Development of an EN8 Steel Stepped Rotor by a Novel Engraving Milling Technique

TL;DR

This paper introduces a new engraving milling technique to manufacture small EN8 steel rotors with high surface quality.

Contribution

A novel CNC engraving milling method is developed and validated for rotor fabrication with minimal surface roughness.

Findings

Feed and plunge feed were identified as the most influential parameters affecting surface quality.

The lowest average roughness achieved was 0.11 µm on the rotor blade surface.

FE-SEM micrographs confirmed uniform tooth profiles and burr formation at edges.

Abstract

The rotor or impeller is a rotational and key part of a pump and compressor. This article presents the detailed development process of a rotor of small size constructed from an EN8 steel cylindrical blank using a novel technique based on a computer numerical control engraving milling machine (CNC-EMM) equipped with a 4 mm tungsten carbide end mill cutter. We fabricated a total of twenty-eight stepped rotors following the Box–Behnken Design (BBD) DoE technique at fourteen distinct combinations of CNC-EMM variable parameters, namely rotational speed, feed, and plunge feed. Average roughness ‘Ra’, an important surface quality indicator, has been considered and presented in this article, as a quality measure for the fabricated rotors. Feed and plunge feed have been identified as the most influencing variable parameters as per an analysis of variance (ANOVA) test. The lowest average roughness value obtained by this process for the rotor blade was 0.11 µm. A micrograph obtained from a field-emission scanning electron microscope (FE-SEM) showed a uniform and accurate tooth profile along with burr formation at corner edges. This study claims to establish engraving milling as a viable alternative to other manufacturing processes used for rotor blades. The findings of this study are useful to scholars, engineers, and researchers who are exploring new ways to fabricate mechanical parts and components.

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