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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36 views

Does plastic expand at colder temperatures?

After placing a dry solid block of nonporous plastic material in the freezer for a while, I was surprised to find out when I retrieved it that it had expanded globally by a few inches. Which type of ...
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30 views

How to get this hydraulic system working and help identifying parts and their function

I have recently acquired a 1982 Arburg 220-90-350 injection moulding machine, mainly just as a hobby to further my knowledge on injection moulding machines and control systems as I plan to modernise ...
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29 views

Fix plastic tub (leak) and resist applied forces

I hope I'm not too much off topic here. I'm hoping it can make sense as a mechanical engineering question. There is a crack in the front of the tub of my front loading washing machine. As you can see ...
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18 views

Limit state design/ LRFD of short steel columns

Why do we use the yield strength as the limiting strength in short column design when using limit state design. Why is the full capacity of the material not utilized (as is the case with beams when we ...
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1answer
52 views

How to know the material of key-top?

There are keys (push buttons) on the front panel of an avionics device that fits inside the aircraft cockpit. I need to know the material of which those key-tops are made from. I can guess the ...
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2answers
36 views

How did OXO manufacture this colander with such intricate wall feature?

Here's my guess, but I would love to hear another perspective. I think this is injection molded. This colander has draft angles and the two mold halves use an intricate step-like wall pattern to ...
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1answer
42 views

How did OXO get text into this inside feature?

I am a student trying to learn about how OXO made this cup. Here are some constraints that I know: I figured out that the text on the outside can be made using screen printing, but then I don't think ...
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56 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 ...
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1answer
111 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 ...
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25 views

Can I use polymer clay to make a mold and then melt HDPE plastic in it in the oven?

Can I use polymer clay to make a mold and then melt HDPE plastic in it in the oven? My goal is to be able to dig a fairly uncomplicated shape in a polymer clay block and then fill that mold with small ...
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1answer
21 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 ...
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1answer
15 views

Designing an injection molding mold for a part with a certain parting line and ejector pin location

How do you design a mold to create that part? The only way I can think of is to make the parting line horizontal to the part instead of vertical. But is there any way to design the mold so that the ...
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2answers
326 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"...
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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. On 1/13/2020, I wrote to hello@drinkarizona.com, which was ...
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35 views

How to select the correct Bolt/screw Torque for sealing?

My coworkers and I are finally testing our agriculture sensor on the field. As you can imagine, the moisture and dust are important variables to keep aside from the electronics inside our product. ...
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570 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? [...
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60 views

Cutting lego “+” cross-axle holes, lego knobs?

In short, I'm looking for ways to reasonably precisely machine a "+"-axle hole, Lego compatible sockets, Lego compatible knobs, Lego compatible round peg/axle holes, and other cutouts for Lego-...
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3answers
118 views

How to get corrugated plastic roofing strips to span 3m for rainwater exclusion experiment without building additional ground supports?

I'm trying to build structures to exclude some percentage of rainwater on experimental plots. I have three 20ft beam supports across the plot, spaced 3m apart and held in place by 4x4 posts that were ...
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2answers
329 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) ...
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1answer
238 views

Adhesion of Super Glue (containing ethyl cyanoacrylate) and PVDF (polyvinylidene fluoride) film

Would it be considered safe to use super glue, which contains ethyl cyanoacrylate, to attach a PVDF film to a metal alloy? It says super glue is not recommended for polyethylene or polypropylene. ...
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2answers
167 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 ...
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3answers
379 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 ...
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21 views

Must I use viscoplastic model to fit the thermoplastic material

I need to do the simulation with a specified material. It is known as a thermoplastic. During the simulation, I need to define the material property. I need to choose whether it is viscoplastic or ...
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1answer
44 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 ...
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417 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 ...
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39 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 ...
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1answer
113 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 ...
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1answer
477 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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2answers
67 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
838 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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17 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 ...
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1answer
253 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. ...
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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 ...
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183 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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64 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.
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2answers
102 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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41 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 ...
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2answers
78 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.
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140 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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3answers
204 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 ...
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2answers
154 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 ...
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2answers
5k 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 ...
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106 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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30 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 ...
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2answers
96 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, ...
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1answer
70 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 ...
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1answer
272 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 ...
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119 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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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 ...
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31 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?