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Questions tagged [plastic]

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0
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1answer
21 views

Generic category of PBT thermoplastic

I'm an EE, but I'm working on a project at work where I need to venture into materials science & chemistry. My question is, does thermoplastic, Polybutylene terephthalate (PBT), fall into any of ...
4
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1answer
38 views

How are non-continuous internal threads palstic inejction molded?

I'm trying to figure out how the heck some of these plastic bottle caps are injection molded. By having the thread on the inside of a cap, this obviously creates an undercut. Now I've watched some ...
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0answers
34 views

Polyurethane with microbial resistance properties

I'm looking for a polyurethane with microbial resistance. Doing some research I found two commercial types: DESMOPAN 9392A and DESMOPAN 2792A. Both are manufactured under GMP conditions and limited ...
1
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1answer
34 views

What type of plastic is a good clear, flexible plastic for prototyping? (~0.5mm - 1.5mm thick)

I'm prototyping a hardware that involves many thin walls to bend around curves and such, so it needs to be flexible, cheap, and also transparent. It may also be the same plastic used in a production ...
2
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1answer
24 views

Shear strength polymers

I was looking for some shear strength properties of common polymers/plastics.... I have not found any usefull information yet. I know polymers aren't that linear elastic, but I expected to find some ...
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0answers
25 views

What plastics are commonly used for light diffusion?

I'm looking to create a mass-manufactured custom display similar to a seven-segment display found on alarm clocks. What material is commonly used to diffuse the light? The challenge I'm facing is ...
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2answers
39 views

What type of resin should be used to injection mold an instrument mouthpiece?

I'm designing an electronic musical instrument and need to injection mold the mouthpiece. This is my project: Multiwind. The mouthpiece needs to be safe to go in the mouth, opaque (preferably black),...
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6answers
163 views

How to create an airtight connection between Stainless Steel and PTFE?

I have these two parts shown below, the bottom cylindrical part is stainless steel, the rectangular upper piece is PTFE (Teflon). The SS prongs from the lower part need to insert into the holes of the ...
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0answers
13 views

What FDA compliant plastics can have contact with alochol (wine)?

I am able to find that the class for materials that can be in contact with wine (~10-15% alcohol by volume) is called Class VI-A and Class VI-C, but I am not able to find a list of materials that are ...
2
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1answer
91 views

How would I put a barcode of other scannable code on a coffee cup?

I am interested in mass producing a reusable coffee cup (à la KeepCup) with a scannable id on it. Cup will be plastic or glass, ideally glass. ID code will need to survive being washed regularly. ...
3
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1answer
55 views

Molding thermoplastic over sensitive components

I have an electronic assembly that is heat sensitive. Due to the incorporation of a CR3032 coin cell battery, it can survive being heated to a maximum of 60 degrees C. I want to coat this assembly in ...
0
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1answer
29 views

Glue plastic to glass with chance for easy removal later

I have a 3d printed (ABS or PLA) case which houses small single board computer. I want to glue it to glass (car's windshield from the inside) so that it sticks nicely and does not vibrate. However, ...
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1answer
46 views

Why there are grooves at inner side of plastic nasal spray cap?

My suggestion was that they are for Tamper-evident band, but there isn't one beneath the cap.
4
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0answers
56 views

What plastic material blocks the most amount of light?

If I have a grid array of LED's surrounded by roughly 0.7mm thickness plastic walls. What material at this thickness would prevent light bleed side to side so that individual LED's can light up but ...
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0answers
32 views

How to make machined plastic part slippery for small dry particles

We have a plastic part that is a receptacle for small ( < 1mm ) particles. It is a disk with a shallow cone shaped indent made using a drill. When a particle is placed in the receptacle it should ...
1
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2answers
72 views

What manufacturing process could be used for this part?

How might the "shell" in this picture be manufactured? What process could be used to achieve this geometry? It is made from plastic.
0
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1answer
59 views

How would I get my hands on something I designed in Solid works?

Lets pretend I designed a plastic Lunchbox, like the ones pictured below in solid-works. What processes or options are involved in obtaining a physical sample of my design?
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0answers
22 views

Replacing LED plastic housing

I have recently asked a question about LED color changes in liquid nitrogen, and confirmed that it was caused by changes in the size of the band gap. Now I am wondering, if it's possible to create a ...
1
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3answers
94 views

How to build a transparent double hollow helix at home

I'm building a product prototype for a client. We are trying to figure out the best way to build a hollow helix capable of transporting liquid at home. Something similar to this: So far our best ...
3
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2answers
87 views

Designing bulk material handling system for injection molding

does anyone have any resources for designing a bulk material handling system for an injection molding outfit? Currently we get material in gaylords and vacuum it to the hopper on each molding machine ...
3
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2answers
673 views

Which plastics dissolve in petroleum?

The thin steel float used in my car (which was built in the UK in the early 60s, which I'm assuming is why it's not originally plastic) has rusted to a point where it's leaking in fuel and therefore ...
1
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1answer
86 views

Plastic Vacuum Cleaner Part — Why did they design it this way?

I've designed a whole lot of different parts and products in my time: Plastic, metal, lighting products, electrical products and automotive parts. I generally can look at a product and figure out why ...
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0answers
22 views

Required clearance for moving part (Push Button)

I'm designing a push button made from most likely ABS but possibly TPE, it presses a surface mount button on a PCB with 0.9mm travel. The ABS button is 8x8mm Square and travels through 4mm of ...
1
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2answers
81 views

Why not use fire-retardant plastics everywhere?

Some plastics will sustain a flame. Others won't. Not spreading a fire is obviously preferable in almost every circumstance. What advantages do combustible plastics have over non-combustible plastics, ...
3
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0answers
53 views

Which coating best exploits “darker when wet” phenomena

This "practice calligraphy" paper has a special coating that amplifies the contrast between light/dark when a wet brush is applied. The physics behind this effect has been explained: Why do wet ...
1
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1answer
96 views

What sort of plastic is this? What would you call this color scheme?

I saw this plastic on a baby changing station and was wondering what sort of plastic it was. It seems like injection molding plastic but I'm not sure which one and also what pepper color scheme that ...
5
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1answer
96 views

How are protective sheets attached to plastics?

When you buy plastic sheets such as acrylics, polycarbonate sheets etc, they come with a paper/plastic protective film. Like in this image : Protective Film for Acrylic Sheet PMMA Panel You notice ...
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0answers
75 views

Is parallel layering within a material stronger than perpendicular layering (e.g. as in corrugated plastic)?

I'm trying to figure out whether parallel layering of a material between two outer surfaces (with or without spaces between the layers) is more resistant to pressure applied perpendicular to the ...
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0answers
13 views

Plastic tensile bars for Tye testing

We make plastic tensile bars per astm 638. The problem that I'm having is the bars are breaking outside the gauge marks in the reduced section of the samples. I'd like to know as to what I can do to ...
0
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1answer
30 views

Can I inject plastic in a RTV mould?

Can I inject plastic in a RTV mould? Will the interior of the mould get deformed by pressure?
2
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2answers
95 views

Plastic Injection Moulding a Piece with Undercuts

I am a newcomer to Plastic Injection Molding and would really appreciate some advice. I have a prototype object that will be made from a type of polypropylene. I only need a maximum of 10 units ...
4
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1answer
634 views

Difference between 'plastic yielding' , 'plastic yield strength', plastic strength' and 'plastic stress'?

I am going through a literature where these terms are regularly used and I am confused are they different and if yes then what does each term mean? I also want to know relation of plastic strength of ...
3
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1answer
110 views

Finding initial length of a bended plastic sheet (Bend Allowance)

I have a 1.5 mm thick plastic sheet part which hast to be bent at a joint 0.3 mm thick by ~ 10 Deg. I know (found from design drawing) compressed and stretched lengths of the joint. How can I find the ...
3
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2answers
695 views

How to attach lycra / leather to Polyurethane foam?

What would be the best solution for attaching polyurethane foam to a lycra sheet of material. I was thinking a chain or pad stitch or possibly glue, but not sure if sewing would be the best ...
6
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3answers
504 views

Silicon and silicones

Why Silicon can be used in many engineering materials like oil (Silicone oil), grease, caulk, rubber(PDMS), resin? What property of Silicon allows so?
2
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1answer
358 views

thickness and other specifications PC + ABS for allowing light through?

So we are developing a plastic case, where we want light to be diffused through the case. The light is kept 2-3 mm away from the inside wall. I wanted to know what thicknesses allow passage of light, ...
4
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1answer
438 views

How do I cut a crack into a polymer/plastic?

We need to cut a very thin crack into a polymer plate for a research project. The closest thing to what we are looking for is Wire EDM but since the polymer we are using is not conductive we cant use ...
70
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8answers
28k views

Why do glass windows still exist? (Why haven't they been replaced by plastics?)

Glass is fragile and impractical to transport, install and repair. Even worse, glass kills and hurts people when it breaks. Falling to the streets like guillotines during earthquakes and bomb raids. ...
0
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1answer
46 views

Plastic wrapper stretch [closed]

I'm studying how industrial plastic film pallet wrappers work. The wrappers apply a certain amount of pre-stretch to the plastic film (by means of different rolls) before applying it to the object ...
0
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1answer
314 views

What is a transparent material that insulates well? [closed]

I need to create a transparent box that can stay warm inside while in cold temperatures, below 0 degrees, for as long as possible. Glass and plastic are transparent but afaik they don't insulate that ...
3
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1answer
141 views

How can I process plastic to give the impression of a leather finish?

During the '80s and the '90s, a lot of media cases were made of thermoformed PVC. I believe this trend was created by Disney and Blackbourn with their VHS cases. Then with DVDs, industrial standards ...
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3answers
10k views

How to determine whether plastic is ABS or Polypropylene?

I have a pump that I want to use to pump a solvent. It is hard black plastic so I'm pretty confident it is either ABS or polypropylene (it wasn't expensive enough to be some more exotic plastic). My ...
2
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0answers
54 views

Identifying coefficients to determine cutting speed for PA6 plastic

As part of a study at work, I have to calculate the cutting speed and feed rates for cutting plastic. I have found a formula for cutting speed calculation: $$v={{C_V*K}\over{T^m+t^{x_v}+s^{y_v}}}$$ ...
6
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2answers
2k views

What should the size difference be between a lid and a container?

I am designing a box and lid (for a home-made micro computer). Using Autodesk Inventor (Student Version), I've created my box which looks something like this: I plan on 3D printing (ABS Plastic) the ...
1
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1answer
628 views

What screw for 2.0 mm plastic hole in housing

I'm thinking about using the Bopla UM 32009 housing for my product. It has little standoffs for attaching PCBs. These standoffs are made of plastic, and seem to be drilled (or molded?) to a diameter ...
5
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1answer
105 views

Limits of Injection Molding Regarding Overhung Edges

I'm looking to redesign a seal my company currently uses. The original task was to re-source it from a lower cost supplier with the same design as is in current production. However, the supplier doesn'...
1
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1answer
49 views

How to rebuild and lubricate worn plastic parts?

I'm hoping to rebuild a joystick (sidewinder strategic commander), though the parts inside it are a bit too wobbly because they have been worn beyond tolerances. Due to this wobbling on one (rotation) ...
3
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2answers
478 views

Best plastic composite alternative to wood

I am planning to replace the material that is used for Cricket Stumps. Cricket is a game similar to baseball. One difference is the presence of 3 successive stumps between the hitter and catcher. ...
5
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2answers
844 views

Can I seal the inside of a water well to use it as water reservoir when the well is dry?

We've had unusually dry weather and our well has run so low that we had to call in a water hauling company to refill it a few days ago. The water man told me that even though he dumped in ~ 1000 ...
4
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0answers
115 views

Calculating a pull force between two pieces of plastic

I have an HDPE pin, 2 mm high, 2 mm diameter, that I impress into a flat plaque of hot HDPE. It is not hot enough to melt the pin, but still hot enough that the material will shrink 4% in 24 hours. ...