High performance peel grinding of steel shafts using coarse electroplated CBN grinding wheels

B Denkena,M Wilckens,A Krödel

doi:10.1007/s11740-021-01047-1

Abstract

Grinding is widely known for its low material removal rates and high surface quality. However, recent developments in production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than 300 µm. These superabrasive CBN-grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined with turning processes before hardening and finishing the work piece by grinding. However, the turning process can be eliminated by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper explores the limits of grinding wheels using grains with a size of B602 during soft and hard machining in comparison to conventional B252 grains. It is shown that the use of coarser grains leads to lower process forces, higher (tensile) residual stress and higher surface roughness. Residual stress and surface roughness are of less importance as these grains are to be used mainly in roughing operations with ensuing finishing operations for the required surface properties. Over all investigations, especially in hard machining, neither grain nor tool wear was observed for the B602 grains, whereas the B252 tool was severely clogged during the experiments. Additionally, the grinding force ratio indicates that the coarse grain tools have not yet reached their productivity limit as it increases over all investigated feeds. This indicates improving tool performance with lower amounts of rubbing for increasing feed rate during hard grinding and shows the potential for the industrial use of higher feed rates with larger grains.

Highlights

Increasing demand for quality and efficiency in production technologies creates high pressure to optimize machine tools, tools, and processes
With increasing numbers of grains throughout the contact area, the process forces are enhanced. This leads to lower process forces for larger abrasive grains as larger grains reduce the number of abrasive grains in the contact area
Since cubic boron nitride (CBN) grains beyond grain sizes d g > 300 μm have only recently been introduced, there has been no research into their performance

Summary

Introduction

Increasing demand for quality and efficiency in production technologies creates high pressure to optimize machine tools, tools, and processes. Geometrically undefined cutting with its significance for high-precision parts and high-quality surfaces needs to be constantly improved to meet the markets demands [1, 2]. High performance grinding with cutting speeds of vc > 80 m/s and depths of cut of a e > 0.3 mm instead focuses on high material removal rates [3]. Tawakoli [4] introduced the concept of High Efficiency Deep Grinding (HEDG) as a combination of deep-creep feed grinding with efficient high-rate grinding [5]. Further studies, including the work of Stephenson [6], Morgan [7], and Jin [8] investigated the industrial application of HEDG. The full scope of the processes applicability and its limits is, not fully explored

Methods

Results

Conclusion