The die roll of fine-blanking parts is an important indicator when evaluating quality of parts. In this paper, the formation of die roll during the punching process is analyzed through the difference of the velocity of material between the die roll area and center area. At first, an assumption is made that every die roll is determined by the volume proportion of the part and waste area in the circular affected zone, and it is proved by simulation. In addition, the introduction of insertion block can prevent the fracture on the shearing surface without V-ring. In consideration of waste affect area and insertion block, a novel combined method is designed to decrease the die roll. It turns out that the height of die roll can be reduced by as much as 70% in both FEM simulation and actual experiment, which shows a great potential in fine-blanking industry.

A green, simple and low cost process for production of well dispersed, small size silver nanoparticles with narrow distribution from 3 nm to 15 nm was described. In this method, silver nanoparticles were prepared in aqueous medium by employing wolfberry fruit extract as both reducing and stabilizing agent without utilizing any other capping and reducing agent. The generation of metallic nanoparticles was observed by change of color and the UV–vis absorption spectroscopy. The obtained silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the as-synthesized silver nanoparticles are highly crystalline in nature, spherical in shape. The reaction times, silver nitrate concentrations and wolfberry fruit extract amounts play crucial roles in the synthesis of small silver nanoparticles. The method displayed in this paper offers a very hopeful mean to prepare other noble nanoparticles using renewable materials as reducing and capping agent.

•The changes of magnetic properties during the punching process were investigated.•The relationship of small-angle grain boundary and microhardness was discussed.•The crystal orientations in the area of about 200 μm from the edge were changed.In an attempt to investigate the effects of punching process on crystal orientations, magnetic and mechanical properties in non-oriented silicon steel, the steel sheet was punched for circular shape of Φ40 mm. The crystal orientations and small-angle grain boundaries were characterized by electron backscatter diffraction (EBSD). The results indicated that the initial crystal orientations within a distance of 200 μm away from the sheared edge were significantly changed after the punching process. In this area, the fractions of the directions with a high value of magnetocrystalline anisotropy energy Ea, 〈1 1 1〉, 〈2 1 2〉 and 〈1 1 2〉 can reach up to 0.619. However, the fractions of the directions 〈0 0 1〉 and 〈1 1 3〉 accounts for only 0.096, which have a lower value of Ea. Moreover, the fraction of small-angle grain boundaries markedly increased in the area of about 200 μm from the sheared edge, which is mainly attributed to the dislocations multiplication and dislocations motion. The magnetic domain structures were characterized by an optical microscope according to the Bitter method. The results showed that the width of magnetic domain in the sheared edge was much larger than that in the center and the patterns also existed a big difference. The Vickers HV0.1 method was employed to measure the microhardness of the sheared edge. It was found that the values of microhardness within a distance of 400 μm away from the sheared edge decreased from 259 to 167 due to the effect of work hardening, which is mainly caused by the dislocations pile-ups near the grain boundaries.

Recently, additive manufacturing is one of the most focused research topics due to its explosive development, especially in manufacturing engineering and medical science. In order to build 3D complex scaffolds with multi-biomaterials for clinical application, a new 3D multi-nozzle system with dual-mode drives, i.e. ejection and extrusion was developed. In this paper, much effort was made to gain fine control of droplet and excellent coordination during fabrication. Specifically, the parameters that influence the size and stability of droplet most was intensively studied. Considering that the biomaterials used in the future may have much difference in properties, the combination of parameters was investigated to facilitate the settings for certain-sized droplets, which are potentially eligible for bio-printing. The dispensing nozzles can work well both in independent and convergent mode, which can be freely switched. Outstanding to the most currently used 3D bio-printing techniques, this system can fabricate scaffolds with multimaterials of both low viscosity (by pneumatic dispensing) and high viscosity (through motor extrusion). It is highly expected that this system can satisfy clinical application in the near future.

A simple and environmentally friendly method was developed for preparing colloidal silver nanoparticles in aqueous solutions using silver nitrate, sodium alginate and glucose as silver precursor, capping agents and reducing agents, respectively. The formation of silver nanoparticles was observed by the change of color from colorless to yellow. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV-visible spectroscopy (UV-vis) and X-ray diffraction (XRD). The TEM images show that the particles are small, well dispersed and spherical in shape with a narrow distribution from 3 nm to 12 nm. The XRD demonstrates that the obtained metallic nanoparticles are single crystalline silver nanoparticles. The effects of the reaction time, the reaction temperature and the concentration of silver ion and reducing agent on the particle size were investigated by the UV-vis spectra. The present process is an excellent candidate for the preparation of silver nanoparticles because it is simple, free-pollutant, inexpensive and easy to perform. The method may be extended to other noble metals, such as Au, Pd and Pt, for medicinal, industrial and technological applications.

Extrusion freeforming is a facile approach to produce complex 3D structures with controlled architecture and porosity. In this work, a new slurry system, mainly containing hydroxyapatite (HA) and sodium alginate (SA), has been used to fabricate porous hydroxyapatite scaffolds. After cross-linking in 5% calcium chloride (CaCl2) solution for 24 h, HA–SA composite scaffolds were sintered at 1000–1300 °C for 2 h. The properties of HA–SA composite scaffolds before and after sintering have been investigated. The new slurry system has greatly improved the quality of porous hydroxyapatite scaffolds.

Silver nanoparticle (Ag-np) is a new kind of antibacterial agent which is widely used in medical supplies. In this study, a simple approach is described to obtain Ag-doped HA scaffolds. Hydroxyapatite (HA) bone scaffolds with controllable pore size were fabricated by a micro-syringe extrusion system. Sintered HA scaffolds were then immersed in silver reaction hydrosol in order to get Ag-doped HA scaffolds. SEM and EDS shows a uniform distribution of silver nanoparticles on the surface of HA scaffolds. Such Ag-np doped HA scaffolds, displaying a good antibacterial activity against Escherichia coli (E. coli), are likely to prevent bone implant associated bacterial infections.

The minimal demands for scaffolds include a guaranteed strength over time. In this study, a novel porous HA/β-TCP bioceramic scaffold with micro-ribs structure was fabricated by extrusion deposition technique and microwave sintering. Micro-ribs were placed at the center and corners of scaffold along the direction of load. Mechanical behaviors were studied to verify the strengthening effect of micro-ribs. Compared to the scaffold without micro-ribs, the average compressive strength of newly developed scaffold was remarkably improved from 28.3 MPa to 45.6 MPa under the porosity of 50%. Moreover, it also exhibited more stable and longer lasting mechanical strength during degradation in vitro. The effectiveness of micro-ribs on improving the mechanical performance of scaffolds provided a structural design reference for bone tissue engineering.Highlights► Porous HA/β-TCP scaffold with designed micro-ribs was obtained by combining extrusion deposition technique with microwave sintering method. ► The strengthening effect of micro-ribs on the HA/β-TCP porous scaffold was investigated, and found that scaffolds with micro-ribs exhibited more stable and long lasting mechanical strength even in degradation. ► The effectiveness of micro-ribs on improving mechanical performance of scaffolds provided a structural design reference for bone tissue engineering.

•Silver nanoparticles is prepared using stearic acid as capping agents in aqueous.•Stearic acid is first used for synthesis of silver nanoparticles in aqueous solution.•No organic solvent was used in the synthesis process.•The small, well-dispersed, spherical particles are from 3 to 15 nm.•This newly developed method can be extended to the synthesis of other metal colloid.A practical and convenient method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 15 nm is reported. Silver nitrate, stearic acid and hydrazine hydrate, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by the change of color from milky white to dark red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis) and X-ray diffraction (XRD). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles. The effects of the reaction temperature, the amount of stearic acid and ammonia on the particle size were investigated. The obtained silver nanoparticles are stable and will possibly be used in electronic applications. The preparation method is simple and may be extended to other noble metal for other technological applications.