The importance of dimensional stability in the tire carcass.
Reinforcement fibers with dimensionally stable properties - high modulus and low shrinkage - have made an important contribution to tire performance in recent years. Advances like improved cornering and handling, greater tire-curing uniformity, tread wear, prolonged endurance and better tire economics are the result of advances in dimensional stability dimensional stability,
n See stability, dimensional. .
For these reasons, improvements in modulus and shrinkage in tire yarn have been the focus of fiber suppliers' R&D in the past 15 years. Table 1 shows just how important dimensional stability is to a tire's performance, appearance and cost.
[TABULAR DATA NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. ]
The carcass carcass, carcase
1. the body of an animal killed for meat. The head, the legs below the knees and hocks, the tail, the skin and most of the viscera are removed. The kidneys are left in and in most instances the body is split down the middle through the sternum and the vertebral of a pneumatic tire Noun 1. pneumatic tire - a tire made of reinforced rubber and filled with compressed air; used on motor vehicles and bicycles etc
bicycle wheel - the wheel of a bicycle is responsible for the transmission of all forces that pass between a vehicle and the road surface over which it is driven. Factors such as ride comfort, braking ability, lateral/longitudinal acceleration and tire durability are intimately linked to the specification and performance of the carcass. Small changes in the construction of the carcass can have significant effects on the performance of the tire/vehicle combination. The selection and application of materials for this application is therefore extremely important.
Characteristics of dimensional stability
The dimensional stability of a thermoplastic A polymer material that turns to liquid when heated and becomes solid when cooled. There are more than 40 types of thermoplastics, including acrylic, polypropylene, polycarbonate and polyethylene. fiber reflects its inherent tensile modulus. Several mathematical definitions exist, but one of the most common ones is the algebraic sum as distinguished from arithmetical sum, the aggregate of two or more numbers or quantities taken with regard to their signs, as + or -, according to the rules of addition in algebra; thus, the algebraic sum of -2, 8, and -1 is 5.
See also: Sum of the fiber's EASL EASL European Association for the Study of the Liver
EASL European Association of Sinological Librarians
EASL English As a Second Language
EASL Existing Automation System Level (FAA) (elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. at specified load In civil engineering, specified loads are the best estimate of the actual loads a structure is expected to carry. These loads come in many different forms, such as people, equipment, vehicles, wind, rain, snow, earthquakes, the building materials themselves, etc. ) and thermal shrinkage. These parameters are important to the material development engineer, and to the tire process engineer and designer, because they define the ability of a fiber to be treated to a desired modulus without reaching an undesirably high level of thermal shrinkage. The level of shrinkage associated with a defined modulus as measured by the EASL has a profound effect on the tiremaking process and the final tire characteristics. These effects are associated with the changes that occur as the cord shrinks during tire curing and subsequent cooling, and can result in varying effects on the tires:
* Variations in the tire size/dimensions (differences in section width and circumference);
* differences in tire uniformity Tire Uniformity refers to the dynamic mechanical properties of pneumatic tires as strictly defined by a set of measurement standards and test conditions accepted by global tire and car makers. (due to uneven shrinkage around the tire);
* tire durability (due to cord/compound movement and tire geometry);
* carcass splice depressions (sidewall side·wall
1. A wall that forms the side of something.
2. A side surface of an automobile tire, between the edge of the tread and the wheel rim.
Noun 1. indentations due to shifting of in-tire carcass cord modulus);
* variations in tire performance (due to in-tire cord properties).
The continually improving dimensional stability and related properties of the advanced tire cords provide a number of benefits over conventional polyester to tire makers and tire consumers. Among these benefits are:
* Longer tire life and theoretical greater fuel economy due to lower hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. and resulting lower heat generation;
* tire manufacturing economies resulting from the elimination of the need for the post-cure inflation (PCI (1) (Payment Card Industry) See PCI DSS.
(2) (Peripheral Component Interconnect) The most widely used I/O bus (peripheral bus). ) process in radial tire production;
* improved tire uniformity;
* reduced sidewall indentations at the carcass splices to meet auto industry tire quality standards.
Standard polyester (PET) vs. advanced polyester
The first polyester yams to be commercialized during the 1970s and the early 1980s for applications such as passenger tire carcass reinforcement were of a quality that we today call "regular" or "standard" polyester.
During those early days of polyester application development for tires, the carcass splice depression (sidewall indentation in·den·ta·tion
A notch, a pit, or a depression. , or SWI SWI Software Interrupt (ARM CPU instruction)
SWI Social Welfare Institute
SWI Secure Windows Initiative (Microsoft)
SWI Steel Window Institute (Cleveland, Ohio) ) was one of the main weak points of polyester reinforcement. Sidewall indentations may occur in monoply tire sidewalls adjacent to the body splice region (figure 1a). The high (double) cord density in the splice overlap yields half the stress per cord compared to the non-splice cord. Consequently, the overlapped cords undergo less elongation during tire inflation and the result is a localized radial depression (indent To align text some number of spaces to the right of the left margin. See hanging paragraph. ) in the sidewall (figure 1b). The tire is not affected structurally, but this cosmetic aspect is important in many markets.
Other problems with standard polyester for tire building could be resolved by:
* Adjusting fabric treating conditions to modify the relative levels of shrinkage and modulus;
* adjusting the tire building and curing processes.
It was difficult to treat standard polyesters such that they met minimal technical requirements for passenger radial tires, and fiber technology had not yet begun to develop alternatives in the form of advanced polyesters with improved dimensional stability.
Fiber suppliers' R&D efforts finally paid off when the first advanced polyester became commercially available in the early 1980s. The missing ingredient, i.e., dimensional stability, had finally been captured.
Understanding advanced polyester's growth for tires
The magnitude of the dimensional stability changes achieved with PET is clearly shown by the product line in table 2. In comparison, 1X30 and 1X40 DSP (1) (Digital Signal Processor) A special-purpose CPU used for digital signal processing applications (see definition #2 below). It provides ultra-fast instruction sequences, such as shift and add, and multiply and add, which are commonly used in math-intensive (dimensionally stable polymer) fibers exhibit 20% and 50% higher intermediate modulus compared to first generation DSP fibers (1X90/93), but with 1X40 slightly deficient in strength. 1X40 was designed to possess the dimensional stability to displace rayon at reduced cord weight/ tire and still have the strength to permit this substitution. The newly emerging 1X50 has both high strength and dimensional stability.
[TABULAR DATA NOT REPRODUCIBLE IN ASCII]
Today, tire makers in the U.S., Japan and Australia are using advanced polyesters for virtually all passenger radial tires. In Europe, where polyester is rapidly replacing rayon as the reinforcement of choice, every tire maker is either using or evaluating polyester fabrics for tire reinforcement. A similar pattern is unfolding in developing countries of Central Europe Central Europe is the region lying between the variously and vaguely defined areas of Eastern and Western Europe. In addition, Northern, Southern and Southeastern Europe may variously delimit or overlap into Central Europe. , Africa and the Middle East, where the utilization of polyester has become more apparent in the last 18 months.
Two main technical reasons explain why polyester is being specified or evaluated so often for tire reinforcement today:
* The technical performance of polyester has now reached the point where its use in radial passenger tires can significantly improve tire performance. In addition to passenger radials, other tire types such as light truck, agricultural and recreational vehicle tires are now being produced with advanced dimensionally stable polyester.
* Sufficient experience has been gained to support the use of polyester in tires previously thought to be outside of its design range, i.e. H, V and Z speed rated tires. Indeed, current generation polyester fibers Noun 1. polyester fiber - a quick-drying resilient synthetic fiber consisting primarily of polyester
polyester - any of numerous synthetic resins; they are light and strong and weather resistant , when combined with sufficiently well developed conversion, tire design and tire processing technology, are well suited for use in the full range of radial passenger tires.
Manufacturing of tires with advanced polyester cord
The evaluation of a new reinforcement material is always considered as a heavy task requiring large internal development resources and involving tire building and intensive tire testing (tire measurements of sidewall indentations, handling, tide, uniformity, plunger energy, high speed and endurance performance, etc.). However, a tire manufacturer can still be interested to evaluate a new reinforcement like advanced polyester for two main reasons:
* Introduction of a new tire line (radialization, tires for export markets, original equipment markets, etc.);
* substitution of the current reinforcing material (rayon or nylon) to decrease the cost and/or increase the performance competitiveness of its tires.
In order to gain the maximum benefit from the available technology it is important that tire companies Manufacturer Country Est. Brands and Subsidiaries
Aeolus Tyre China
Alliance Tire Company Ltd. Israel 1950 Amtel-Povolzhye, Kirov; Amtel-Chernozemye, Voronezh
Apollo Tyres Ltd. work closely with the fiber makers from the first stages of tire design in order to ensure that the correct decisions regarding fiber and fiber characteristic choices are considered. Fiber companies have technical expertise and can offer valuable assistance for the makers when making decisions regarding fiber type, strength requirements, replacement ratios, fabric treating and adhesive systems and even offer the services of extensive laboratory facilities and technical personnel to assist in evaluating and testing activities.
First steps in evaluating a new polyester
The first contact with polyester is obviously through laboratory evaluation. While it is unlikely that this evaluation can eliminate the need for tire performance testing Performance Testing covers a broad range of engineering or functional evaluations where a material, product, or system is not specified by detailed material or component specifications: Rather, emphasis is on the final measurable performance characteristics. , it should be able to "screen" for an easier selection of potential cord candidates. Polyester treated cord samples covering a wide range of physical properties, twist levels and material types can be easily and quickly prepared on a laboratory single-end treating unit. This unit reproduces the exact treating conditions experienced by a tire cord in a majority of industrial dipping units.
Realistic projections of the change in properties from treated cord to cured tire and from cured tire to run tire can also be realized in those laboratory simulations as well as the assessment of the inherent fatigue and adhesion properties of the reinforcement.
These preliminary results should bring interesting insights to the tire design engineer on the potential improvements in tire performance he or she might expect when using polyester and enable a fair comparison with existing reinforcements.
When using advanced polyester reinforcement, one aspect of the fabric testing process becomes of primary importance - the measurement of the cord shrinkage. Inexpensive and standard apparatus exist and should be part of the standard equipment of the raw material testing laboratory.
In addition to the laboratory evaluation of the material itself, it is important to study precisely its compatibility with the neighboring neigh·bor
1. One who lives near or next to another.
2. A person, place, or thing adjacent to or located near another.
3. A fellow human.
4. Used as a form of familiar address.
v. rubber compound. Several factors in rubber are important in controlling the chemical degradation of polyester cord and the adhesion of polyester cord to rubber. The amines amines (mēnz´),
n.pl organic compounds that contain nitrogen. released from some accelerators during vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold. might lead to this degrading phenomenon called aminolysis.
Carcass stocks which minimize or eliminate the presence of amines retain good performance in polyester tires in severe tests. These stocks contain vulcanization accelerators that do not liberate amines or additives. Rubber chemical suppliers can recommend the best suited accelerators when polyester reinforcement is being used.
Provided that the laboratory results are satisfactory, at this stage the definition of a treated fabric specification should be considered in light of the reasons why polyester reinforcement is being envisaged (new tire or material substitution).
The choice of the polyester yam type and linear density, construction and twist level, fabric characteristics and treated cord properties is made through extensive technical exchanges and at its best when partnership between the tire manufacturer and the fiber supplier exist.
When substituting rayon or nylon for polyester, cost and performance considerations should always be kept in mind. The actual substitution will heavily depend on:
* The application of the tire (passenger, light truck or heavy duty);
* the utilization in the tire (carcass or belt);
* the market (original equipment, replacement, exports);
* the performance/economy trade-off.
As an example, table 3 shows some of the theoretical trade offs that are possible in a normal monoply tire when substituting rayon with polyester in the carcass. The two conversion strategies considered here are equal strength and equal endcount. When considering equal endcount, the replacement of 1650/2 denier de·ni·er 1
One that denies: a denier of harsh realities.
Noun rayon by 1000/2, 1300/2 and 1500/2 denier polyester has been calculated. The conclusions to be drawn from this exercise are two fold:
* On an equal strength basis the weight of fiber in the tire carcass can be reduced by over 30%.
* The availability of multiple constructions to replace the rayon construction at equal endcounts allows significant variations in strength/weight to enable the tire manufacturer to obtain the desired balance between fiber usage and carcass strength.
Table 3 - rayon to polyester conversion properties Yarn (Decitex) Strength Strength Weight per cord in tire in tire Base - rayon (*) 100 100 100 1840/2 SII 1100/2 PET (1X30) 97 100 65 at equal strength 1100/2 PET (1X30) 97 97 62 at equal epdm(**) 1440/2 PET (1X30) 124 125 82 at equal epdm(**) 1670/2 PET (1X30) 138 143 94 at equal epdm(**)
(*) Index to which other constructions are compared. Weight are related to dry rayon base (**) ends per decimeter dec·i·me·ter
n. Abbr. dm
A metric unit of length equal to one-tenth (10-1) of a meter.
Noun 1. decimeter - a metric unit of length equal to one tenth of a meter
A typical substitution scenario would give higher carcass strength and toughness (110-130%) and lower fiber weight (80-90%) for overall reduced fabric cost.
One important consideration when designing tires for today's original equipment applications is the ever increasing pressure from the vehicle manufacturers to reduce tire weight, improve uniformity and reduce rolling resistance Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when an object such as a ball or tire rolls. It is caused by the deformation of the wheel or tire or the deformation of the ground. .
Less material - eliminating one body ply (mathematics, data) ply - 1. Of a node in a tree, the number of branches between that node and the root.
2. Of a tree, the maximum ply of any of its nodes. in the carcass
The significant tenacity advantage that polyester has over rayon gives the tire designer an opportunity to completely eliminate one body ply from some tire designs while maintaining tire strength. This opportunity might be combined with the fact that the total amount of rubber per square meter Noun 1. square meter - a centare is 1/100th of an are
centare, square metre
area unit, square measure - a system of units used to measure areas deposited on the fabric during the calendering calendering, a finishing process by which paper, plastics, rubber, or textiles are pressed into sheets and smoothed, glazed, polished, or given a moiré or embossed surface. process can be reduced substantially due to the difference in cord gauge between rayon and the polyester construction. However, the decision on the rubber gauge to be used still needs to be based on the compound viscosity and the tire building technology.
Apart from the close examination of the carcass compound, a first trial with advanced polyester tire cord does not usually necessitate any other heavy modification of the tire design critical parameters unless important endurance problems are already present. The optimization of these parameters will start as soon as the first plant trials have been completed and once the first results (indoor and outdoor) have been obtained.
One important aspect of this first exercise is obviously to become familiarized fa·mil·iar·ize
tr.v. fa·mil·iar·ized, fa·mil·iar·iz·ing, fa·mil·iar·iz·es
1. To make known, recognized, or familiar.
2. To make acquainted with. with the new reinforcement, from the calender CALENDER. An almanac. Julius Caesar ordained that the Roman year should consist of 365 days, except every fourth year, which should contain 366, the additional day to be reckoned by counting the twenty-fourth day of February (which was the 6th of the calends of March) twice. to the ply cutting, from the tire building into the curing, and from the pulley pulley, simple machine consisting of a wheel over which a rope, belt, chain, or cable runs.
A grooved pulley wheel like that used for ropes is called a sheave. wheel to the road (figure 2).
With the utilization of polyester, the potential to design tires with overall improved rolling resistance, lower weight and better performance becomes apparent. In this way, polyester gives the tire designer the flexibility and tools which allow the manufacturer to meet die requirements of his customer, i.e. the vehicle maker.
[1.] "Tire cord and cord to rubber bonding," T. Takeyama, J. Matsui and M. Hijiri, in Mechanics of Pneumatic Tires, U.S. Department of Transportation, 1981.
[2.] "Dimensionally stable PET fibers for tire reinforcement, "P.B. Rim and C.J. Nelson, Rubber World, Vol. 2, May 1991.
[3.] "An approach to laboratory fatigue testing on tire cords," A.L. Promislow, ISIFM Meeting, May 1991.
[4.] "PET substitution for rayon in European radial passenger tires, "P.B. Rim, C.J. Nelson and D.S D.S Drainage Structure (flood protection) . Liu, Kautschuk Gummi Kunstoffe., Vol. 45,1992, p. 268.
[5.] "The behavior and performance of PET reinforced passenger tires," Kautschuk Gummi Kunstoffe., Vol. 45, 1993, p. 297.
[6.] "Polyester breakthroughs in fiber performance, " G.S. Rogowski, Kautschuk Gummi Kunstoffe, April 1994, pp. 276-278.
[7.] "Polyester fiber for radial tire reinforcement, " J.D. Burrows Burrows is a provincial electoral division in the Canadian province of Manitoba. It was created by redistribution in 1957, and formally came into existence in the provincial election of 1958. The riding is located in the northern part of Winnipeg. , presented at the conference on the New Direction in the Rubber Industry, Zlin, Czech Republic Czech Republic, Czech Česká Republika (2005 est. pop. 10,241,000), republic, 29,677 sq mi (78,864 sq km), central Europe. It is bordered by Slovakia on the east, Austria on the south, Germany on the west, and Poland on the north. , 22-23 November 1994.
[8.] "How polyester is changing the European tire-making business," J.D. Burrows, presented at TyreTech 95, Turin, October 1995.