Optimization of machining parameters for turning AISI 4340 steel using Taguchi based grey relational analysis

679-685<span style="font-size:9.0pt;mso-bidi-font-size: 12.0pt" lang="EN-US">In metal cutting, the choice of cooling method influences the deformation mechanism, which is related to the cutting forces, tool wear and surface finish of the parts. The deformation mechanism of AISI 4340 steels machining conditions is known to be very different from that of commonly used industrial materials. Therefore, the effect of cutting parameters and cooling methods on cutting forces, tool wear and surface roughness in machining of AISI 4340 steel is of particular interest. This paper investigates experimentally and analytically the influence of various process parameters, given as cutting speed (v), feed rate (f) and different cooling conditions (i.e. dry, wet and cryogenic in which liquid nitrogen used as a coolant) using uncoated tungsten carbide insert tool on three major characteristics (cutting force, tool wear and surface roughness) of a turned AISI 4340 steel part. The Taguchi’s L9 orthogonal array, analysis of variance (ANOVA) and grey relational analysis (GRA) are executed to study the effects, significance, percentage contribution and optimum settings of given process parameters. The results obtained show that the machining performance can be improved by this approach. </span

Original report: Transtibial and transportal techniques of anterior cruciate ligament reconstruction provide similar functional outcome: A comparative study conducted at an armed forces hospital

Background: The debate about the best arthroscopic technique for the anterior cruciate ligament (ACL) reconstruction surgery using semitendinosus (ST) quadruple graft is still unresolved. The aim of the present study was to compare the results of arthroscopic ACL reconstruction surgery techniques (transtibial [TT] and anteromedial portal [AMP]) using ST quadruple graft in terms of functional outcome. Materials and Methods: A total of 50 male patients with ACL tear were operated using the arthroscopic technique. The patients were divided into two groups (TT group and AMP group) and studied prospectively. The TT group (n = 24) included the patients in which femoral tunnel was prepared using the tibial tunnel. While the AMP group B (n = 26) included the patients in which femoral tunnel was prepared through the anteromedial arthroscopic portal. All these patients were assessed regularly and at follow-up of 1 year functionally using Lysholm Knee Score. Two groups were matched in terms of age, mode of injury, and side involved. Results: The average age of the patients in Group TT and AMP was 31.2 years (range: 22–43 years) and 30.6 years (range: 21–45 years), respectively. The mean Lysholm score improved significantly (P < 0.001) from 55.19 (range: 38–66) preoperatively to 82.65 (range 69–100) at the final follow-up in Group TT and 53.54 (range: 38–66) preoperatively to 82.04 (range: 59–100) at the final follow-up in group AMP. However, there was no significant difference in the mean Lysholm score while comparing the two groups at the final follow-up. Conclusion: ACL reconstruction surgery using ST quadruple graft with TT and transportal techniques provide similar functional outcome at 1-year follow-up

Surface roughness measurements in NFMQL assisted turning of titanium alloys: An optimization approach

Abstract The prediction and optimization of surface roughness values remain a critical concern in nano-fluids based minimum quantity lubrication (NFMQL) turning of titanium (grade-2) alloys. Here, we discuss an application of response surface methodology with Box–Cox transformation to determine the optimal cutting parameters for three surface roughness values, i.e., R a, R q, and R z, in turning of titanium alloy under the NFMQL condition. The surface roughness prediction model has been established based on the selected input parameters such as cutting speed, feed rate, approach angle, and different nano-fluids used. Then the multiple regression technique is used to find the relationship between the given responses and input parameter. Further, the experimental data were optimized through the desirability function approach. The findings from the current investigation showed that feed rate is the most effective parameter followed by cutting speed, different nano-fluids, and approach angle on R a and R q values, whereas cutting speed is more effective in the case of R z under NFMQL conditions. Moreover, the predicted results are comparatively near to the experimental values and hence, the established models of RSM using Box-Cox transformation can be used for prediction satisfactorily

Coexistence of Cerebellopontine Angle Tumor and Frontal Convexity Meningioma at Distinct Location – A Rare Case Report and Review of Literature: A rare coexistence two brain tumors at distinct location

The perioperative management of brain tumors can be significantly impacted by the presence of another intracranial tumor at a distinct location. We report a rare case of an adult who developed two primary brain tumors, a frontal convexity meningioma and a cerebellopontine angle (CPA) tumor at anatomically disparate locations. In our patient, it was unambiguously decided to address the CPA tumor first as it had led to multiple cranial nerve palsies and obstructive hydrocephalus. The relevant literature helped us better extrapolate the patient presentation and management of this disastrous presentation swiftly

Coexistence of Cerebellopontine Angle Tumor and Frontal Convexity Meningioma at Distinct Location – A Rare Case Report and Review of Literature

The perioperative management of brain tumors can be significantly impacted by the presence of another intracranial tumor at a distinct location. We report a rare case of an adult who developed two primary brain tumors, a frontal convexity meningioma and a cerebellopontine angle (CPA) tumor at anatomically disparate locations. In our patient, it was unambiguously decided to address the CPA tumor first as it had led to multiple cranial nerve palsies and obstructive hydrocephalus. The relevant literature helped us better extrapolate the patient presentation and management of this disastrous presentation swiftly

Performance evaluation of cubic boron nitride tool in machining of titanium (grade-II) under minimum quantity lubrication

18-26The advantages of metal cutting fluids in machining are prominent, yet their utilization is accompanied by health and environment hazards. Besides, stringent environmental policies make the manufacturers to change over to dry turning, which is not viable during the machining of sticky material like titanium alloys. Therefore, the usage of minimum quantity lubrication (MQL) can be considered as a possible solution and a one step towards green manufacturing.The aim of this work is to investigate the machinability of titanium (grade-II) alloy with cubic boron nitride (CBN) tool under MQL conditions. The machining tests was performed under varying conditions of process parameters such as cutting speed (Vc), feed rate (f) and side cutting edge angle (approach angle ϕ). The experiments were planned and executed using response surface methodology (RSM). The tangential force (Fc), tool wear (VBmax) and power consumption (K) were selected as the response variables. The outcomes demonstrated that the Fc increases with the increase in feed rate and decreases with the increase in cutting speed and approach angle. Whereas the VBmax and K increases with the increase in feed rate as well as cutting speed. There is very less effect of approach angle on VBmax and K. Moreover, the results have been presented and optimized process parameters are obtained through multiple response optimizations using desirability function approach. In the end, the optimized parameters under MQL conditions are compared with the wet and dry turning. The MQL conditions have shown better results over wet and dry machining

Lower radial nerve palsy in mid shaft humerus fracture using medial plating

Background: The fixation of the fracture is considered to be the best treatment option for early mobilization in midshaft humerus fracture. The aim of the present study is to compare the functional outcome after fixation of midshaft humerus fracture using medial and anterolateral plating techniques. Materials and Methods: Sixty-one patients with midshaft humerus fracture were operated using medial and anterolateral plating technique. In Group A (n = 30), the patients were operated using medial plating for fixation while in Group B (n = 31), the patients were operated using anterolateral plating. The patients were assessed clinically, radiologically and using Mayo elbow score and the University of California-Los Angeles (UCLA) shoulder rating scale. Results: Both the groups were matched in terms of age, gender, mode of injury, side involved, and duration of injury to surgery. Postoperative radial nerve palsy was observed in four patients in Group B which was found to be statistically significant (P = 0.04). The mean UCLA shoulder score improved significantly, 28.53 in Group A and 29.16 in Group B at the final follow-up (P < 0.001). The mean Mayo's elbow score also improved significantly, 85.33 in Group A and 87.41 in Group B at the final follow-up (P < 0.001). There was no significant difference in terms of functional outcome at the final follow-up while comparing both the groups. Conclusion: The medial and anterolateral plating techniques for midshaft humerus have the similar functional outcome. The medial plating technique is associated with lower radial nerve injuries

Is CT scan a predictor of instability in recurrent dislocation shoulder?

Purpose: Glenoid bone defect and the defect on the posterior-superior surface of the humerus “Hill-Sachs lesion” are the commonly seen bony lesions in patients with recurrent dislocation shoulder. Computed tomography (CT) scan is considered as the best option in assessing the bony defects in the recurrent dislocation shoulder. The aim of this study was to assess the clinical and radiological co-relation in the patients with recurrent dislocation shoulder. Methods: Forty-four patients of recurrent dislocation shoulder who were evaluated between January 2015 and December 2017 at a tertiary care center, clinically and radiologically using CT scan and meeting the inclusion criteria, were included. The correlation between the clinical history of the number of dislocations and the bone loss using CT scan was evaluated. Two sided statistical tests were performed at a significance level of α = 0.05. The analysis was conducted using IBM SPSS STATISTICS (version 22.0). Results: All the patients were male with mean age of 25.95 (SD ± 4.2) years were evaluated. Twenty-four patients sustained injury in sporting activities while 20 patients sustained injury in training. There were an average of 4.68 (SD ± 3.1, range 2–15, median 3) episodes of dislocation. Forty-one patients had the glenoid bone loss while 40 had the Hill-Sachs lesions. The mean glenoid width defect was 10.80% (range 0–27%) while the mean Hill-Sachs defect was 14.27 mm (range 0–26.6 mm). The mean area of bone loss of the glenoid surface was 10.81% (range 0–22.4%). The lesions were on track in 34 patients and off track in 10 patients. Conclusions: CT scan of the shoulder joint is an effective method for assessing the amount of bone loss. The number of dislocations are correlated significantly with off-track lesions and the amount of bone loss on the glenoid and Hill-Sachs lesion. The glenoid width bone loss of more than 9.80% or Hill-Sachs defect of more than 14.80 mm are the critical defects after which the frequency of dislocations increases. Keywords: Shoulder joint, Recurrent dislocation, Hill-Sachs lesio

Acute compartment syndrome of forearm without facture in a toddler

Acute compartment syndrome is an orthopedic emergency. In pediatric population, there should be a high index of suspicion for its early detection, especially when it is not associated with a fracture. We present here a case of a toddler, who developed acute compartment syndrome of forearm following a trivial trauma without fracture. Pain out of proportion and increased analgesic requirement are fairly reliable signs and should raise the suspicion of compartment syndrome for the treating surgeon. Despite various methods being available for measurement of intracompartment pressure, the diagnosis largely remains clinical. Ability to actively contract the muscle in the presence of elevated compartment pressure is an indicator of the viability of muscle. The case has been presented to sensitize the young surgeons regarding the possibility of compartment syndrome following simple fall without fracture. The clinical condition was timely diagnosed, and immediate surgical decompression resulted in good functional recovery