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Questions tagged [friction]

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statics exam question about friction

In a statics exam I had the question in the picture attacehd and I had some trouble understanding it. The question is so Under the effect of torque Mo rotates a wheel (radius r) with constant ...
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1answer
44 views

Ideal funnel design for powders

I'm designing a funnel/bottle for a powder. My goal is to have all of the bottle's powder contents come out when inverted. However, the powder has a tendency to stick to itself (like flour or brown ...
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0answers
29 views

Why increasing the coefficient of friction results in evenly distributed load in rolling machines?

I'm designing a rolling machine for reduction of steel ingots of $5 mm$ to $1.96 mm$ thick. I can convince myself using equations why increasing the coefficient of friction (in case of lubrication ...
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1answer
156 views

How to find required clamping force of bolts to prevent flange faces from twising due to torque?

I have a gearbox adapter that bolts onto a flange and I need to work out how much clamping force is needed to prevent the faces from slipping and keep the bolts in tension rather than shear when ...
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2answers
45 views

Does a washer really increase static friction force?

Suppose I have a bolt that goes through a hole in a plate and is under tension. If I place a washer between the bolt head and the plate, does static frictional force (torque actually) really double? I'...
2
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2answers
81 views

Materials to use for a low friction cable-pull

I'm posting this question on this stack-exchange site, because it appeared to be the one made for this kind of questions. If this happens to not be the case, I'm sorry, I didn't know better. Also ...
1
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0answers
105 views

How Can You Calculate Force to Overcome Friction From an O-Ring Seal?

I essentially have a piston in a tube that is sealed with an O-Ring and actuated with a solenoid. The friction of the O-Ring however, is higher than estimated (guessed as far as I can tell) by the ...
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1answer
61 views

Pan and tilt mechanism

this is my first project that i am working on. I want to make a IR sensor mount using stepper motors. I seen this on youtube and would like to make a similar design. I plan on using aluminium ...
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0answers
31 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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0answers
50 views

Where to find this kind of low friction pulleys?

I'm looking for examples of or references to the following type of pulleys, wherein the pulley system comprises a low friction ring or sheave, a fixing rope loop and a spacer element. The aim of the ...
2
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1answer
63 views

Mechanical device that creates friction when rotating?

I am designing a mock-up aircraft throttle, like one of these: In an airplane, it it slides forward and backward to control the thrust of the engines. The problem is, I am not sure how to go about ...
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1answer
105 views

Multilayered Bearing Spinner

I have a few questions relating to a multiple layered spinner that uses ball bearings to reduce friction, kind of similar to a fidget spinner. The image below is an example of the multilayered bearing ...
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0answers
41 views

What limits the power rating of a V belt drive?

We know that belt drives are limited in their max possible power rating and most high power/torque applications use gear drives. I wanted to know the main factor that limits the power/torque rating ...
3
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1answer
147 views

Deriving the amplitude of a coulomb (dry friction) damped spring

This is my first time posting anything, but I could not figure out the derivation of the amplitude of the spring for the 4 first oscillations. I am not acquainted with the effect and calculations of ...
2
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3answers
95 views

Building a machine from an ideal physics problem

I have a physics professor for whom I'd like to build a machine. Featured in a problem he is notorious for assigning students, originally from Kleppner and Kolenkow's "Mechanics," the machine causes ...
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0answers
29 views

Wax gear-chain and diamagnetic levitation

Gear chains are limited when turned on one end by static friction as the chain reaches a point where the teeth of the gears will break before enough force is applied to overcome static friction. Some ...
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0answers
65 views

Torque needed to keep a wheel spinning at high RPM

I have a treaded wheel which is 16'' diameter and 4'' across (trailer wheel). If I want it to spin constantly at 2750 RPM, what amount of torque do I need to apply to combat friction and air ...
2
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1answer
140 views

Does oil actually “attract” dirt?

The conventional wisdom consistently holds that "oil (or grease) attracts dirt", giving rise to the need for seals and dry-lubricants. But I've always considered that to be loose thinking, the truth ...
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4answers
400 views

Brake pad materials for use against an aluminium surface [closed]

For a project that I am a part of, we are in need of a brake pad material for use against an aluminum surface without causing any damage to it. So far through my research, the only safe alternative ...
4
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1answer
46 views

Dimension of the unidirectional mechanical clutch

This is a problem from the book Engineering Mechanics Statics vol-1 by Meriam Kraige. The elements of a unidirectional mechanical clutch are shown in the figure.A torque $M$ applied to the outer ring ...
3
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1answer
56 views

Normal force between two boards

This is a problem from the book Engineering Mechanics Statics vol-1 by Meriam Kraige The rectangular steel yoke is used to prevent slippage between the two boards under tensile loads $P$ .If the ...
1
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1answer
38 views

Can the hysteresis phenomenon be considered as a (type of) friction

I was wondering whether the hysteresis (in particular, mechanical motion systems) can be considered under the class of friction. From theory, I know that the frictional forces are direction, and ...
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0answers
52 views

Spinning a balanced load with DC motor

Enclosed within a consumer electronic, I would like to spin a small balanced load. The device will be rotated relative to gravity, but no other direct forces will be applied to the load. A coreless ...
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1answer
318 views

Is a gear usually held on a shaft friction or an adhesive?

So, where I work, we have this arcade game, which is a classic claw machine. IN order to raise the claw up and down the machine makes use of a worm gear, like so: (although for the meticulously ...
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2answers
569 views

Good material for friction disk for a torque hinge?

What kind of material(s) would make a good friction disk, or disks, for a friction hinge, or torque hinge? This will be for the hinge on an arm that needs to be adjustable and also hold it's position ...
3
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1answer
95 views

Recreating Focaults Pendulum

I am having issues building a recreation of Focaults Pendulum (basic, inexpensive, undergrad project). At this point, I am going to purchase aircraft cable or suspension cable unless someone can ...
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3answers
435 views

Applications with combination of high friction and low wear?

What would be some common applications involving high friction and low wear rates? for example, gear-driven mechanisms which require high friction between the gear teeth but ideally low wear between ...
1
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1answer
421 views

How do I model the friction on a rolling pulley wheel, which holds weight, on a horizontal cable?

I am currently designing a motorized zipline trolley that will carry a person on a horizontal cable, so I am trying to calculate the friction on the wheels to determine what kind of motors I need. I ...
0
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1answer
239 views

Are “interference fit” equations appropriate for calculating barrel stress?

I am curious about calculating stress at various points along a barrel as a bullet is being fired through it. The interference fit (press/friction fit) equations immediately come to mind, but I am ...
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0answers
351 views

Torque transmitted by a friction clutch

How can we calculate the torque transmitted from the engine to the transmission by the clutch and from the transmission to the engine? We know the transmission torque and inertia, the engine torque ...
3
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3answers
126 views

Understanding net torque from an actuator

This will probably sound like a silly question, but here goes.... Let's say I have an actuator, with a torque rating of 1 Nm. I then connect it to a wheel, which starts rotating at a constant ...
1
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1answer
128 views

Apply constant load to an electric motor - low tech way

I want to know how much I can over-drive a small electric motor. Its speed at the rated voltage is too slow, so I want to find a higher voltage that won't blow it. It will only be used intermittently, ...
1
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0answers
47 views

how to calculate the speed ratio (Rotational speed to advancing speed) in friction stir welding

I am a student and I work in the friction stir welding of a hardened aluminium alloy 7075-T6, and I want to confirm about this information before I put it in the article. I found in the literature ...
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3answers
1k views

Is there any material that has a higher kinetic friction than static friction?

Is there a material that has higher kinetic friction than static friction? You can assume it's sliding on any surface you want. Better if you come up with one that has this property on a standard ...
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2answers
104 views

Adding a lubricant to an already lubricious material, how is CoF affected?

I have a dry film moly-graphite lubricant (CoF=.075) and a lubricious CVD coating (CoF=.05). The CoF of each of these lubricious materials was determined using the same ASME standardized test. The ...
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2answers
276 views

Can a 2 HP motor move a 1,000 lbs flat-bottom boat across a flat material surface?

There is a small 13' long x 6' wide, 1,000 lbs (total weight of everything) all-fiberglass white pontoon boat with dual flat-bottom fiberglass pontoons. (Each flat pontoon bottom is 2' in width, with ...
4
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1answer
498 views

Determine coefficients of friction based on the torque required to rotate a part on a shaft

I'm trying to model a part that rotates on a shaft. I measured empirically that it has a static torque of around 500 N·mm and a dynamic torque of around 400 N·mm. I want to simulate it in CAD but my ...
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1answer
421 views

Pacejka Formula - natural values

For my racing game I am using a simplified Pacejka Magical Formula: $\mu_{lateral} = \mu_{0} * \mu_{1} * D * \sin(C * \arctan(B * x - E * (B * x - \arctan(B * x))))$ Where: $\mu_{lateral}$ is ...
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2answers
2k views

Not a good idea to rub two of the same material against each other?

I've read that it's not a good idea to rub two surfaces of the same material against each other, e.g., plastic against plastic, metal against metal. Plastic against metal is preferred. Why is this the ...
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4answers
11k views

Why use bushings of different material than what they contact?

I've heard that materials that need to slide against each other should be of different materials. Why is that?
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2answers
375 views

Suggestions for low friction surface materials for a “beltless static treadmill”

I'm currently developing a treadmill for clinic gait research. If I were to build a flat treadmill with no moving surfaces what materials or coatings would be worth exploring as walking surface. ...
1
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1answer
529 views

Design of Wheels/Tires for a RC Car [closed]

Background Information: My design team is trying to create a small RC car that can climb a 30 degrees incline that is 6inches high. We have two motors on a 3 wheels vehicle with the motors powering ...
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1answer
372 views

Sumo-bot Wheel Help - Sticky tires or Wide & less friction tires? [closed]

I am building a sumo-bot and our competitors have thin sticky tires, while we have wider and less sticky tires. The diameter is the same, and the gearbox/motor is the same. Who will win? PS: Sticky ...
3
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1answer
1k views

Practical uses of superfluids [closed]

I am wondering whether and how superfluids (possibly at room-temperature, if that is possible at some point) can be of any practical use in mechanical or electrical engineering or other fields. I ...
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0answers
115 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. ...
9
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0answers
211 views

What type of ultrasonic transducer would be suitable for ultrasonic welding? [closed]

Project background: I am working on a project where i need to weld plastic using ultrasonic transducers. Problem: Since I'm still learning engineering, I have a hard time figuring out what all the ...
9
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2answers
1k views

What causes friction in magnetic bearings?

Magnetic bearings work by levitating a rotating shaft so that it is not in contact with its supports. This greatly reduces the friction of the system. In all of the literature that I have seen on ...
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2answers
1k views

Are jeweled bearings commonly used for applications other than mechanical timepieces?

Jeweled bearings use a metal spindle with a jewel lined pivot hole (pictured below). They have been important in the manufacture of mechanical timepieces since the early 1700's. Their importance ...
7
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5answers
6k views

How do you attach something temporary to a smooth metal shaft?

I want to attach something small to the smooth metal shaft of a small motor (2-3 mm in diameter), like fan blades, but I want it to be temporary. If I make it too loose, then the fan won't turn at ...
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5answers
5k views

How can I improve traction on a wheeled vehicle yet reduce friction?

This is inspired by a project I undertook for my Physics class last year; I'd like to apply it in the future. Background: For the project, I and a few classmates were required to build a small car ...