# 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.

35 questions with no upvoted or accepted answers
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167 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. ...
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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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### 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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### 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: $$v={{C_V*K}\over{T^m+t^{x_v}+s^{y_v}}}$$ ...
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1 vote
68 views

### 1960s coloring in manufacturing of fabric and plastic

I'm a art historian and would like to know why, in the 1960s, clothes and plastic products seem to have come in limited colours (e.g. white, yellow, red), whereas the 70s saw for instance orange, ...
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1 vote
35 views

### replacing the sound a small toy speaker makes

not sure if this counts for this community, and im open to suggestions where this would belong but im looking for advice. i have no experience in working with physical hardware, as the limited ...
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1 vote
41 views

### Why are these food stretch films (LLDPE) holding one one-thousandth of the weight in reality than what is expected from the datasheet values?

I am trying to reproduce analytically the results found in this experiment where a weight of 3 x 5 lbs (6,8 kgs total) breaks the cling wrap (LLDPE) which is stretched over a medium size cooking pot. ...
1 vote
84 views

### Help me find a material with low acoustic impedance but high wave velocity

I'm trying to find a material that would have two seemingly opposite qualities. I need something with low acoustic impedance, like a plastic, but also with high wave velocity like a metal. Here are ...
1 vote
98 views

### 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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1 vote
37 views

### 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 ...
• 161
1 vote
63 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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1 vote
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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 ...
1 vote
144 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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1 vote
87 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 ...
• 111
1 vote
41 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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1 vote
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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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### Mechanical fasteners for HDPE pipe and sheet?

I need to fasten pieces of HDPE together but I’ve heard gluing HDPE is difficult. I've bought sheets and pipes to make a feeder for a tortoise. I will be using the sheets for covers for the pipes. The ...
112 views

### Designing a tea strainer: Plastic vs stainless steel

Some time ago, I finished designing a tea strainer and I had a prototype printed from a certain heat resistant type of plastic (https://xometry.pro/de/materialien/standard-heat-resistant-pc-artig/) ...
69 views

### Injection molding - Probability of plastic pouring into connector

I have some metal pins that I want to be molded in parts of the final assembly. Meaning that, the mold will be made to accept those metal pins, which are positioned in the mold so that when the ...
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### Specific Heat, Pore Fluid In ABAQUS

I want to model a problem that the theory behind is in the "Coupled Pore Fluid Flow and Stress Analysis" context that there is in the ABAQUS online documentation, version 2022. The link to ...
39 views

### Finding alternative for Metal bolted joint in Plastic part

I am developing a design for HDR Brachytherpy interstitial Template that has to be completely in plastics. There is a shaft of 25 mm and length 130 mm, which is held by a plate of 10 mm thickness and ...
42 views

### Valox 420 30% glass wear

I am seeking assistance regarding thermoplastic material wear on a new product I am developing. The attached image is molded out of Valox 420 30% glass. In the left side image, the locking dents are ...
44 views

### Polymer material selection for injection molding

I'm trying to select injection moulding materials, and need some assistance to find the right products. I have a component that is made up 2 parts; an inner insert and an outer overmould. Originally ...
37 views

### What methods can be used to stabilize a vibratory bowl used for orientation

I have a project where we are using a vibratory bowl to feed in parts to an assembler. The issue I am having is that the calibration sticker on the side is very out and a single line is very difficult ...
43 views

### Are there plastics harder than heat-treated steel?

I've been reading that plastics harder than steel have been developed. The drill guide in the photo is made of heat-treated steel. Is there a plastic hard enough to substitute for heat-treated steel, ...
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### What is an appropriate way to compare the impact properties between a plastic and a metal?

I'm currently looking at trying to compare the impact strengths between polycarbonate and aluminum to see which one performs better if made into a box and dropped. My intuition says that aluminum can ...
55 views

### 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 ...
47 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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### 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. ...
606 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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### 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 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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### 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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23 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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