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General Category => General Discussion => Topic started by: nc43bsa on December 21, 2022, 03:53:24 PM

Title: Plastics
Post by: nc43bsa on December 21, 2022, 03:53:24 PM
Does anyone here know how to determine what plastic an object is made from?

I'm attempting to repair a part from a 30 year old Cadillac that has been discontinued by GM, and I can't find a used part.
Title: Re: Plastics
Post by: cliffrod on December 21, 2022, 04:08:50 PM
Smooth on offers a variety of products for production and reproduction, all professional quality product and support.  Check out their website for information about possible solutions to your project-
 https://www.smooth-on.com/ (https://www.smooth-on.com/)

Simple testing of product, although it may require sacrificing some of the original material-
 https://www.twi-global.com/technical-knowledge/faqs/faq-how-using-simple-manual-tests-can-i-identify-an-unknown-plastic-material (https://www.twi-global.com/technical-knowledge/faqs/faq-how-using-simple-manual-tests-can-i-identify-an-unknown-plastic-material)
Title: Re: Plastics
Post by: guzzista on December 21, 2022, 04:23:06 PM
Well equipped body repair shops have pro  plastic welding equipment that can make for a perfect repair. Worth checking out.  As per mending, JB Weld Plastic Bonder 2 part epoxy does a great job  regardless of plastic type. When combined with  metal mesh backing or Simpson Tie perforated plate or similar DIY perforated  thin metal it can make for a super strong repair. My 30 year old Corvette was literally held together by JBWeld plastic bonder
Title: Re: Plastics
Post by: pehayes on December 21, 2022, 06:08:58 PM
If you can make a reasonable bodge repair, perhaps the piece can then be cast in plaster or such and poured with new plastic.  I have a two part (powder and solvent) casting kit (Plast-Aid) that molds small plastic things hard as a rock.  Seriously strong stuff.  Watch here:  https://www.youtube.com/watch?v=1YGzjWeK-nY (https://www.youtube.com/watch?v=1YGzjWeK-nY)

Patrick Hayes
Fremont CA
Title: Re: Plastics
Post by: RinkRat II on December 21, 2022, 10:39:07 PM

       Might check around your area for someone with a 3D printer, depending how big the part is.

       Paul B :boozing:
Title: Re: Plastics
Post by: Paul_Tim on December 22, 2022, 02:30:19 AM
Have a good look on the inside surface of the part, most automotive plastics have been marked with part number, manufacturing date code and a code identifying the material for the past 30+ years.
I've a set of fairing parts for a 32 year old Yamaha next to me in the workshop, they tell me it's ABS and I've two date codes 07-91 and 04-96 indicating that some have been replaced at some point in its life.

There are a number of websites with decoders for the material.

Good luck.
Title: Re: Plastics
Post by: Tom on December 22, 2022, 03:12:27 PM
Check the reverse side of the part.  There should be some info about the type of plastic.  Check this out.  https://www.youtube.com/watch?v=lkaKLowAsrI  or   https://www.youtube.com/watch?v=0A9yvmLR-K0
Title: Re: Plastics
Post by: LowRyter on December 22, 2022, 05:40:26 PM
Well equipped body repair shops have pro  plastic welding equipment that can make for a perfect repair. Worth checking out. As per mending, JB Weld Plastic Bonder 2 part epoxy does a great job  regardless of plastic type. When combined with  metal mesh backing or Simpson Tie perforated plate or similar DIY perforated  thin metal it can make for a super strong repair. My 30 year old Corvette was literally held together by JBWeld plastic bonder

that
Title: Re: Plastics
Post by: averb on December 23, 2022, 09:16:31 PM
Toms suggestion is a good one, however if you can't find a marking and at 30 years old there's a reasonable chance you wont, try this chart - https://partec.qld.edu.au/wp-content/uploads/2018/08/Plastics_Identification_Flow_Chart.pdf  The one Cliff posted earlier misses out on quite a few materials commonly used in automotives

Cheers

Steve
Title: Re: Plastics
Post by: bigbikerrick on December 23, 2022, 11:45:42 PM
This company Polyvance ,has a great chart for identifying plastics for repair
Rick.

https://www.polyvance.com/identify.php
Title: Re: Plastics
Post by: JJ on December 26, 2022, 07:47:14 AM
Sorry...I could not resist....Classic movie scene... :laugh: :grin: :wink: :thumb: :bow: :cool: :boozing:

https://www.youtube.com/watch?v=eaCHH5D74Fs
Title: Re: Plastics
Post by: Tom on December 27, 2022, 05:54:00 PM
He says it's $16 from Harbor Freight.

https://www.youtube.com/watch?v=aIMl9vtRqPg

More plastic welding techniques. 

https://www.youtube.com/watch?v=7IMAtlPSORs