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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What does it mean for a polymer to absorb water and how does this relate to hydrophobicity?

My materials teacher mentioned a polymer that is used for its hydrophobic properties but also can absorb water. How can a polymer do both of these things?
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Expanding a small rubber ring

I have a bunch of small rubber rings that I need to conduct testing on. The rings start at about 15mm ID, and need to expand to 65mm and be held there for months. Right now, my solution for expanding ...
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How can I recycle LDPE or HDPE from plastic mesh tree guards?

I have thousands of plastic mesh tree guards like this one: The trees are now grown and I would like to recycle them. From a quick search online, they seem made from UV-resistant high density ...
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Fire rated EN 13501-1 B-s1/s2, d0 sheets

I'm trying to learn more about the type of sheets I can get for a project, I would of course go for polycarbonate if not for its price, currently the project with PC will cost \$600-\$700 but I'm ...
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Plasticity (stress(strain)) interpolation in Abaqus

The stress-strain data for a plastic deformation is given in table.   I have two questions related to how that table is treated: How is data interpolated? Is it piecewise linear or something else? ...
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What rubber to use to grip stainless steel?

I need to secure a plastic bobbin on a 316SS shaft so it can be wound in a winding machine. There is a potential for undesirable axial and rotational drift that I need to prevent. My initial thought ...
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2 votes
3 answers
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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 ...
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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 ...
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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 ...
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How to design stiff plastic sheet

I am making a cylinder of polypropylene that must be pressurized (2 bar). The rough dimensions of the current design (A) are 7 cm tall, 5 cm in diameter, and wall thickness of 1-2 mm. The issue is ...
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If I make refillable yogurt and sour cream pots (that I fill as a service), would that be better than buying yogurt in plastic pots and recycling?

I am trying to find out how I can get yogurt or sour cream in an eco friendly way. I know the films on the supermarket plastic pots are currently not recycled, so that's not great... If I start a ...
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Finding Safety Factor for Plastic Snap Fit Cantilever

I'm trying to get a safety factor of $n\geq2$ for the root of my snap fit beam (pic at bottom of the post). I have gone through the calculations to get the SF at the root's edge from the geometric ...
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1 answer
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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?
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Best DIY material for a high-torque cog or gear?

I am making a gear/cog to attach to a high torque stepper motor. I can realistically make it out of the following variety of materials: 3D printer PLA/PLA+ etc. layered PLA/PLA+ and fiberglass made ...
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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 ...
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Heat-shrinking vinyl

I want to make a vinyl stencil on a curved surface. I already use vinyl stencils with a vector cutter like Silhouette to make designs on flat surfaces. I also use heat-shrinking tape for insulating a ...
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6 answers
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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 ...
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2 votes
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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 ...
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2 answers
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Selecting material for plastic hinge

I have designed a plastic part shown in blue that will be injection moulded. The part is a lever that takes 1 mm of movement downward and outputs 6 mm of movement upward. Circled in green is a hinge ...
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1 answer
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Rubber that remains Elastic in Hot and Dry Application

I work for a valve manufacturing company and our customers have an application where very large volumes of hot (200F), dry air pass through our valve. As a consequence, the rubber (carboxylated ...
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1 answer
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Adhesive to connect metal with a coating to plastic that resists mineral oil

I have a peristaltic pump that was having some leaks because of connections between the tubing so I decided to replace it all with a single piece of tubing. Upon doing this though, I observed that the ...
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1 answer
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Salt grinder and corrosion

I am looking for a kitchen salt grinder. I know salt is an aggressive compound and it needs a little bit of attention when we design products. Since most of grinders have plastic-made or stainless ...
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Recommendation of different materials for 3D printing flexible parts

I am planning to 3D print this part from solidworks. I am hoping to achieve a good level of flexibility with the clasps in this part. Thin circular arc in the Top drawing. and Wider circular arc in ...
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2 answers
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Building a coffee maker - food grade, heat resistant material?

Background I want to build a drip-style coffee maker for fun. My "design" features a sealable cylindrical housing for the water and heating element. Silicon tubes will carry boiling water ...
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IP grade for specific plastic case

I´m designing an access control device and I need to place it in a plastic case so it can be easily installed on a wall, for example. Also, the PCB will have a special coating for humidity protection. ...
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1 answer
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3D printer printing out cotton-candy like material after repeated use

I recently purchased a JGMaker Magic 3D printer. It worked well for about 3 months [first picture], but now it is having a lot of trouble. As you can see in the images below, when printing new pieces, ...
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Searching for a material that respons to voltage change

For a project, I need a transparent ball that is rigid, but under application of a voltage changes it's size, like a self-inflating balloon. Because it's rigid, however, and thus would break when ...
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How to get soft touch matte finish on my resin cast parts?

I'm working on a prototype electronic consumer product for which I intend to use silicone molds with polyurethane casting to get the plastic body. I have seen a few products with a smooth satin finish ...
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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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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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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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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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-1 votes
1 answer
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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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2 answers
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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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-1 votes
1 answer
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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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3 votes
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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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1 vote
1 answer
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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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1 vote
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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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1 vote
1 answer
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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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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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2 votes
2 answers
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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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4 votes
2 answers
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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. I understand PP recyclable would be #5 triangle. #7 means ...
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1 vote
1 answer
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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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3 votes
1 answer
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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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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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3 answers
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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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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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1 answer
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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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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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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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