Simple Solutions That Work! Issue 7

With this issue’s theme being a back-to-basics approach, we have focused on some simple items that are often overlooked as not being as important as they are. Without having these fundamentals in check, production issues downstream will certainly ensue. We will cover: • Sand Calibration • Resin Calibration • First and Last Sand • Compaction Force - Drop & Stop Sand Calibration Mixers use either a sand slide gate or a sand dam gate to control the amount of sand delivered to the mixing chamber. Slidegate – On mixers equipped with a sand slidegate, the sand slidegate’s air cylinder slides a steel “gate plate” with a hole drilled through it directly underneath the mixer’s sand inlet. This allows sand to flow through the gate plate hole into the mixing chamber. The diameter of the gate plate hole determines how much sand enters the mixing chamber and ensures that this amount is consistent, cycle after cycle. The following table shows an approximate relationship between the diameter of the sand slide gate plate hole and the amount of sand per minute entering the mixing chamber (actual volume may vary, depending on grain type and fineness). Hole Diameter Flow Rate (Pounds/Minute) 3/4” 24 1-1/16” 50 1-1/4” 70 1-1/2” 125 2” 215 2-3/16” 300 2-7/8” 500 3-1/2” 700 Dam Gate – On articulated mixers equipped with a sand dam gate, an adjustable gate at the inlet end of the sand delivery conveyor controls the amount of sand flowing under the gate to the mixing chamber. Raising the gate increases sand volume; lowering it decreases volume. In the case of a mixer that has a dual speed belt to achieve high and low sand flow rates, it should be set up so that the high rate is at full belt speed and the dam is adjusted to deliver the desired high sand level. For the low rate, the gate should be kept in the same position and the speed of the belt reduced via the Variable Frequency Drive to deliver the desired low sand level. Resin Calibration After determining the pounds/ minute of sand to be delivered to the mixing chamber, the next step is to determine the proper RICH McNEELY National Sales Manager PALMER MANUFACTURING & SUPPLY, INC. ARTICLE TAKEAWAYS: 1. Sand slide gates versus sand dam gates 2. Making sand usable from the beginning to the end of the cycle 3. Never underestimate the importance of compaction MOLDING BASICS MIXER AND COMPACTION CALIBRATION 50