Introduction to Mechanics of Orthogonal Cutting - Metal Cutting Theory and Dynamometry

TL;DR

Mechanics of orthogonal cutting explains the primary and secondary shear zones, chip deformation, and various models used to understand the process.

Transcript

hello students my name is santosh kumar hv i am the course instructor for the subject machining sciences and tool design we are discussing module number one metal cutting theory and dynamometry in that we are discussing a topic mechanics of orthogonal cutting the various studies has been done and it is evident that mechanics of orthogonal cutting w... Read More

Key Insights

• 🐿️ Mechanics of orthogonal cutting involves primary and secondary shear zones, chip deformation, back chip roughness, and strain inhomogeneity.
• 🦾 Different models, such as the Ernst and Merchant model and the card model, are used to understand the mechanics of orthogonal cutting.
• ✈️ The Ernst and Merchant model emphasizes the concentration of shear at a single plane, while the card model envisions shear occurring layer by layer.

Questions & Answers

Q: What are the primary and secondary shear zones in orthogonal cutting?

In orthogonal cutting, the primary shear zone is where substantial deformation occurs, while the secondary shear zone experiences negligible deformation.

Q: Why is the back of the chip rough in orthogonal cutting?

The back of the chip is rough due to strain inhomogeneity, where some regions of the material deform more than others, resulting in a wavy surface.

Q: Are all steady-chained chips behavior consistent with the model in Figure A?

No, according to Ernst and Merchant, steady-chained chips do not always behave according to the model in Figure A, where shear is concentrated at a single plane.

Q: How does the card model explain shear in orthogonal cutting?

The card model suggests that shear occurs layer by layer, with each layer sliding over the other as the tool moves, analogous to cards sliding over each other.

Summary & Key Takeaways

• Mechanics of orthogonal cutting involves a primary shear zone, a secondary shear zone, uncut chip thickness, and cut chip thickness.

• Deformation occurs once the material nears the shear zone, with substantial deformation in the primary shear zone and negligible deformation in the secondary shear zone.

• The back of the chip is rough due to strain inhomogeneity, and the material exhibits negative strain hardening.