• Discussion about railroad topics everywhere outside of North America.
Discussion about railroad topics everywhere outside of North America.

Moderators: Komachi, David Benton

  by ZFAN85
China Challenges World Wagon Industry
The three major indices to gauge the technical level of railway freight car industry include (1) the precision-and-accuracy index, the basis on which rests wagon’s running performance that works as foundation of freight transportation efficiency, (2) the tribological index, the basis on which rests wagon’s working life , a decisive factor in determining the maintenance-and-repair cycle of a freight car, and (3) the efficiency-and-consumption index .the basis on which rests freight car industry’s financial performance , pivotal to economization on man power, material and power resources, reducing environmental pollution, and shortening production cycle.
The precision coating technology created in China is just such a comprehensive technology that surmounts all the three indices existing in traditional technology; a technology with Chinese own intellectual property; a technology that has been published and recommended by well known American and English magazines ,like Machine Design ,Design Engineering; a technology with exact railway practices that has been sanctioned by the Chinese M inistry of Railways to be used in steam locomotive ,and has made great progresses in recent years with experiences in mining and other machinery industries; a technology that follows closely to the requirements of Chinese long term plan for science and technique developments, promising a prosperous and bright future。To clarify this point of view, some explanations are given below:

1. Features of “the Precision Coating Technology”as distinguished from traditional technology .
[1.1]Advanced composites are used as coatings on one of the twin working surfaces of the mating pieces to be repaired or modified , to form a metal to composite working couple, exhibiting excellent tribological and mechanical properties For example, the wear rate of the DP series of high polymeric composites is as low as one seventh of that of the Babitt wearing-proof alloy generally used in railway wagon and coefficient of friction of the DP series against steel is only one tenth of that of iron to steel working couple The life of working couples are thus lengthened considerably. Moreover, machine repair from now on , is no longer simply a recovery of the machine to the levels at the years of manufacturing ,but also an updated reformation ,following step by step along with improvements of composites. Composite coating, in addition, eliminates the high working temperatures of welding, thus widens the scope of repairs.
[1.2] Precision Coating is an one step technology for repairing or modification of machinery parts instead of the traditional technology, including welding, heat treatment, repeatedly roughing, finishing in different machine tools and tedious manual fitting techniques. Therefore, cut working procedure and transportation in between the procedures, down to 10 or 20%, depending on the complexity of the machinery parts. Meanwhile, no investment on expensive special-purpose machine tools, heat treatment equipments, high technique workers is necessary. Batch repair and batch production are made possible. High efficiency and low expenditure so achieved are impossible for the traditional technology now playing the dominating role in machine industry.

Moreover, since coating process for all the surfaces of the work piece, is accomplished in a pre-made , accurately adjusted mould, in a single operation , exchangeability of the product is guaranteed . During the first minutes of coating process, when composite still remains in semi-fluid state , relative positions of the surfaces or work pieces can be adjusted to almost any precision level as needed. For example, concentricity, and surface contact higher than 90%, may be attained ,inconceivable to traditional technique,
Advanced composite ╂ mould coating techniques make up the sophisticated weapons for the precision technology

2,Influences of precision coating technology upon freight manufacture and repair level. As an example, some of the influences upon the up-to-date, U.S patent K4 or K5 type swing bolster bogie, as jointly designed by Chinese and U.S engineers is given as follows:
[ 2.1] Influences upon Freight Precision Index
In China an asphalt mixer made in Sweden costs 14, 500,000 RMB while asphalt mixer of the similar specification, made in China costs only 7,000,000 RMB. Price is halved. Similar facts occurred to other construction machineries. One of the main reason is our machinery breakdown intervals and working life between main repairs are only 1/3 and 1/5~1/20 respectively, the value of the famous foreign machineries. Here , precision, especially the assembling precision , a tedious problem to the traditional technology, is the decisive factor in market competition .So does wagon .
For example, one of the critical precision indexes for a wagon is axle-distance limit, namely the maximum tolerable deviation from ideal parallelism and distance between axles. Diversification of rotating directions of almost one hundred pairs of wheels of a freight train result not only in the loss of haulage capacity and train speed, which arises from the increased resistances, but also in the deteriorated wear of rails and wheel flanges and worsened friction between working surfaces of all the working couples in a bogie frame. The higher a freight train’s speed and the heavier the load it carries, the more adverse the effects of such diversification. Of this, all the designers involved are quite aware. But, since axle distance deviation is an accumulation of a series of tolerances of the machinery parts from bolster center plate to freight wheels, even all the errors is minimized by careful, precision tool cutting and fitting, with high cost and long production period, improvement can be achieved is still quite limited. That is why axle-distance limit of K5, and many other technically advanced bogies, preserve 2mm.as a compromise. When precision technology is adapted, with its superior techniques, all the errors occurred during the repairs can finally be compensated through the coating of roller bearing adapter Thus, axle-distance tolerance can be compressed to 0.1~0.2mm.quite easily. It is obvious, how remarkable the running quality and working live of wagon may be promoted, through the10~20 times upgrade of precision index.
[2.2] Influences upon Indices of Tribological Performance and freight safety
Data of tribological tests from M2000 testing machine indicates, performances of DP series composites developed by the Chinese railway system is remarkably superior to the conventional metals used in the K5, K6 bogies, as described above. Not only the composite itself is wear resistant, even more important is, it protects the surface of the opposite work piece [usually the heavier piece or piece that is hard to strip or repair. For example, composite coated roller bearing adapter protects the much complex side frame structure] almost intact. The principal and total amount of repair work are thus reduced, in contradiction to the traditional hardening process, which improves wear resistance of one work piece at the sacrifice of the other. This has been testified by the successful instances in which scrapped, case hardened sliding blocks in steam locomotives were revived with better perfomances easily and economically, through the process of precision coating .
According to analysis published in Chinese rolling stock magazines, during the year 2004, over 80% of freight car breakdowns and accidental repairs were bred of three major causes: (1) inferior precision, (2) inferior tribological performance, and (3) high internal stress or crack arising from welding. All these causes representing the weakness of the traditional technology can be conquered by the use of precision technology. For example a severe threat to railway safety today, is the repeatedly broken of connecting bolts of center plate. can be overcame easily by improving surface contacts between center plate, bolster and connecting bolts, with composite coating.
Thus, the replacement of the traditional technology by precision technology is really an effective measure, or a leap forward, for railway safety.
[2.3]influences upon Indices of Efficiency and Consumption
Precision technology cuts or simplifies 80 to 90 % procedures of production processes, tap and fully utilizes potential life of work piece , the foundation of high efficiency and low consumption for rail freight manufacture and repair. For example, the roller bearing adapter, a crucial bogie part, have too many working surfaces to be repaired economically by welding and machining. is usually discarded when it approaches the allowable wear limit, even in well equipped wagon works .With precision technology it may be repaired easily everywhere, without any welding or machining facilities. The cost of the repaired bearing adapter ,with much longer working life and better performances, is about only 1/3 of the cost of a new adapter。There are nearly 500,000 wagons in China with 4,000,000 bearing adapter. Hundreds of millions of RMB may be saved annually in this single item
Advanced design principles and advanced manufacture, repair technology are the two indispensable relatively links of the freight industry. Technical innovation is obviously another promising way to approach 21,st century world freight level.
The suggested Chinese creative mode of freight industry at present, for 25 tonnage, 120km/hr speed, follows the formula:
Design principals of K5,K6 bogies ╂Machinery precision coating technology.
A test run procedure for vindicating the feasibility of the precision coating technology in Chinese wagon industry has now been put on the agenda. The dispute still need to be settled is whether we should assure our present railway safety and personal interests by refusing the precision coating technology, or should we promote railway safety and social benefits though the precision coating technology with probable risks?
Supports and cooperation from experts, industries, and railway units every where, are sincerely welcomed .

Written by : Fan Zhe, Senior engineer
Tel. : 86-0562-6803200 86-021-64865068
E-mail : [email protected]
Address :701 Rolling Stock Works, Tong Ling, Anhui, China
  by Komachi

I don't believe we need a second incarnation of this thread when one will do. I am going to lock this one and delete it within three days or so, while discussion will be carried out on the other copy of this thread.