“Effect on cutting force in turning hardened tool steels with cubic boron nitride inserts.”

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

2. 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

3. 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.

4. 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]

5. 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.) 

6. Models & Design Principles • Table 1. material properties, heat treat process, application

7. Models & Design Principles • Table 2. Cutting process parameters in numerical simulations

8. 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

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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

15. Conclusions • Industrial Use? • 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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