Applications
(3) Heat-resistant, high-speed series. When constructed of super engineered plastic, this series can work continuously in temperatures up to 250 ° C, and the chains can convey objects with speeds up to 200 m/min. (4) Anti-chemical series. These chains are made of super engineered plastic and resist most organic solvents, inorganic salts, acids, alkalines, and oxidizers. There is a “super anti-chemical” series with pins made of titanium. (5) Electroconductive series. This series has electric resistivity of 10 6 Ω •cm. These chains are suitable where dust collection, electronoise, and elec- trosparks should be avoided. (6) Plastic pin series. In this series, chains and pins are made of engineered plastic. Compared to the standard series, these chains are 15 to 25 percent lighter in weight and are easy to disassemble for recycling. A larger-diameter pin and unique design make this a very strong series. In fact, it has almost the same allowable tension as the standard series. Table 4.1 shows the features of each type of TPU 836 chain. Coefficient of fric- tion and maximum allowable load are under the following conditions: room temperature, non-lubricated, chain speed 10 m/min., and stainless steel rail. 4.1.2 Guide Rail Materials The guide rails for engineered plastic chains are usually made of 304 stain- less steel with a good finish, MC nylon, or ultra-high molecular-weight poly- ethylene (UHMW). For steel chains, guide rails are made of plastic. For heat-resistant and high-speed applications, make sure you consider the following points: (1) When the chain operates within normal temperatures at high speeds, choose a guide rail that is made of carbon steel or stainless steel with polished, hard chrome-plating. (2) When the chain operates in high temperatures, consider a polished stainless steel guide rail. Remember to allow for heat expansion, and fix only one end of the guide rail.
Table 4.1 Types of Engineered Top Chains
Maximum Maximum Coefficient Maximum Chain Speed Ambient of Allowable
Material
(m/min.)
Temp. (°C)
Friction Load (kN)
Standard
Polyacetal
50 50
80 80
0.25 0.17 0.20 0.30 0.25 0.17
0.98 0.98 0.98 0.50 0.70 0.88
Low-Friction
Special Polyacetal
Heat-Resistant Anti-Chemical
Super Engineered Plastic Super Engineered Plastic
200
250
40 50 50
80 80 80
Electroconductive Special Polyacetal
Plastic Pin
Special Polyacetal
156
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