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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69 views

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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1answer
42 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?
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53 views

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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3answers
88 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 ...
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1answer
35 views

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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6answers
573 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 ...
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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 ...
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2answers
60 views

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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1answer
23 views

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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1answer
29 views

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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1answer
57 views

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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44 views

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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2answers
45 views

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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33 views

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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1answer
77 views

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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36 views

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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15 views

Readily available PVC plasticizer

I'm looking for products that can be used as non-toxic PVC plasticizers. I've used ATBC as a product that I can add to, for example, the inside of a pool toy, which with time absorbs it and becomes ...
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0answers
22 views

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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1answer
38 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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32 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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1answer
32 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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0answers
19 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
53 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
43 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
45 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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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 ...
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1answer
1k 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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44 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
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 ...
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1answer
21 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
899 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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2answers
244 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 ...
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1answer
40 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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1answer
1k 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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100 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
157 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
627 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
319 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
272 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
555 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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22 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
47 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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1answer
656 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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41 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
128 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
688 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
77 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
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 ...
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18 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
392 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. ...