Working Out The Details: Process Parameters
Entrained moisture from condensation can cause voids or cosmetic defects in the molded part.Care should be taken to equilibrate material to the molding facility environment before opening the packaging to avoid condensation.
Drying is not recommended for Bakelite® Molding Compounds. If packaging has been damaged or visible moisture is apparent in the material, contact a Bakelite Synthetics Bakelite® product representative for technical assistance.
Preheat the mold to the recommended temperature. Make sure the preheated material is at the correct temperature. Begin the molding process.
Attach the nozzle to the barrel and, with the mold closed, move the injection unit forward until the nozzle is in contact with the sprue bushing. Turn on heaters. When the barrel, nozzle and mold have stabilized at the recommended temperatures, back the injection unit as far away from the sprue bushing as possible. With the screw in the forward position, open the feed hopper and allow material to flow into the unit. Dose up to 30% of the approximate final shot volume and inject the material into the open air. Repeat the dosing process two to three times increasing the amount until the approximate shot volume for the final part is reached and the material appears fully plasticized with no visible granules. At this point, clean the nozzle tip, sprue bushing and remove all extruded material. Move the injection unit into position with the nozzle against the sprue and begin the normal production process. Adjust the final shot volume during the first few molding cycles as necessary, until the process is stable at the target part weight and operating parameters.
Processing Guide: Shut-Down Procedures
Stop preheating material after the final dose has been loaded into the mold. Stop the press after ejection of the final part and turn off heaters. Remove all flash and clean the mold of any material residue. Close the mold once it is clean.
Stop the press from cycling after ejecting the last part and shut off the material flow from the feed hopper. Back the injection unit away from the mold and purge out the remaining material in the screw. When the screw is empty, remove and clean the nozzle, making sure that no material is left in the threads. Turn off heaters. Remove all flash and clean the mold of any material residue. Close the mold once it is clean.
Process Interruption Procedures
If the process will be interrupted for an extended period of time, stop preheating material. Begin preheating material when process is ready to be restarted.
If the process will be interrupted for an extended period of time, shut off the material feed on the hopper, back the injection unit away from the mold and purge out the material in the screw. After the interruption is over, cycle a few doses of material through the barrel and make sure it is fully plasticized with no visible granules before restarting the molding process. Check the first few parts after the restart carefully to make sure they are properly molded. If it is not possible to purge material from the barrel during the interruption, go through the full shutdown procedure and restart using the startup procedure.