Questions tagged [plastic]

Plastic (material): materials consisting of any of a wide range of synthetic or semi-synthetic organic compounds that can be molded into solid objects. This includes thermos-softening & thermos-hardening plastics.

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82
votes
9answers
36k 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 (Why haven't they been replaced by plastics?)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. ...
9
votes
0answers
238 views

What type of ultrasonic transducer would be suitable for ultrasonic welding? [closed]

Project background: I am working on a project where i need to weld plastic using ultrasonic transducers. Problem: Since I'm still learning engineering, I have a hard time figuring out what all the ...
7
votes
5answers
20k 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 ...
7
votes
3answers
472 views

Information regarding plastic hinges that can hold the position

I am trying to find some information regarding the design of plastic hinges that can move freely but also hold a position in any degree, like in this little camera: https://www.kickstarter.com/...
6
votes
2answers
2k 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 ...
6
votes
2answers
4k 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 ...
6
votes
1answer
698 views

How are non-continuous internal threads plastic injection 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 ...
6
votes
2answers
8k views

Finding the pull-through capacity of a nutted bolt and washer in ASA plastic

I have a uniform load applied to the underside of a plastic sheet which is to be resisted by the combination of a bolt, washer, and nut as depicted below (the other end of the bolt is secured and will ...
5
votes
3answers
570 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?
5
votes
1answer
154 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'...
5
votes
1answer
212 views

Minimising permeation rate of hydraulic fluid through hydraulic hose

I am designing an experiment where the hydraulic hose is going to be subjected to relatively high internal pressure for prolonged period of time and it is absolutely imperative that the rate of ...
4
votes
6answers
575 views

Increasing torsional-stress resistance of an Auger at its motor-shaft joint

An auger is used to move plastic balls and is rotated by a stepper motor. Due to the balls getting jammed sometimes, this induces stress on the auger at the motor-shaft junction and breaks. Images ...
4
votes
1answer
139 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 ...
4
votes
1answer
2k 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 ...
4
votes
1answer
799 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 ...
4
votes
2answers
304 views

What is the composition of Arizona Ice Tea 1gal plastic bottles stamped #7 OTHER and PP COMPATIBLE?

I wished to know the composition of Arizona 1gal plastic jugs that I have. The bottom is stamped PP COMPATIBLE and has a #7 OTHER RIC code. I understand PP recyclable would be #5 triangle. #7 means ...
4
votes
2answers
137 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 ...
4
votes
2answers
161 views

Thermoplastics that are permeable to water - high diffusion coefficient

I want to know if there are some fairly common thermoplastics that allow water to pass through (by diffusion) at a relatively high rate (on the order of days). For example, PET water bottles leak ...
4
votes
0answers
127 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. ...
3
votes
2answers
511 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. ...
3
votes
2answers
116 views

Is there any difference between an-elastic and visco-elastic materials?

Most of the sources that I had read about either talks about anelasticity or viscoelasticity, they don't compare both. From what I have read so far ,both anelastic and viscoelastic materials are the ...
3
votes
1answer
718 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 ...
3
votes
1answer
2k views

What plastic material is best for a snap-fit design?

I'm designing a plastic holder that will secure a metal part with snaps. Which plastic will be able to take multiple removals and re-insertions without getting weaker (bent out of shape) over time? [...
3
votes
2answers
79 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 ...
3
votes
2answers
7k 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 ...
3
votes
1answer
72 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 ...
3
votes
2answers
1k 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 ...
3
votes
0answers
65 views

Any Idea of This China's "Transparent Concrete"?

I am currently make an attempt to make miniaturized version of this China's solar highway on my garage https://www.youtube.com/watch?v=zK8FvzI3yDA Just so i can re-evaluate the performance However, I ...
2
votes
2answers
1k views

What does 50% RH mean?

I'm looking to determine the difference between the two yield strengths on a Matweb material property table for DuPont Performance Polymers Zytel® 105F BK010 PA66. The top is for "50% RH; ISO 527-1/-2"...
2
votes
1answer
422 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. ...
2
votes
1answer
49 views

How well does epoxy bond to PETG / ABS vs Wood?

I know that PLA does not bond at all, just peel right off But i'm wondering about PETG or ABS Will they bond just as well as wood?
2
votes
2answers
160 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 ...
2
votes
2answers
167 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 ...
2
votes
3answers
38 views

What materials could non-flammable (blowtorch resistant) "plastic" submarine furniture be made of?

In a documentary on Russian submarines they show non-flammable furniture that's made of some kind of plastic of foam. They test/demonstrate it with a blowtorch that is capable of cutting metal (they ...
2
votes
1answer
167 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 ...
2
votes
1answer
749 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, ...
2
votes
1answer
197 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 ...
2
votes
0answers
25 views

Narrowing down injection moulding material selection

How do I narrow down specific values when selecting a plastic for injection moulding? My part is uniform in wall thickness and thins out where a hinge a present. Properties: Will not go under many ...
2
votes
0answers
56 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: $$v={{C_V*K}\over{T^m+t^{x_v}+s^{y_v}}}$$ ...
1
vote
2answers
308 views

Why not build container ships from plastic?

This may sound crazy but bear with me. I was thinking about why cargo ships are built from such heavy material as steel, while smaller boats are often made of plastics. I know cargo ships carry a lot ...
1
vote
6answers
1k 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 ...
1
vote
3answers
588 views

PTFE sheet vacuum forming

I need to make PTFE caps on my test tubes. Why PTFE? The test tubes contain industrial solvent mixtures & the rubber caps that came with the test tubes are very, very slowly being dissolved. I ...
1
vote
2answers
98 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, ...
1
vote
3answers
110 views

Mechanical fasteners made of HDPE?

I need to fasten pieces of HDPE together but I’ve heard gluing HDPE is difficult (after all, glue comes in HDPE containers, and the glue doesn’t get stuck in the bottle). Using mechanical fasteners ...
1
vote
2answers
693 views

Push button design for small gadget

I'm looking at designing a small gadget (think something like a Fitbit in size) where the case has a couple of buttons on it. For various reasons the buttons have to be around the narrow side (edge) ...
1
vote
1answer
66 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.
1
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2answers
80 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.
1
vote
1answer
36 views

Alternative to high cost plexiglas and polycarbonate for large project

I am planning the construction of a large scale dodecahedron infinity mirror, and so far the largest cost by far are the glass (or similar clear, hard material) pentagons. Each panel would be screwed ...
1
vote
1answer
2k views

Safe temperature thresholds for #2 HDPE and #5 PP plastic

It would be convenient to use a temperature adjustable heat plate (element)/mug warmer for the massive amount of blender bottles accumulated over the years. What are safe thresholds to safely warm the ...
1
vote
1answer
23 views

Rc Car BodyShell created

Growing up I would have these RC Car, they had the cover which eiher a cover of a truck or any brand of cars, I could take this cover off and then change the batteries of the rc car or just check the ...