thermal expansion and grip

[Meteor02]

good of. even today they turn me, defined a project the customer decides to take care directly of the mold.... Let's forget the fact that he paid me in advice almost as much as he would cost the mold, arrived the mold we go to put in the machine, we connect our beautiful control unit to the coolings we impose a temperature of 60° and the mold seizes (and should turn to 80°). I ask who is of the trade (magari tool ) how do you handle tolerance pins holes?
Are you going to the eye? do not know polymers and their operating temperatures? Do you directly remove the plug from the mold project without increasing it then maybe you work with a increased cutter? Recently all that enters the lab seems done by a miller at the 1st job on a mold... I take the thorns to increase them, subtract the increased thorns and insert the normalized thorns in the holes you as you manage this small detail that apparently is ignored by the majority of the toolists?

 

[TECNOMODEL]

but why do you have to increase the thorns? And what are the thorns for you?
Maybe you mean the columns? If so you make the hole as indicated by the builder of columns, you "plan" columns and bushings in the mold and everything works, just lubricate.
you make molds that work at 100/130° and column grip problems are not there.

 

[Meteor02]

but why do you have to increase the thorns? And what are the thorns for you?
Maybe you mean the columns? If so you make the hole as indicated by the builder of columns, you "plan" columns and bushings in the mold and everything works, just lubricate.
you make molds that work at 100/130° and column grip problems are not there.

I used the term they use in the lab. by plug I mean columns without bushing, such as extractors. in the specific case the extraction castle (which also moves the male) has been guided by 4 columns without bushings (y a porcade) that tend to grip, plus the extractors do not tend to grip, grip their own... I usually proceed as described above but I wondered how you do tools/frestors, for an extractor of 6 that hole do if the mold works with water "cold" 18° and that hole if it works at 110°? I usually calculate thermal expansion and proceed as I said maybe there's some faster system?

 

[TECNOMODEL]

never needed to increase the holes if the mold works hot.
I think the problem is another.
material of the mould, or an error in the positions of the holes that leads to an abnormal "cold".
for an extractor you make the classic hole in h7 and there are no problems, whether the mold works in "cold" or hot work.
in parentheses, no polymer in my memory is printed with such cold molds.

 

[Meteor02]

no polymer should be printed so cold but vague to explain to the production manager... the answer is the particular is not technical and so I have 10/15% more jokes (and go direct fridge). it seems strange to me, because the holes are made in h7 but the mold up to 30 ° works well as it heats more grip. with thermal gun the mold is having a uniform temperature. What do you mean by mold material? for the moment this problem happened to me both with ergal molds and with 2 in acc reclaimed all made by external suppliers. I have to go to production tomorrow to disassemble and verify the alignment of the holes but I do not explain why at low temperature it does not trouble. thanks to the delucidations, in fact drilling in h7 avoids me to increase the thorns taking away a lot of work I bang a little too (http://www.chimica-online.it/test-fisica/esercizi-dilatazione-termica.htmI've never had these problems, but apparently neither do you.

 

[rinato]

external question: is the mold very long? Could the thermal expansion at temp. of work be different between the different pieces and the inter axis of the extractors and relative holes of sliding?

 

[Meteor02]

the mold is about 800x500 I had also thought of a temperature difference in the various areas of the mold but with control with thermal gun the temperature is homogeneous. I noticed that the extractors don't turn and here I put the problem of tolerances. I have to go to the workshop tomorrow and disassemble everything and check the flow of every single element. an interactive day

 

[TECNOMODEL]

Perhaps the fact that it grips when it warms up is only a coincidence, grip after a certain time of work, which looks down also involves an increase in temperature.
It should be necessary to have the mould underhand in order to give a judgment, certain that on a 800x500 put the columns of the table without bushings
Whose project is it? I, given the problems, would bring it back to those who did it and find the solution.
the speech of the thermal expansion that reborn is not acceptable.
extractors run in a hole calibrated only in the mobile plate, in the table the hole has a game, usually, of 0.5.
verify that the holes are not tight, the extractor must flow well even dry.
if it flows with difficulty is probably that the cause of the grip.
if you can post some image of the mold, who knows that you can't understand something more.

 

[Meteor02]

Unfortunately the mold comes from the Bulgarian and because it needs production touches the boiling potato. . as I said the molded nn extractors rotate which makes me think that the hole is narrow. I'm going to disassemble everything and control one by one the scorings hoping that nn's wrong to align the holes.

 

[TECNOMODEL]

that not rolled up mold can fit us, as long as the head seat on the table is accurate and prevents you from turning.
I'd say the first thing to do is exactly what you said.

a curiosity, if you can say, the project of the mold was also done abroad?

 

[Meteor02]

here is optimized the project of the particular x make it "printable" according to the qualitative requirements of the customer. it has been defined the orientation of the piece and its closures modified the thicknesses, sforms defined the point of injection and made a fast simulation of injection. the maths and information were sent by the customer to the tool in Bulgarian that designed the mold according to the information received. I must say that the mold is also done well and with good finishes.
in the while I checked the whole and as I thought the holes were at minimum tolerance that allows fatigue the manual movement even of the single extra extractor the holes were not downloaded and I find a narrow hole of 240 mm deep. for the moment I solved by removing 0.1 on each extractor and column and the movement of the extraction castle turns out free. I will then have to download and alease the holes so as to be able to mount normalized spare parts.

 

[TECNOMODEL]

You took 0.1? Sure? Be assured.
If they haven't downloaded the holes, I think they're hard to run.
but how did they make a precise hole 240 mm long? What diameter are we talking about?

 

[rinato]

Perhaps the fact that it grips when it warms up is only a coincidence, grip after a certain time of work, which looks down also involves an increase in temperature.
It should be necessary to have the mould underhand in order to give a judgment, certain that on a 800x500 put the columns of the table without bushings
Whose project is it? I, given the problems, would bring it back to those who did it and find the solution.*The speech of thermal expansion that reborn is not acceptable. *extractors run in a hole calibrated only in the mobile plate, in the table the hole has a game, usually, of 0.5.
verify that the holes are not tight, the extractor must flow well even dry.
if it flows with difficulty is probably that the cause of the grip.
if you can post some image of the mold, who knows that you can't understand something more.

*ot patience technomodel: Is it not acceptable because I might be right and the mold is poor and spreads unacceptablely, or is it unacceptable the idea that can happen? As a precondition, I don't know that plastic molds are in sight and that castroneries are easy... and if yours is a rhmanzine, well come.

 

[TECNOMODEL]

No ramanzine, you jokes?
It is not acceptable as theory because the size of the pieces are similar, so the elongation is equal.
I try to explain myself better: you have a 1000-long mold, the stretching of steel is about 0.01 each temperature on one meter.
the extraction table is as long as the mold, the temperature will be the same as the plates, therefore the elongation is equal.
In addition you put that the holes of the extractors in the table are wider generally 0.5 mm, so any small expansion differences are compensated widely.
for me the problem is what indicated us meteor, narrow holes and without unloading.
if not gripper there would be no wonder.

 

[Meteor02]

At last the rogna is printing problem solved and fortunately no gag. the customer arrives at the end of the day to pick up the first pieces (because here you work calmly) I would have liked to post some photos but being a new article did not seem to me the case. with all this rush making a mold in Bulgarian really makes little sense and creates difficulties. Thanks so much for the support, technomodel the next molds I throw down try to make them with the drilling in h7 if you reduced the beat I owe you a beer.

 

[rinato]

ot: I have (I had) a customer who makes quotes x dies quits here, then goes from the Italian moldist moved in wool, and if he does not make the Chinese price (I believe less than 1/10 of our) not even to him from the job, while recognizing him the skills. but from the Chinese there is no...

 

[Meteor02]

Some Chinese mold happened to me a couple to throw just someone to fix and a perfect pair.
Now if you go to the cina you pay a medium sized mold 5000 euros, maybe you save to suff. x settle it in case of trouble, and at the worst you put little back. here the customer has made the project to an architect who has never heard of plastic molding, so pays the advice then goes to Bulgarian (where sure he has spared but nn so much) sends the mold in Italy (why nn print in Bulgarian?) this does not work and pay the firm machine + 2 people to disassemble the mold, the accommodation etc etc... I don't think it's a big deal. at least now he has withdrawn the first pieces and is pleased . I do not say that the Bulgarian has worked badly, everyone happens to have to make adjustment during the test molds, but with all this rush to complicate my life