Simple Solutions That Work! Issue 18

10 4) Care should be taken that no direct impact occurs to the tungsten carbide insert on the mixing blade. Tungsten carbide has a very high resistance to abrasion, but a very low impact resistance. A needle-type descaling gun will minimize the chances of damaging the carbide tips but it will take longer to clean. Operator/cleaners should report damaged blades so they can be replaced if necessary. The blades do overlap some so a small chip out of a corner is not a concern. If enough carbide is missing from a blade, there will be a ridge built up on the wall of the mixing chamber. Since sand travels along the periphery of the chamber, it will be forced inward at these ridges and may cause the mixer to plug. 5)Observe the sand inlet throat to the mixer. There should not be any buildup on these walls. Buildup on these walls will eventually restrict the flow of sand into the mixer. The first sign of this will be excess dry sand at the end of the cycle until this reserve is cleared out. 6) Before closing the mixing chamber door, be sure to clean all door mating surfaces to allow the door to return to its original position. Sometimes it is necessary to blow off the loose sand on the door and in the joint. Again, these surfaces can be coated with a release agent to facilitate easier clean up later. 7)Close the doors and tighten the clamp so that the limit switch(es) are closed. 8)It generally it is not necessary to clean the chemical ports at the end of every shift if the air jets are properly set. However, it is a good idea for the ports to be checked prior to calibration. This is a convenient time to do this since the nozzles will be removed anyway. The mixer shaft must not be rotating when any rod is inserted into the chemical inlets. PREVENTIVE MAINTENANCE 1) Grease both front and rear drive shaft bearings once every 200 running hours. One shot is sufficient. DO NOT OVER-LUBRICATE the bearings! Over- lubrication will shorten bearing life faster than no lubrication at all. 2)Once per week, with the mixer locked out, open the chamber doors and place a pry bar under the shaft near each end and pry up. There should be no movement 3)Mixer shafts equipped with threaded blades should be checked for proper angle and jam nuts should be tight. Note: Shafts designed to use pinned blades are available. This eliminates the possibility of blade orientation changing. 4)Check to see that no chemicals are accumulating in the chamber near the ports. If raw chemical is present, determine why this is occurring – pump delay time, sluggish valve activation, or leakage through valves. 5)Check purge air lines that no resin has backed up into them. If there is evidence that chemical has backed up into the purge air lines, check/replace check valves. Inoperative check valves can permit resin to reach the solenoid valve bank and damage/destroy the valves. The recommended routing of the purge airlines has changed since some mixers were sold. Below is the recommended routing. This routing reduces the chances of resin reaching the check valves. Contact: JACK PALMER jack@palmermfg.com Purge lines Check valves