analysis of die breakage causes

MTD SA, Route de Muraz 16, CH 3960 Sierre, Switzerland

[email protected] / www.m-td.com

ANALYSIS OF DIE BREAKAGE CAUSES

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MTD SA, Route de Muraz 16, CH 3960 Sierre,Switzerland [email protected] / www.m-td.com

The customer designed a die for an aluminium profile in alloy 7108.

The die broke on the press and the customer wants to know the root causes of breakage

THE SITUATION





We realize a complete extrusion simulation:

Aluminium flow and pressure

Aluminium and die temperature

Die stresses and deformations

THE M-TD SERVICE PROVIDED





INPUT DATA

To realize the analysis we received from customer the necessary data: 3D CAD models of the die

2D drawing of the ring and the bolster

Process parameters

THE M-TD SERVICE : ANALYSIS





ANALYSIS PREPARATION

1. Adjust model the die including addition of ring and bolster

2. Modeling the aluminium by subtraction of die

TIME SPENT : 45 minutes

THE M-TD SERVICE : ANALYSIS OF FIRST VERSION





ANALYSIS PREPARATION

3. Mesh parameter preparation

4. Meshing the aluminum and the die

TIME SPENT : 1h 15






ANALYSIS CALCULATION

We proceed in 4 steps to run the complete analysis:

1. Run flow and pressure

2. Run alloy and die temperature

3. Run die stresses

4. Run displacement

TIME SPENT : 2h






1. Profile velocity:

THE M-TD SERVICE : RESULTS ANALYSIS

The flow is globally well balanced Adjustments are need on bearing length





2. Pressure:


Pressure is high Press parameters must be adjusted to reduce it





3. Aluminium temperature:


Temperature is ok for this alloy.





4. die temperature:






5. Die stress:


Crack lines observed on the die appear clearly on the simulation results





5. Die stress:

THE M-TD SERVICE : RESUTLS ANALYSIS

The different cuts has shown that tress into bridges are too high (more than 900 Mpa). Stress is concentrated at the junction of the mandrel core and bridge due to shear effect.





6. die displacement:


Z movement of mandrel cores is around 0.55mm.

Shearing effect : The mandrel core is moving higher than bridges





6. die deformation:


Movement of mandrel core appear clearly





The simulation has reflected the results observed on the press

Die design needed be reviewed to reduce shear effect

Our advices were to modify bridges shape:

Increase the depth

Enlarge the top of the bridge

Take care about grinding

Increase aluminium temperature

THE M-TD SERVICE : CONCLUSION




analysis of die breakage causes

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