Explicit dynamics Analysis of Machining with Planer

CHALLENGE: Machining with Planer

OBJECTIVE: to simulate the machining operation by using a planer and observe their behaviour at 2 different velocities

First, Explicit Dynamics module is loaded on Ansys Workbench and the following materials are assigned.

Materials Selected For Analysis:

Structural steel

Steel 1006 (Engineering Data> Explicit Materials)

The file containing the model is imported to Ansys SpaceClaim for verification. The geometry is as shown below:

The model is then loaded on Ansys Mechanical APDL for analysis.

Geometry: After the parts are renamed based on preference, ‘Rigid’ behavior is selected for the planer tool as it is not our concern for analysis. The workpiece behavior is kept as ‘Flexible’ and Steel 1006 material is assigned to it.

Connections: Since the default connections created by Ansys were bonded, they are deleted and not used for analysis.

Meshing: The cutting tool is complex geometry and the workpiece is a simple one. So a ‘Tetrahedron’ patch conforming method is applied to the cutting tool and the workpiece is meshed based on the number of divisions. For the workpiece, the 4 edges are selected using the edge filter and ‘Number of Divisions’ is chosen for the definition type. The resulting mesh is shown below.

Analysis Settings: An end time of 7.5E-004 is selected for the Explicit dynamics analysis. This is the time frame for which the solver should generate the result. All other values are kept as per default.

Boundary Conditions: During the machining operation, the workpiece has to remain fixed and the cutting tool moves over it in the x-direction. In accordance, a fixed support is applied to the bottom face of the workpiece. For the respective cases, velocity values are defined for the cutting tool in the X direction, keeping velocities in Y and Z direction to be zero.

Solution: The results selected for analysis are Equivalent Stress and Total Deformation. The User Defined Result for Temperature can be selected only after the solver generates a solution. It is done by clicking on Solution Information>Worksheet>Temperature (from Available Solution Quantities). The results are then evaluated and compared.

RESULTS:

Case 1: Cutting Tool Velocity= 20,000 mm/sec

Energy Conservation Graph:

Equivalent stress:

Total Deformation:

Temperature (User Defined Result)

Case 2: Cutting Tool Velocity= 15,000 mm/sec

Energy Conservation Graph:

Equivalent stress:

Total Deformation:

Temperature (User Defined Result)

COMPARING THE RESULTS:

	Equivalent stress Max (MPa)	Total Deformation Max (mm)	Temperature Max (deg C)
Case 1: 20,000mm/sec	676.75	29.259	376.95
Case 2: 15,000 mm/sec	675.12	23.16	363.51

INFERENCE:

1. While generating the solution for Case 2, i.e, velocity of 15,000mm/sec, the solver showed an error regarding high energy error. The solution was then generated by increasing the Maximum Energy Error from 0.1 to 0.2 in the Analysis Settings.
2. When the cutting tool velocity increases, the total deformation and temperature in the body increases due to increase in shearing action. Not much change is observed in Maximum equivalent stress for the two cases. However, as evident from the images, the stress experienced by the workpiece at the final position of planer tool is higher in case 2 i.e, when planer tool velocity is lower. This is because of residual stresses in the system due to incomplete planing operation.
3. It can be observed that when planer tool velocity is increased, the tool travels till the end of the workpiece and thus, shears more material. Increase in cutting velocity increases the Material Removal Rate (MRR) and reduces the chances of larger Built-Up Edge (BUE) formation. To increase productivity, from a manufacturing stand-point, the velocity of 20,000mm/sec is preferred.

ANIMATION:

Equivalent stress: https://youtu.be/XTjptKjjSZc

Total Deformation: https://youtu.be/Xl0W7Wx0clc

Temperature: https://youtu.be/L7ODfAGQ_co