Key Engineering Materials Vols. 407-408

Abstract: The connotative meaning and trend of bionic design and manufacturing was analyzed. A new bioforming technology was presented, which will offer a new way to solve the difficulties in manufacturing of bionic micro-nano structures, and the layout of bioforming technology was also plotted. Several different bioforming technologies targeting typical bionic products were introduced. Compared with traditional manufacturing methods, to machine complicated micro/nano shapes, structures, functional interfaces with bioforming technology has more advantages, which showed that bioforming technologies would have great potential applications in energy-saving, environmental protection, and micro/nano fields.

Abstract: Cutting tools have been improved to endure severe environments in cutting operations. Especially, ceramic film coating technologies are important. Recently, film structure is optimized and tensile stress in film is controlled, as a result new tools which have the newest coating achieved double the tool life and 1.5 times higher efficiency compared with conventional tools. In tool design, progressive molding and sintering techniques allow more complicated tool shapes which have high rake angles to reduce cutting force, higher accuracy equivalent to grinding class tools and more excellent performance.

Abstract: WC-βt-Co alloys have been widely applied to cutting tools because they are superior to WC-Co alloys in oxidation, plastic deformation and adhesion resistances. In this study, the effects of HIP treatment, WC grain size and content of βt phase on bending fatigue characteristics were investigated for fine and coarse-grained WC-6.7mass%βt-10.4mass%Co alloys （6.7βt(F) and 6.7βt(C) alloys） and fine-grained WC-20mass%βt-11.3mass%Co alloy (20βt(F) alloy) by comparing with the case of fine-grained WC-10mass%Co alloy（10Co(F) alloy） without βt phase. The results obtained were as follows: 1) The bending fatigue life of HIP-ed 6.7βt(F) alloy was longer than that of normally sintered 6.7βt(F) alloy. The S-N curve of HIP-ed alloy showed a small gradient in a high stress range and a large gradient in a low stress range. 2) The fatigue life of HIP-ed 6.7βt(F) alloy remarkably decreased in the high stress range, but slightly decreased in the low stress range, compared with that of 10Co(F) alloy. 3) The fatigue life of HIP-ed 6.7βt(C) alloy was superior in all the stress range, compared with that of HIP-ed 6.7βt(F) alloy. 4) The fatigue life of HIP-ed 20βt(F) alloy was shorter than that of 6.7βt(F) alloy in all the stress range．The above-mentioned results were mainly discussed relating to the fatigue fracture origins such as pore, Co pool, agglomerate of βt grains, etc.

Abstract: Chemical vapor deposition (CVD) diamond coatings were deposited on milling cutter substrate using a hollow substrate holder. The substrate is WC–Co cemented carbide contained 6% of cobalt concentration. Structures and stress state of diamond films were analyzed by scanning electron microscopy (SEM) and Raman spectroscopy. It was found that the diamond coating is of the same quality at the same cutting tool deposited on a hollow substrate holder. Diamond (sp3) bonds are better developed with substrate temperature of ~760°C. A higher or lower substrate temperature could lead to a higher non-diamond carbon content in the films. A higher substrate temperature could lead to a higher thermal stress. The compressive stress increases when the substrate temperature is higher or lower than 760°C. The concentration of amorphous phase in the coatings is low with CH4 concentration of 1.0% and 1.5%. A higher non-diamond carbon content and defects in the diamond coatings increase with the increase of CH4 concentration, which leads to the compressive stress value does not increase significantly under a high CH4 concentration.

Abstract: This paper describes the effects of novel nitriding technique used in various carbide cutting tools. In manufacturing, eco-friendly machining is demanded of late. So far, many kinds of methods were made practical, for example MQL process. Through the development of coating technology, dry cutting process has been used and even now more improvement of tool life is required. Both coated and the non-coated carbide tool were applied with novel nitriding to elongate their tool life. The results show novel nitriding decreased the coated carbide tool wear and improved its tool life 1.4 times longer than non-treated carbide. Similarly, the non-coated carbide tool wear decreased and built-up edge on tool surface reduced. These improvements may be derived from the hardening effect on the binder material within the carbide tools.

Abstract: The gear plunge shaving process is a widely used process for soft finishing of gears in the gear manufacturing industry. But it is difficult and expensive to profile plunge shaving cutter, because the cutter must be ground by a cone grinding wheel on a special grinder. A new method, profiling gear shaving cutter on the shaving machine, i.e. a CBN dressing gear which has the same parameters with the machined gear is clamped in place of the workpiece on the shaving machine and profiling the cutter in shaving process, is put forward. Meshing and Tooth contact analysis of shaving cutter profiling has been considered. Meshing equation of profiling process and equation of shaving cutter gear blank after profiling are obtained. Experiment testified that it is an applied method and has many advantages.

Abstract: Inconel 625® contained Ni 61%, Cr 21.5%, Mo 9% and so on is one of the nickel base super heat resistant alloys and is used for parts in food machine. The nickel base alloys are generally difficult-to-cut materials because of high thermal resistance, high work-hardening, high chemical activity and low thermal conductivity. In tapping, furthermore, the tool failure such as chippings, cracks and tool fractures has been frequently observed owing to low rigidity of tool. This paper deals with the influences of surface treatment, tool geometry etc. on the cutting phenomena such as the tool failure, the cutting force and so on when tapping Inconel 625® using the high speed steel tool. The damage of oxidizing tool is slower than that of nitriding tool. The large thrust force in backward tapping causes the rapid tool fractures. The smaller helix angle leads to the lower thrust force in backward tapping.

Abstract: In this study we attempted to suppress chatter vibration in end-milling of austenitic stainless steels with an end-mill having different helix angles. We showed there were two types of chatter vibration in end-milling with a conventional end-mill with regular helix angle. The two types of chatter vibration depend on the cutting speed. We detected these two types of chatter vibration by the developed monitoring method using laser Doppler vibrometers. We classified the two types of chatter vibration according to chatter generating tendency, frequency and vibration mode. We showed that chatter vibration generated at lower cutting speeds was regenerative chatter vibration. On the other hand, chatter vibration generated at higher cutting speeds was another type. We showed that a end-mill with different helix angles could prevent generative chatter vibration at lower cutting speeds and was also effective in suppressing chatter vibration at higher cutting speeds.