Questions tagged [plastic]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0
votes
0answers
28 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-...
0
votes
3answers
73 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 ...
1
vote
2answers
93 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) ...
0
votes
0answers
30 views

Factors for Rope Elasticity

What factors, given the same material, change the elasticity of a rope? For instance, nylon rope can be configured to stretch elastically anywhere between 5% and 30% under a specific load. This is ...
1
vote
1answer
36 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. ...
0
votes
2answers
102 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
3answers
107 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 ...
0
votes
0answers
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 ...
1
vote
1answer
34 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 ...
5
votes
1answer
115 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 ...
1
vote
0answers
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 ...
1
vote
1answer
41 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 ...
2
votes
1answer
81 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 ...
0
votes
2answers
49 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),...
1
vote
6answers
376 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 ...
0
votes
0answers
15 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 ...
2
votes
1answer
150 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. ...
3
votes
2answers
74 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 ...
0
votes
1answer
38 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, ...
1
vote
1answer
51 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.
4
votes
2answers
89 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 ...
1
vote
0answers
39 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 ...
1
vote
2answers
75 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.
0
votes
1answer
69 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?
1
vote
3answers
136 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 ...
2
votes
2answers
134 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 ...
3
votes
2answers
2k 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 ...
1
vote
1answer
99 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 ...
1
vote
0answers
27 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 ...
1
vote
2answers
89 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, ...
3
votes
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 ...
1
vote
1answer
134 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 ...
4
votes
1answer
104 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 ...
1
vote
0answers
13 views

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 ...
0
votes
1answer
30 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?
2
votes
2answers
126 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 ...
4
votes
1answer
1k 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 ...
2
votes
1answer
120 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 ...
3
votes
2answers
988 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 ...
5
votes
3answers
538 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?
2
votes
1answer
398 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, ...
4
votes
1answer
541 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 ...
73
votes
8answers
31k 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. ...
0
votes
1answer
48 views

Plastic wrapper stretch [closed]

I'm studying how industrial plastic film pallet wrappers work. The wrappers apply a certain amount of pre-stretch to the plastic film (by means of different rolls) before applying it to the object ...
0
votes
1answer
452 views

What is a transparent material that insulates well? [closed]

I need to create a transparent box that can stay warm inside while in cold temperatures, below 0 degrees, for as long as possible. Glass and plastic are transparent but afaik they don't insulate that ...
2
votes
1answer
142 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 ...
7
votes
4answers
12k 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 ...
2
votes
0answers
54 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: $$v={{C_V*K}\over{T^m+t^{x_v}+s^{y_v}}}$$ ...
6
votes
2answers
3k 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 ...
1
vote
1answer
774 views

What screw for 2.0 mm plastic hole in housing

I'm thinking about using the Bopla UM 32009 housing for my product. It has little standoffs for attaching PCBs. These standoffs are made of plastic, and seem to be drilled (or molded?) to a diameter ...