Green Machining Process Research Articles

Machinability of Green Powder Metallurgy Components: Part I. Characterization of the Influence of Tool Wear

The green machining process is an interesting approach for solving the mediocre machining behavior of high-performance powder metallurgy (PM) steels. This process appears as a promising method for extending tool life and reducing machining costs. Recent improvements in binder/lubricant technologies have led to high green strength systems that enable green machining. So far, tool wear has been considered negligible when characterizing the machinability of green PM specimens. This inaccurate assumption may lead to the selection of suboptimum cutting conditions. The first part of this study involves the optimization of the machining parameters to minimize the effects of tool wear on the machinability in turning of green PM components. The second part of our work compares the sintered mechanical properties of components machined in green state with other machined after sintering.

High Velocity Compaction : Overview of Materials, Applications and Potential

Since 2000, CETIM has been equipped with a High Velocity Press that can deliver up to 5 shots per second with each blow accurately set up (up to 20000J) thanks to the impact velocity regulation (up to 11m.s-1). Through different projects, CETIM and its scientific and industrial partners have evaluated the potential of this new technology in terms of materials and component shape. Various kinds of powder materials were studied: metals, ceramics and polymers. The HVC process was used with success to manufacture gears, large parts and multilevel components. More than, the green machining process that enables shapes to be produced that would otherwise be impossible to compact is improved by the high density of HVC parts and it is also an opportunity to produce components with very hard sintered materials.

Windmill-type ultrasonic micromotor fabricated by thermoplastic green machining process

A miniaturized windmill-type piezoelectric ultrasonic motor (USM) was developed using a thermoplastic green machining process. A thermoplastic body, consisting of 60 vol% piezoelectric material and 40 vol% thermoplastic binder, was CNC-machined to create windmill-type blades at the center of a green disk. After the binder burnout and sintering processes, the disk was poled in the thickness direction. By applying an AC field in the thickness direction, the inward blades at the center of the disk converted the radial displacements into tangential ones, causing the shaft at the center to rotate. When the USM stator with dimensions of 5.2 mm (diameter) × 0.6 mm (thickness) was operated in the principal radial vibration mode (260 kHz) at 20 V p–p, the displacements of the blades in the x- and y-directions were 40 and 20 nm, respectively. The characteristics of the USM, monitored by using a non-contact method with a moment of inertia of 3.6 kg mm 2, consisted of a maximum torque of 22 μN m, a maximum speed of 16.4 rad/s, and a maximum efficiency of 12%.

グリーンマシニングによるラピッドプロトタイピングの試み

A new rapid manufacturing process of metallic parts using green machining has been developed. In this process, metal powder for metal injection molding is hardened using water base binder, and made into a green body. After drying the green body, it is machined by small automatic milling machine. Machined parts are sintered after that, and rapidly manufactured parts are obtained. In this process, the green body has enough strength for machining, and we can use a small, cost-effective milling machine developed for wood or plastic materials. The machining time of the green body is short compared with other material processing. We can obtain low cost rapid prototyping of metallic parts by this green machining process.

グリーンマシニングによるチタン製品のラピッドプロトタイピング

A new rapid manufacturing process of metallic parts using green machining has been developed and already achieved for manufacture of stainless steel parts. In this process, metal powder for metal injection molding is hardened by a solution of PVA in water as binder. This green body is prepared for machining. This process is used a small and cost-effective milling machine, and the green body is easily machined. Meanwhile, rapid manufacturing of titanium parts for implant is desired in the medical field. This process makes it possible to produce a suitably sized medical implant. Therefore, we applied the green machining process to the production of titanium parts for the purpose of manufacturing implants with law cost and short lead-time.