Simple Solutions That Work! Issue 18

9 HOW TO ISSUE JACK PALMER President Palmer Manufacturing & Supply, Inc. ARTICLE TAKEAWAYS: • Release agents make removal of buildup easier • Needle-type descaling guns minimize damage to carbide tip blades • Grease front & rear drive shaft bearings once every 200 running hours How to Properly Clean & Maintain Mixing Chambers T here is tremendous amount of excitement when a new mixer is installed. Operators are formally trained on its operation, cleaning, and maintenance. The manual is detailed and serves as a reference guide for many years. However, while mixers can serve a foundry for decades, finding the manual in good shape after a seasoned operator has retired is often difficult. We hope this guide will provide the reference material you need to properly maintain your mixing chambers. CLEANING It is essential to keep the discharge chute clean enough to allow the full flow of sand to exit without backing up into the mixer. The sand will buildup on the walls of this chute but the amount of running time before it requires cleaning is variable. The faster the sand is designed to set up, the faster it will build up on the walls of the discharge chute. It is not uncommon for the chute to require cleaning 4 times per shift 2-hour, 4-hour, 6-hour, and end of 8-hour shift. It is necessary to stop the mixer and allow the shaft to come to a complete stop before attempting to clean the discharge chute. If it is the practice of the foundry to take breaks around the times suggested above, then it is most efficient if the mixer operator shuts down the mixer and begins his break period ahead of the rest of the line. Boxes can be stripped before the sand gets too hard. Then the operator comes back to the line first. The mixer shaft should have stopped turning by that time and the discharge chute can be cleaned. (Look at the motor fan to be sure it has stopped turning.) The mixer should be locked out before proceeding. A long chisel in a pneumatic chisel hammer works well. It is necessary to clean all the way up to the chamber minimizing the restrictions to flow. Some foundries find it advantageous to apply a release agent to the walls of the discharge chute to make it easier to remove the buildup from the walls. It is necessary for the walls to be clean on the first application of release agents. The filler type aluminized coatings can be rubbed in with a cloth on a stick or rod. This will not prevent buildup but it will make it much easier to remove. Generally, it is necessary to clean the blades on a continuous mixer at the end of each shift. Again, it depends on the amount of running time and the setup speed. Faster setting sands buildup faster. The relationship between the end of the mixing blade and the inside diameter of the mixing tube is a key factor in the efficiency of the mix. DO NOT remove the sand lining of the mixing chamber during the normal daily cleaning operation. 1) Shut-off main power to the mixer, lock-out, and keep the key in the possession of the person doing the cleaning. 2)Release the clamp(s) and open the mixing chamber door. Be careful to stay away from the door clamping posts as the mixer opens. Never place your hand on the middle edge of one opened door while opening the other in two door mixers. The hand can get pinched between the two doors. 3) Remove the major buildup from the mixing blades and drive shaft. It is not necessary to make these pieces “clean as new.” Continued on next page