How is this molded PVC part made?

Postby soapscum » March 18th, 2013, 10:37 am


soapscum
 
Posts: 9
Joined: January 13th, 2008, 12:54 am
Hello All-
I wonder if anyone knows from experience how an object like this PVC hot water bottle is made?

It seems that the 'neck' is too narrow to pull a core out of a dip mold. Considering the opening on top it doesn't seem extrusion blow-molded... Are these injection molded in two separate halves and welded toegether?...or....
Attachments
url.jpg
url.jpg (5.13 KiB) Viewed 4406 times

Re: How is this molded PVC part made?

Postby Cyberdemon » March 18th, 2013, 5:58 pm

User avatar

Cyberdemon
full self-realization
full self-realization
 
Posts: 2787
Joined: February 7th, 2006, 11:51 pm
Location: New York
Usually these kinds of things are formed in sheets and then RF welded around the edges like a blister pack.

Re: How is this molded PVC part made?

Postby soapscum » March 18th, 2013, 7:01 pm


soapscum
 
Posts: 9
Joined: January 13th, 2008, 12:54 am
That makes sense- thank you for the input Cyber.

Re: How is this molded PVC part made?

Postby nxakt » March 19th, 2013, 7:00 am

User avatar

nxakt
full self-realization
full self-realization
 
Posts: 956
Joined: March 15th, 2010, 5:11 am
Location: Central Shanghai
Slush molded. Like rotomolding with liquid PVC that gels on the inside of a heated mold. Same as rubber duck or boots.

http://www.google.com/patents/US2974373.pdf

Re: How is this molded PVC part made?

Postby Dan Lewis » March 19th, 2013, 7:29 am

User avatar

Dan Lewis
step three
step three
 
Posts: 183
Joined: December 6th, 2005, 5:47 pm
+ 1 -- Slush Molded

Re: How is this molded PVC part made?

Postby Lmo » March 19th, 2013, 1:01 pm

User avatar

Lmo
Moderator
Moderator
 
Posts: 3849
Joined: January 20th, 2004, 5:29 pm
Location: Pismo Beach, CA
The "stopper" detail might be kind of hard to get with a welding operation.

hot water bottle 1.jpg
hot water bottle 1.jpg (30.68 KiB) Viewed 4152 times


another product (German)
hot water bottle 7.jpg
hot water bottle 7.jpg (20.35 KiB) Viewed 4144 times


hot water bottle 2.jpg
hot water bottle 2.jpg (36.57 KiB) Viewed 4152 times


But carefully check out this remarkable old image ... it's huge. But it's still an enigma... If there is a mandrel on the inside how do they get it out, and what forms the end detail that the stopper fits into...? In the top photo, it looks like there is a black insert for the stopper that is inserted into the vulcanizing mold, but that still leaves us with how is the interior formed.

Photo identified as B.F. Goodrich, 1939.
hot water bottle 4.jpg
Lew Morris
"It's what you discover, after you know it all, that counts." _ John Wooden

New to the boards? Please read before you post ->Discussion Boards Posting Standards

Re: How is this molded PVC part made?

Postby mo-i » March 19th, 2013, 1:31 pm

User avatar

mo-i
full self-realization
full self-realization
 
Posts: 1106
Joined: November 30th, 2004, 5:46 am
Location: Germany
The process might have changed over time. I don't think Sean Penn does the nightshift there, anymore.

mo-i
I am not young enough to know everything.
Oscar Wilde

Re: How is this molded PVC part made?

Postby Lmo » March 19th, 2013, 3:22 pm

User avatar

Lmo
Moderator
Moderator
 
Posts: 3849
Joined: January 20th, 2004, 5:29 pm
Location: Pismo Beach, CA
Knew that guy looked familiar... interesting old-school process shot though, don't you think?
Lew Morris
"It's what you discover, after you know it all, that counts." _ John Wooden

New to the boards? Please read before you post ->Discussion Boards Posting Standards

Re: How is this molded PVC part made?

Postby soapscum » March 19th, 2013, 8:09 pm


soapscum
 
Posts: 9
Joined: January 13th, 2008, 12:54 am
Oh wow that old-school process image is amazing! The resolution and quality of the photo when you click on it is great (got any more of those?!?)

You can clearly see the entire mandrel at the bottom of the image- with a few strips of rubber laid on it ready to go into the compression mold. I guess he pulls it off by hand.

Re: How is this molded PVC part made?

Postby mo-i » March 28th, 2013, 1:45 pm

User avatar

mo-i
full self-realization
full self-realization
 
Posts: 1106
Joined: November 30th, 2004, 5:46 am
Location: Germany
Okey, in the light of this thread being featured on the main page just in time for the easter holidays I took a more serious approach and delayed my return to the family for one more hour of research. After some deep digging I'v learned, that the German manufacturer of hot water bottles "fashy" takes pride in having "revolutionised" the manufacturing process to the use of "thermoplastic" materials instead of rubber in 1968.

In fact the process today will be a form of blowmoulding, the best hints can be found in this french patent filing from 1978:

- http://www.freepatentsonline.com/4169493.html

Today one can find some pictures of "hot water bottle mould" on Alibaba as expected:

Image

This as far as I could get without actualy visiting a plant. Sorry mates, still no clue on the Sean Penn time travel,
which is a much more involving matter, altogether.

Happy Easter (Holidays), everyone !

mo-i
I am not young enough to know everything.
Oscar Wilde


Return to materials and processes

©2014 Core77, Inc. All rights reserved
about | contact us | advertise | mailing list