Conduction-Based Thermally Assisted Micromilling Process for Cutting Difficult-to-Machine Materials

Timo Platt,Alexander Meijer,Dirk Biermann

doi:10.3390/jmmp4020034

Timo Platt, Alexander Meijer + Show 1 more

Open Access

https://doi.org/10.3390/jmmp4020034

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Abstract

The increasing demand for complex and wear-resistant forming tools made of difficult-to-machine materials requires efficient manufacturing processes. In terms of high-strength materials; highly suitable processes such as micromilling are limited in their potential due to the increased tool loads and the resulting tool wear. This promotes hybrid manufacturing processes that offer approaches to increase the performance. In this paper; conduction-based thermally assisted micromilling using a prototype device to homogeneously heat the entire workpiece is investigated. By varying the workpiece temperature by 20 °C < TW < 500 °C; a highly durable high-speed steel (HSS) AISI M3:2 (63 HRC) and a hot-work steel (HWS) AISI H11 (53 HRC) were machined using PVD-TiAlN coated micro-end milling tools (d = 1 mm). The influence of the workpiece temperature on central process conditions; such as tool wear and achievable surface quality; are determined. As expected; the temporary thermal softening of the materials leads to a reduction in the cutting forces and; thus; in the resulting tool wear for specific configurations of the thermal assistance. While only minor effects are detected regarding the surface topography; a significant reduction in the burr height is achieved.

Highlights

Innovative production technologies such as sheet-bulk metal forming, a process which is developed and investigated in the Collaborative Research Centre Transregio 73 (DFG SFB/TR 73), often require dies with complex geometries and tailored surfaces made of hard and wear-resistant materials
Difficult-to-machine materials reduce the potential of micromilling with regard to process forces and tool wear, which can lead to poor machining quality and efficiency [5,6,7]
A workpiece temperature of TW = 260 ◦C led to a significant reduction in process forces compared to a machining at reference temperature TW,Ref = 20 ◦C

Summary

Introduction

Innovative production technologies such as sheet-bulk metal forming, a process which is developed and investigated in the Collaborative Research Centre Transregio 73 (DFG SFB/TR 73), often require dies with complex geometries and tailored surfaces made of hard and wear-resistant materials. This increases the need for suitable machining processes to efficiently produce complex dies with secondary shape elements, such as tooth cavities, with relatively high accuracy [1,2]. The results have been transferred to the thermally assisted micromilling of a HWS AISI H11 (52 HRC)

Experimental Setup

Results and Discussion

Tool Wear

Surface Roughness

Burr Formation

Conclusions