Large-area Electron Beam Irradiation Research Articles

Study on Metal Film Formation by Large-area Electron Beam Irradiation

Study on Metal Film Formation by Large-area Electron Beam Irradiation

Study on Applicability of Large-Area EB Irradiation to Micro-Deburring

In a large-area electron beam (EB) irradiation method developed recently, high energy EB can be obtained without focusing the beam, and large-area EB with almost uniform energy density distribution of 60mm in diameter can be used for instantly melting and evaporating metal surface. Then, the surface smoothing and surface modification of metal molds made of steel, cemented carbide and ceramics can be performed efficiently. When the large-area EB is irradiated to a sharp edge, the material removal remarkably progresses at the edge due to the heat accumulation and EB concentration there, which leads to the edge rounding. Our previous study clarified that micro-deburring was also possible by using this phenomenon. Moreover, this method would be effective for removal of discontinuous micro burrs generated by thermal machining processes, such as EDM and laser cutting. In this study, the possibility to completely remove micro burrs generated in EDM was experimentally investigated. The difference in micro-deburring characteristics with the type of workpiece material was also investigated. As a result, the EDM micro burrs with a height of about up to 50μm could be completely removed by this method. Furthermore, it was made clear that the magnetic property of workpiece materials greatly influenced the deburring characteristics, and the thermal property such as melting point and thermal conductivity also did.

1102 Film Formation Mechanism in Alumina Coating by Large-area Electron Beam Irradiation

1102 Film Formation Mechanism in Alumina Coating by Large-area Electron Beam Irradiation

Corrosion behaviour of a rapidly solidified Al87.4Co7.9Ce4.7 layer prepared by large area electron beam irradiation

In this study, a bulk crystalline glass forming alloy with the composition of Al87.4Co7.9Ce4.7 (at.%) was rapidly solidified by large area electron beam (LAEB) surface melting of an as-cast starting material. Glancing angle XRD results show that, providing appropriate processing parameters are selected, a predominantly amorphous layer ∼5μm thick can be produced. However, under non-optimum processing conditions treated layers are compositionally inhomogeneous and comprise, in the main, crystalline regions. LAEB treated layers also exhibit a degree of surface cracking as well as micron-sized localised craters and ejected particles formed during electron beam irradiation. Potentiodynamic polarisation tests show that treated layers exhibit enhanced corrosion resistance compared to the as-cast bulk alloy; with the predominantly amorphous layer having the lowest current density. Examination of corroded samples following potentiodynamic tests reveals that cracks limit the effectiveness of the treated layer as a barrier to corrosion.

Study on Possibility of Micro-deburring by Large-area Electron Beam Irradiation

Study on Possibility of Micro-deburring by Large-area Electron Beam Irradiation

Fundamental Study on Micro-deburring by Large-area EB Irradiation

In a large-area electron beam (EB) irradiation method developed recently, high energy EB can be obtained without focusing the beam. Then the large-area EB of 60mm in diameter with uniform energy distribution can be used for instant melting of metal surface. The previous studies clarified that the surface smoothing of metal mold made of steel, cemented carbide and ceramics can be performed efficiently. Also this method can be applied to the surface finishing of biomaterials, such as stainless steel and titanium alloy. In this method, the sharp edge is rounded to about half hundred microns in radius under relatively high energy density conditions, since the material removal remarkably progresses there due to the electron concentration and heat accumulation at the edge. In this study, the possibility of micro deburring was investigated by using the preferential edge removal effect in the large-area EB irradiation. Experimental results showed that the micro-deburring was possible by large-area EB irradiation, and the burr height decreased with increasing the energy density of EB and the number of irradiation. The burr of about 10 m generated in EDM could be removed completely. Furthermore, micro-burrs at the edge of several small holes could be removed at once.

Fundamental Study on Sputter Deposition of Ceramic Film by Large-Area Electron Beam Irradiation

The sputter deposition of ceramic film on metal mold steel surface by large-area electron beam (EB) irradiation was discussed. The large-area EB has high energy density enough to generate plasma above the workpiece surface during the surface smoothing process, which causes the sputtering of target material set near the workpiece surface. The sputter deposition of target material with simultaneous surface melting and resolidification of workpiece surface by large-area EB would improve the adhesion between the deposited film and the workpiece. Short ceramic tube made of alumina or zirconia as a target was put on the substrate surface of steel, and large-area EB was irradiated to the surface. The workpiece surface component and structure after the irradiation were investigated using EDX and XRD analysis, in order to discuss the possibility of large-area EB irradiation as a new coating method.

Surface finishing of intricate metal mould structures by large-area electron beam irradiation

The advancement of polymer moulding tools is increasingly focused on imparting not only form but also surface texture for functionality to the surfaces of parts that are created. Furthermore, the increasing demand for inexpensive and higher quality micro-components means that tools for replication processes must take advantage of advanced manufacturing techniques. Tools created by processes such as micro-investment casting, as in this case, may often suffer from excessive surface roughness, malformed edges and general deformation. This results in higher de-moulding forces and a reduction in fidelity of moulded parts to design intent. In this study, large-area electron beam irradiation (EB) is shown to be an effective technique for improving these metrics. For the first time, large population, high aspect ratio micro-features are subject to this process and the mechanisms of smoothing and key enhancement phenomena are demonstrated. The possibility of including EB irradiation in an integrated process chain for arriving at net shape is also discussed. Surfaces of protruding features are shown to have surface roughness reduced significantly from 126 to 22 nm Ra value, with bottom substrate also similarly improving from 150 to 27 nm Ra. Bottoms of recessed features are also observed to have much improved surface finishes. ‘Doming’ of tops of column features is also demonstrated, further enhancing form. These features would be far too fragile to be polished by any other mechanical method.

Repair of EDM induced surface cracks by pulsed electron beam irradiation

This study investigates the use of the large-area electron beam irradiation technique to improve the properties of the EDM’d surface of AISI 310 stainless steel so that a tolerable, or even desirable recast layer may be produced. The short cycle-time of the irradiation process combined with the large incident area of 60mm diameter makes it an attractive surface modification technique for metal moulds and engineering components. This study showed that by varying acceleration voltages and the number of irradiation cycles (shots), that as well as an improvement of surface finish, repair of cracks induced by the EDM process is possible. The mechanism of this repair is also investigated. XRD analysis also shows that crystalline texture can be introduced by the irradiation process with the (111) planes of the austenite phase orienting parallel to the surface. This has potential advantages for introducing anisotropic layers for enhanced corrosion resistance.

Surface modification of cemented carbide by EB polishing

Cemented carbide has many excellent properties. However, it is sometimes difficult to apply conventional surface finishing or surface modification methods for the cemented carbide. The possibility of surface modification by large-area electron beam irradiation, namely EB polishing was discussed. The surface structure of the EB polished cemented carbide was observed by TEM. The hardness and the water repellency were tested. Also, the separation force of molded resin from the surface was measured for evaluating the releasability of the resin. The water repellency and the releasability of the molded resin could be improved by EB polishing, because the surface structure changed.

大面積電子ビーム照射による超微粒子超硬合金の表面処理

Cemented carbide has many excellent properties like high strength, high hardness and high wear-resistance. However, it is often difficult to apply conventional surface finishing or surface modification methods because of its excellent mechanical properties. The purpose of this research is to improve the surface characteristics of cemented carbide by large-area electron beam irradiation. The possibilities of surface smoothing and surface modification were discussed with varying the energy density of electron beam and the number of pulse. The following results were obtained from the experimental analysis. The frequency of surface roughness of surface irradiated by large-area electron beam became lower, and glossiness was higher than those of initial surface. The contact angle of water on electron beam irradiated surface was higher than that on initial surface, which means that the surface has high water repellency. Oil extension area investigated for evaluating lipophilicity was smaller than that of initial surface. The separation force of molded resin measured for releasability evaluation could be reduced by large-area electron beam irradiation. From these experimental results, it was made clear that the surface characteristics of cemented carbide can be improved by large-area electron beam irradiation.

A17 EBポリッシングによる超硬合金の表面改質(OS8 放電加工(1))

Cemented carbide has many excellent properties, such as high strength, high hardness and so on. However, it is difficult to apply conventional surface finishing or surface modification methods for the cemented carbide. In this study, a new surface modification method by large-area electron beam irradiation (EB polishing) was proposed. The surface structure of the EB polished cemented carbide was observed by TEM. Then the surface characteristics, such as hardness, water repellency and releasability of molded resin were evaluated. The experimental results clarified that the water repellency and the releasability of the molded resin could be improved because the surface structure changed by EB polishing.

Surface Modification of Stainless Steel for Surgical Tool by EB-Polishing

A new surface finishing method by large-area electron beam irradiation (EB-polishing) for stainless steels for orthopedic surgical tool was proposed in our previous paper, and it was shown that high-efficient surface finishing was possible by the EB-polishing. In this report, the surface structure of EB-polished stainless steel is analyzed by TEM and EDX. Also, surface modification effects such as resistance to corrosion and blood repellency are evaluated. Then, the applicability of the EB-polishing as a new surface modification method of stainless steel for orthopedic surgical tool is discussed.

E27 Addition of Surface Functions to Orthopedic Surgical Tools and Jigs by Large-area Electron Beam Irradiation(Electrical machining)

In the large-area electron beam (LAEB) irradiation method used in this study, electron beam with high energy density can be irradiated without concentrating the beam, so that LAEB of 60 mm in diameter can melt or evaporate metal surface instantly. In this study, the surface characteristics of LAEB irradiated stainless steels for orthopedic surgical tools and jigs, such as resistance to bacteria adhesion, blood repellency and corrosion resistance were investigated. Experimental results clarified that these surface characteristics could be improved by LAEB irradiation. Therefore, LAEB irradiation method enables the high-efficient surface treatment of surgical tools and jigs.

Large-area electron beam irradiation for surface polishing of cast titanium

Cast titanium is a known hard-to-polish material, and its final polishing step is a perpetual challenge. The best way to tackle this challenge lies in automatic and non-mechanical polishing methods. Against this background, the suitability of large-area electron beam (EB) irradiation was examined in this study. In parallel, the optimum condition for efficient surface polishing was investigated. Cast titanium specimens were prepared, whereby their surface glossiness, surface roughness, and corrosion resistance were measured before and after EB irradiation. After EB irradiation, favorable results were observed: the cast titanium surface became smooth, the glossiness increased, and corrosion resistance was enhanced. These results were attributed to the low heat conductivity of titanium. With mechanical polishing, this property results in temperature rise and burnout reaction of the titanium surface with oxygen and the abrasives. However, during EB irradiation, the low heat conductivity of titanium was an advantage in raising the surface temperature to the melting point, such that a smooth surface was yielded after solidification. Based on the results obtained, automatic polishing by EB seemed to be a suitable polishing method for metal frameworks of removable dentures, and an efficient one too by saving time and effort.

High Efficiency Surface Finishing of Metal Mold by Large-area Electron Beam Irradiation (3rd Report)

A new finishing process for metal molds by large-area electron beam irradiation (EB polishing) was proposed and the fundamental effects of EB irradiation conditions on surface finishing, the surface modification effect and others were investigated in the previous report. As a result, the surface roughness on the whole surface within 60mm in diameter could be reduced from 6μmRz to less than 1μmRz in just a few minutes under a proper condition, and the surface roughness could be well improved even if the surface tilting angle is close to 90 degrees. In addition, the corrosion resistance of metal mold surface could be improved. However, small craters sometimes were generated on the EB irradiated surface, which might deteriorate the quality of products. In this study, the relationship between crater generation and workpiece material was examined. Experimental results made it clear that the generation of crater and its disappearance were repeated on the surface with EB irradiation, and the generation of crater greatly depends on the nonmetallic additives in base material, particularly on MnS. Moreover, the impurity of workpiece material also has a significant influence on the crater generation.

Surface finishing of stainless steels for orthopedic surgical tools by large-area electron beam irradiation

Surgical tools and jigs are initially machined by multi-axis milling. Then surface finishing is carried out mainly by hand lapping. As these tools undergo repeated use, the removal of burrs, scratches and rust from the surfaces is also performed manually after each operation. These finishing processes are time-consuming and costly. In this study, a new finishing method by large-area electron beam irradiation is proposed. Electron beam (EB) with high energy density can be obtained without focusing the beam, and large-area EB can be used for instantly melting or evaporating the metal surface. Stainless steel for surgical tools and jigs was treated by the large-area EB irradiation method. The experimental results show that highly efficient surface smoothing of stainless steels by large-area EB irradiation may be achieved. In addition, the resistance to corrosion and blood repellency can be improved simultaneously with surface smoothing.

A new polishing method of metal mold with large-area electron beam irradiation

A new polishing method by large-area electron beam (EB) irradiation is proposed in this study. In the large-area EB irradiation equipment used here, an EB with high energy density is irradiated without focusing the beam. An EB irradiation in a few microseconds with a maximum diameter of 60 mm can be used for melting metal surface instantly. The experimental results made it clear that the surface roughness decreases from 6 μmRz to less than 1 μmRz in a just few minutes under a proper machining condition. The corrosion resistance of metal mold surface also could be greatly improved by large-area EB irradiation. Furthermore it is clarified that even the surface roughness of tilting surface close to 90° could be well improved. Therefore, large-area EB irradiation method has a high possibility to become a high-efficiency polishing method of metal mold.

High-efficiency finishing process for metal mold by large-area electron beam irradiation

Abstract A new finishing process for metal molds by large-area electron beam (EB) irradiation is proposed in this study. In the large-area EB irradiation equipment used here, an EB with high-energy density is irradiated without focusing the beam, and so the EB with a maximum diameter of 60 mm can be used for melting or evaporating metal surface instantly. Experimental results show that the surface roughness decreases from 6 μmRz to less than 1 μmRz in just a few minutes under proper machining conditions. The corrosion resistance of metal mold surface also could be greatly improved by large-area EB irradiation. Furthermore, the surface roughness of tilting surface close to 90° could be well improved. Therefore, large-area EB irradiation method has a possibility to become a high-efficiency finishing process for metal molds.

A New Surface Modification Method of Metal Mold by Large-area Electron Beam Irradiation(Electrical machining)

We have already proposed a new surface finishing process for metal molds by large-area electron beam (EB) irradiation in the previous report, and the effects of EB irradiation conditions on surface smoothing characteristics were investigated. As a result, the surface roughness could be reduced to less than 1μmRz in just a few minutes under a proper condition. Furthermore, the surface roughness of tilting surface close to 90 degree also could be well improved, which indicated that in the case of small simple shaped mold consisting of relatively small tilting surfaces, the smoothing of the whole surface is possible without moving and tilting the mold. In this paper, the surface characteristics of the EB irradiated surface were discussed by TEM observation, XRD analysis, and corrosion test. The surface structure changed by large-area EB irradiation, and consequently, the corrosion resistance of metal mold surface could be improved well.