Stuart McAllister October 10, 2007 “Effect on cutting force in turning hardened tool steels with cubic boron nitride inserts.” Authors: Mohammad Robiul Hossan & Li Qian Journal of Materials Processing Technology Volume 191, Issues 1-3, 1 August 2007, Pages 274-278 Stuart McAllister October 10, 2007

Introduction A performance comparison of turning various hardened steels with CBN inserts is not available in literature. FEA results in terms of forces are presented for orthogonal high-speed machining of: AISI 52100 hardened bearing steel AISI H13 hot work tool steel AISI D2 cold work steel AISI 4340 low alloy steel

Introduction The following effects on forces were investigated: Cutting speed Feed Cutter Geometry Workpiece hardness FEA results were compared with the experimental results reported in the referenced literature.

Models & Design Principles AdvantEdge software used: To perform numerical simulations with FEA 2D Lagrangian FEA modeling software Models created: FEA model Machining process model Material properties model Friction model Detailed information on models in Ref. [10]

Models & Design Principles Fig. 1 shows the schematic of orthogonal cutting conditions used for the 2D finite element mesh. The cutting tool is characterized by rake angle, relief angle, and cutting edge radius. The process parameters include feed f, cutting speed V, and depth of cut (doc). (Fig. 1.) 

Models & Design Principles Table 1. material properties, heat treat process, application Material UTS YS E Heat Treat Process Application H13 1990 1650 210 Quench, annealing, stress relieving Die casting dies 52100 1640 1230 Quenched, harden Bearings D2 2940 2200 Harden Gages, long-run dies 4340 1300 1200 Quench, temper General application

Models & Design Principles Table 2. Cutting process parameters in numerical simulations Workpiece hardness 44, 48, 52, 58 HRC Workpiece material AISI 52100, D2, H13, AISI 4340 Tool insert CBN Depth of cut (mm) 0.2 Feed (mm) 0.15, 0.3, 0.45, 0.6 Cutting speed (m/min) 140, 180, 240 Rake angle (°) −5, −15, −25 Edge radius (mm) 0.02, 0.06, 0.1, 0.2 Relief angle (°) 6

Results Data on cutting forces is essential: For minimizing distortion of machine components, workpiece, fixture, and cutters. For selecting a machine and machine tool with adequate power. Forces arising from orthogonal cutting: Cutting Force – in direction of cutting speed Feed Force – normal to cutting speed

Results Forces do not change much with cutting speed within the recommended cutting speed range. Fig. 2. Effect of CS and workpiece material on cutting force. Fig. 3. Effect of CS and workpiece material on feed force.

Results Feed has the most significant effect on cutting and feed forces. Forces increase with the increase in feed due to an increase in chip load. Fig. 4. Effect of feed and material on cutting force. Fig. 5. Effect of feed and material on feed force.

Results Force increase as tool radius increases. Forces increase as rake angle decreases. Fig. 7. Effect of rake angle and tool material on cutting force. Fig. 6. Effect of tool edge radius and tool material on cutting force.

Results Force increases as hardness increases. Forces increase as depth of cut increases. Fig. 8. Effect of hardness and tool material on cutting force. Fig. 9. Effect of depth of cut on forces.

Conclusions Predicted cutting forces agree with available literature data with reasonable accuracy. Cutting force and feed force increase with increasing feed, tool edge radius, negative rake angle, and workpiece hardness. Feed force is a larger force component than cutting force in hard turning. Consistent with experimental and numerical results of other researchers.

Conclusions Under same turning conditions: AISI 4340 highest cutting force AISAS 52100 highest feed force AISI D2 lowest cutting and feed forces Further work should include: More experimental runs to verify conclusions Investigating temperature, shear angle, chip geometry, shear stress, plastic strain rate Using 3D FEA model simulations

Conclusions Industrial Use? Technical Advancement? A performance comparison of turning hardened steels with CBN inserts now available. Technical Advancement? No, but more information on hard turning available. Industries impacted? Those that perform hard machining with CBN inserts will have more data available to them.

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