minimum Quantity Lubrication (MQL)

In this study an experimental investigation of effects of cutting parameters on surface roughness during end milling of aluminium 6061 under minimum quantity lubrication (MQL) condition was carried out. The experiments were carried out to investigate surface quality of the machined parameters and to developed mathematical models using least square techniques. Spindle speed (N), feed rate (f), axial depth of cut (a) and radial depth of cut (r) has been chosen as input variables in order to predict surface roughness. The experiment was designed by using central composite design (CCD) in which 30 samples were run in a CNC milling machine. Each of the experimental result was measured using Mitutoyo surface tester. After the predicted surface roughness values have been obtained the average percentage errors were calculated. The mathematical model developed by using least square method shows accuracy of 89.5% which is reasonably reliable for surface roughness prediction. With the obtained optimum input parameters for surface roughness, production operations will be enhanced

Cutting Parameters Effects on Surface Roughness During End Milling of Aluminium 6061 Alloy Under Dry Machining Operation

In this project an experimental investigation of the cutting parameters effects on surface roughness during end milling of aluminium 6061 under dry machining operation was carried out. The experiments were carried out to investigate surface quality of the four machined parameters and to developed mathematical models using least square approximation techniques. Spindle speed (N), axial depth of cut (a) radial depth of cut (r) and feed rate (f), has been chosen as input variables in order to predict surface roughness. The experiment was designed by using central composite design (CCD) in which 30 samples were run in a CNC milling machine. Each of the experimental result was measured using Press-o-firm and Mitutoyo surface tester. After the predicted surface roughness values have been obtained the average percentage errors were calculated. The mathematical model developed by using least square approximation method shows accuracy of 91% which is reasonably reliable for surface roughness prediction. With the obtained optimum input parameters for surface roughness, production operations will be enhanced

Comparative Analysis of Chatter Vibration Frequency in CNC Turning of AISI 4340 Alloy Steel with Different Boundary Conditions

In this study, an experimental investigation of chatter vibration frequency in CNC turning of AISI 4340 Alloy Steel material was carried out, with uncoated carbide tool insert (TPG 322) on Fanuc 0i TC CNC lathe machine, with two boundary conditions. The experimental design adopted for this study is the Taguchi parameter design with L9 orthogonal array. Turning tests were carried out on nine samples of the test-piece material for the clamped-free (C-F) condition, and the tests replicated on another set of nine test-pieces for Clamped-Pinned, so-called C-SS workpiece boundary condition.  Chatter vibration frequencies were measured using MXC-1600 digital frequency counter and the frequency plots continuously analysed through DTO 32105 sound signal and frequency analyzer. The main objective is to investigate the process parameters’ performances on the work-piece material of AISI 4340 alloy steel, and to carry out comparisons between the two different boundary conditions vis-à-vis the effects of process parameters which are cutting speed, feed rate and depth of cut on the chatter vibration frequency for the orthogonal turning operation. Chatter vibration frequency values for the C-SS scenario were found to be up to 30% lesser when compared to the C-F machining scenario. Introduction of the tailstock used in pinning the free-end of the slender work-pieces reduced the chances that workpiece would bend; whereas absence of the pinned end means that workpiece may be skewed at an angle in the chuck with increased dynamic deflections at the free end leading to more aggressive workpiece and cutting tool perturbations which are known to favour cutting instability

Comparative analysis of aluminium surface roughness in end-milling under dry and minimum quantity lubrication (MQL) conditions

In this study an experimental investigation of effects of cutting parameters on surface roughness during end milling of aluminium 6061 under dry condition and minimum quantity lubrication (MQL) condition were carried out. Spindle speed (N), feed rate (f), axial depth of cut (a) and radial depth of cut (r) were cutting parameters chosen as input variables in the investigation of the surface roughness quality. The experimental design adopted for this study was the central composite design (CCD) of response surface methodology. Thirty samples were run in a CNC milling machine for each condition and the surface roughness measured using Mitutoyo surface tester. A comparison showing the effects of cutting parameters on the surface roughness for dry and MQL conditions in end-milling of aluminium were evaluated. Surface roughness values for MQL condition were lower with up to 20% reduction when compared to dry conditions. MQL cutting condition was found to be better and more reliable because it is environmentally friendly and gives better surface finish. With the obtained optimum input parameters for surface roughness, production oper- ations will be enhanced

Development of a Rocket Stove Using Woodash as Insulator

Abstract A rocket stove which serves as a cheaper and more safer alternative to conventional method of cooking, employing the use of solid fuels has been developed. The construction was done with our locally available metallic materials for the body and combustion chamber of the stove, using teak (khaya grandifoliala) wood ash as an insulator. An analysis of the thermal and mechanical properties of the insulating wall, fuel magazine, combustion chamber, and chimney were also performed; the law of energy conservation was used to determine the stove thermal efficiency which is 37.3%, while the Newton’s law of cooling was used to determine the convection heat transferred by the stove body (150864 J/kg) and Stefan-Boltzmann law was used to determine the amount of heat radiated by the stove body (49.2 J/kg), thus, signifying its suitability for home heating. A less expensive but very effective materials mixture containing galvanized steel and wood ash were found to have thermal properties comparable to that of fired vermiculite and stainless steel materials which are more expensive in other improved stove designs

EVALUATION OF CHATTER VIBRATION FREQUENCY IN CNC TURNING OF 4340 ALLOY STEEL MATERIAL

In this study, an experimental investigation of chatter in CNC turning for 4340 Alloy Steel material was carried out. Empirical study of chatter and critical cutting condition in CNC turning has been conducted through a well- designed three-factor three-level experiment, and regression models developed for chatter frequency prediction with up to 99.5% accuracy for the material. The arising model and the mean-effect plots of the cutting speed, feed rate, and depth of cut against Signal-to-Noise (S/N) ratio indicates that increasing feed rates and depth of cuts would bring about increase in chatter vibration frequency while high cutting speeds would have attenuating effects on chatter vibration frequency, thereby suppressing it. The percentage contribution of the cutting parameters to chatter vibration frequency established, and optimal machining condition for the machine chatter optimization obtained at a cutting speed of 320 m/min, feed rate of 0.05mm/rev and depth of cut of 0.5mm. The optimal chatter vibration frequency for the turning tests was found to be 130.00 Hz. With the obtained optimum input parameters for chatter vibration frequency, production operations will be enhanced

Stability Analysis of Model Regenerative Chatter of Milling Process Using First Order Least Square Full Discretization Method

Regenerative chatter is an instability phenomenon in machining operation that must be avoided if high accuracy and greater surface finish is to be achieved. It comes with its own consequences such as poor surface finish, low accuracy, excessive noise, tool wear and low material removal rate (MRR). In this paper, an analytical method base on first order least square approximation full-discretization method is use for the stability analysis on the plane of axial depth and radial depths of cut. A detail computational algorithm has been developed for the purpose of delineating stability lobe diagram into stable and unstable regions using mathematical models. These algorithms enabled the performance of sensitivity analysis. From the results axial depth of cut enhances the unstable region and suppresses the stable region. This means that inverse relationship exists between the axial and limiting radial depths of cut thus highlighting the need to determine the maximum value of their product for achieving maximized MRR thereby reducing the chatter in the milling process. It is also seen that the peak radial depths of cut occasioned by the lobbing effects occur at fixed spindle speeds irrespective of the axial depth of cut. Similarly, the rise in spindle speed enhances the stable region and suppresses the unstable region. This means that for us to have chatter-free milling process, parameters like axial and radial depths of cut should be carefully selected together at high machining speed. With these behaviour, one can locate the productive spindle speed at which the lobbing effects occur and depths of cut combination for the operator

Primary hepatic neuroendocrine carcinoma: report of two cases and literature review.

Background: Primary hepatic neuroendocrine carcinoma (PHNEC) is extremely rare. The diagnosis of PHNEC remains challenging-partly due to its rarity, and partly due to its lack of unique clinical features. Available treatment options for PHNEC include surgical resection of the liver tumor(s), radiotherapy, liver transplant, transcatheter arterial chemoembolization (TACE), and administration of somatostatin analogues. Case presentation: We report two male PHNEC cases and discuss the diagnosis and treatment options. Both cases presented with abdominal pain; case two also presented with symptoms of jaundice. The initial diagnosis for both cases was poorly differentiated grade 3 small-cell neuroendocrine carcinoma, based on imaging characteristics and the pathology of liver biopsies. Final diagnoses of PHNEC were arrived at by ruling out non-hepatic origins. Case one presented with a large tumor in the right liver lobe, and the patient was treated with TACE. Case two presented with tumors in both liver lobes, invasions into the left branch of hepatic portal vein, and metastasis in the hepatic hilar lymph node. This patient was ineligible for TACE and was allergic to the somatostatin analogue octreotide. This limited treatment options to supportive therapies such as albumin supplementation for liver protection. Patient one and two died at 61 and 109 days, respectively, following initial hospital admission. Conclusions: We diagnosed both cases with poorly differentiated grade 3 small-cell PHNEC through imaging characteristics, immunohistochemical staining of liver biopsies, and examinations to eliminate non-hepatic origins. Neither TACE nor liver protection appeared to significantly extend survival time of the two patients, suggesting these treatments may be inadequate to improve survival of patients with poorly differentiated grade 3 small-cell PHNEC. The prognosis of poorly differentiated grade 3 small-cell PHNEC is poor due to limited and ineffective treatment options. BMC Clin Pathol 2018 Mar 1; 18:3

Contributions of the VitisGen2 project to grapevine breeding and genetics

The VitisGen projects (2011-2022) have improved the tools available for breeding new grapevine cultivars with regional adaptation, high quality, and disease resistance. VitisGen2 (the second project in the series) was a multi-state collaboration (USDA-Geneva, New York; University of California, Davis; USDA-Parlier, California; Cornell University; Missouri State University; University of Minnesota; South Dakota State University; Washington State University; North Dakota State University; and E&J Gallo, California) to develop improved genetic mapping technology; to identify useful DNA marker-trait associations; and to incorporate marker-assisted selection (MAS) into breeding programs. A novel genetic mapping platform (rhAmpSeq) now provides 2000 + markers that are transferable across the Vitis genus. rhAmpSeq has been used in California, New York, Missouri, and South Dakota to identify new QTL for powdery and downy mildew resistance. In addition, fruit/flower traits that would normally take years to phenotype have been associated with predictive markers accessible from seedling DNA (e.g. malate metabolism, anthocyanin acylation, bloom phenology and flower sex). Since 2011, the project has used MAS to screen thousands of grape seedlings from public breeding programs in the United States and has produced “Ren- Stack” public domain lines to enable simultaneous access to 4 or 6 powdery mildew resistance loci from single source genotypes. High-throughput phenotyping for powdery and downy mildew resistance has been revolutionized with the Blackbird automated-imaging system powered by artificial intelligence for image analysis. Affordable DNA sequencing along with phenotyping innovations are transforming grapevine breeding