3. Important Things to Consider Know what material is to be conveyed Overall dimensions Weight Type of container, its condition, material and center of gravity
14. Good Practices Supports over 30-in elevation should be braced off the conveyor frame. Support height should not be three times the width without external bracing. Figure only two-thirds of the rollers under the load as actually carrying the load. Have only three rollers under the load at all times. For the roller spacing, subtract 1-in from the load length and divide the remainder by three. Use the next smaller value.
15. Good Practices Roller Centers for hard surface items , 12 to 18-in or greater. Roller Centers for wooden pallets or soft surface products, 6 to 8-in . Standard length of conveyors is 10 ft. Maximum speed of loads is 180 ft/min
18. Belt Conveyors Belt conveyors are used for inclined and declined movements of loads. The belt is supported on rollers or a metal bed called a slider bed. A return idler roller can also be used when roller is spaced on 10-ft maximum centers.
19. Slope For smooth-bottom plastic tray = 15o maximum For cartons = 25o maximum For 30o slope, extra care must be considered
22. Rules of Thumb: Belt Conveyors Belt Conveyors are for high capacity and long distances (a mile or more, but several hundred feet in a plant), up inclines of 30o maximum. A 24-in wide belt can carry 3000 ft3/hr at a speed of 100 ft/min, but speeds up to 600 ft/min are suited for some materials. Power consumption is relatively low.
23. Rules of Thumb: Screw Conveyors Screw Conveyors are suited to transport of even sticky and abrasive solids up inclines of 20o or so. They are limited to distances of 150 ft or so because of shaft torque strength. A 12-in diameter conveyor can handle 1000- 3000 ft3/hr, at speeds ranging from 40 to 60 rpm.
24. Rules of Thumb: Bucket Conveyors Bucket Conveyors are suited to vertical transport of sticky and abrasive materials. With 20 x 20-in buckets, capacity can reach 1000 ft3/hr at a speed of 100 ft/min, but speeds up to 300 ft/min are used.
25. Rules of Thumb: Pneumatic Conveyors Pneumatic Conveyors are for high capacity, short distance 400 ft transport simultaneously from several sources to several destinations. Either vacuum or low pressure 6-12 psig is used with a range of air velocities from 35-120 ft/s depending on the material and pressure and air requirements.
26. Assignment: Enumerate and explain how safety can be implemented in material handling equipments. Explain reasons of accidents in case of conveyors. Give few examples of conveyor failure. Explain brief design of conveyors. Enumerate standard maintenance requirements for conveyors.
