CR4 - The Engineer's Place for News and Discussion ®


Previous in Forum: Sticker Removal Needed   Next in Forum: Toluene Gravure Formulation
Close
Close
Close
8 comments
Member

Join Date: May 2007
Posts: 5

High Gloss Plastic Finishes on Television LCD Frames

06/24/2016 6:40 AM

Hi Folks I would like to understand the techniques to get high gloss finish (black or white) typically observed in plastic frame used in LCD television or monitors. Please advise if it is due to material of the cavitiy of injection mould or due to plastic material being moulded. I will appreciate if you could advise technical details in terms of material grades both for mould and material being molded. Also if any typical alloys or additives help, please provide information on that as well. Regards Ind_design

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Guru

Join Date: Oct 2008
Posts: 39042
Good Answers: 1533
#1

Re: High Gloss Plastic Finishes on Television LCD Frames

06/24/2016 9:30 AM

Asking others to do your work for you is not a good way to succeed.

Nearly all molded plastic housings are painted after molding.

Perfect surface gloss is difficult to obtain consistently.

Lot to lot color variations in molding pellets is common.

Swirl, flow and other patterns are also a problem with surface finish.

Hire a consultant. You're asking someone to do a lot of work to educate you for free!

Register to Reply
Anonymous Poster #1
#3
In reply to #1

Re: High Gloss Plastic Finishes on Television LCD Frames

06/24/2016 1:06 PM

Going by his past record he doesn’t like work and finds someone else.

Register to Reply
2
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 17942
Good Answers: 1029
#2

Re: High Gloss Plastic Finishes on Television LCD Frames

06/24/2016 11:30 AM

..."Three factors typically affect gloss: mold-surface finish, processing parameters, and the material being molded. To get a truly high-gloss part without additional processing, OEMs and molders should address all three.

A polished-steel tool surface transfers its high-gloss finish to the plastic during molding. Although relying solely on mold texture can be costly in terms of tool maintenance and insufficient to meet high-gloss requirements, it is an important aspect of high-gloss part production.

During processing, higher mold temperatures lead to glossier parts when resin is filled with glass fibers or other reinforcements. However, boosting mold temperature means extending cooling times and, consequently, raising part costs.

For glass-fiber-reinforced resins, holding pressure — or gas-packing pressure in the case of GAIM — is an important process parameter, too.

Special resin formulations can ensure parts meet aesthetic and performance requirements when tool modifications and processing conditions alone are not enough or are too costly.

For example, Ticona developed a 15% glass-filled polybutylene terephthalate (PBT)/polyethylene terephthalate (PET) blend for an appliance handle. The raw material is economical, has a 760-mm flow that permits molding of long channels, doesn’t require longer cycles to develop high gloss, is colorable, and maintains a good balance of mechanical properties.

The blend lets PET, commonly found in clear disposable beverage bottles, reach the surface before PBT, which is more commonly used for its engineering properties. The PET surface layer crystallizes in the hot mold to form a glossy surface. Specially formulated color additives contribute to part gloss while tinting the part to the OEM’s desired shade.

The “show” side (the side customers see) of GAIM parts molded with the blend had 86.7% the gloss of the glass standard at 60°. Conventionally injection molded parts achieve 90 to 100% gloss while GAIM parts molded without optimized resins only reach 55% gloss.

Finished parts are UV-stable under indoor lighting and resist scratches, stains, detergents, cleaners, and chemicals. They have good mechanical strength and creep resistance despite being lighter than traditionally injection-molded parts."

http://machinedesign.com/news/get-high-gloss-parts-reinforced-polyester-resin-and-gas-assisted-injection-molding

__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Register to Reply Good Answer (Score 2)
Member

Join Date: May 2007
Posts: 5
#4

Re: High Gloss Plastic Finishes on Television LCD Frames

06/25/2016 1:21 AM

Thanks SolarEagle! Really appreciate your feedback.

Register to Reply
Guru

Join Date: Oct 2008
Posts: 39042
Good Answers: 1533
#5
In reply to #4

Re: High Gloss Plastic Finishes on Television LCD Frames

06/25/2016 10:20 AM

You will note that Solar Eagle simply performed a Google search to get the information for you.

Something any reasonably intelligent person could have done in 5 minutes.

I suggest that you try it the next time you have an assignment.

How to Search the Internet: 9 Steps (with Pictures)

Register to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 17942
Good Answers: 1029
#6
In reply to #5

Re: High Gloss Plastic Finishes on Television LCD Frames

06/25/2016 1:12 PM

Haha, are you casting aspersions on my abilities as being mundane?

__________________
Life is like riding a bicycle. To keep your balance you must keep moving. A.E.
Register to Reply
Guru

Join Date: Oct 2008
Posts: 39042
Good Answers: 1533
#7
In reply to #6

Re: High Gloss Plastic Finishes on Television LCD Frames

06/25/2016 2:05 PM

Never!

Register to Reply
Power-User

Join Date: Jan 2015
Posts: 105
#8

Re: High Gloss Plastic Finishes on Television LCD Frames

06/27/2016 11:33 AM

After over 20 years in the plastics business I would say that the answer to your question is 'Yes'.

It is due to the mold material and the 'plastic material' as you say.

Any further info can be, as SE has shown, found on the internet. Even simpler and more precise would be to pay a local mold builder or molding shop to answer your questions. We don't know the shape, the type of mold desired, cycle time target, or quantities. These are a few things that the designer will need to consider, variable with each application.

That is a hint, more than I should give out.

Register to Reply
Register to Reply 8 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (1); Ind_design (1); lyn (3); SolarEagle (2); Torqued (1)

Previous in Forum: Sticker Removal Needed   Next in Forum: Toluene Gravure Formulation

Advertisement