Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old May 1st 19, 09:23 PM posted to rec.crafts.metalworking
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Default Springs in a Mold

Yesterday I had a customer request I add springs to a mold at the last
minute. (Literally at the last minute I had just sent him a screen shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them
He was talking about springs to help open the mold. I can't think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.

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Old May 1st 19, 09:27 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Aug 2012
Posts: 1,482
Default Springs in a Mold

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen

shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them. He
was talking about springs to help open the mold. I can't


** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.


  #3   Report Post  
Old May 2nd 19, 03:05 AM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Nov 2006
Posts: 12,540
Default Springs in a Mold

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen

shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them. He
was talking about springs to help open the mold. I can't


** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.


Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)

--
Ed Huntress
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Old May 2nd 19, 12:13 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Apr 2012
Posts: 321
Default Springs in a Mold

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen

shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them. He
was talking about springs to help open the mold. I can't


** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.


Seems like the mold with springs would be hard to hold closed, and
would likely leak. I've never cast baits, just bullets and sinkers.

Pete Keillor
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Old May 2nd 19, 07:53 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Aug 2012
Posts: 1,482
Default Springs in a Mold

"Ed Huntress" wrote in message
...

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen

shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them. He
was talking about springs to help open the mold. I can't


** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.


Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the molding
from its weight alone. This customer also wants some ABS molds down the
road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for various
things. Candy molds, resin casting molds, etc. Molds to make molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless it’s a speed vise I
suspect it would be better to attach the mold to the vise jaws just like you
do on a hydraulic clamping system on a bigger injection machine. Opening
the vise opens the mold. I figured out how I would do it anyway, and I will
make the springs easily removable. Then if he decides they are more trouble
than they are worth he can just popped them out and pitch them.



  #6   Report Post  
Old May 2nd 19, 08:37 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Nov 2006
Posts: 12,540
Default Springs in a Mold

On Thu, 2 May 2019 11:53:04 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
.. .

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen

shot
of the cut simulation and was getting ready to take it to the machine.)

Other than the irritation and disruption of last minute changes on fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of them. He
was talking about springs to help open the mold. I can't


** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original design,
never answered if he had seen that before, but he did specify he wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with opening
the mold? I visualize them in the types of molds I make and I just see
them being an encumbrance.


Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the molding
from its weight alone. This customer also wants some ABS molds down the
road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for various
things. Candy molds, resin casting molds, etc. Molds to make molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless its a speed vise I
suspect it would be better to attach the mold to the vise jaws just like you
do on a hydraulic clamping system on a bigger injection machine. Opening
the vise opens the mold. I figured out how I would do it anyway, and I will
make the springs easily removable. Then if he decides they are more trouble
than they are worth he can just popped them out and pitch them.


When you shop for mold springs (they're still made by several
companies, as I learned when I Google-checked for my mental health and
declining memory), you'll note there are round-wire springs and
square-wire springs. Square wire is preffered; They're stronger and
can fit in a slightly tighter space.

--
Ed Huntress
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Old May 2nd 19, 11:02 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Aug 2012
Posts: 1,482
Default Springs in a Mold


On 5/2/2019 12:37 PM, Ed Huntress wrote:
On Thu, 2 May 2019 11:53:04 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
...

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen
shot
of the cut simulation and was getting ready to take it to the

machine.)

Other than the irritation and disruption of last minute changes on

fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of

them. He
was talking about springs to help open the mold. I can't

** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For

most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic

press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would

delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original

design,
never answered if he had seen that before, but he did specify he

wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with

opening
the mold? I visualize them in the types of molds I make and I

just see
them being an encumbrance.


Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody

is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a

handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold

silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the

molding
from its weight alone. This customer also wants some ABS molds down

the road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for

various
things. Candy molds, resin casting molds, etc. Molds to make

molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless it’s a speed vise I
suspect it would be better to attach the mold to the vise jaws just

like you
do on a hydraulic clamping system on a bigger injection machine.

Opening
the vise opens the mold. I figured out how I would do it anyway,

and I will
make the springs easily removable. Then if he decides they are more

trouble
than they are worth he can just popped them out and pitch them.


When you shop for mold springs (they're still made by several
companies, as I learned when I Google-checked for my mental health and
declining memory), you'll note there are round-wire springs and
square-wire springs. Square wire is preffered; They're stronger and
can fit in a slightly tighter space.


Since its new to me I figured I'd just use springs from my junk
collection and measure the force of the springs. Then order springs to
suit after that. I set up a little jig a while back to measure travel
of springs under weight on a platform for calculating spring force. I
was doing some airgun modifications. Its a pretty simple tool and easy
to make.

I never would have thought to look for "mold springs" or "square mold
springs." Thanks.

Since there is some heat in when injecting thermo plastics I was
concerned about spring life.
  #8   Report Post  
Old May 3rd 19, 03:49 AM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Nov 2006
Posts: 12,540
Default Springs in a Mold

On Thu, 2 May 2019 15:02:46 -0700, Bob La Londe
wrote:


On 5/2/2019 12:37 PM, Ed Huntress wrote:
On Thu, 2 May 2019 11:53:04 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
...

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen
shot
of the cut simulation and was getting ready to take it to the

machine.)

Other than the irritation and disruption of last minute changes on

fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of

them. He
was talking about springs to help open the mold. I can't

** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For

most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic

press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would

delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original

design,
never answered if he had seen that before, but he did specify he

wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with

opening
the mold? I visualize them in the types of molds I make and I

just see
them being an encumbrance.

Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody

is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a

handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold

silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the

molding
from its weight alone. This customer also wants some ABS molds down

the road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for

various
things. Candy molds, resin casting molds, etc. Molds to make

molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless its a speed vise I
suspect it would be better to attach the mold to the vise jaws just

like you
do on a hydraulic clamping system on a bigger injection machine.

Opening
the vise opens the mold. I figured out how I would do it anyway,

and I will
make the springs easily removable. Then if he decides they are more

trouble
than they are worth he can just popped them out and pitch them.


When you shop for mold springs (they're still made by several
companies, as I learned when I Google-checked for my mental health and
declining memory), you'll note there are round-wire springs and
square-wire springs. Square wire is preffered; They're stronger and
can fit in a slightly tighter space.


Since its new to me I figured I'd just use springs from my junk
collection and measure the force of the springs. Then order springs to
suit after that. I set up a little jig a while back to measure travel
of springs under weight on a platform for calculating spring force. I
was doing some airgun modifications. Its a pretty simple tool and easy
to make.

I never would have thought to look for "mold springs" or "square mold
springs." Thanks.

Since there is some heat in when injecting thermo plastics I was
concerned about spring life.


I'll bet that heat is a consideration in applying mold springs. In the
end, you'll probably want to get some made for the job.

--
Ed Huntress
  #9   Report Post  
Old May 4th 19, 01:28 AM posted to rec.crafts.metalworking
external usenet poster
 
First recorded activity by DIYBanter: Aug 2012
Posts: 1,482
Default Springs in a Mold

On 5/2/2019 7:49 PM, Ed Huntress wrote:
On Thu, 2 May 2019 15:02:46 -0700, Bob La Londe
wrote:


On 5/2/2019 12:37 PM, Ed Huntress wrote:
On Thu, 2 May 2019 11:53:04 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
...

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen
shot
of the cut simulation and was getting ready to take it to the

machine.)

Other than the irritation and disruption of last minute changes on

fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of

them. He
was talking about springs to help open the mold. I can't

** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For

most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic

press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would

delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original

design,
never answered if he had seen that before, but he did specify he

wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with

opening
the mold? I visualize them in the types of molds I make and I

just see
them being an encumbrance.

Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody

is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a

handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold

silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the

molding
from its weight alone. This customer also wants some ABS molds down

the road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for

various
things. Candy molds, resin casting molds, etc. Molds to make

molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless it’s a speed vise I
suspect it would be better to attach the mold to the vise jaws just

like you
do on a hydraulic clamping system on a bigger injection machine.

Opening
the vise opens the mold. I figured out how I would do it anyway,

and I will
make the springs easily removable. Then if he decides they are more

trouble
than they are worth he can just popped them out and pitch them.

When you shop for mold springs (they're still made by several
companies, as I learned when I Google-checked for my mental health and
declining memory), you'll note there are round-wire springs and
square-wire springs. Square wire is preffered; They're stronger and
can fit in a slightly tighter space.


Since its new to me I figured I'd just use springs from my junk
collection and measure the force of the springs. Then order springs to
suit after that. I set up a little jig a while back to measure travel
of springs under weight on a platform for calculating spring force. I
was doing some airgun modifications. Its a pretty simple tool and easy
to make.

I never would have thought to look for "mold springs" or "square mold
springs." Thanks.

Since there is some heat in when injecting thermo plastics I was
concerned about spring life.


I'll bet that heat is a consideration in applying mold springs. In the
end, you'll probably want to get some made for the job.


Just for the heck of it I searched on the McMaster Carr website for
"mold springs" and they produced several results for "die springs"
including long section that can be cut to length as needed.
  #10   Report Post  
Old May 4th 19, 02:48 AM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Nov 2006
Posts: 12,540
Default Springs in a Mold

On Fri, 3 May 2019 17:28:55 -0700, Bob La Londe
wrote:

On 5/2/2019 7:49 PM, Ed Huntress wrote:
On Thu, 2 May 2019 15:02:46 -0700, Bob La Londe
wrote:


On 5/2/2019 12:37 PM, Ed Huntress wrote:
On Thu, 2 May 2019 11:53:04 -0700, "Bob La Londe"
wrote:

"Ed Huntress" wrote in message
...

On Wed, 1 May 2019 13:27:47 -0700, Bob La Londe
wrote:

Typo corrected below ***

On 5/1/2019 1:23 PM, Bob La Londe wrote: Yesterday I had a customer
request I add springs to a mold at the last
minute. (Literally at the last minute. I had just sent him a screen
shot
of the cut simulation and was getting ready to take it to the
machine.)

Other than the irritation and disruption of last minute changes on
fully
approved designs I'm not against doing it, but I don't think I've seen
that before. Now, I am not talking about ejector pins. I am familiar
with them, although the types of molds I make don't make use of
them. He
was talking about springs to help open the mold. I can't

** help but

think about
how I would do it, but I'm not sure its really of any use. Most hand
injected or hand poured molds are just easily pried apart. For
most of
what I do the media doesn't not have any significant bond to the mold
material and a release agent is not even used. Sure for some resins a
release agent is used, but again the mold opens fairly easily.

I don't think I'd use springs in any automated operation either. The
molds halves are just attached to the platens (?) of the hydraulic
press
portion of the injection machine. Hydraulic pressure pushes them
together and hydraulic pressure pulls them apart. What purpose would
springs serve?

I explained that adding a new feature at the last minute would
delay his
order and increase the cost. I also asked him if he had seen that
before and how it was used. He decided to go with the original
design,
never answered if he had seen that before, but he did specify he
wanted
that on future molds. Ok... more money for me I guess.

Have any of you seen a mold with springs built in to assist with
opening
the mold? I visualize them in the types of molds I make and I
just see
them being an encumbrance.

Bob, return springs for injectors and springs to open molds were
common not many years ago, when I was covering the field. The
mold-opening springs were being replaced by hydraulics at the time so
maybe they're gone now.

But I'm not sure what kind of molding you're doing. Injection molding?
If so, there's plenty of design data around for mold springs. I just
did a quick check on Google to make sure I haven't lost my mind - yet.
d8-)


My work is 99.99% cold low pressure (100 psi peak maybe if somebody
is ham
handed and puts their body weight on the injector) injection or low temp
(under 1000F) casting molds. Split about 50:50. I have done a
handful of
"high pressure" molds for ABS and other thermo plastics, but its not my
primary market. This particular one was for a low pressure cold
silicone
media. They also have a very heavy steel core which is removed after
injection media has fully cured. The core will probably eject the
molding
from its weight alone. This customer also wants some ABS molds down
the road, so maybe that's what he was thinking of.

I sometimes make master molds from which I make silicone molds for
various
things. Candy molds, resin casting molds, etc. Molds to make
molds, but
this is my first mold to make a final product from silicone.

Ok. I guess I could see using springs in a mold that is used in a vise
under a table top injection machine. Still unless its a speed vise I
suspect it would be better to attach the mold to the vise jaws just
like you
do on a hydraulic clamping system on a bigger injection machine.
Opening
the vise opens the mold. I figured out how I would do it anyway,
and I will
make the springs easily removable. Then if he decides they are more
trouble
than they are worth he can just popped them out and pitch them.

When you shop for mold springs (they're still made by several
companies, as I learned when I Google-checked for my mental health and
declining memory), you'll note there are round-wire springs and
square-wire springs. Square wire is preffered; They're stronger and
can fit in a slightly tighter space.


Since its new to me I figured I'd just use springs from my junk
collection and measure the force of the springs. Then order springs to
suit after that. I set up a little jig a while back to measure travel
of springs under weight on a platform for calculating spring force. I
was doing some airgun modifications. Its a pretty simple tool and easy
to make.

I never would have thought to look for "mold springs" or "square mold
springs." Thanks.

Since there is some heat in when injecting thermo plastics I was
concerned about spring life.


I'll bet that heat is a consideration in applying mold springs. In the
end, you'll probably want to get some made for the job.


Just for the heck of it I searched on the McMaster Carr website for
"mold springs" and they produced several results for "die springs"
including long section that can be cut to length as needed.


Yeah, that rings a bell. It's been a long time since I covered
toolmaking, so I'm vague on details. But I remember that the suppliers
sold them color-coded for spring rate; round or square wire; and other
options for which my memory fails me.

Have you looked at any of the mold-design books, Bob? I have one here
somewhere (probably boxed, in the attic, or I'd look it up), and I
distinctly remember that springs were a subject covered.

Good luck. If you do a little research, I think you'll find that the
uses of springs in molds has been well worked out.

--
Ed Huntress


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