Cleaning Rubber From A Surface

Rotary wire brush in a drill?

Are you sure your testing surface truly simulates a roadbed? It doesn't seem like it should be covered with melted rubber.

I would redesign the simulator to more accurately represent a real road. Then just wipe down with some 409 or similar cleaner and a rag after each use.

I've got tires with a 60,000 mile warranty. They are wearing slowly, but I'm quite sure they're not melting.

In addition to the medium not being very much like a road because roads don't contain melted rubber, are you at liberty to tell us what the medium is? A patch of 80 grit glued on a board, a SS zest grater, sub-floor adhesive on a cinder block with a bunch or gravel dumped on it?

We're on the right track, (pun intended), I would design the simulator to use a disposable belt, much like the wide ones used for floor sanders, yes, 60 or 80 grit should work. After x amount of tests, simply throw it away and replace.

I used to work as a research chemist in the rubber industry. I developed a line of additives to promote adhesion between rubber and metal. Unfortunately, my mold releases did not always work, and I had to remove the chemically bonded rubber from different test equipment (MDR Rheometer) and part molds. The only two approaches that worked for me were two of your no-no's--either soaking in an aggressive solvent (like hexane or toluene) or taking a butane torch to the rubber then polishing the metal's surface.

You might try oil (preferably hot) with low volatile content. Food oils (coconut, peanut, linseed, etc.), buttermilk, and acidic fruit juices are fairly aggressive toward natural rubber, but their effects might be too slow for your group.

Allow me to clarify some details:

The machine, as currently used has a 120 grit sandpaper belt glued to it. Tires are cycled on the machine for testing at speeds up to 100 kph. Tests will go one for a number of days with occasional breaks.

A byproduct of the prodecure is a buildup of rubber on the belt.

Now, the company is moving to plates to simulate a roadbed. They have a variety of road surfaces such as concrete, asphalt and gravel with varying types of aggegrates bonded into the matrix. These can be attached as needed. There is again a problem with rubber buildup.

This rubber does not actually melt. My mistake for a poor choice of words to describe this. The kids are trying to duplicate this buildup by melting rubber onto plates given them. They do not have access to used plates with buildup; they were assigned the task as part of their project to figure out a way to simulate the builldup. They have actually gotten some good results in duplicating the buildup effect.

They are investigating some citrus based cleaners as a part of the project, but something like that is as strong as they can go with chemicals. I will expand upon this discussion as warranted. Thanks again.

All I'm coming up with is no-no's.

Check with these people. It looks like they carry environmentally friendly products that might fit the bill.

http://www.aircraftspruce.com/menus/cs/cleaners_zrpm.html

Hello standarded.

I am still a little fuzzy about some of your details (no surprise to some), but I would offer the idea of a grinding wheel dresser.

I am afraid the mechanical action may be too violent, simply eroding the wear surface as well as loosening the undesirable tire compound so it can be blown away. Is this the right path?

I've actually thought briefly of the idea of a wheel dresser. I think it would work for an initial process of breaking up the buildup and then following up with some type of finishing process like a brush.

The main issue would seem to be to build some "compliance" into the device such that sufficient force is present to secure the dresser in place and to fracture the buildup, but not damage the substrate (road surface).

The kids are doing some tests to figure out how hard the rubber buildup is; they might be able to work from that to figure out how to incorporate a dresser. I appreciate the suggestion.

I have a further suggestion along the same line:

Mount this to a pivoting plate, swing into place, adjust pressure with screw. Not an endorsement, here is more info on this item.

Looks like a step in the right direction, but (IMHO) could do with it being a lot wider.

I would tend to agree with wider... perhaps purchase dressers as replacement parts, line up three or four together on a custom manufactured base.

Still not sure about the rather agressive nature of these; might be too much abrasion on substrate. Maybe start with a hand dresser to test before going to trouble of manufacturing a dud item.

I like this one. This might just be the idea the kids need for fracturing the buildup.

I appreciate the info.

How about a combination of Doorman's abrasive wheels with a final cleanup with WD-40?

Is the rubber stuck when it is initially deposited, or does it take time to get compressed into the wear surface? If it is not stuck until after a pass or two, a preventive air puff or vacuum (perhaps with brushes attached) would do the trick.

We use citrus based cleaner to remove cured RTV silicone but the parts have to be soaked in the fluid for 24 hours to soften the rubber. We still have to use wire brushes to remove the residue but we are trying to get parts clean enough to go in a vacuum chamber.

Most sanding belts are cleaned with a large soft eraser material. It collects the cuttings from the grid and drops freely from the belt.

No experience, but best I could suggest would be a driven cylindrical wire brush with a comb diametrically opposite the 'road' surface to clean the brush.

Is it a moving surface simulation (continuous belt forming a 'rolling road')? If so, should make cleaning easier. Fit brush at point of smallest radius (to get the rubber out from between the grit or whatever), and rotate brush counter to belt direction.

My suggestion would be to use the sticky side of adhesive tape to "pluck" the pulverised rubber from the matrix that you are using.

The 3M company (amongst others) also has available "double sided" tape and other options that might also warrant review.

Their adhesive 365 or 366 is particularly good at this sort of thing.

Another alternative might be the use of simple "blue tack" rubbed on the surface in a sufficintly large wad would incorporate the rubber residue into the wad and remove it from your wheels.

A final suggestion would be to coat it with PVA type adhesive, allow to dry, the peel it off the surface, hopefully removing all the pulverised material.

Have fun "opening" the minds of the students to alternative ideas and proposals.

A combination of two of the ideas above: tire is rotating pressed up against the sand-belt which should also be rotating, possibly slightly slower to add some friction, then for cleaning the sand-belt, first mount a heavy duty stationary brush up against the sand-belt opposite the tire, and above the brush mount a rotating wheel with double sided tape on it. You could also place a plastic shield in between the top of the brush just prior to the tape wheel contact point on the sand-belt to keep most of the airborn particles from flying onto the tape thus leaving the tape to pick up what the brush didn't remove... You could mount a number of brushes stationary up against the rotating sand-belt...

simple - use dry ice at -40deg it will freez and then just chip it away - pound it in to dust and sweep it up

Unless of course they are testing winter tires. I hope my tires don't freeze solid on the mornings when it is below -40.

I didn't see if anyone has mentioned freezing. At very low temperatures the rubber will stiffen significantly. Perhaps a rotary wire brush driven by the sandpaper immediately after chilling, or possibly just bending the sandpaper around a small radius rod or roller when chilled.

At least some rubbers have a negative coefficient of thermal expansion. It might even be that the chilling and flexing will reshape the rubber particles sufficiently that upon re-heating, they would shrink and release from the sandpaper.

If you can get the roadway upside down (i.e. get to the underside of the belt) then gentle heating (to melting) cooling and gentle brushing should do it.

I know a herb called wintergreen dissolves rubber, but i believe modern tyres don't contain much natural rubber so i'm sure it would work. Also i'm ignorant about whether or not wintergreen is benign to people.

Wintergreen is used as a natural remedy for aches & pains, usually as a rubbing ointment.

I know a herb called wintergreen dissolves rubber, but i believe modern tyres don't contain much natural rubber so i'm sure it would work. Also i'm ignorant about whether or not wintergreen is benign to people.

I just reread my post and discovered i left out the word 'not'. I'm NOT sure it would work on modern tyre "rubber".

OOOOOPS

Not an easy task. Having worked in the rubber industry, I have been there. I would try as much build up prevention as I could. High pressure air or fluid blast at the contact point with the blow-off directed at a vacuum source for the majority of containment. This is the method used to prevent build-up in some forms of precision grinding. Can work without volatile chemicals and should be containable.

I'm not sure I fully understand the mechanicals of the set up so I'll go through a couple of scenarios.

Rubber buildup on a smooth drum/wheel: Think of it as a veneer that is being bonded to the surface of the wheel. So, remove it as if you are producing a sheet of rubber veneer, with a knife/blade adjusted to constantly, or occasionally as required by the test, scrape of the rubber bits as soon as they attach, or after a certain desired thickness is deposited. You did want to replace your lawn mower blade this year, didn't you?

Rubber buildup on a drum/wheel with sand paper as an abrasive surface: I imagine that rubber detaches from the tire due to abrasion, heat, grain structure and I'm sure many other reasons, and attaches to the surface material mechanically as well as adhesively (softening/melting to conform to the surface texture) or other ways. The question here is do you intend to let the heat created at the interface of the tire and drum be absorbed by both the tire and the drum, to emulate a country road on a sunny day or does the temperature of the drum not matter _{of course it does but I'll look at it both ways}. If the temperature of the abrasive surface doesn't matter, you can use a long belt sander abrasive belt and a tensioning roller to allow the belt to cool so as to reduce the interface temperature so the belt is not as hot and the rubber particles have less of a chance to conform and bond to the belt. The inclusion of an air knife to remove particles soon after transfer, adjusted to have minimal effect on the temperature of the tire, would increase the efficiency of particle removal in combination with a brush of appropriate stiffness. Cobbled up duct work could contain and collect the particles for further study and reduce the mess. If as much heat as possible is to remain in the belt, eliminate the long belt and air knife. Maybe a call to the boys at 3M abrasives/adhesives will get you information on brush styles that will work without removing the abrasive particles. Or start a side project to determine the best brush stiffness in the development of the overall project. It happens every day in industry. Keep it real.

Just a few details and discussion, as well as some review of what the project is about;

The practice at this company has been to use an abrasive belt glued to the surface of the road simulator. While there are some confidentality issues that prevent me from fully describing the device, let me add one detail that may give you an idea of the geometric shape of the device...the radius is constant, and a specific numerical value.

Now, the abrasive belt is being supplanted by fabricated plates to be bolted to the road simulator. Various types of road surfaces (asphalt, cement and different types and sizes of aggregates blended into the matrix) are available.

Test runs about 24 hours at a clip, with occasional breaks. Before the testing starts, the surfaces are treated with a substance to prevent rubber buildup. This does help, but not completely.

Task is to remove this buildup, or what will be judged to be an acceptable amount.

The kids are limited budget wise. So, technologies like acoustics and dry ice blasting are out. Also, they have to collect the debris, which will consume some of the budget. Not much, but some.

Toxic chemicals and some dry media such as glass beads are a no-no. They investigated a commercial airport runway cleaner, but it has sodium hydroxide in it; that was shot down early in the process. Something akin to the strength of a citrus cleaner of a "household" strength is about as far as they can go. Oils are out as well, unless they come up with a way to clean that off and collect all the liquids and the debris. The friction coefficient of the surface needs to maintained fairly closely to that of the surfaces before testing.

Also, there is a 30 minute time limit.

The kids are putting together tests under loading to analyze brush performance and endurance. Also, they are testing various types of nozzles for liquid spraying to optimize performance and help with liquid containment.

My feeling is that a combination of simple processes will be required to make this happen. Thanks to everyone for your responses.

Would medium to high pressure steam fit into the scheme of things?

Trying to picture this. Am I right in assuming that the shape of each plate is part of the surface of a cylinder (with radius equal to "a specific numeric value")? When you first mentioned "plates", I jumped (seemingly erroneously) to the conclusion that they were flat (2D) - which is where I got lost.

Could I imagine that they are similar in shape to the contact areas of the commutator of a DC brush motor?

Make our lives a lot easier if you posted a sketch!

Could you use a simple blade downstream of the wheel contact point to plane the debris off? If the blade were angled the debris would be directed to one side for collection.

I'm not sure there is a "down steam".

It does sound like wheel spin on the spot - not like any tyre or rim testing setup I've seen - or racetrack rubber scenario.

I'm kinda thinking the "kids" are being asked to find a solution for an originally flawed test design/apparatus.

Maybe you're right, I was imagining a wheel against a spinning drum.

Like Nigh, I was assuming that both the tire and the sandpaper were moving, although I was picturing a belt, to have a flat surface.

If the sandpaper 'road' is NOT moving, then all they are simulating is the initial tire slip at 'pop the clutch'.

If they are trying to simulate any kind of driving, then the 'road' should only be stopped at initial startup, and then be moved along by the tire. I think only a belt could realistically represent a road. A standard benchtop belt sander would work fine, as long as the pressure of the tire on the surface was not too great. Depending on the kind of motor, it might be possible to use the motor as a generator to add resistance to the belt's motion (representing air resistance of the car and/or climbing an incline).

Check out the link in #41. Tyres rotate, drum rotates.

Down here in New Zealand we use ultra high pressure water for both rubber removal and removal of flushed bitumen from our roads

Dip it in LN2 and then hit it with a hammer. the rubber will shatter. this is what molders of custom oil well packer elements with expensive overmolded springs do when there is a molding problem and they want to recover the springs for re-use.

Good morning.

The kids came by the shop late yesterday with an update. Now before I start, I will again state that while I can't specifically describe the machine they are working with, I did find this document on the web.

http://www.mts.com/stellent/groups/public/documents/library/dev_002230.pdf

Since it's a public document, I see no harm in providing the web address.

Now, to the update. I had the advantage of the kids showing me the taping of their review session with their advisors; several professors in their department.

So, here are a few things...Liquids of ALL types seem to be out. One of the "advisors" was (I feel) overly stringent in his condemnation of their even considering any liquids.

Indeed, the advisors seem to want to push the groups (there are 4 different ones working on the problem) to some common solution, instead of allowing some latitude in selecting a solution.

It would appear today that they are leaning to a brushing operation, with some type of pre-brush operation to at least partially break the residue buildup, and maybe a post-brush process as well, along with a vacuum to collect the debris.

Also, another interesting point I was not aware of until yesterday. The thing has to be operated from outside of a closed room. The kids can pass umbilicals through an opening, and go in and set it up and tear down, but they have to run the process outside the room.

A last idem is this; the kids are refining their process to adhere their rubber samples to the plates. Currently, it's baking at 175C (350F). They want to set up a fixture that would allow them to apply force during the bake ops. I suggested some type of medium that would sit on top of the rubber coated plate (plate would sit in fixture, coat with rubber, apply "medium", attach top cover, load to apply pressure). Since their plates are currently gravel bonded in a matrix, the surface is not 100% smooth, so some medium with give to fill the "nooks and crannies" would be needed. Maybe in addition an intermediate sheet to separate the rubber from the medium, to prevent intermixing of the two. The topic of using sand as a medium was broached, but the idea of a sheet material to separate the sand and rubber is an issue.

Anyway, they're working away on it. These young men and women would make about anyone proud for how dedicated they have been to doing this.

Martin guitars used a "vacuum sandwich" fixture type system to apply even pressure to bond the inner stiffeners of the back panel of the guitar before assembly. Vacuum constriction is also used in the manufacture carbon fiber items. They just place the item in a purpose made plastic bag and draw out the air. The individual panels you are dealing with would fit nicely unless you need more pressure then atmospheric, in which case you place the vacuum bagged piece into a pressure vessel. Maybe get Kentucky Fried Chicken on board. I joke...but then I'm sort of serious. As long as an idea gets across. Most restaurants have steam/pressure cabinets to process bus pans of vegetables. I think waaay outside the box.

I just thought of this. Remember the adds on TV about storing 25 blankets under your bed in a plastic bag that is vacuumed down using a home vacuum cleaner. That's a good cheap way, with heavy duty garbage bags, to do an initial study as to the suitability of that system. Need a deeper vacuum, raid the science building, unless, of course, you/they are the science building.

So, if the 'plate' is really a big rotating drum, what's wrong with having a fixed blade sitting just above the surface to remove the debris build up? This is a common industrial method.

I'm guessing, of course, that the idea is to present a "fresh" simulated road surface at each rotation of the drum. If the surface choice for a particular test is to be perfectly smooth, a scraper blade would be fine. If the surface is textured, a scraper blade can only shear off buildup above the highest point of the surface, otherwise damaging the textured surface, leaving the remaining buildup filling the valleys and "poisoning" the data.

OK, I can see that, so maybe a scraper for the high stuff with a wire wheel or brush for the embedded material.

I reckon if the brush worked, it would never build up high enough to need the scraper. Wouldn't have thought it could rip that much rubber off in one rev!

Well, I would like to report on the final outcome of this project that these kids worked on. They completed it, got graded, and several are graduating.

First, let me update you on what actually happened. The college organizing the projects had an open forum for all project teams, and then each individual team presented their solution to the group of professors assigned to advise them, and representatives of the sponsoring company, as well as "interested onlookers".

Their solution was a cylindrical brush driven by a motor; these components mounted to a pivoting frame (basically a square tubing frame, with two uprights and two tubes connecting the uprights); this mounted to a secondary frame mounted to the floor, and the "brushing frame" was pivoted with a clever little device, powered by a small motor, which screwed a rod end "in and out" to allow the brush to press against or be pulled away from the surface to be cleaned. A simple set of timing indicators would allow an operator to monitor the movement in and out, and allow for simple adjustment of the brush to compensate for wear.

Well, I was talking to the company rep afterwards, and he indicated that they would probably use this design, or at least the basic concept. It seems the other teams proposals were far more complicated (and expensive), using computers, sensors and actuation devices to do the same tasks that "my team" proposed their simple design and a service tech would do.

However, the kids did not get as good a grade as I feel they deserved. It seems that the professors were more impressed with the complexity of their fellow students' projects. I has asked one of the professors after the event finished about his comments during the presentation, as he highly praised the efforts of the other teams, and their designs. He responded to my question as to his apparent favoring the designs which featured all the electronics and computers, and his response was "that is wave of future". My next question was what would happen when this stuff broke, would this design be quite so appealing?

His response was that I just did not understand that "this is what is needed today, this crude device is not correct".

I finished by telling him that the company rep told me that the "crude device" was what they were actually looking to use, and also asked this professor if he had actually worked in industry at any point. He indicated that he had been strictly in academia, and seems to have no "practical" experience.

So, that's that. I think the kids got a bit shortchanged grade-wise, but at least their design might just see the light of day. And, all of them but one (to date) have good job offers waiting for them. I am proud of what they did. If we get more young people like these in engineering, the future might just be pretty decent for them.

Congratulations to you and "your team" on a job well done.

Sorry to hear about the short-sightedness of the profs - they could all do with a couple of years in the real world, especially if they're trying to train students for that environment. What was their discipline - "Theoretical Engineering", or maybe IT?

Sounds like your group produced what we would regard as a good, practical , cost effective solution. Congratulations for that.

The reaction from the judge is exactly what you find with new graduates entering engineering. It takes a while to beat them into shape but it sounds like you are giving your students a head start. Keep on doing what you do, the world will be a better place for it.