Parametric Study of the Effect of Feed Speed and Power on Laser Cut Quality of 4130 Steel
Samples of 4130 steel were cut by a CO2 laser and the effects of power and feed rate on kerf width, surface roughness, striation frequency and the size of heat affected zone (HAZ) were studied. It was observed that power had a major effect on kerf width and size of HAZ, while feed rate affects were secondary. In the other hand, surface roughness and striation frequency were affected most by feed rate. At low power levels the smallest kerf width and HAZ are obtained and the effect of feed rate is moderate. Low feed rates gave good surface roughness and low striation frequency. For optimum cut quality, kerf width, HAZ and surface roughness are kept minimum. However operating conditions that satisfy these requirements while maintaining high productivity could not be identified.
The oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge
Over the past two decades CO2 laser cutting has grown from an obscure laboratory technique into an important branch of manufacturing engineering. The most commonly cut materials are steels and a great deal of industrial and scientific research has been carried out on the laser-material interactions that generate a cut. This paper concentrates on the phenomena which give rise to a cyclic cutting event when a CO2 laser in conjunction with an oxygen jet is used to cut mild steel. The nature of the cut edge striation produced by the cyclic oxidation reaction is explained thoroughly and a possible oxidation cycle is postulated. It is demonstrated that the key to understanding the cyclic nature of the cutting event is the self-limiting nature of the oxidation of the steel in the cut zone.
Study on shaping spherical Poly Crystalline Diamond tool by Micro-electro-Discharge Machining and micro-grinding with the tool
Micro-electro-Discharge Machining (Micro-EDM) for shaping of a spherical tool made of Poly Crystalline Diamond (PCD) has been developed for the purpose of enabling a grinding process of a micro-free form surface on hard and brittle materials. Using this spherical PCD tool as a grinding tool, the surface roughness of a minute flat plane (90 × 70 µm), which was ground into tungsten carbide, has 28 nm Rz and 5 nm Ra. This paper describes the capabilities of spherical PCD tool grinding with the following results.