Chip Loading Research Articles

Performance of a new segmented grinding wheel system

This paper investigates the mechanical and thermal effectiveness of a new segmented grinding wheel system with controlled radial coolant supply. The applicability of the system was examined in terms of grinding forces, specific energy and ground surface integrity in plunge grinding of AISI 4140 steel. It was found that compared with a standard grinding wheel, the new system enhanced the grindability with a lower specific energy and less application of coolant. It was also found that the new grinding system could effectively maintain the sharpness of active cutting edges, evidenced by the minimisation of ploughing and rubbing deformation in ground workpieces. The cleaning capacity of the wheel was improved and chip loading on wheel surfaces was avoided. Meanwhile, the new wheel system generated better surface integrity without tensile residual stresses.

Thermal Investigation of GaN-Based Laser Diode Package

We investigated thermal behavior of GaN-based laser diode (LD) packages as a function of cooling systems, die attaching materials, chip loading conditions, and optical performances. The electrical thermal transient technique was employed for the thermal measurement of junction temperature and thermal resistance of LD packages. The results demonstrate that the total thermal resistance of LD packages is controlled mainly by the packaging design rather than the chip structure itself. Significant changes in thermal resistance with input current were observed under a natural cooling system because of the sensitive change in the heat transfer coefficient with the change in temperature. Employment of PbSn as a die attachment was more advantageous over the Ag-paste in the thermal behavior of LD packages. The LD package with epi-down structure resulted in the lower thermal resistance compared to one with epi-up structure. A continuous increase in junction temperature was measured after lasing. It was attributed to an increase in the thermal resistance of LD when it took the optical power into an account. Effective input power was decreased by the lasing and led to high thermal resistance values.

Thermal analysis of GaN‐based laser diode package

AbstractThis paper reports on the thermal behavior of GaN‐based laser diode (LD) package as functions of cool‐ing systems, die attaching materials, and chip loading conditions. Thermal resistance and junction tem‐perature was determined by electrical‐thermal transient method. Significant change of thermal resistance with input current was observed under natural cooling condition due to the sensitive change of heat trans‐fer coefficient (h ) with temperature. Employment of PbSn as a die attachment was more advantageous over Ag‐paste in thermal behavior of LD package. Compare the thermal resistance of LD packages epi‐down and epi‐up structures. The partial thermal resistance from junction to submount is 4.68 K/W for epi‐down structure, and 9.65 K/W to epi‐up structure. The results demonstrate that the total thermal resistance of LD package be controlled mainly by the packaging design rather than the chip structure itself. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Image processing of grinding wheel surface

Identifying the situation of grinding wheel wear and loading is a very important issue for high-efficiency grinding operations. This paper presents a new method that detects and identifies the chip loading and cutting edge wear of a grinding wheel using the image processing toolbox of the MATLAB package. The different optical characters of the metal chips and the abrasive grains are analysed. The Sobel operator is adopted to make the edge detections. A sensitivity threshold based on the global condition is used to lower the noise. Image dilation and erosion processes are used to ensure that the edge of each loaded chip is covered by a continuous section. The ratios of chips are calculated and displayed to monitor the wheel surface working status.

Integrated‐circuit‐pressed ceramic‐package antenna

AbstractA novel integrated‐circuit‐pressed ceramic‐package antenna is proposed for the first time. The antenna is intended for use in the single‐chip solutions of wireless transceivers using deep submicron complementary metal‐oxide semiconductor (CMOS) technology. The prototype antenna printed on a dual‐in‐line integrated‐circuit‐pressed ceramic package is comparatively studied at 2.4 GHz with and without CMOS chip loading. The results show that CMOS chip loading greatly increases the impedance bandwidth, but slightly decreases the radiation efficiency of the antenna. The loaded antenna achieves an impedance bandwidth of 15.7% and a radiation efficiency of 64 ± 4%, which are sufficient for most applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 143–147, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20233

Automated parallel DNA sequencing on multiple channel microchips.

We report automated DNA sequencing in 16-channel microchips. A microchip prefilled with sieving matrix is aligned on a heating plate affixed to a movable platform. Samples are loaded into sample reservoirs by using an eight-tip pipetting device, and the chip is docked with an array of electrodes in the focal plane of a four-color scanning detection system. Under computer control, high voltage is applied to the appropriate reservoirs in a programmed sequence that injects and separates the DNA samples. An integrated four-color confocal fluorescent detector automatically scans all 16 channels. The system routinely yields more than 450 bases in 15 min in all 16 channels. In the best case using an automated base-calling program, 543 bases have been called at an accuracy of >99%. Separations, including automated chip loading and sample injection, normally are completed in less than 18 min. The advantages of DNA sequencing on capillary electrophoresis chips include uniform signal intensity and tolerance of high DNA template concentration. To understand the fundamentals of these unique features we developed a theoretical treatment of cross-channel chip injection that we call the differential concentration effect. We present experimental evidence consistent with the predictions of the theory.

チタンの砥粒反応性と研磨

Titanium is a difficult-to-machine metal, due to its high reactivity with abrasives. The cutting rate of alumina is significantly low. In contrast, at higher rotational speed and greater grinding force, the cutting rate of carborundum is much greater, but accompanied by severe loss of the tool. Since titanium has low thermal conductivity, the grinding temperature influencing titanium-abrasive reactions should be kept from rising. Relatively low rotational speed and small force are recommended. In addition, the tool should not be depressed against the work during grinding but moved over the work, otherwise unfavorable results are yielded: abrasive attrition, chip loading and oxidation of the surface, or grinding burn. Since polishing is also a procedure of cutting by abrasives, inhibition of titanium-abrasive reaction is an important key to efficient polishing. Recently, two finishing techniques were successfully applied in dentistry, electrochemical buffing and mechanical buffing with colloidal silica as abrasive. When the reaction-inhibition mechanism is clarified in these techniques, a new development will be possible.

Optimisation of face-milling cutters by use of a computeraided milling-system simulator (Camss)

This paper focuses on the improvement of the cutting process in milling operations by the reduction of vibrations. For that purpose, a non-uniform chiploading pattern is considered as the design parameter, which is achieved by controlling individual insert geometry, namely axial rake and radial rake angles. In the development of the system model, a complete governing equation that describes the milling process is derived and formulated. The model can represent the closed-loop configuration that consists of the cutting process, structural dynamics and a feedback loop. Based on this model, a computer-aided milling-system simulator (CAMSS) is developed. It takes into account the forced-vibration criterion as well as the self-excited vibration to optimise the cutter geometry. Therefore, it should be able to investigate the effects of cutter geometry on chip loading and vibration. A series of comparisons showed that the optimal cutter was subject to fewer vibrations and lower cutting forces than the conventional one.

Effect of variety and plant age on the cyanide content of whole-root cassava chips and its reduction by sun-drying

The cyanide content of fresh whole-root chips of two cassava varieties (CMC-40, low-cyanide, and CMC-84, high-cyanide) as affected by plant age (9–12 months) was determined monthly, as was the effect of sun-drying, either on concrete floors (plain or black-painted) or on inclined trays, on cyanide elimination. Total cyanide contents in fresh chips of variety CMC-84 were always higher (772 ± 167 vs. 436 ± 111 mg/kg DM) than those of variety CMC-40, and in both varieties cyanide contents in chips decreased as plant age increased. Most of the cyanide in fresh chips was found as bound cyanide (66% for CMC-40 and 79% for CMC-84), but the proportion of free cyanide was higher than values previously determined in the separate root tissues. Sun-drying on inclined trays normally required less time than on a concrete floor; at the fresh chip loading rate used (8.5–9.0 kg m −2) for floor drying, no appreciable differences in drying times and cyanide elimination were found between plain and black-painted concrete surfaces. Sun-drying on a concrete floor eliminated more cyanide (86–93% of initial level), for both varieties, than on inclined trays (61–87%). Most of the remaining cyanide in chips dried on a concrete floor was found as free cyanide (62 ± 16% for CMC-40 and 59 ± 18% for CMC-84), but in chips dried on trays these values were considerably lower (25 ± 11% for CMC-40 and 19 ± 8% for CMC-84). Results are discussed in relation to the maximum hydrocyanic acid concentration (100 mg kg −1) that has been set as a quality standard for cassava chips or pellets.

On the theory of a two-stage A-C. rotary amplifier

This paper proposes a new method for establishing the relations of specific energy of a material for sinusoidal multi-cutters in groove-sawing process. Effects of specific energy on sinusoidal multi-cutters with different cutter geometries, cutter locations, cutters arrangements, and cutter-by-cutter overlap ratios are studied. Experimental results prove that the specific energy is function of undeformed cutting areas in groove-sawing process. The groove sawing force in 3-axis is decomposed by cutting force in x-direction, side force in y-direction and vertical force in z-direction. The average specific energy of sinusoidal multi-cutters for workpiece Al 6061 in different wavelength (n = 1–7) is 1580 MPa, the average specific coefficient in y-direction is 0.44 and the average specific coefficient in z-direction is 0.20. The chip loading on each cutter is related to the average cutting depth, cutting width and cutter angle. The maximum chip loading of cutter order occurs in cutting overlap-area ratio between 0.22 and 0.23. The specific energy with multi undeformed cutting areas demonstrated the trend as the exponent decay. The specific energy varied with cutter location on sinusoidal wave, and the maximum variation of error occurred on cutter number n = 3 per unit wave. The groove-sawing force model for sinusoidal-wave cutters can be established for the function of multi undeformed cutting areas by known specific energy, and it agreed well with the experimental results. Variations of error for sinusoidal multi-cutters are investigated for different cutter topologies. Through the geometry parameters design for multi-cutters to reduce specific energy on machining, the maximum material removal rate and longer tool life can be achieved.