Bingheng Lu

A web-based manufacturing service system for rapid product development

This paper proposes a novel integrated system of rapid product development based on rapid prototyping, and develops a networked manufacturing service system which offers better support for the rapid product development in small and medium sized enterprises by taking full advantage of the quickly evolving computer network and information technologies. The architecture of the networked manufacturing service system is presented. Furthermore, some of the key issues, including modelling and planning a manufacturing chain, selecting feasible collaborative manufacturers, queuing a manufacturing task, using the synchronously collaborative work environment, and constructing a suitable running platform, are described in detail. Java-enabled solution, together with web techniques, is employed for building such a networked service system. Finally, an actual example is provided illustrating the application of this service system.

Custom fabrication of a composite hemi‐knee joint based on rapid prototyping

Purpose – To present a custom design and fabrication method for a novel hemi‐knee joint substitute composed of titanium alloy and porous bioceramics based on rapid prototyping (RP) and rapid tooling (RT) techniques.Design/methodology/approach – The three‐dimensional (3D) freeform model of a femur bone was reconstructed based on computerized tomography images via reverse engineering and the 3D reconstruction accuracy was evaluated. The negative image of artificial bone was designed with interconnected microstructures (250‐300 μm). The epoxy resin mould of a hemi‐knee joint and the negative pattern of an artificial bone were fabricated on Stereolithography apparatus. Based on these moulds, a titanium‐alloy hemi‐knee joint and a porous‐bioceramic artificial bone were created by quick casting and powder sintering (known as RT) techniques, respectively. After assembling, a composite hemi‐knee joint substitute was obtained.Findings – The 3D reconstructed freeform model of the femur bone conformed to the origina...

Investigation of the overlapping parameters of MPAW‐based rapid prototyping

Purpose – To fabricate fully dense components with low costs, a rapid prototyping (RP) system based on micro‐plasma arc welding (MPAW) was developed. The appropriate process parameters were investigated to build the parts with good mechanical properties and surface smoothness.Design/methodology/approach – A simplified overlapping model between deposited tracks was established to investigate the relationships among the overlapping parameters, such as the ratio of width to height of the deposited track cross‐section (λ), scan spacing and overlapping ratio. Some ER308L stainless steel parts were built by different overlapping parameters, and the surface smoothness, tensile strength and elongation of the parts were tested.Findings – The overlapped surface smoothness, tensile strength and elongation of the parts built with larger λ were better than those built with smaller λ. The longitudinal tensile strength and elongation of the parts were better than the transverse data.Research limitations/implications – T...

Design and fabrication of CAP scaffolds by indirect solid free form fabrication

Purpose – To fabricate the self‐hardening calcium phosphate composite scaffolds with controlled internal pore architectures using rapid prototyping (RP) techniques and investigate their in vitro bone tissue engineering responses.Design/methodology/approach – The three‐dimensionally interconnected pores in scaffolds can facilitate sufficient supply of blood, oxygen and nutrients for the ingrowth of bone cells, tissue regeneration, and vascularization. It is essential for bone tissue engineering to provide an accurate control over the scaffolds material, porosity, and internal pore architectures. Negative image of scaffold was designed and epoxy resin molds were fabricated on sterolithography apparatus. Calcium phosphate cement slurry was cast in these molds. After self‐hardening, the molds were removed by pyrolysis and the resulting scaffolds were obtained.Findings – Eight scaffolds with 54.45 percent porosity were tested on an Instron machine. The average compressive strength measured was 5.8±0.8 Mpa. Cyt...

Fabricating the Steam Turbine Blade by Direct Laser Forming

Direct Laser Forming (DLF) is a new layer additive manufacturing technique. It is difficult to control the forming process because many technological parameters interplay. Besides three kinds of laser scanning modes (namely, offset contour line mode, parallel line mode, and the offset contour line combined with parallel line fill mode), the effect of the defocusing amount of both laser beam and powder stream on the forming process is investigated in detail in the article. It is shown that the forming quality is better when the defocusing amount of both laser beam and powder stream are, respectively, between −0.5 mm to 0.5 mm and −3 mm to −1 mm, and at the same time, the self-healing phenomenon (namely, the plane quality of the top surface of part tends to decrease) is firstly found under the open loop condition. Based on the forming mechanisms under different defocusing amount, and the comparative study of three kinds of laser scanning modes, high definition steam turbine blade is fabricated by DLF using the hybrid scanning mode. Consequently, some complex metal parts in aerospace field can be near-net-shape formed by DLF.

Fabrication of artificial bioactive bone using rapid prototyping

A new technique based on rapid prototyping (RP) is proposed to fabricate the mould of artificial bone composed of a nontoxic soluble material. The mould has both an external structure that exactly coincides with the replaced natural bone and an internal 3D scaffolds simulating the bone microtubule structure. By injecting self‐setting calcium phosphate cement (CPC) with bone morphogenetic protein (BMP, a kind of bone growth factors) into the cavities of the mould, the CPC solidified and the micropores can be formed after the internal 3D scaffolds is dissolved, finally the artificial bioactive bone can be produced. This approach is better than the traditional fabrication process, which the latter method cannot fabricate an artificial bone with inter‐connective micropores so as to realize the osteo‐induction for lack of bioactivity. Through animal experiments, it shows that the simulated inter‐structure could provide artificial bone with proper voids for the growth of the bone tissue and the quick activation, and hence effectively speed up the bone growth by means of activating osteo‐conduction and osteo‐induction. So, the new method of fabricating artificial bone with biological behaviors is justified.

High‐Performance Piezoelectric Nanogenerators with Imprinted P(VDF‐TrFE)/BaTiO3 Nanocomposite Micropillars for Self‐Powered Flexible Sensors

Piezoelectric nanogenerators with large output, high sensitivity, and good flexibility have attracted extensive interest in wearable electronics and personal healthcare. In this paper, the authors propose a high-performance flexible piezoelectric nanogenerator based on piezoelectrically enhanced nanocomposite micropillar array of polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE))/barium titanate (BaTiO3 ) for energy harvesting and highly sensitive self-powered sensing. By a reliable and scalable nanoimprinting process, the piezoelectrically enhanced vertically aligned P(VDF-TrFE)/BaTiO3 nanocomposite micropillar arrays are fabricated. The piezoelectric device exhibits enhanced voltage of 13.2 V and a current density of 0.33 µA cm-2 , which an enhancement by a factor of 7.3 relatives to the pristine P(VDF-TrFE) bulk film. The mechanisms of high performance are mainly attributed to the enhanced piezoelectricity of the P(VDF-TrFE)/BaTiO3 nanocomposite materials and the improved mechanical flexibility of the micropillar array. Under mechanical impact, stable electricity is stably generated from the nanogenerator and used to drive various electronic devices to work continuously, implying its significance in the field of consumer electronic devices. Furthermore, it can be applied as self-powered flexible sensor work in a noncontact mode for detecting air pressure and wearable sensors for detecting some human vital signs including different modes of breath and heartbeat pulse, which shows its potential applications in flexible electronics and medical sciences.

Fabrication of a calcium phosphate scaffold with a three dimensional channel network and its application to perfusion culture of stem cells

Purpose – The purpose of this paper is to adopt rapid prototyping (RP) technology to fabricate self‐hardening calcium phosphate composite (CPC) scaffolds with a controlled internal channel network to facilitate nutrient supplying and cell growth using RP technique and investigate their in vitro performance.Design/methodology/approach – Porous scaffolds should possess branched channels to ensure uniform cell feeding and even flow of culture medium to promote uniform cell attachment and growth. A new three dimensional (3D) flow channel structure has been designed based on conversation of energy and flow. The CPC scaffold possessing such a channel network was made by indirect solid free form fabrication. Negative model of scaffold was designed by Pro/E software and its epoxy resin mold was fabricated on a sterolithography apparatus and the CPC slurry was filled in these molds. After CPC was self hardened, the mold was baked. The mold was removed by pyrolysis and then the designed scaffold was obtained.Findin...

Integrating cross-sectional imaging based reverse engineering with rapid prototyping

This paper presents an integrated system of cross-sectional imaging based reverse engineering (RE) and rapid prototyping (RP) for reproducing complex objects. The system consists of four modules: cross-sectional image measurement, 3D reconstruction, stereo lithography (STL) file generation, and RP slice file generation. During cross-sectional image measurement, the object to be measured is encased within resin and then milled, layer-by-layer, using an NC milling machine. After each layer is machined, a CCD camera is used to capture the newly exposed cross-sectional image of the object. The contours of the cross-sectional image are further extracted through image processing and segmentation. A collection of the contour data is acquired by the cross-sectional image measurement module. While a 3D CAD model can be reconstructed by the 3D reconstruction module from the contour data, its STL file and RP slice file are generated directly from the contour data. The algorithm for STL file generation from cross-sectional contours consists of three major steps: (1) preprocessing of cross-section images for data reduction, (2) Delaunay triangulation of contours in the first and last layers and (3) triangulation of contours between adjacent layers. This integrated system and the processing algorithms are further validated through four examples.

Investigation of ink transfer in a roller-reversal imprint process

Roller imprint is considered as one of the processes suitable for patterning on a large-area flexible substrate, which is critical for macroelectronics manufacturing. In contrast to other published roller imprint processes (such as hot-embossing roller imprint or ultraviolet roller imprint), the roller-reversal imprint (RRI) process investigated in this paper starts with pattern coating of an ink (mostly a liquefied electronics material, such as a semiconductor polymer) on a mould roller and ends with transferring the ink already patterned on the roller to the substrate, so it can obtain micropatterns with a precise profile yet leave no residual film on the substrate. One of the critical issues in obtaining patterned ink on the substrate with the required profile by the RRI process is to ensure a complete ink transfer from the microcavities on the mould roller onto the substrate. In this paper, a mathematical model is proposed to analyze the mechanics of the ink transfer, and a criterion for a complete ink transfer is derived. Furthermore, the effects of imprint force on the ink transfer are also demonstrated by an analysis of the elastic deformation of the substrate. The simulations and corresponding experiments show that the ink transfer in the RRI process is strongly dependent on the ratio of work of adhesion at the ink–mould and ink–substrate interfaces, and the critical ratio for a complete ink transfer is determined mainly by the profile of microcavities on the mould featured by the aspect ratio and the sidewall angle. The ink transfer model can be used to select proper materials (including the ink, surface energies of the mould roller and substrate) in the RRI process, and can also be regarded as a guideline for profile designing of the microcavities on the mould roller used in the RRI process.