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Do inserts need to be preheated to tooling temperature in injection molding?
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Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
Do inserts need to be preheated to tooling temperature in injection molding?
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Do inserts need to be preheated to tooling temperature in injection molding?


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  Post Number #1  
Old 11th April 2008, 10:28 AM
sadhusong

 
 
Total Posts: 39
Question Do inserts need to be preheated to tooling temperature in injection molding?

Hello all
as instructed injection with serts such as shaft, the shaft should be pre-heated as tooling temperature,i would like to get help for theory of this and is this mandatory?

and i found some supplier does not do this.

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  Post Number #2  
Old 11th April 2008, 10:32 AM
Phil Fields

 
 
Total Posts: 376
Re: inserts injection

My past experience in injection molding (15 yrs ago), we never pre-heated inserts.

Phil
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  Post Number #3  
Old 16th April 2008, 01:42 PM
john

 
 
Total Posts: 15
Re: Do inserts need to be preheated to tooling temperature in injection molding?

I have been insert molding for over 30 years and the only time we pre heated inserts was on a small nylon over steel insert part that was machined afterward. The rational for this was to keep the bubbles / shrink voids out of the part so it could be machined smoothly with no pits.
  Post Number #4  
Old 16th April 2008, 02:21 PM
Randy's Avatar
Randy

 
 
Total Posts: 8,560
Re: Do inserts need to be preheated to tooling temperature in injection molding?

What do your engineers say?
  Post Number #5  
Old 18th April 2008, 10:15 AM
Edward Nell

 
 
Total Posts: 2
Re: Do inserts need to be preheated to tooling temperature in injection molding?

Quote:
In Reply to Parent Post by sadhusong View Post

Hello all
as instructed injection with serts such as shaft, the shaft should be pre-heated as tooling temperature,i would like to get help for theory of this and is this mandatory?

and i found some supplier does not do this.
If you are doing rubber to metal/plastic injection moulding, then preheating will start the adhessive to start reacting before you have had time to inject the product. That would lead to failures
  Post Number #6  
Old 20th April 2008, 08:39 AM
bgwiehle

 
 
Total Posts: 154
Re: Do inserts need to be preheated to tooling temperature in injection molding?

Quote:
In Reply to Parent Post by Edward Nell View Post

If you are doing rubber to metal/plastic injection moulding, then preheating will start the adhesive to start reacting before you have had time to inject the product. That would lead to failures
True, but there are times when it is an advantage -- in our case, we pre-heat when the metals are particularly large or thick and when the rubber portion is especially thin. We control time and temperature of the pre-heating as well as the molding process, and test adhesion as well as dynamic properties. Also, the pre-heat temperatures are not as high as the molding temperature.

B.G. Wiehle
  Post Number #7  
Old 20th April 2008, 10:31 AM
Jim Wynne's Avatar
Jim Wynne

 
 
Total Posts: 14,161
Re: Do inserts need to be preheated to tooling temperature in injection molding?

Quote:
In Reply to Parent Post by sadhusong View Post

Hello all
as instructed injection with serts such as shaft, the shaft should be pre-heated as tooling temperature,i would like to get help for theory of this and is this mandatory?

and i found some supplier does not do this.
I think the answer is, "it depends." For example, I found the attached PDF from DuPont that says this about some of their plastics:
Quote:
Inserts should be preheated before molding (200 °F for DelrinŽ , 250°F for ZytelŽ , MinlonŽ and RyniteŽ ). This minimizes post mold shrinkage, pre-expands the insert and improves the weld line strength.
If your suppliers lack technical resources in their own compaies, it might be best to talk to an application expert from their resin supplier about your parts and the best way to proceed.
Attached Files: 1. Scan for viruses before opening, 2. Please report any 'bad' files by Reporting this post, 3. Use at your Own Risk.
File Type: pdf 002_DCI281.pdf (136.9 KB, 673 views)

Last edited by Jim Wynne; 21st April 2008 at 08:30 AM.
Thanks to Jim Wynne for your informative Post and/or Attachment!
  Post Number #8  
Old 20th April 2008, 10:37 AM
Ajit Basrur's Avatar
Ajit Basrur

 
 
Total Posts: 6,064
Re: Do inserts need to be preheated to tooling temperature in injection molding?

Quote:
In Reply to Parent Post by Jim Wynne View Post

I think the answer is, "it depends." For example, I found the attached PDF from DuPont that says this about some of their plastics:
Jim, the info provided is very good but the attachment is not correct - it titles 1984 and is something else
Thanks to Ajit Basrur for your informative Post and/or Attachment!
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