Advanced Materials Research Vols. 472-475

Abstract: This paper proposal an apparatus and processing steps to realize 3d laser marking onto the target's surface directly. A camera is attached to an ordinary inner engraver and laser source is multiple used for measuring and manufacturing respectively. Through steps successively including Camera Calibration, 3D Measuring, Surface Reconstruction, Image Ditching, Texture Mapping, Computer Aid Design (CAD), Computer Aid Manufacture (CAM) Calculation and Computer Numeric Control (CNC) Control, an inner engraver can become a 3D marking machine in a manner which is both novel and cheap.

Abstract: The calculation of product cost in modern manufacturing enterprises includes assigning direct costs and indirect costs (overhead) to products. Direct material and direct labor costs can be traced to individual products or batches of products. However, because overhead is an indirect cost and benefits more than one product, it is difficult if not impossible to determine the true overhead cost associated with the overhead resources consumed to manufacture individual products produced. The factory resources included in overhead are an important component of manufacturing product. Overhead costs have traditionally been allocated to products using allocation bases which are correlated to the incurrence of cost such as direct labor hours, direct labor cost, or machine hours using one or few plant-wide allocation base for this purpose. The resulting product costs are used for external financial reporting and are also often used internally as a source of information for management decisions. The information provided by traditional cost systems is often so inaccurate it causes managers to do the wrong things. Further, traditional product costing offers little help to managers in their efforts to reduce costs. Activity based costing is a technique that allocates cost based on activities and volumes that cause cost. The use of these cost causes, called cost drivers, significantly increases product cost accuracy and also encourages managers to take cost-cutting actions that result in true cost savings to the firm. This paper will explore activity based costing and how it can help manufacturers to increase product cost accuracy and to reduce costs.

Abstract: This paper deals with the microstructure and thermal shock behavior of laser remelting of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) deposited by plasma spraying. The microstructures of the coatings were analyzed by scanning electron microscopy (SEM). It was found that the as-sprayed ceramic coating had laminated structure with high porosity. However, the coating exhibited a dense lamellar-like layer with segment cracks on the remained plasma-sprayed porous layer. Thermal shock experiments for the two kinds of TBCs were performed by water quenching method. Testing result showed that the laser-remelted TBC had better thermal shock resistance than the as-sprayed one. The damage mode of the as-sprayed TBC was great-size whole spalling. In contract, the failure mechanism of the laser-remelted one was mainly local pelling. Segmented cracks of the top ceramic coatings caused by laser remelting improved the stress accommodation and were mainly attributed to the enhancement for thermal shock life of TBC.

Abstract: As diode laser is simple in structure, small size, longer life expectancy and easy modulation and the advantages of low prices, widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost. in order to output high power, in this paper, we utilized polarization coupling technology to couple two 808nm laser diode stack together, and designed the optical system to expand and focus the beam, through the experiment, we realized the overall efficiency more than 60%, focusing the beam size of 2×2mm2.

Abstract: Considering the efficiency and microscale requirement of melting polymer in micro-injection process, we present an experimental analysis of the CO2 laser irradiating Polyamide 12 (PA12) based on the photo-thermal effect of laser-materials interaction. The orthogonal experiments of laser plasticizing were designed by Taguchi method of Minitab software, the influence of process parameters on PA12 plasticization was investigated, and the effect sequence rule of the experiment parameters to melting depth was analyzed. Accordingly，the optimal process parameters combination on PA12 plasticization were obtained，i.e. laser power 3 W, beam diameter 2 mm, scanning velocity 200 mm/min, scanning distance 0.5 mm and environment temperature 20°C.

Abstract: Purpose – The objective of this study is to investigate the effect of various parameters on rapid prototyping parts for processes of sintering metallic powder by using fiber laser via the design of experiments (DOE) method. Design/methodology/approach – Experiments based on the DOE method were utilized to determine an optimal parameter setting for achieving a minimum amount of porosities in specimens during the selective laser sintering (SLS) process. Analysis of variance (ANOVA) was further conducted to identify significant factors. Findings – A regression model predicting percentages of porosities under various conditions was developed when the traditional Taguchi’s approach failed to identify a feasible model due to strong interactions of controlled factors. The significant factors to the process were identified by ANOVA. Research limitations/implications – Four controlled factors including pulse frequencies and scan rate of laser beams, laser power and scan line spacing with particle sizes of 5µm of the powder base material had significant influence on the sintering process. Future investigation planned to be carried out for achieving multiple quality targets such as the hardness and the density for 3D parts. Originality/value – The implementation of the DOE method provided a systematic approach to identify an optimal parameter setting of the SLS process; thus, the efficiency of designing optimal parameters was greatly improved. This approach could be easily extended to 3D cases by just including additional parameters into the design. Additionally, utilization of the normality analysis on the residual data ensured that the selected model was adequate and extracted all applicable information from the experimental data.

Abstract: The surface absorption coefficient of S304L stainless steel during Nd:YAG pulse laser welding process was derived by using the inverse engineering technique. The thermal-elastic-plastic finite element method is employed to calculate the temperature distribution, melting pool depth and shape with specific heat source. The derived melting pool depths and diameters with different values of absorption coefficient were compared with experimental results. In this study, the least square error method is used to obtain the equivalent absorption coefficient. The results show that the equivalent absorption coefficient of S304L stainless steel is in the range of 0.1~0.25 for low power intensity Nd:YAG impulse laser welding.

Abstract: Based on the electrode finishing technique in electrical discharge machining (EDM), a new method is proposed in the article to fabricate minitype cutting tool efficiently. The research on the techniques to attain the minitype cutting tool was based on analyzing the feature of EDM on minitype cutter. The process of fabrication for minitype cutting tool is determined, and the minitype grooving tools with the characteristic sizes of 70 μm were made of two types of materials. This fabrication method proved to be applicable to high efficiency fabrication of minitype cutting tool. The factors affecting precision of minitype cutter were analyzed, the causes for worse shape precision and surface roughness were described specifically, and the suggestions to improve the machining quality were proposed.

Abstract: Bone drilling is widely used in orthopedics and dental surgery; it is a technically surgical procedure. Recent technological improvements in this area are focused on efforts to reduce forces in bone drilling. The aim of this study was to compare changes in cutting force during dental bone drilling at various drilling conditions and drill tool geometry. In the present in vitro study, dog jaw bone with uniform thickness of cortical bone was used. Cutting force changes were measured during drilling process. Drill jig was designed and manufactured to fix jaw workpiece and mounted on the tool dynamometer to measure cutting force in drilling process. The dental implant drilling tests were conducted at various cutting speeds and feed rates. In this study drilling thrust force was observed 1.5~3.6[N] for MS type implant drilling and 3.1~4.9[N] for conventional high speed steel drilling, respectively. This further research will provide a basic quantitative approach for the timely issue of wide application of implant drilling in dental and orthopedic surgery fields.

Abstract: On basis of the introduction for the composition of carried-load assistance system and the control mechanism of hydraulic pressure valve for lower extremity exoskeleton, the position control loop is built. The control system is designed by frequency domain method using the PID parameters combined with lead correction network. Simulation results show that the control method can servo the angle of knee joint as human’s natural walk as well as the harmonious of man-machine moment. According to performance test of hydraulic pressure control system, the flow and pressure in piston is analyzed considering different load, the pressure of oil box and movable mode. Test results show that hydraulic pressure valve control system can realize efficiently slow walk carried 30 kilogram load, up and down stairs.