rubber components used in voting machines. - polycarbonate sheet uses
Clock-in voting machines are used in many constituencies across the United States because they are relatively low cost, easy to adapt to long or multi-language voting and produce more or less machines
A permanent record that can be read.
After the last presidential election, the methods used in some parts of Florida have led to a rethink of their suitability.
In addition to other factors, the durability of rubber parts is also questioned (ref. 1).
Two types of devices are used.
In both cases, the metal
The pen tip stylus is placed in a position on the punch card ballot paper by a circular hole on the transparent molded polycarbonate sheet over, presumably equivalent to the voter's choice with this stinking, "Chad ", trough formed by a rubber strip lying directly under the punch card.
The gap between rubber strips is smaller than Chad (or thestylus).
In this way, these pieces can be captured by the machine;
These are actually recycled in some areas.
The force required to drive the stylus is quite variable (25 to 80grams)
Because there are several types of stylus as well as variations in punchcards.
Based on the model developed by byIBM many years ago, Votomatic machine uses a molded T-
A parallel-arranged rubber bar of vulcanization, fixed by a flat area at both ends fixed in the plastic (ABS)
Frame of equipment. Unused T-
From the machine manufactured in 1975, strips and strips used and stored in environmental conditions were obtained (ref. 2).
The decomposition of the compound indicates the following points: plus a small amount of fatty acids, phenol antioxidants and asulfur-
Aromatic amine curing system.
It is basically a 65 durometer Aplaten or roll cover, with a tensile strength of more than 17 MPa under the best scraping spoon and a limit elongation of about 350%.
The surface of the unused part does not show any signs of oozing or blooming. The 25-year-
The old sample has grown to about 70 degrees but no trace of evidence has been shown
Cracks under low magnification, even at the end of the clamp.
75 [accelerated aging of unused samples for 100 hoursdegrees]
C. The increase in the hardness of ledto is roughly the same.
One machine for voting stars-
The gap provided by the slot, not the way the individual is arranged-strips.
The compound used is Bayer Texin 285, polyester TPU.
While this compound produces 85 durometer A, due to the slightly thinner configuration provided, the force required to drive the stylus is roughly the same as that of the Votomatic machine.
Got an unused pad and a pad that used four elections (ref. 3).
The hardness of the latter does not increase compared to the unused liner (82-86 durometer A).
The above samples were inspected by dynamic mechanical analysis (DMA)
The point bending fixture is adjusted so that the amplitude of the deformation is similar to the amplitude of the deformation caused by astylus in the punching machine.
The sample was not reduced to a standard thickness, but was found in a typical voting machine, that is, the TPU sample was slightly thinner than the br/NRanalogs.
In Figure 1, the relationship between the elastic modulus of two unused samples and the deformation frequency is plotted. [GRAPH OMITTED]
The two conclusions are obvious.
At low frequencies, there is not much difference in the response of TPU and br/NR compounds.
At present, it is not known whether the TPU compound is specifically used to approximate the dynamic properties of the original Ding benzene/NR compound, or simply as a durable material that can be directly injection molded.
Secondly, the range of applied deformation frequencies required to cause a significant increase in apparent elastic modulus is far greater than the range found on site, and even assuming that voters who strike quickly without studying the ballot papers are used (
No instructions to say).
In Figure 2, the relationship between the elastic modulus of the sample used and the frequency is plotted.
TPU samples are basically unchanged.
The band of the benzene/NR compound shows a considerable increase in modulus, but only at a frequency far beyond what may be encountered on site. [GRAPH OMITTED]
Maintenance of voting machines includes removal, removal of accumulated debris, and treatment of rubber strips with silicone, such as for cleaning typewriter panels.
Folk legend has it that this treatment "restores" the rubber, assuming that some of the ingredients are absorbed into the composition and affect its performance (ref. 4).
Both types of waste rubber strips were treated with sotreated, allowing the applied spray to dry at room temperature.
The repetition of the tests described in figure 2 yields the same result.
This maintenance procedure is likely to have the effect of removing paper fibers from the acting surface of the strip, restoring the friction coefficient to its original level.
To sum up, the elastic components of the punch card machine seem to have satisfactory durability for the intended use.
Unreadable votes are likely to be largely due to human error rather than the fact that machines are not suitable for service. References:(1. )Case No. 00-
2808. Gore, Lieberman and others. , v.
Harris, Bush, Cheney, etc.
Leon County Circuit Court, Florida, December. 2, 2000. (2. )
Provided by the United States joint election Supply Corporation
Napa, California. (3. )
Provided by election data
California Valley Center. (4. )
For a practical example of remediation in this area, see RubberWorld, 20 pages, July 2000.
Technical guidance from Richard Grossman with Halstab, supplier oflead base and other thermal stabilizer.
He started his career in the rubber industry in 1957.
He also worked in polysar, synthetic products, Cook color and polymer services.