principle of the process structure process modeling defects design for manufacturing (dfm)

Module 5c 1

Principle of the process

Structure

Process modeling

Defects / control

Design For Manufacturing (DFM)

Process variation

Module 5c 2

Shaping Processes For Plastics - Extrusion

Die configurations and extruded products

Extruded product depends on the shape of die

Solid profiles

Module 5c 3

Die configurations and extruded products

The main quality problem is related to die swell.

There are several methods to overcome the die swell

a. Increase die opening length

b. A draw operation follows the extrusion

c. For non-round shape, a correction is needed.

Desired shape

Correction

Module 5c 4

Die configurations and extruded products

Defects in Extrusion – melt fracture

Turbulence flow at the entrance of the die

Module 5c 5

Die configurations and extruded products

Defects in Extrusion – sharkskin or bambooing

Friction between die and extrudate

Module 5c 6

Principle of the process

Structure

Process modeling

Defects / control

Design For Manufacturing (DFM)

Process variation

Module 5c 7

Design For Manufacturing – Plastics Extrusion

Shrinkage is a root cause. In the figure below, there are three common types of problems

Module 5c 8

Design For Manufacturing – Plastics Extrusion

Module 5c 9

Design For Manufacturing – Plastics Extrusion

Module 5c 10

Design For Manufacturing – Plastics Extrusion

DFM guideline – wall thickness:

Module 5c 11

Design For Manufacturing – Plastics Extrusion

DFM guideline – wall thickness:

Module 5c 12

Design For Manufacturing – Plastics Extrusion

DFM guideline – wall thickness:

Module 5c 13

Design For Manufacturing – Plastics Extrusion

DFM guideline – sink marks:

Module 5c 14

Design For Manufacturing – Plastics Extrusion

DFM guideline – hole location:

Module 5c 15

Design For Manufacturing – Plastics Extrusion

DFM guideline – hole location: