Dear all concerns,
I have some questions about cold extrusion process for medium carbon steel. My material is round bar. Diameter is around 35 – 50 mm. Total reduction area around 35 – 45%.
1. What are differences in technical detail if we compare only single and multi step while other parameters are the same such as material’s properties, total reduction’s ratio, initial and output shape, total force, ram speed, friction coefficient etc?
In my opinion, multi steps is better than single step because it has lower residual tensile stress after extrusion due to its has lower strain‘s rate.
2. If I found micro crack (not as big as Chevron) on centerline portion in round bar after extrusion.
2.1 How to solve this problem correctly? Currently, I have been modified lubrication (Phosphate film), increase extrusion step, decrease die‘s angle.
2.2 In case of micro-crack defect, my current ultrasonic cannot detect it. Are there other suitable tools can detect this kind of defect in process? I prefer for automatic detection machine because I have to inspect 100% of production part.
Thank you for your suggestions or direct me to the useful information source
I have some questions about cold extrusion process for medium carbon steel. My material is round bar. Diameter is around 35 – 50 mm. Total reduction area around 35 – 45%.
1. What are differences in technical detail if we compare only single and multi step while other parameters are the same such as material’s properties, total reduction’s ratio, initial and output shape, total force, ram speed, friction coefficient etc?
In my opinion, multi steps is better than single step because it has lower residual tensile stress after extrusion due to its has lower strain‘s rate.
2. If I found micro crack (not as big as Chevron) on centerline portion in round bar after extrusion.
2.1 How to solve this problem correctly? Currently, I have been modified lubrication (Phosphate film), increase extrusion step, decrease die‘s angle.
2.2 In case of micro-crack defect, my current ultrasonic cannot detect it. Are there other suitable tools can detect this kind of defect in process? I prefer for automatic detection machine because I have to inspect 100% of production part.
Thank you for your suggestions or direct me to the useful information source
