Tip Breakage Research Articles

Wear and breakage of TiAlN- and TiSiN-coated carbide tools during high-speed milling of hardened steel

In the high-speed machining of hardened steel for the die and mould industry, determining how to reduce the wear of coated carbide tools and improve their machining efficiency and quality has been an important subject. This study investigated the high-speed machining of hardened steel (SKD11/HRC 62, S136/HRC 51) using two types of PVD-coated carbide tools (TiAlN and TiSiN) to determine the mechanism of cutting tool wear and breakage and the effects of tool angle, tool diameter, tool extended length, cutting force and cutting-induced vibration on the tools. The results indicated that the dominant wear patterns of coated carbide tools included flank wear, rack face wear, breakage and micro-chipping. The modes of breakage of the coated carbide tools used for the high-speed milling of hardened steel were coating peeling, chipping and tip breakage. The lives of the cutting tools coated with TiSiN were longer than those of the tools coated with TiAlN due to reduced abrasive wear. The tool extended length during machining caused chips to transform from spiral chips into c-shaped chips and produce sawtooth chips as the length increased. The selection of the optimal tool extended length can deliver the minimum cutting force, a small degree of tool wear and the best machining quality. The characteristics of the cutting force can distinctly reflect abnormal conditions as the cutting tool wears. A tool with a small rake angle, suitable clearance angle and large helix angle will not only reduce the cutting force but also ensure a smooth cutting process and generate less cutting tool wear.

Transcatheter closure of patent vertical vein after repair of total anomalous pulmonary venous connection.

Background:Vertical vein is left patent in some cases of supra-cardiac total anomalous pulmonary venous connection (TAPVC) when there is hemodynamic instability due to noncompliant left atrium and ventricle. After the peri-operative period, this results in features of pre-tricuspid shunt.Materials and Methods:Three cases with patent vertical vein following repair of supra-cardiac TAPVC presented with features of pre-tricuspid shunt on follow-up. Trans-catheter closure of patent vertical vein was performed using vascular plug in all three subjects.Results:The procedure was technically successful in all the patients. There was a complication related to catheter tip breakage in one of them, which was successfully managed. There was no impingement on pulmonary vein in any of the patients.Conclusion:Patent vertical vein following TAPVC repair results in features of pre-tricuspid shunt. Transcatheter closure of the patent vein is feasible.

Intraocular Foreign Body of a Vitreous Cutter Tip Fragment

Purpose: To report a case of intraocular foreign body of a vitreous cutter tip fragment. Case summary: A 60-year-old women was referred by her ophthalmologist with a two-day history of visual disturbance in her right eye. She had undergone pars plana vitrectomy, barrier laser and C3F8 gas injection due to pseudophakic rhegmatogenous retinal detachment in our retinal service center four months previously. Slit-lamp biomicroscopy of her right eye showed cornea stromal edema with Descemet membrane folding. Gonioscopic examination revealed a metallic foreign body in the direction of the 6-o ’clock anterior chamber angle. Anterior chamber irrigation with successful removal of the metallic foreign body using intraocular foreign body forceps was performed. The removed intraocular foreign body was a vitrectomy cutter tip fragment 20 gauge in size and 3 mm in length. After surgery, the corneal stromal edema disappeared and her visual acuity in the right eye recovered. Conclusions: Intraoperative breakage of vitreous cutter tips can occur and cause toxic ocular tissue reaction. Care should be taken against vitreous cutter tip breakage during vitrectomy. J Korean Ophthalmol Soc 2010;51(1):141-144

Long-term storability of different sugarbeet genotypes – Results of a joint IIRB study

In 2008/09 and 2009/10, storage trials with 12 sugarbeet genotypes were carried out under different conditions in six countries. The genotypes were grown in strips and harvested in September/November either by machine (using good agricultural practice) or by hand. Samples were then stored either in nets incorporated in clamps or in separate nets/bags or containers inside a barn or climate room. All samples were weighed and analyzed before and after storage for sugar (by polarimetry), potassium, sodium, amino nitrogen, total soluble nitrogen, sucrose, glucose, fructose, raffinose, betaine and glutamine content. After storage the samples were also examined visually. Differences between the genotypes were observed for root tip breakage, sprouting, moulds and rot, although these differences were not unambiguous in all experiments and varied between the observations in the different countries. The sugar losses ranged from 0 to 66% of the initial amount and seemed to be related to various biotic and abiotic factors. Root damage by machine harvest and storage temperature were dominant factors in relation to the sugar losses. Genotypes also showed significant differences in sugar losses, but a strong interaction with year and site existed. Correlations could be found between sugar losses and initial sugar content (r = –0.66), initial betaine content (r = –0.62) and root tip breakage (r = +0.66) and after storage, moulds (r = +0.87), rot (r = +0.88) and invert sugars (r = +0.89). Chemical analyses showed differences between the genotypes for the decrease in beet quality after storage, not only by a reduction in sugar content but also by an increase in invert sugar and soluble nitrogen.

Development of Spike Wavelet Analysis and Its Application to Damage Analysis on Gearbox

Impulsive sound and vibration signals in gear system are often associated with their faults. Thus these impulsive sound and vibration signals can be used as indicators in condition monitoring of gear system. The traditional continuous wavelet transform has been used for detection of impulsive signals. However, it is often difficult for the continuous wavelet transform to identify spikes at high frequency and meshing frequencies at low frequency simultaneously since the continuous wavelet transform is to apply the linear scaling (a-dilation) to the mother wavelet. In this paper, the spike wavelet transform is developed to extract these impulsive sound and vibration signals. Since the spike wavelet transform is to apply the non-linear scaling, it has better time resolution at high frequency and frequency resolution at low frequency than that of the continuous wavelet transform respectively. The spike wavelet transform can be, therefore, used to detect fault position clearly without the loss of information for the damage of a gear system. The spike wavelet transform is successfully is applied to detection of the gear fault with tip breakage.

Damage Detection of a Gear with Initial Pitting Using the Zoomed Phase Map of Continuous Wavelet Transform

Impulsive vibration generated by localized gear damage can be used as an indicator for damage detection. Local damage induces an abrupt increase of the amplitude and phase lag of the impulsive vibration signal measured on the gearbox. Relatively large damage like “tip breakage” can be easily detected by the amplitude map of CWT (continuous wavelet transform) for the impulsive vibration signal measured on the gearbox. However, minor damage like “initial pitting” cannot be detected with the amplitude map. To overcome this problem, in this paper we take into account the phase map for a damage signal. The zoomed phase map of CWT is successfully applied to the detection of minor gearbox damage.

Fabrication of Internally Tapered Capillaries for Capillary Electrochromatography Electrospray Ionization Mass Spectrometry

In this study, we report a novel procedure for fabricating internally tapered capillary columns suitable for the coupling of capillary electrochromatography (CEC) to electrospray mass spectrometry (ESI-MS). The internal tapers were prepared by slowly heating the capillary end in a methane/O2 flame. Due to continuous self-shrinking of the inner channel of the capillary, the inside diameter of the opening was reduced to 7-10 microm. The procedure is easy to handle, with no requirement for expensive equipment as well as elimination of problematic grinding of the tip. Several advantages of these new internal tapers, as compared to using externally tapered columns, are described. First, the problems of poor durability and tip breakage associated with external tapering were successfully overcome with the internal taper. A comparison of the online CEC/ESI-MS between external versus internal tapers showed that the latter provides enhanced electrospray stability, resulting in significantly lower short-term noise and very short-term noise values. In turn, the more rugged design of internal tapers allows performing CEC/MS utilizing a harsh polar organic mobile phase, which was not previously successful using an external taper due to higher operating current and electrospray arcing. Next, data on the reproducibility of the internally tapered CEC/MS column using warfarin and beta-blockers as model analytes are presented. For example, when comparing the reproducibility for separation of warfarin under reversed-phase conditions, the internal taper demonstrated superior intraday % RSD (1.6-3.4) as compared to the external taper intraday % RSD (5-6). Last, the applicability of performing quantitative CEC/MS with internally tapered capillaries is demonstrated for simultaneous enantioseparation of beta-blockers. Impressive quantitative results include good linearity of calibration curves (e.g., R2 = 0.9940-0.9988) and limit of detection as low as 30 nM. The sensitive detection of a minor impurity of one enantiomer at the 0.1% level in a major chiral entity buttresses the suitability of compliance with FDA guidelines.

Suture Passer Tip Breakage During Laparoscopic Ventral Hernia Repair

Laparoscopic ventral hernia repair generally employs a tacker and a suture passer to secure the mesh to the abdominal wall. We reviewed cases of Gore Suture Passer tip breakage during these procedures and their management. Surgeons performing laparoscopic ventral hernia repair were asked about encountered complications relating to the Gore Suture Passer instrument. Charts of the patients with significant alteration in the course of their procedure secondary to such complication were reviewed. Two cases of suture passer tip breakage were identified. One required fluoroscopy to localize and recover the tip, resulting in significant prolongation of the operation. The other required conversion to laparotomy with mesh removal; the tip of the Gore Suture Passer was found in the pelvis and the hernia was repaired with a Stoppa technique. The Gore Suture Passer tip may break during laparoscopic ventral hernia repair, which may significantly complicate the case.

Applicator Dispenser Kit Recalled; Tip Breakage Cited

Applicator Dispenser Kit Recalled; Tip Breakage Cited

A smart boring tool for process control

A mechatronic metal cutting tool has been developed to improve the accuracy and flexibility of line boring machining in the automotive industry. Laser position sensors and piezoelectric actuator were integrated into the rotating body of the boring tool. To compensate the boring bar droop and effects of cutting forces, a fast tool servo utilizing feedback control of the boring tool insert position was designed and embedded in the rotating tool assembly. In addition to position control, a self-monitoring algorithm that utilizes disturbance estimator has been put together in the controller. Experimental results demonstrated that the developed cutting process controller improves the accuracy of the boring tool as well as reliably detects the process failures, such as tool tip breakage, without additional monitoring equipment.

CUTTING PROCESS DIAGNOSTICS UTILISING A SMART CUTTING TOOL

A new sensorised boring tool has been developed to enhance the flexibility and precision of line boring processes. A position sensor and tool tip actuator to control and its controller electronics were integrated into a cutting tool. To take further advantage of this highly sophisticated tool, a process diagnostic method based on cutting force measurement method was developed. An observer implemented in the tool controller estimates the disturbance to the actuator using the tool position sensing information. The estimated disturbance is the same as cutting force applied to the tool tip. The algorithm utilising the cutting force to detect cutting process faults, such as tool tip breakage and misalignment of workpiece has been designed and tested experimentally.

Fault Detection of a Gear with Initial Pitting using the Boomed Phase Map of Continuous Wavelet Transform

Vibration transient generated by developing localized fault in gear can be used as indicators in gear fault detection. In this paper, we propose the zoomed phase map for a fault signal using continuous wavelet transfers to detect this vibration transient. Local fault induces the abrupt fluctuation of load exciting tooth and phase lag in the vibration signal measured on the gearbox. The relatively large fault like tip breakage easily can be detected by the clear fluctuation of exciting load. However, minor fault like initial pittingcannot be detected using the load fluctuation. To defect this kind of minor fault, the phase map for a fault signal is taken into account. The phase lag by minor fault is observed well in the zoomed phase map.

Monitoring drill conditions with wavelet based encoding and neural networks

Encoding of thrust force signals of microdrilling operations with wavelet transformations and classification of estimated coefficients with adaptive resonance theory (ART2)-type neural networks are proposed for detection of severe tool damage just before complete tip breakage occurs. The coefficients of the wavelets were classified both directly and after a secondary encoding to reduce the humber of inputs. Direct classification of the wavelets was found to be more reliable in the sixty-one cases studied. The proposed approach was also tested with two sampling intervals. Large sampling intervals were used to inspect complete drilling cycles. Smaller sampling intervals were used to focus on thrust force variations during the motion of the machine tool table when it is driven by a stepping motor. It was found that the data collected at smaller sampling intervals were easier to classify to detect severe damage to the tool.

Submicron tip breakage and silanization control improve ion-selective microelectrodes.

Probable causes of failure of otherwise well-constructed liquid ion-exchanger (LIE) micro-electrodes of average tip size less than 0.15 micron were examined. The problem could be attributed to two major variables, both localized at the tip: partial tip occlusion during fabrication prevents the generation of an electromotive force (small or absent slope and/or selectivity, high resistance); or poor hydrophobicity of the tip permits water to displace the resin from the tip (small or absent slope and/or selectivity and low electrode resistance). Controlled dry tip breakage on paper coated with glassine to final tip sizes well below 0.5 micron (confirmed by scanning electron microscopy) improves the yield of usable electrodes severalfold. Adequate silanization of the tip and consequent retention of resin at the tip can be predicted from the contact angles observed at the glass-LIE-backfilling solution interface. Satisfactory silanization can be achieved despite high ambient humidity. No evidence of shunting of Na+-LIE microelectrodes by the glass wall was seen. In the isolated perfused proximal tubule of Ambystoma tigrinum, the mean intracellular Na+ activity recorded by broken-tip electrodes (13.7 +/- 1.9 meq, n = 4) was similar to that recorded by intact electrodes (15.5 +/- 1.1 meq, n = 31).

Snapdragon Stem Tip Breakage as Related to Stem Lignification and Flower Color1

Abstract Breakage in the floret area of the stem which occurs during harvesting or post-harvest handling in commercially mature snapdragons was investigated. The point of breakage was not influenced by the number of open florets on the stem, provided many unopened buds remain at the apex. Breaking occurred lower on the stem in crops harvested during fall as opposed to summer months. The break point appears to be related to the end of the concentric column of safranin stainable, lignified xylem. Although not without exception, breakage also appears related to flower pigmentation in that anthocyanin (red) containing cultivars tend to break high whereas aurone (yellow) containing cultivars break low in the floret area. These factors suggest a competition for phenyl propanoid precursors which are consumed in both lignification and pigmentation.