Why don't tire manufacturers prescrub tires?

[Guest]

It is actualy used more to make tool production cheaper (Such as cheaper, longer lasting molds, and faster production).

From a production point of view, I cannot see why an extra step to remove the slick layer shouldn't be added. it would be simply one additional step, if at all. A simple solutioin would be to use a mold lubricant that degraded quickly when exposed to oxigen in the air, or uv from sun light.

This is the kind of thing that Tire producers would probably like to know about as a complaint. Both producers looking for an edge over their compeditors, as well as industry regulators need to know that this is a problem.

Mold life won't change by a perceptible amount from the use of mold-release agents. The release agent allows the tire, and its attached vents, to not stick to the mold.

As I wrote earlier, there would be more than a single step. To be more specific, the tire would need to be washed. To be more effective, the washing should penetrate between the tread blocks. This would require some combination of high pressure hot water and rapidly spinning brushes. Keeping water out of the inside of the tire would be necessary, so that drying the inside of the tire could be avoided. This would likely involve mounting the tire on temporary chucks and inflating it (can be done in about 5 seconds). Selecting the chucks for different tires would require a sorting step, and probably moving pallets of tires. After washing, the tire would need to be dried, probably by hot air blown at high speed, something like the driers in automated car washes. The dirty water then needs to be pumped to the factory's waste treatment plant.

Some of the mold release (usually some sort of greasy soap) is probably incorporated into the outer few thousandths of an inch of the tread rubber. To remove that, the tire would need to be buffed. The tire would first be remounted amd inflated on the temporary chucks. Buffing could be manual, using cloth wheels attached to flexible drives. That system would be prone to non-uniformity, gouging the tire at some spots, and missing others. So it would be better to have a series of buffing wheels that would press against the tire while the tire was itself rotated. This would require another sorting step, as each tire would require buffing machine settings to match its profile.
Buffing generates dust, which would have to be controlled, and probably would be done in a booth from which air would be filtered.

Tire treads have marking codes on them, both colored lines and combinations of letter and numbers. The codes are applied as the tread is extruded. Codes tell the factories which tire the tread goes on, what mold an assembled tire goes in, how the tire is to be inspected and balanced, and how it will be handled in warehouses after it leaves the factory. Buffing would likely remove this marking, so another marking codes would need to be applied after buffing.

Not everything can be designed to degrade by exposure to light, and I strongly suspect that mold release agents are among those things.

So, I believe that it is worth the few minutes needed to scrub a new tire with water and a brush, or to ride the bike to a car wash and hit the tires with hot water. Then ride slower, at lower lean angles for a hundred miles.

 

[BentRod]

just because I'm stubborn, I'm going to support my earlier claim that mold release helps lower tool cost and increase mold life.

Tires are cast in machined, metal molds. most likely internally cooled.
Rubber is forced into these molds, where it is solidified, and then released, hopefully in one piece. if you do not have mold release then:
you either have to deal with some percent of production coming out of the mold in multiple pieces as some bits of rubber will likely stick to the walls of the mold. You can imagine that when this happens, production must stop while some unlucky fellow scrapes out the stuck chunks.
OR
you must machine your molds to a fine surface finish. these surfaces would have to be polished from time to time, by hand. The increase in surface finish would either mean cutting much slower on more precise milling machines, (using more cutting heads, I might add) or doing 2 complete passes, (adding hours, if not days to the production time for a set of molds)

hence, to cut costs.. mold release is nessisary.


Second point.. again, because I'm stubborn.

I understand not everything can be made as easily as to fall off in the sun, or simply dissolve in the air. However, this lube that is covering our tires and causing accidents to the unlucky, reaks of lack of thought. the design objective would be simple. a cost effective lubricant, capable of widthstanding high temperatures that will not mix with the rubber in the tire, and can be easily removed post production.

something such as fine fly ash. it is widely available and almost free. application to the mold could be done using static charges, there by ensuring an even coat. Static electricity could also ensure that there is no mixing of fly ash with the rubber compound by using like charges.
The tires would only need to washed with pressurized water, which could then be filtered, recovering the fly ash for disposal.

but then, this is just an idea. my point is that making new tires slick is not nessisary for production, and that if the correct people are informed, then this problem can be resolved, rather then us continually complain to each other in some hope to make our selves feel better about having to scrub new tires.

 

[tkent02]

Is it really a problem???

95% of those who buy tires never go anywhere near the limits of traction, those who do should know how new tires work. On a car you just slide a little, a bike squirms around but if you expect it to happen it's no big deal.

I always thought it took several heat cycles from driving/riding at high speed to get a new tire working well.

Modern tires have great traction even before they are scrubbed, it only gets better.

Who cares, really? Go easy for a day or so.

 

[Steve]

Whether or not you remove the mold release before riding, there is another advantage of riding easy for about 100 miles. :shock:

For those of us that ride, that is, wear the tires out before they dry-rot, the profile of a worn tire can be significantly different than a new one. The bike will handle different on this altered profile, and it will take a bit of easy riding to get used to the new profile.


.

 

[Guest]

Bent, I had a career that is best described as "making new processes work in factories making tires and rubber products". The tech section of this forum is filled with unforseen consequences when a repair method doesn't work properly. Those consequences can be bigger than the problem that the repair was meant to fix. Same thing applies in factories. Tire molds have been tried with super smooth surfaces, and with various coatings to facilitate easier tire release. Tread designs are limited by mold release concerns. I don't consider mold release a cost-reduction item, since it is absolutely needed for production at all. Without effective mold release agents would costs thousands of dollars each, since more time would be spent cleaning molds than in curing tires. Tires leave a residue on molds, and is mostly oxidized oil from the rubber compounds. This residue slowly builds up. Eventually, the mold must be removed from production and cleaned. When I was in that industry, glass bead blasting was most commonly used, and it needed to be used carefully to not damage the molds. Chemical treatments have also been tried.

I can't begin to imagine how any dry substance could be used. I believe that fly ash is abrasive, wouldn't want it in factories. I also believe that it would be hell on workers' lungs. The containment problems would be outrageous. High voltages needed for electrostatic applications are inherently dangerous. Electrical isolation of a mold from the curing press would require a significant press re-design. Very, very expensive.

Have you ever been in a tire curing room?

 

[80GS1000]

So, if one were to call/write Michelin/Bridgestone/Pirelli/Metzeler etc and complain about slick and slippery new tires, do you think they would actually care and/or do something about it? We want grip, not slip from our new tires.

 

[salty_monk]

I would think the most likely reason for using mold release is two-fold.


1: they can run faster cycle times & still get the tyre out successfully which has a huge impact on cost.

2: if a tyre was to get stuck in the mould it's a big cost to free it & if the safety's don't trigger you run the risk of closing the tool on the now hard rubber & breaking something.

I don't whether any of the companies would give a monkey's about a letter suggesting this. The machinery discussed earlier would be a huge capital investment. I'm sure they would rather spend it on more moulding eqt.

Does anyone actually know someone who had an accident specifically because of this issue? Surely it just takes a bit of care. 100 miles or so isn't far.

Dan