Evaluating the influences of the cutting parameters on the surface roughness and form errors in 4-axis milling of thin-walled free-form parts of AISI H13 steel

Abstract

The machining of complex surfaces such as those present in rotors, impeller blades, thin-walled parts among other engineering components has been commonly carried out in multi-axis CNC machines programmed by CAD/CAM software. Even with a significant aid of the CAD/CAM systems, the users are responsible for defining an optimal set of cutting parameters, relying on their practical knowledge. This task gets harder when thin-walled parts have to be milled, because besides the problems caused by the limit of rigidity of the cutting tool, there is also the limit of rigidity of the thin-walled parts. Few works can be found on current literature concerning this issue. Then, the current work aims to analyse the influences of the cutting parameters: feed per tooth (f z); radial depth of cut (a e); and cutting direction (up and down milling), on the form errors and surface roughness of thin-walled parts manufactured by 4-axis milling using AISI H13 steel. The results show that the cutting direction (up/down milling) was the major variable to affect the form errors. Down milling left more than 0.2 mm of material on the machined part. On the opposite, up milling removes up to 0.2 mm more material than it should be. ANOVA shows that the influence of the f z on the form error is slightly higher than a e influence. In extreme cases, it can be about 1.5 times more influent than a e. Down milling and the highest values of a e and f z tested proved to be a good set of cutting conditions for milling free-form thin-walled parts, because with these conditions a good surface roughness, a positive form error and higher productivity were obtained.

Analysis of the Machining Process of Titanium Ti6Al-4V Parts Manufactured by Wire Arc Additive Manufacturing (WAAM)

“…Although down milling usually gives a better surface quality, in this case, the up-milling strategy led to a lower Ra value. This particular effect was also observed in a previous study carried out by Oliveira et al [27]. They conclude that the origin of this result could be linked to the fact that the most vulnerable element in terms of vibration is the part and not the cutting tool.…”

Deflection Error Prediction and Minimization in 5-Axis Milling Operations of Thin-Walled Impeller Blades

“…The effects of the cutting tool parameters such as tool helix angle to the accuracy and quality of machined parts is studied by Bolar and Joshi [10] in order to increase accuracy of machined parts by using the milling operations. Effects of machining parameters to the surface roughness and form errors in 4-axis milling of thin-walled free-form parts is studied by de Oliveira et al [11]to reduce the deflection errors in the machined parts.…”

Thin-Wall Machining of Light Alloys: A Review of Models and Industrial Approaches

“…Cutting parameters for thin-wall machining are also studied from an experimental and statistical point of view [13,89,90,91,92,93,94]. Researchers developed experimental models based on ANOVA results by analyzing how the cutting parameters and machining strategies affect the roughness and the dimensional error.…”