No abstract

This article presents a laboratory machine designed to perform orthogonal micro-cutting experiments. The machine allows an accurate control of the various cutting parameters and a direct comparison of micro-and macrocutting tool-material data bases. Research with the machine will focus on validating the application of macrocutting data to at least a range of microcutting applications and to define the limits beyond which such applications are no longer possible. The paper describes the machine and its design specifications and provides the validation of the performances claimed. The machine can cut in a reproducible manner with depths of cut as low as 1 lm, at speeds in the range 50-1000 mm/s, while measuring the cutting and thrust forces. The variability in nominal depth of cut is equal or better than 1 lm. Application examples illustrate the influence of lubrication and lead additions on the cutting process and demonstrate that the machine is indeed suitable for the application for which it was designed.

Seven model polydimethylsiloxane (PDMS) networks were obtained by hydrosilation of a difunctional vinyl-terminated PDMS prepolymer with a SiH-containing cross-linker. Viscoelastic experiments, completed by size exclusion chromatography and static light scattering experiments, were performed in order to study the influence of molecular parameters on the dynamic properties around the sol-gel threshold. The dynamic critical parameter u was determined from experiments close to and above the sol-gel threshold. Our results show that the growth mechanism of PDMS clusters and the viscoelastic behavior are a function of the ratio NN_{e} , where N and N_{e} are, respectively, the numbers of Kuhn monomers between branch points and between entanglements. For NN_{e}<1 , the growth mechanism of clusters is the critical percolation and u=0.69 , and for NN_{e}>1 , the growth mechanim of clusters is the diffusion-limited cluster aggregation and u=0.76 .