Cut Thickness Research Articles

Development of the construction of the cut-off blade from circular saws

The aim of this article is to develop the design of the cut-off blade from circular saw, as a way of reducing consumption of cutting tool during cutting operations. The work is carried out in order to increase the reliability and service life of the cut-off blade of disk type, material of cutting parts are made of high speed steel P6M5. It is proposed the design of fixing of proposed cutter in the lathe tool carriers. The influence of the degree of sharpening the cutting edge on the firmness of cutting-off blade is offered. It is proposed to determine the severity of the blades by scanning on background of millimeter divisions by scanner with high resolution, allowing controlled rounded cutting edge with radius of 0,2 mm by diamond bar. Edge rounding allowed receiving increase sustainability of the tool to 1,8 times in a determined range of thickness of cut.

Alignment in knee flexion position during navigation-assisted total knee arthroplasty.

The aim of this study was to demonstrate the lower limb alignment in knee flexion position after navigation-assisted total knee arthroplasty using the gap technique and to identify the correlative factors. One hundred and twenty consecutive osteoarthritic knees (120 patients) were prospectively enrolled for intraoperative data collection. All TKA surgeries were performed using the navigation system (OrthoPilot™, version 4.0; B. Braun Aesculap, Tuttlingen, Germany). Before and after final prosthesis implantation, the lower limb navigation alignment in both knee extension (0°) and knee flexion (90°) position was recorded. The knee flexion alignment was divided into three groups: varus, neutral and valgus alignment. To determine the factors of the alignment in knee flexion position, preoperative demographics, radiologic and intraoperative data were obtained. Pearson's correlation (r) analysis was performed to find the correlation. The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were compared between groups. Although all postoperative extension alignment was within neutral position (between -2° and +2°), postoperative knee flexion alignment was divided into three groups: varus (≤-3°), 24 cases (20%); neutral (between -2° and +2°), 85 cases (70.8%) and valgus (≥+3°) alignment, 11 cases (9.2%). There were a good correlation of alignment in knee flexion position with the rotation of femoral component relative to posterior condylar axis (r=-0.502, p=0.000) and weak correlations with posterior femoral cut thickness (lateral condyle) (r=0.207, p=0.026), medial flexion (90°) gap after femoral component rotation adjustment (r=0.276, p=0.003). Other variables did not show correlations. There were no statistical clinical differences between varus, neutral and valgus knee flexion alignment groups. About 30% of the cases showed malalignment of more than 3° in knee flexion position although with neutral alignment in extension position. The knee flexion alignment had a good correlation with the rotation of femoral component relative to posterior condylar axis. Neutral alignment in knee flexion position may be adjusted by femoral component rotation especially by the use of navigation system. IV.

Numerical Study of Residual Stresses Induced by High Speed Milling Hardened SKD11 Steel

A thermo-mechanical numerical model for high speed milling hardened SKD11steel is developed to study the influences of mechanical load and thermal load on residual stresses for each feed. The residual stresses are predicted, which are induced by high speed milling hardened SKD11 steel. Based on a simplified two-dimension assumption, the continuous feed numerical model of high speed milling hardened SKD11 steel is developed. A modified Johnson–Cook (J-C) model considering the effect of phase transformation on flow stress is employed to model residual stresses. The results show that residual stresses dominate over the mechanical load and its impact becomes more and more significant for the posterior cut. The tensile surface residual stresses of posterior cut becomes larger than the previous cut but the work hardening thickness of posterior cut becomes thinner in the condition of this study.

Analysis of chip formation mechanisms and modelling of slabber process

During the primary transformation in wood industry, logs are faced with conical rough milling cutters commonly named slabber or canter heads. Chips produced consist of raw materials for pulp paper and particleboard industries. The process efficiency of these industries partly comes from particle size distribution. However, chips formation is greatly dependent on milling conditions and material variability. Thus, this study aims at better understanding and predicting chips production in wood milling. The different mechanisms of their formation were studied through orthogonal cutting experiments at high cutting speed for beech and Douglas fir. Under these conditions, ejection of free water inside wood can be observed during fragmentation, particularly on beech. As previously seen in quasi-static experiments, chip thickness is proportional to the nominal cut thickness. Moreover, the grain orientation has a great influence on the cutting mechanisms, so as the nominal cut and the growth ring widths. This chip fragmentation study finally allows the improvement of the cutting conditions in rough milling. In order to optimize machine design as well as cutting geometry, a geometrical model of a generic slabber head was developed. This model allows the study of the effective cutting kinematics, the log-cutting edges interactions and the effective wood grain direction during cutting. This paper describes the great influence of the carriage position on cutting conditions. The results obtained here can be directly used by milling machine manufacturers.

The tibia first technique with tensor measurement is useful to predict the soft tissue tension after implantation in unicompartmental knee arthroplasty.

The tibia first technique in unicompartmental knee arthroplasty (UKA) may have the advantage that surgeons can obtain a balanced flexion-extension gap. However, changes of the soft tissue tension during UKA have not been elucidated yet. The purpose of this study was to examine the correlation between the soft tissue tension before the femoral osteotomy and after the femoral component is in place using the tibia first technique in UKA. Thirty UKAs for isolated medial compartmental osteoarthritis or idiopathic osteonecrosis were assessed. The actual values of the proximal and posterior femoral osteotomy were calculated by adding the thickness of the bone saw blades to the thickness of the bony cut. Using a UKA tensor designed to facilitate intra-operative soft tissue tension throughout the range of motion (ROM), the original gap before the femoral osteotomy, the component gap after the femoral osteotomy, and component placement were assessed under 20-lb distraction forces. The mean actual thickness of the distal femoral osteotomy was 6.5 ± 1.3 mm and the posterior femoral osteotomy was 7.4 ± 1.3 mm. The distal thickness of the prosthesis was set to 6.5 mm and the mean posterior thickness of the prosthesis used in this study was 5.8 ± 0.3 mm. There is a positive correlation between the original and component gap throughout the ROM (R > 0.5). The original and component gap showed the same kinematic pattern from full extension to 90° of knee flexion. However, the component gap was significantly higher compared to the original gap after 120° of knee flexion (P < 0.001). Despite the fact that the component gap values were significantly higher compared to the original gap value in deep flexion, there is a positive correlation between the original and component gap throughout the ROM. The discrepancy during deep flexion was due to the posterior design of the prosthesis that is designed to be thinner than the actual thickness of the posterior osteotomy. These results suggest that the tibia first technique with the tensor have the advantage that surgeons can predict final soft tissue tension before femoral osteotomies with the prosthetic design and help restore natural knee kinematics, potentially improving implant survival and functional outcomes.

Lathe check characteristics of fast growing sengon veneers and their effect on LVL glue-bond and bending strength

Fast growing sengon (Paraserianthes moluccana) is largely rotary-cut to produce veneer for core plywood production. In order to provide better information on veneer production and utilization, in this study the effects of wood juvenility and veneer thickness on lathe checks of rotary-cut sengon veneers were evaluated. Before veneer manufacturing, sengon logs were boiled at 50°C and 75°C for 4 and 8h, respectively. The boiled logs were peeled to produce veneer of 1, 1.5, and 2mm in thickness. Lathe checks of veneers were measured on the loosed side at every 5mm veneer length under an optical video microscope and their frequency, depth, and length were characterized. Twenty sampling points of 5mm veneer length were prepared from each segmented ring of 1cm width from pith to bark. Isocyanate resin adhesive were used to produce laminated veneer lumber (LVL) of 20mm thick, which consisted of 24-ply of 1mm veneer thick, 14-ply of 1.5mm veneer thick, and 11-ply of 2mm veneer thick, for glue bond and bending strength test. Results showed that wood juvenility and veneer thickness determined the frequency, depth and length of lathe checks for the sengon rotary-cut veneers. In general, the frequency of lathe checks of the veneer increases with increasing veneer thickness, and also increases from pith to bark. Boiling of logs before rotary-cutting could decreases the frequency of lathe check of the veneer. The results indicated that boiling of logs at 50°C for 8h and at 75°C at least 4h before peeling the logs could minimize the frequency of lathe check in manufacturing rotary cut veneer thickness of 1, 1.5, and 2mm from juvenile wood of fast growing sengon. The frequency of lathe check affects significantly the glue bond and bending strength, in which the glue bond, modulus of elasticity (MOE), and modulus of rupture (MOR) decrease as the frequency of lathe checks increases.

Investigations into Cutting Forces and Surface Roughness in Micro Turning of Titanium Alloy Using Coated Carbide Tool

Micro turning is one of the tool based micromachining process used for manufacturing axi-symmetric miniaturized parts. This paper presents the development of micro turning setup and investigations on cutting forces and surface roughness during micro turning process. Titanium alloy (Ti6Al4V) and coated carbide tool (TiN/AlTiN) is considered as work piece and tool material respectively. Experiments have been conducted by varying the cutting speed, feed and depth of cut. Piezoelectric dynamometer is used to measure the cutting forces during the process. Cutting forces decreases by increasing the cutting speed due to thermal softening where as at low depth of cut, cutting forces increases with increase of cutting speed due to material strengthening effect. Surface roughness increases when uncut chip thickness is less than the edge radius, due to rubbing and ploughing action. Improved roughness is observed when uncut chip thickness and depth of cut is greater than edge radius.

Combined Use of a Femtosecond Laser and a Microkeratome in Obtaining Thin Grafts for Descemet Stripping Automated Endothelial Keratoplasty: An Eye Bank Study

To evaluate the use of a femtosecond laser combined with a microkeratome in the preparation of posterior corneal disks for Descemet stripping automated endothelial keratoplasty (DSAEK). This experimental study involved ultrathin DSAEK tissue preparation of 22 donor corneas unsuitable for transplantation. The first cut was performed with an Intralase® FS60 laser and the second cut with a Moria CBm 300-µm microkeratome. The thickness of the first cut was modified for each cornea to obtain a final graft thickness of less than 110 µm. Precut and postcut central pachymetry were performed with an ultrasonic pachymeter. Central endothelial cell density (ECD) was calculated before and 24 hours after tissue preparation. Final graft thickness was 105.0 ± 26.1 (SD) µm (range 65-117). The mean microkeratome head cut thickness was 324.5 ± 10.9 µm (range 310-345). Precut and postcut ECDs averaged 2250 ± 222 and 2093 ± 286 cells/mm2, respectively, representing 6.9% of cell loss. No corneas were perforated. Femtosecond FS60 lasers and Moria CBm 300-µm microkeratomes can be used sequentially to prepare consistently thin DSAEK grafts with no irregular cuts or cornea perforations.

Influence of lubricant and coolant fluid on the cutting force in small-increment planing

The critical cut thickness is determined in planing various materials. With greater thickness, the use of lubricant and coolant fluid reduces the cutting forces. Therefore, with limited rigidity of the technological system, the use of lubricant and coolant fluid is only expedient at above-critical cut thickness.

Effects of interatomic potentials on the determination of the minimum depth of cut in nanomachining

The minimum depth of cut (MDC) is a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents the material removal in a nanomachining process, where a sharp diamond tool with an edge radius of few atoms acts on a crystalline copper workpiece. The molecular dynamics (MD) simulation results show the phenomena of rubbing, ploughing and cutting. The formation of chip occurred from the depth of cut thickness of 1~1.5 nm. Also, the effects of the interatomic potentials on the MDC have been presented.

Comparative imaging of the vesicular glands in New Zealand white rabbits (Oryctolagus cuniculus)

This study investigated the morphological topographic features of the vesicular glands (gll. vesiculosae) in 10 sexually mature and clinically healthy male New Zealand White rabbits, aged 12 months, with body weights from 2.8 kg to 3.2 kg. The glands were observed by ultrasonography in 2 planes, transversal and sagittal. The approach was percutaneous transabdominal prepubic. The rabbit vesicular glands were visualized as a solid heterogeneous echoic finding. Using computed tomography, we scanned the pelvis in the transversal plane through the first sacral vertebra, at a cut thickness of 3 mm. The vesicular glands were visualized as transversally ovoid, homogeneous, and hyperdense soft tissue structures. Our observations on ex vivo frozen sagittal and transversal cuts of the pelvis showed analogous morphological and anatomic characteristics to those obtained by ultrasonography and computed tomography. The imaging features of normal domestic rabbit vesicular glands can be used as a morphological basis for the interpretation of some glandular lesions.

Side effect of metenolone enanthate on rats heart in puberty: Morphometrical study

The aim of this study was the investigation of effects of the metenolone enanthate (ME) that is used among athletes as doping and muscle amplifier, on hearts of male and female rats that are in puberty using morphometrical methods. A total of 36 rats which were divided into three separate groups (Experiment, ME; vehicle, PO; control, C) each consisting of 6 male and 6 female rats were used. 0.5 mg/kg metenolone enanthate was applied intraperitoneally into experiment subjects 5 times a week over a period of 4 weeks. At the end of experiment, rats were euthanized and their hearts were cut at the level of musculus papillaris after the fixation in formalin. Hearts were taken out and embedded in paraffin wax. Photos were taken at cut surfaces, and thickness, diameters and surface area levels were measured. Left ventriculus mass (LVM) and left ventriculus mass index (LVMI) were calculated. In the study LVM (p<0.005) and LVMI (p<0.05) were found to be significantly higher in the ME group in females whereas left ventricular lumen diameter (LVLD) were found to be significantly lower (p<0.05). Thus left ventricular hypertrophy development was observed. LVM and LVMI were found to be similar in ME and C groups among male rats and the highest level of these data were found in the group. LVM and LVMI were higher among females (p<0.006). In conclusion, it has been shown that the adverse effects of ME on heart were developing starting from puberty and resulting with the enlargement of the heart and left ventricular hypertrophy and especially among females this condition was more evident. It has also been discussed that the continuous use of drugs may further enhance this condition.

Novel Image-matching Software for Postoperative Evaluation After TKA

Although 2-dimensional assessments using postoperative plain radiographs have been used after total knee arthroplasty (TKA) in previous studies, a strong possibility exists that deviation can occur when assessing 3-dimensional (3-D) objects. The purpose of this study was to test the hypothesis that novel 3-D image-matching software could accurately assess the positioning of implants and could be a useful tool in postoperative evaluation after TKA.Total knee arthroplasty was performed in 30 consecutive patients. Intraoperatively, the thickness of each bone cut was measured. Postoperatively, the thickness of each part of the bone cut was measured using Athena Knee (SoftCube Co, Ltd, Osaka, Japan) 3-D image-matching software. The results revealed no significant differences in the medial compartment and significant differences of approximately 1 mm in the lateral compartment. The difference was possibly caused by the remaining cartilage in the lateral compartment. Linear regression analysis revealed a statistically excellent correlation between intra- and postoperative values in all parts of the bone cuts. Although the 3-D image-matching software used in this study was originally developed for preoperative planning in TKA, it is considered accurate enough to assess the positioning of implants with respect to the bone after TKA.

Determination of the Minimum Depth of Cut in Nanometric Machining Using Molecular Dynamics Simulation

The Minimum Depth of Cut (MDC) is a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents an evaluation of a cutting process where a sharp diamond tool with an edge radius of few atoms acts on a crystalline copper workpiece. The molecular dynamics (MD) simulation results show the phenomena of rubbing, ploughing and cutting. The formation of chip occurred from the depth of cut thickness of 1-1.5nm.

Femtosecond laser and microkeratome preparation of ultrathin (UT) DSAEK Grafts, the six months clinical results

AbstractPurpose To evaluate the use of a femtosecond laser and a mechanical microkeratome to prepare ultrathin posterior corneal disks for Descemet stripping automated endothelial keratoplasty (DSAEK) and to assess associated visual results, disk thickness and endothelial cell loss.Methods This clinical study involved ultrathin DSAEK tissue preparation used in 28 patients with endothelial dysfunction. The first cut was performed with an Intralase FS60 laser and the second cut with a Moria CBm 300‐ microkeratome. The thickness of the first cut was modified for each cornea to obtain a final graft thickness of 120 µm. Post‐op central graft thickness was performed with corneal laser tomography (Spectralis). Central endothelial cell density (ECD) was calculated before, 3 and 6 months after surgery.Results Final graft thickness was 92.9+28.5 µm, 83.1+23.6 µm, 77.2+16.9 µm and 74.3+27.5 µm at one week, one three and six months post‐op, respectively. No loss of corneas due to irregular cuts or perforation during preparation. The mean BSCVA was 0.4, 0.5, 0.7 and 0.7(0.39, 0.35, 0.16 and 0.17 LogMAR) after one week, one, three and six months post‐op, respectively. A 26.3% and 31.2% endothelial cell loss was observed after 3 and 6 months of the surgery, respectively. Significant positive correlation between BCVA (logMAR) and central graft thickness at 1 and 3 months was observed (r=0.76,p=0.01; r=0.73,p=0.01) as well as between BCVA (logMAR) at 3 months and preoperative central graft thickness (r=0.82,p=0.007; Spearman correlation). Patients without bullous keratopathy achieved better visual outcome at 3 months (p=0.04, Mann‐Whitney test).Conclusion Femtosecond laser and microkeratome can be used sequentially to prepare custom ultrathin DSAEK grafts with no loss of corneas. This procedure minimizes the variability inherent to microkeratomes and allows very quick recovery of visual acuity after posterior lamellar keratoplasty.

Femtosecond laser and microkeratome preparation of ultrathin (UT) DSAEK grafts

AbstractAn important limitation of DSAEK is that some eyes do not achieve good visual acuity despite a clear cornea and minimal residual astigmatism. The thickness of the stromal lamella may influence the final visual acuity and better results may be achieved with thinner grafts. We describe a new technique that combines a femtosecond laser with a microkeratome to obtain consistently thin grafts, with no loss of corneas. This clinical study involves ultrathin DSAEK tissue preparation used in 28 patients with endothelial dysfunction. The first cut was performed with an Intralase FS60 laser and the second cut with a Moria CBm 300‐µm microkeratome. The thickness of the first cut was modified for each cornea to obtain a final graft thickness of 120 µm. Post‐op central graft thickness was performed with corneal laser tomography (Spectralis). Associated visual results, disk thickness and endothelial cell loss before and after surgery were evaluated. Final graft thickness was 88.3+27.6 µm, 77.2+26.6 µm and 74.3+27.5 µm at one week, one and three months post‐op, respectively. No loss of corneas due to irregular cuts or perforation during preparation. The mean BSCVA was 0.41, 0.52, and 0.72(0.39, 0.28 and 0.14 LogMAR) after one week, one and three months post‐op, respectively. Precut and post‐op (3 months) ECDs averaged 2553 cells/mm2 and 1882 cells/mm2, respectively, representing 26.3% endothelial cell loss after 3 months of the surgery. Femtosecond laser and microkeratome can be used sequentially to prepare custom ultrathin DSAEK grafts with no loss of corneas. This procedure minimizes the variability inherent to microkeratomes and allows very quick recovery of visual acuity after posterior lamellar keratoplasty.

An analytical force model for orthogonal elliptical vibration cutting technique

The elliptical vibration cutting (EVC) technique has been found to be a promising technique for ultraprecision machining of various materials. In each overlapping EVC cycle, the thickness of cut (TOC) of work material, and the tool velocity get continuously varied. These two inherent phenomena, in fact, introduce transient characteristics into its cutting mechanics, which are considered to be different from the one applied for conventional cutting technique. Recently, a few theoretical models have been developed to understand the material removal mechanism with the EVC technique; however, in those studies, the transient phenomena were not considered. In the present research, an analytical force model for the orthogonal EVC process was developed in order to fully understand the EVC mechanism, and to more accurately predict the transient cutting force values. Three important factors: (i) transient TOC, (ii) transient shear angle, and (iii) transition characteristic of friction reversal were investigated and analyzed mainly based on geometric modeling and the Lee and Shaffer's slip-line solution. Mathematical evaluation shows that they may have significant influence on EVC process, and thus on its output performance. In order to validate the proposed force model, a series of low-frequency orthogonal EVC tests were conducted. The experimental transient cutting force values were compared with the predicted values calculated using the proposed model, and they are found to be in a good agreement with each other.

Distribution of unit forces on the tool nose rounding in the case of constrained turning

The development of force models is important in understanding the effects of tool edge geometry where the tool edge radius is of similar value to the depth of cut. In this paper it is demonstrated that both the rounding of the tool edge and the rounding of the tool nose affect the chip formation process and the quality of the machined surface.The distribution of unit forces on the nose of a tool is presented in detail. The main assumption in all the considerations was constant temperature conditions in the cutting zone, maintaining the thermo-mechanical properties of the work material at a constant level. The experiment was conducted for free and non-free turning, and in both cases the temperatures and forces were measured.For free cutting the distribution of unit forces on the tool edge rounding was investigated—the minimal thickness of cut and characteristic equations for forces Fc and Ff were determined. Then the unit forces distribution was recalculated for the case of non-free turning with rounded tool nose. The summed forces for non-free turning were compared with measured values, for verification of the cutting force model.The distribution of unit forces along the tool nose revealed nonlinearities influencing tool and machined surface integrities. The unit forces acting on the rake face were established to determine the length of the active part of the tool where the conditions for chip formation were favorable. Distribution of unit forces acting on the rake face in the reverse direction indicated the conditions in which a chip was pushed away from the transient surface.The distribution of unit forces acting on the flank face in the feed direction was found to determine the machined surface quality. The range of negative values of unit forces defined the conditions for moving away of the non-machined material (under the condition hj<hmin) in a direction opposite to the feed. This work material was found to be responsible for the effect of material side flow.

Design and development of power operated banana slicer for small scale food processing industries

A power operated rotary banana slicer suitable for small scale processing was designed and developed based on engineering properties of banana varieties, namely Nendran and Dwarf Cavendish. This banana slicer mainly consists of feeders for round slicing, cutter, power transmission mechanism, base support and frame. The power operated rotary slicer with three blade cutter that was operating at 360 rpm speed was developed to overcome drawbacks of existing hand or power operated rotary slicers and to meet the demand of small scale processing industries. This slicer has slicing efficiency of about a 93&amp;ndash;94% with effective capacity of about 100 kg/h for both varieties. The mean thickness of cut for both varieties was about 2.00 &amp;plusmn; 0.194 mm, whereas mean roundness was of 0.84 and 0.70 for Nendran and Dwarf Cavendish varieties respectively.

Ultra-Precision Machining Technology Based on Dynamic Minimum Thickness of Cut for Machined Single Crystal Materials

The dynamic minimum thickness of cut for the ultra-precision machining surface quality is important influence. Between tool and the workpiece for the friction coefficient were analysised, the relationship of the friction coefficient and the MTC were discussed, and the MTC and its effects on surface roughness were a theoretical analysised and experimental verification with processed single crystal copper and single crystal aluminum by AFM’s diamond tip. The results show: the MTC of single-crystal copper (single crystal aluminum) is 5.2nm (8.2nm) in stable cutting conditions. Further processing single crystal copper (ingle crystal aluminum) with cutting thickness of 5.2nm (8.2nm), and the surface roughness Ra160nm (Ra110nm) is obtained. So the MTC is evolving with the friction coefficient and the force ratio, theoretical MTC tends to be minimal value then before the adhering effect to reach remarkable. Appropriate adjustments cutting parameters, the cutting process can always micro-cutting phase to reach the steady-thin chip, and no plowing phenomenon. So the surface residues highly were reduced and higher surface quality was achieved.