A little too late, but here we go. There are several effects. The most significant are: 1) Lines of molten plastic where the flow of melt has a different velocity. A good place to search for is the sprue. That's why engineers are very careful when designing the mold, especialy in the case of transparent parts; 2) Due to the friction of several molten particles, one could find burnt or degradated material on the surface of the part that is being produced. Again, this is all due to the friction and self heating of the melt in the screw. Actually the heaters on the screw are used only to regulate the end temperature of the zones on/in the screw. The majority of the heat in the melt comes from friction. Why's that - I don't know if there's a theoretical answer. And finally due to the different velocity of the flow, you could find weld lines on the surface. Where to find them? Well, near a cavity or an opening on the part, but not only. This is again due to difference in the temperature of the material. Of course the line of weld is likely the most probable place to break or crack if a certain force is applied
Can this techniques be used for extrusion machines? For example, instead of a conical screw, I use a conical barrel to make turbulence in the plastic?. Example. My screw is 1 inch. The plastic flows through the pipe with the band heaters, and then the pipe opens up to one and a half inches and back down to 1 inch with a heater also on the larger section. Reason is, I am building a diy extrusion machine and the cost of a conical screw is our of my budget.
Yes, and no. Laminar flow assumes that all molecules are oriented and flowing parallel to one another. True laminar flow in plastic melt flow is unlikely.
@@MastaSquidge Fluid molecules can be influenced by air or voids throughout the flow, unlike plastic. Both are moving in the same direction in parallel, so technically it's the same.
@@MastaSquidge Being a plastics process engineer for 42 years, I and other engineers always called it a laminar flow through the barrel. To cool a mold quicker turbulent flows were more efficient than laminar flows. Hence the reasons for differences in molding terminologies. We had to differentiate the two flows.
@plasticman3952 that's understandable for practical purposes/local jargon, but I don't see any significant value to referring to it that way over just calling it fountain flow. Especially as that's the formal standard.
Great video, thank you for providing it.
good video..that is usefull for me,
What is the significant effect of a different flow speed to the molded product?
#Arvin Tiongco #Arvin Tiongco What is the significant effect of a different flow speed to the molded product? @. Artisan Mould co.,ltd @Arvin Tiongco
A little too late, but here we go. There are several effects. The most significant are: 1) Lines of molten plastic where the flow of melt has a different velocity. A good place to search for is the sprue. That's why engineers are very careful when designing the mold, especialy in the case of transparent parts; 2) Due to the friction of several molten particles, one could find burnt or degradated material on the surface of the part that is being produced. Again, this is all due to the friction and self heating of the melt in the screw. Actually the heaters on the screw are used only to regulate the end temperature of the zones on/in the screw. The majority of the heat in the melt comes from friction. Why's that - I don't know if there's a theoretical answer. And finally due to the different velocity of the flow, you could find weld lines on the surface. Where to find them? Well, near a cavity or an opening on the part, but not only. This is again due to difference in the temperature of the material. Of course the line of weld is likely the most probable place to break or crack if a certain force is applied
Sir can can you say what is Flux rate in porcheson
This is true for unidirectional flow and when the flow front is not expanding or contracting.
Can this techniques be used for extrusion machines? For example, instead of a conical screw, I use a conical barrel to make turbulence in the plastic?. Example. My screw is 1 inch. The plastic flows through the pipe with the band heaters, and then the pipe opens up to one and a half inches and back down to 1 inch with a heater also on the larger section. Reason is, I am building a diy extrusion machine and the cost of a conical screw is our of my budget.
#Arvin Tiongco What is the significant effect of a different flow speed to the molded product? @. Artisan Mould co.,ltd
#. Artisan Mould co.,ltd good video..that is usefull for me, @Arvin Tiongco
It's called laminar flow
Yes, and no. Laminar flow assumes that all molecules are oriented and flowing parallel to one another. True laminar flow in plastic melt flow is unlikely.
@@MastaSquidge Fluid molecules can be influenced by air or voids throughout the flow, unlike plastic. Both are moving in the same direction in parallel, so technically it's the same.
Except not, but ok. The video literally shows that the plastic in the center is still turbulent.
@@MastaSquidge Being a plastics process engineer for 42 years, I and other engineers always called it a laminar flow through the barrel. To cool a mold quicker turbulent flows were more efficient than laminar flows. Hence the reasons for differences in molding terminologies. We had to differentiate the two flows.
@plasticman3952 that's understandable for practical purposes/local jargon, but I don't see any significant value to referring to it that way over just calling it fountain flow. Especially as that's the formal standard.
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