material lines

[Daniele-san]

Bye to all,
I am naked on this band of the forum
I usually write on pro/engineer... and I don't handle molds
we always have problems with material joint lines (badly moustache) on details in abs (your jpg allego)
until we asked the molder the piece of white color no problem the "baffets" are almost invisible if not backlight instead requiring the piece printed in black abs aim is the "baffets" you see and then as, some client have noticed this "defect" and now rightly we have to find a solution.
would you know how to indicate a material that is well fluidized and that, at the same time it is aesthetically acceptable (the surface is shiny and should not be painted) and that the price is naturally low?

Thank you.
Hi.

 

[SHIREN]

Bye to all,
I am naked on this band of the forum
I usually write on pro/engineer... and I don't handle molds
we always have problems with material joint lines (badly moustache) on details in abs (your jpg allego)
until we asked the molder the piece of white color no problem the "baffets" are almost invisible if not backlight instead requiring the piece printed in black abs aim is the "baffets" you see and then as, some client have noticed this "defect" and now rightly we have to find a solution.
would you know how to indicate a material that is well fluidized and that, at the same time it is aesthetically acceptable (the surface is shiny and should not be painted) and that the price is naturally low?

Thank you.
Hi.

Hi.
from the jpeg you see little
if for moustache indicate the perimeter bavetta in the middle of the mold
I think you should intervene mechanically on it
if as you write you have a doubt about the used materials more or less fluid
test with a pa 6 or nylon
if it corresponds to the specific characteristics of the printed
but that manages the mold or does the injection know very well what to propose
Thank you very much

 

[Daniele-san]

Hi.
from the jpeg you see little
if for moustache indicate the perimeter bavetta in the middle of the mold
I think you should intervene mechanically on it
if as you write you have a doubt about the used materials more or less fluid
test with a pa 6 or nylon
if it corresponds to the specific characteristics of the printed
but that manages the mold or does the injection know very well what to propose
Thank you very much

Hi.
thanks for your intervention.
by "baffo" I mean the ruler that is created near each hole because of the material that fluidizing around the "pin" that creates the hole cools and does not fit firmly.
I hope I've been clear, so it's not about the bottom line due to the mold closure.
regarding the material, we are currently using abs.
pa6 or nylon are not accepted because not aesthetically acceptable.
the surface of the piece must be perfectly polished as part of a professional musical instrument.
Hi.

 

[Mocca]

Bye.
to evaluate solutions you also need to know other aspects such as mold temperature and especially injection points (where they are and how many are) responsible for your problem.
I before trying to make interventions on steel I would contact the suppliers of the injection system and propose to do a filling analysis (moldflow) evaluating the current situation and setting the pressure parameters (obviously to check directly) after which I would try to vary these parameters by looking for the ideal solution. if there are no solutions the next step will be to hypothesize a new injection system.
the details in abs are aesthetically the best but are "rognosis" to inject and, in this case many times more "attacks" are used in the figure.
Say hi.

 

[Dade73]

hello daniele, unfortunately also with an abs even high melt-flow you will struggle to avoid the moustache (welding of the material after each hole), mold about 1000 tons of various abs every year and the problem from you reported I see it daily.
you could try with pp omopolymer melt 50 and module and elastic module of at least 1700.
attention: excellent gloss, if the thicknesses are small becomes fragile at low temperatures, different laughs compared to the abs, lighter piece,......................
Hey, let me know.

 

[Daniele-san]

Bye.
to evaluate solutions you also need to know other aspects such as mold temperature and especially injection points (where they are and how many are) responsible for your problem.
I before trying to make interventions on steel I would contact the suppliers of the injection system and propose to do a filling analysis (moldflow) evaluating the current situation and setting the pressure parameters (obviously to check directly) after which I would try to vary these parameters by looking for the ideal solution. if there are no solutions the next step will be to hypothesize a new injection system.
the details in abs are aesthetically the best but are "rognosis" to inject and, in this case many times more "attacks" are used in the figure.
Say hi.

hello and thanks for your intervention,
the ns test moulder has made many but no has given positive results 8that is to make disappear the "baffi"
Would you have some free time to do me a filling analysis? :tongue:
if you place the file in iges or step format
4 injection points, and I'll tell you how I'll train you.
if you have other feedback are welcome
Thank you.
Hi.

 

[Daniele-san]

hello daniele, unfortunately also with an abs even high melt-flow you will struggle to avoid the moustache (welding of the material after each hole), mold about 1000 tons of various abs every year and the problem from you reported I see it daily.
you could try with pp omopolymer melt 50 and module and elastic module of at least 1700.
attention: excellent gloss, if the thicknesses are small becomes fragile at low temperatures, different laughs compared to the abs, lighter piece,......................
Hey, let me know.

from my mocca answer you can see the figure with injection points.
thickness is 2,3/2.5mm
probably the material change would be a great chance, which price range has this type of material?
Hi.
thanks for your intervention

 

[aiq]

Hi. .
that kind of problem I find it very much on the details made of materials with "literated" additives... or on the transparent details (in pc).
to me the moldists always sell them as "invitable". . .

Say hi.

 

[Dade73]

hi daniele, the polypropylene indicated, to date the purchase to 1.40euro/kg, against 1.90 of the abs, considers a further saving on the overall weight of the piece of about 10-15%.
I forgot to mention less scratch resistance than abs due to the lower elastic module of the material.(2500abs-1700pp)
from historical experience, black only scratches to look at it either with abs or pp or........ more.
Hi.

 

[Daniele-san]

Hi. .
that kind of problem I find it very much on the details made of materials with "literated" additives... or on the transparent details (in pc).
to me the moldists always sell them as "invitable". . .

Say hi.

I confirm on the "invitable" said by the moldists!!!

 

[Daniele-san]

hi daniele, the polypropylene indicated, to date the purchase to 1.40euro/kg, against 1.90 of the abs, considers a further saving on the overall weight of the piece of about 10-15%.
I forgot to mention less scratch resistance than abs due to the lower elastic module of the material.(2500abs-1700pp)
from historical experience, black only scratches to look at it either with abs or pp or........ more.
Hi.

thanks for the clarifications,
a question... .
considering that the mold exists and has always been used with abs, what about the withdrawal percentages? Does he behave the same way as the abs?

 

[Dade73]

As previously mentioned, the retreats change and also in an important way, the manualistic makes you consider a 0.5% withdrawal for abs, and a 2% for the pp, clearly all theoretical.
I recommend a test in the machine, as the percentages shown vary from both the materials used and the molding conditions, if you use a high module pp as recommended the gap on the retreats decreases; then so much good will in the hands of those who are in front of the press and the usual dose of ass.

 

[Daniele-san]

As previously mentioned, the retreats change and also in an important way, the manualistic makes you consider a 0.5% withdrawal for abs, and a 2% for the pp, clearly all theoretical.
I recommend a test in the machine, as the percentages shown vary from both the materials used and the molding conditions, if you use a high module pp as recommended the gap on the retreats decreases; then so much good will in the hands of those who are in front of the press and the usual dose of ass.

.

excuse one thing..just to have clarity..but the pp is not the material that is usually used to make dry or rubbing?
If it were so I would need a more "noble" material considering that it is a piece of a keyboard of a professional musical instrument :biggrin:

 

[Dade73]

dry and tinozze apart, with the pp you make an infinity of applications; the buckets are normally made with price material (second choice) given the poverty of the article and not homopolymer as recommended by me , but copolymer (more flexible, matt and with less scratch resistance.
in case the pp is very well painted (see car bumpers )

 

[Daniele-san]

dry and tinozze apart, with the pp you make an infinity of applications; the buckets are normally made with price material (second choice) given the poverty of the article and not homopolymer as recommended by me , but copolymer (more flexible, matt and with less scratch resistance.
in case the pp is very well painted (see car bumpers )

I don't think this material is useful for my application.
Anyway thanks for your intervention

 

[Daniele-san]

what do you think of mixing the already used abs with a material that makes it more fluid and therefore makes them avoid those unsighted lines of junction called "baffets"?
if you what could use? Does anyone have experience in alchemy like this?:biggrin:

 

[stang64]

what do you think of mixing the already used abs with a material that makes it more fluid and therefore makes them avoid those unsighted lines of junction called "baffets"?
if you what could use? Does anyone have experience in alchemy like this?:biggrin:

Good morning daniele-san,
If I may ask you a question, is the defect present on all holes or are there holes that do not have or have less defect than others? Do the far-off holes have more or less defects than those near the injections?
all previous tips are very useful and all well centered on the possible cause and remedy you should try but if your material has to be that in a mold thought and built only for that without being able to consider changing material, mold, cooling, injection and much more, I don't think you have many possibilities.
if the customer points out the defects that have always been present but first "invisible" an improvement could involve some tests (at least those with alternative materials) and others that I have read are almost obligatory.

for the defect mold/mass temperatures, material thicknesses, type of steel used, injection are parameters to be supervised and deserve tests, not to neglect the gases that prevent the welding of the molten material, are there gas vents in the areas of the defect? Does the defect always occur at the same point?

Hello good work.

 

[Vittorio]

I confirm on the "invitable" said by the moldists!!!

I don't want to ask a stupid question, but the piece to get has constant thickness where these "battles" occur if it wasn't so the cause could be this.
it would be interesting to have a section of fusion at the holes

 

[Daniele-san]

I don't want to ask a stupid question, but the piece to get has constant thickness where these "battles" occur if it wasn't so the cause could be this.
it would be interesting to have a section of fusion at the holes

Sorry the delay of the answer (I was abroad for work) the section of the piece is to constant thickness. If you need, I'll put the section.
Hi.