Check out these injection moulding images:
Random International: Rain Room
Image by Jon’sTripBook
Olympus µ[mju:]-II
Kodak Ultramax 400
Injection-moulded protractor
Image by CORE-Materials
DoITPoMS, University of Cambridge
The colours in the image are the result of birefringence and relate to the residual strain in the polystyrene. The pattern of strain is indicative of the flow of material during the injection process and it highlights the injection point (at 152 degrees on the outer scale), and two ‘weld lines’ (at 338 and on the central bar) where two distinct flows of material meet. The weld line is a common point of failure because there is limited intermixing of the two fronts during the time allowed.
System
Polystyrene (PS)
Composition
Not specified
Reaction
Processing
Polystyrene was injected into a mould from a single point and has flowed round the component to meet at two noticeable ‘weld lines’
Applications
Polystyrene is hard and inexpensive and its use is very widespread. CD cases and clear plastic cups are common examples. Domestic appliance casings are also typically made from PS
Sample preparation
Technique
Cross-polarised light microscopy
Contributor
J A Curran
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
View micrograph in DoITPoMS website
Injection-moulded protractor
Image by CORE-Materials
DoITPoMS, University of Cambridge
The colours in the image are the result of birefringence and relate to the residual strain in the polystyrene. The pattern of strain is indicative of the flow of material during the injection process and it highlights a ‘weld line’ where two distinct flows of material meet. The weld line is a common point of failure because there is limited intermixing of the two fronts during the time allowed.
System
Polystyrene (PS)
Composition
Not specified
Reaction
Processing
Polystyrene was injected into a mould from a single point and has flowed round the component to meet at a noticeable ‘weld line’
Applications
Polystyrene is hard and inexpensive and its use is very widespread. CD cases and clear plastic cups are common examples. Domestic appliance casings are also typically made from PS
Sample preparation
Technique
Cross-polarised light microscopy
Contributor
J A Curran
Organisation
Department of Materials Science and Metallurgy, University of Cambridge