Depth Of Undercut Research Articles

Study of the effect of PCM process parameters on geometry type, Ra, depth of etch, undercut comparing FeCl3 and CuCl2 etchants on Monel 400

ABSTRACT The study mainly focuses on geometrical topographies in photochemical machining (PCM) of Monel 400, using two etchants cupric chloride (CuCl2) and ferric chloride (FeCl3). The experiments were carried out at different etchant concentrations (including a number of chloride ions and weight) and temperatures. A comparative study was carried out on the responses such as depth of etch, undercut, surface roughness (Ra), and geometrical features, viz. etch factor and aspect ratio. This study also implicates the effects of perimeter and geometry type (circle, hexagon, square, rectangle, and triangle) on behaviour of PCM process in the perspective of loss of weight and depth of etching, wherein triangular shape shows 0.1547 µm depth of etching/min and 0.0737 g/min weight loss. The results show that FeCl3 gives 0.8 µm Ra and 13.59 µm/min etch rate with 0.851 etch factor at 80℃ compared to CuCl2. The overall conclusion shows that FeCl3 performs better than CuCl2 in the aspects of PCM for Monel 400.

Mylohyoid Ridge as a Predictor of Available Bone for Implant Placement: A Cone-Beam Computed Tomography (CBCT) Retrospective Observational Study.

Introduction: The posterior mandibular region, due to the presence of vital structures, poses a high risk during implant placement because of its susceptibility to neurovascular injury and perforation of the lingual cortex. A breach in implant length and available bone height may lead to serious intraoperative and postoperative complications. Prediction of the exact location of the inferior alveolar nerve and submandibular fossa anatomy is a prerequisite for ideal implant placement, which is always not possible with conventional radiographic and clinical techniques.Materials and methods: One hundred ten cone-beam computed tomographies (CBCTs) of patients were acquired from the radiological archives of a radiological center in Chennai. DICOM files from CBCT were exported to Bly Sky Plan software. Cross-sections of the second molar and first molar were extracted following the inclusion criteria. The linear dimension between the mandibular canal and mylohyoid ridge and anatomic variables of the submandibular fossa were measured digitally on the left and right sides using software measuring tools. Descriptive statistics were done. The unilateral and bilateral site and gender differences were evaluated. Bone height superior to the mandibular canal was correlated with the submandibular fossa parameters; depth of undercut in the vertical and horizontal directions; and angle of the undercut.Results: The mandibular canal was on average 5.5 mm and 4 mm inferior to the Mylohyoid ridge in the second molar region and first molar region, respectively, with the right and left sides showing no statistically significant difference. The depth of fossa undercut in vertical and horizontal dimensions was higher in the second molar region compared to the first molar region. The height of the deepest point of the undercut in the vertical dimensions showed a positive correlation with the bone available between the mandibular canal and the mylohyoid ridge.Conclusion: Keeping 2 mm of safety factor in consideration, implants can be safely placed up to the mylohyoid ridge in 100% of cases and 2 mm below the mylohyoid ridge in 78.9% of cases in the mandibular second molar region. In keeping with a safety factor of 2 mm, implants can be safely placed up to the mylohyoid ridge in 82.6% of cases and 2 mm below the mylohyoid ridge in 43.1% of cases in the first molar region. A more pronounced undercut was seen in the second molar region than in the first molar region. Deeper fossa undercuts in vertical dimension are associated with more inferior positioning of the mandibular canal.

Factors Influencing Stope Hanging Wall Stability and Ore Dilution in Narrow-Vein Deposits: Part 1

Unplanned ore dilution negatively affects overall mine profitability by increasing operating costs (e.g., mucking, haulage, crushing, hoisting, milling, waste treatment, and low-grade ore upgrading). Eliminating ore dilution requires identifying and controlling the major causal factors, which are related to in-situ stress regimes, depth of stope undercut, ore dip/orientation, stope geometry, and quality of the host rock mass. In-situ stress regimes and depth of stope undercut were examined in a previous publication (see Part I). The results showed that the stability of the stope hanging wall significantly deteriorates when in situ stress regimes and depth of stope undercutting of the access drift increase. Conversely, the extent of plastic zones increases with such an increase. Also, the depth of stope undercutting has no impact on the deformation development of the rock mass. The objective of this paper is to assess stope hanging wall (HW) stability and ore dilution with respect to ore inclination and stope geometry in sublevel, open stoping, narrow-vein mines. A series of two-dimensional elasto-plastic numerical models was built to examine the effect of ore dip angle and stope geometry (height and width) on stope HW stability and ore dilution in a highly stressed environment (in-situ stress ratio = 2.5). The results are presented, discussed, and compared in terms of depth of relaxation zones, extent of plastic failure zones, and total displacement with respect to four stope dip angles (45°, 60°, 75°, and 85°), three stope widths (5, 7.5, and 10 m), and three stope heights (20, 30, and 40 m). Results show that stope HW stability improves when ore dip angle increases (i.e., steeply dipping ore deposits) because the depth of relaxation zones and extent of failure zones decreases. Dip angle had a negligible effect on HW deformation. Less dilution occurred at very steep (85°) inclination angles. At different ore dip angles, stope HW stability greatly deteriorated with increasing stope width and improved with decreasing stope height.

Assessment of anterior maxillary alveolar bone dimensions and morphology for immediate implant planning: A retrospective study using Planmeca Promax CBCT unit

Objectives: To evaluate the dimensions and morphology of the alveolar bone in the maxillary central, lateral and canine regions and to correlate these findings with the age and gender of each subject to provide detailed information for immediate implant planning.Subjects & methods: 112 CBCT scans of both genders with non-extracted maxillary right central, lateral and canine were obtained from the database of the Oral and Maxillofacial Radiology Department, Faculty of Dentistry, Cairo University. For each of the three right maxillary anterior teeth bone height was measured from the crest of the ridge till the nasal floor. The bone width was measured at three levels, namely the cervical, the middle and the apical level. The presence and depth of buccal undercuts was also assessed at the three locations. Additionally, the cross-sectional morphology of the alveolar ridge was determined and classified into three different types.Results: The results of this study showed that the bone height at the right central incisor had the least values; meanwhile the canine had the greatest values. Regarding the bone width, the region of the lateral incisor had the thinnest alveolar ridge at the three levels. In all the three locations however, the alveolar width was greater apically than cervically. Besides, the lateral incisor region showed the highest prevalence for presence of buccal undercuts. The greatest depth of buccal undercut however was found in the canine region, meanwhile the smallest depth was found in the central incisor region. For the cross-sectional morphology, Type I (bell-shape) was the most common in all three locations while Type III (hourglass-shape) was the least common. Age did not affect any of the examined parameters. Males showed more height and width of the alveolar bone, while females showed higher prevalence and greater depth of buccal undercuts in all three locations. Males also showed a greater prevalence of Type I (bell-shape) cross-sectional alveolar bone shape, meanwhile females showed a greater prevalence of Type II (trapezoid-shape) and Type III (hourglass-shape).

Comparative Study of FeCl3 and CuCl2 on Geometrical Features Using Photochemical Machining of Monel 400

In this study, Monel 400 was machined using etchants, like ferric chloride (FeCl3) and cupric chloride (CuCl2) at different temperatures, concentration and type of geometry (viz. circular, hexagonal, square, rectangular and triangular). The study focuses on the comparative impact of input process parameters in perspective of depth of etch, undercut, and weight loss. Comparative study of FeCl3 and CuCl2 determines that the overall performance is better for ferric chloride etchant. The undercut observed in FeCl3 was more than CuCl2, but the better geometrical accuracy found with CuCl2 etchant solution. Type of geometries responsible for the depth of etch and weight loss. Triangular geometry shows higher weight loss and depth of etch. Higher weight loss and depth of etch is observed with FeCl3 than CuCl2 etchant. The weight loss and depth of etch increases from 0.0504g to 0.0737g and 0.0436μm to 0.1547μm respectively for FeCl3 for circular, hexagonal, square, rectangular and triangular shapes. Similarly, for CuCl2 these values are 0.0386g to 0.0686g and 0.0236μm to 0.117μm respectively.

Reduction of Undercuts in Fillet Welded Joints Using Taguchi Optimization Method

This project work focuses on the reduction of weld undercuts using the Taguchi method. The phenomenon of weld undercuts constitutes a major problem for the welding industry. When undercuts occur, and particularly when such cuts are deep, it has a negative impact on the weld as it lowers the integrity and quality of the weldment. Therefore, efforts are made globally to reduce the depth of such weld undercuts to the barest minimum. Several optimization methods have been adopted; however, in this study, the Taguchi method is applied. “The smaller the better components” of the Taguchi method is applied. From the results obtained from applying this Taguchi method, the optimum process parameters obtained are A2-B1-C2, which are a voltage of 20 V, a current of 180 A, and a welding speed of 130 mm/s, required to form an undercut of 0.03 mm. Whereas the existing process parameters used by the company are A1-B3-C, which make an undercut to a depth of 0.09 mm. It is concluded that the use of Taguchi method has been able to reduce the depth of undercut as shown in this study. A step-by-step approach is presented in the study.

ANSI/AWS E308-16 Rutile Electrode : The Effect of Endothermic Materials on Undercut Defect on Low Carbon Stainless Steel

This study is the part of a program to obtain the fundamental knowledge on the effect of endothermic materials on the undercut defect of welding, of which information is scarce in international welding literature. Undercut is one of the most crucial problems which decreases the reliability and restricts the many parameter of welding (like welding speed, weaving pattern, etc.). One reason for this type of defect is excessive current, causing the edges of the joint to melt and drain into the weld; this leaves a drain-like impression along the length of the weld. Another reason is if a poor technique is used that does not deposit enough filler metal along the edges of the weld. A third reason is using an incorrect filler metal, because it will create greater temperature gradients between the center of the weld and the edges. Other causes include too small of an electrode angle, a dampened electrode, excessive arc length, and slow speed. The AWS regulations state that the maximum depth of undercut should not exceed 0.25 mm Cerit (Eng Fail Anal 17:571–578, 2010). In this investigation two rutile coated electrodes are taken. One of these is prepared by increasing the amount of calcite and dolomite with subsequent increase in silica and other electrode is of same composition of AWS/ANSI E308-16 rutile electrodes. This modification improves the slag system of electrode and helps in absorbing excess heat generated during the welding process. Undercuts are measured and other operational behavior like welding current, electrode angle, arc length and electrode travel speed of the electrode were kept constant.

Fundamental Research on the Mechanism of High-Speed Welding Undercut

Undercut is one of the most important problems which restrict welding speed. The research indicated that surface flow direction of welding pool near the periphery is the most important reason of undercut occurred. When the existence of surface active element (e.g. the content of S is about 0.02-0.04% in steel) change the sign of surface tension temperature coefficient to positive, undercut always occurs in TIG moveless welding, and not occurs when the content of S in iron is very low( e.g. S% is less 0.01%). Temperature gradient is the most important factor which influences the depth of undercut. The depth of undercut is bigger with the increase of temperature gradient when the other parameters are the same. When filling metal into welding pool, it restrained the molten metal movement from periphery to the pool center. So it can reduce the tendency of undercut, and eliminate undercut as increasing of filling metal ultimately.

Evaluating the influence of rate of undercutting on the stability of slopes

Cut slopes of alternating soft and hard layers along roads in Jordan are subject to differential weathering, erosion and human activities. This can result in undercutting, leading to rockfalls that endanger traffic. The factors affecting the rate of undercutting and the influence of this on the stability of ten selected road cuts along the Amman–Irbid highway in Jordan were determined. The depth of undercut was measured at selected points and the mean rate of undercutting found to vary from 10 to 73 mm/year. Grain density, bulk density, slake durability, Atterberg limits, porosity and grain size distribution were determined and correlated with the rate of undercut. A positive relationship was found between undercutting and the sand fraction and porosity values and a negative relationship with the slake durability index.

Undercutting conifer seedlings: effect on morphology and field performance on droughty sites

Bareroot 2-0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and ponderosa pine (Pinusponderosa Dougl. ex Laws.) seedlings were subjected to five undercutting treatments, which varied by number and depth of undercut and seedling phenology at time of treatment, so that morphological characteristics at lifting and field performance 4 years after planting on droughty south slopes in southwest Oregon could be evaluated. All undercutting treatments significantly reduced seedling top growth, but changes in root system morphology depended upon treatment severity and species. Treatment effects were generally more pronounced in ponderosa pine than Douglas-fir. Multivariate analysis of variance showed significant treatment effects for both species based on seedling morphology at lifting, but discriminant analyses revealed that these differences existed primarily between undercut seedlings, regardless of undercutting treatment, and controls. In Douglas-fir this separation was largely due to differences in seedling height and in ponderosa pine it was due to differences in tap root biomass. However, no treatment effects were detectable 4 years after outplanting for either species despite record high air temperatures during the first growing season, suggesting that morphological differences at lifting were probably not of sufficient magnitude to affect field performance.