In injection molding production, upper and lower mold work is very important. Mold operator or technician must master following key actions to do a good job of upper and lower mold work.

1.1 Before production, first check whether injection equipment is consistent with mold design: check whether mold perimeter, thickness, positioning ring, gate sleeve, ejector hole distance and other mold data are consistent with equipment used. Be familiar with mold structure and precautions, and confirm mold lifting upward mark.
1.2 Check whether plastic used meets mold design and order plan requirements.

 

2.1 When hoisting mold, a lifting ring must be used. It is strictly forbidden to use water pipe joints and bolts as hoisting hangers. Lifting ring size must be correct and lifting ring must be tightened. Depth should be greater than 1.5 times thread diameter, and people cannot be located under mold during hoisting process.
2.2 When hoisting mold, fastening plate connecting moving and fixed molds must be connected reliably.
2.3 Upper mold personnel select pressure plate, bolts and pads, boosters, positioning rings, wrenches, etc. according to characteristics of mold and equipment, place them on upper and lower mold special tool carts according to specified management requirements, push them to specified area.
2.4 Upper mold personnel should check and clean dirt on injection molding machine, fixed mold seat plate and guide rails to make them clean and clean, deal with knocks and bumps of injection molding machine and static plate. Check arrangement of ejector rods of injection molding machine according to shape of mold. It should be arranged in a rectangular shape with four ejector rods and match position of ejector rod hole of mold. Adjust height of ejector rod of injection molding machine to make it consistent and fixed reliably, and control height difference within range of ±0.1mm. To ensure that force is uniform when product is ejected.

 

2.5 Upper mold personnel confirm that hoisting is balanced and safe and reliable when hoisting mold before hoisting. Pay attention to ensure safety of personnel, equipment and molds during hoisting process.
2.6 Hang mold between injection molding machine and fixed plate, align positioning ring with positioning hole of molding machine and ejection hole of mold, adjust mold so that mold and bolt are evenly spaced and balanced, then clamp mold manually.
2.7 Mold is installed on injection molding machine. Tightening force must be sufficient and mold cannot be misplaced; if it is tightened with a pressure plate, a gasket should be added, and screw-in position of fastening screw should be close to mold body. Number of fastening screws should be sufficient and position of arrangement should make mold evenly stressed. Pad should be consistent with thickness of front and rear fixed plates of mold, and strength should be reliable. It should be placed at lower part of other end of pressure plate according to principle of leverage to maximize pressing force; it is strictly forbidden to use nuts instead of pads to press mold to ensure reliable tightening of mold. For large molds, 6-8 pressure plates should be tightened to prevent mold from sagging due to its own weight, affecting accuracy and service life of mold.
2.8 After installation and tightening, check and adjust center line of main channel of mold and center line of injection molding machine to be on same line.
2.9 Open mold slowly by hand, wipe molding surface or parting surface and three-plate structure mold plate surface from top to bottom, first inside and then outside, with clean knitted cloth or absorbent cotton according to characteristics of mold. Connect cooling water pipe, and do not splash water on molding surface. Eject ejection system, confirm that ejection action is smooth and core pulling is smooth, check mold according to lubrication and maintenance regulations. Mold is completed.

3.1 Before lubricating mold, lubricated part should be wiped clean with clean cotton yarn to remove impurities such as iron foam, use special tools to apply clean sodium-based grease or ejector lubricant to lubricate, so as to avoid impurities in lubricated part that affect accuracy of mold. When lubricating, a thin oil film should be evenly applied, especially for lubrication points close to molding part, grease should be penetrated with cotton yarn and then a very thin layer of sodium-based grease should be applied to avoid extrusion and contamination of plastic parts.
3.2 For lubrication of guide pin, guide sleeve and positioning lock surface, first wipe pin and sleeve positioning lock surface with cotton yarn, then use a brush (clean) to apply a small amount of clean grease evenly to apply a layer of oil film.
3.3 For lubrication of the ejector block, ejector rod and reset rod, use a clean brush to apply a small amount of clean grease evenly to apply a layer of oil film.
3.4 For lubrication of the ejector rod and ejector block in molding part, use a small amount of ejector lubricant.
3.5 For lubrication of core-pulling slider, pull out core-pulling slider, wipe sliding part of core-pulling slider and corresponding sliding groove with clean cotton yarn, apply a uniform thin oil film on block and groove, then install core-pulling slider to limit. To prevent inclined guide pin from breaking.
3.6 For parting surface and grinding surface of mold, use kerosene or industrial acetone to wipe off impurities such as foam, cold material wire, iron slag, ash stains, dirt, etc. on parting surface and mold plate surface.
3.7 Limit screws, limit rods, limit plates on limit guide pins, mold locks, pins and bolts of sequential mold opening mechanism of mold, ejector on ejector block should be kept complete and tight. Cooling water channel and nozzle should be inspected and repaired to remove obstructions, scale and other debris. If necessary, after water channel is cleared with hydrochloric acid, impurities should be blown away with an air compressor, a water pressure test should be performed to ensure that there is no leakage and water channel is unobstructed. Nameplates on mold are complete and clear.

 

3.8 For ejection mechanism (such as rods, blocks, holes, grooves, etc.), mold plate surface, parting surface, grinding surface and core pulling mechanism, guide positioning mechanism, pouring system, hot runner system, exhaust system, and puncture points, rust points, bumps, scratches and squeezed parts of inserts and molding parts should be inspected and smoothed with tools such as files or oilstones, water sandpaper, etc., and removed in direction of light.

4.1 Before use, you must carefully read technical information, understand technical parameters of mold, and debug it strictly according to technical parameters.
4.2 Mold with temperature measuring device must use temperature gauge.
4.3 Mold that needs to be heated by heater should be closed during heating to facilitate uniform heating of mold.
4.4 Before each use of hot runner mold, thermocouple must be checked to see if it is effective, heating circuit is unobstructed, and wiring is correct. Heating wire of hot runner is not allowed to be squeezed.
4.5 Mold must be cleaned before injection molding, and following work must be done:
1) Eject ejector mechanism, apply lubricating oil to active parts such as guide pin, guide sleeve, ejector rod, and return rod.
2) Before closing mold, check that parting surface, exhaust groove, cavity are clean and free of foreign matter. When cleaning molding part, wipe it gently and do not scratch molding surface.
3) Test mold with an empty car and check working conditions of following parts:
A: When debugging mold, mold should be opened and closed 2-3 times. After confirmation, it can be officially debugged. When adjusting ejection distance, it should be gradually increased from small to large, and finally meet requirements. It is strictly forbidden to exceed designed ejection distance, because it will cause serious damage to mold.
B: When mold is ejected, it is necessary to observe whether each ejection part is ejected at the same time. If it is not ejected at the same time, machine should be stopped for inspection and elimination. Ejection mechanism and return mechanism should slide smoothly, flexibly, without jamming and abnormal noise, and gap should be appropriate. Ejection mechanism and return mechanism must return to original position after mold is closed.
C: Guide pin and guide sleeve guide smoothly and positioning is reliable.
D: After mold is closed, there should be no gap between pressure-bearing surfaces (or parting surfaces).

 

E: If mold uses a spring return, ejection mechanism of mold should return to original position at the same time as ejector rod of injection molding machine returns.
F: Check whether inlet and outlet connections of hydraulic core pulling cylinder are correct and whether action is normal.
G: Check whether inlet and outlet connections of hot runner hydraulic cylinder are correct and whether action is normal.
H: Check whether cooling water connection is correct.
4.6 When debugging injection mold, injection pressure and material volume should be gradually increased to required requirements according to principle of gradual progress. It is strictly forbidden to expand mold during first injection to ensure safety and accuracy of mold.
4.7 During production or mold trial, when gate or other parts are stuck to mold, mold surface is not allowed to be scratched during process of removing sticking material.
4.8 If an abnormality is found during production process, operator should give feedback in time, and foreign objects falling into mold should be removed in time.
4.9 When repairing mold on injection molding machine during production, maintenance identification plate must be hung, injection molding machine motor must be turned off and power supply must be cut off. It is strictly forbidden to place maintenance tools, release agent bottles, polishing oilstones and other items in mold. It is strictly forbidden to store items on mold, let alone water cups, rice bowls and other items to prevent rust on mold.
4.10 Lubricating oil must be applied to active parts such as guide pillars, guide sleeves, small guide pillars, small guide sleeves, reset rods, and ejector rods every 4 hours of work.
4.11 Check working condition of spring according to working time of mold, replace fatigued and broken ones regularly to make them return quickly and accurately, ensure that ejector pin and core are not damaged. When replacing reset spring, standard parts should be used, the two ends should not be polished or cut. For springs with a diameter of more than Φ20mm, check whether internal guide rod is bent.
4.12 Check sealing of cooling water nozzle regularly. If it does not meet requirements, it should be replaced in time. Water hole should be descaled and rusted once every month of work.
4.13 Check sealing of hydraulic part regularly. If it does not meet requirements, sealing ring should be replaced in time.
4.14 Gas needle and sealing ring of gas-assisted molding mold should be replaced in time. During use, gas needle should be cleaned with alcohol every two days.
4.15 When production task is completed on last mold, quality of last piece should be checked and mold should be in good condition.
4.16 When mold on injection molding machine is out of use (for more than one day), molding part must be well protected and mold should be closed by spraying rust inhibitor.
4.17 Mold manager should promptly stop and correct any violations in use of mold, make records and provide feedback.

5.1 Mold unloading personnel select special mold unloading tools according to mold specifications and characteristics, put them on special tool cart according to mold management requirements, and push them to designated area. Pressure plate, bolts, pads, etc. and tools after mold unloading are placed on special cart to keep site clean.
5.2 Protect molding parts according to characteristics of mold, maintain mold according to lubrication and maintenance regulations.
5.3 When disassembling cooling water pipe, turn off water nozzle switch of injection molding machine, disassemble water pipe at injection molding machine end, and clean water in cooling water hole of mold before unloading mold. It is strictly forbidden to splash water on mold.
5.4 Install lifting ring (according to upper mold regulations), crane should lift it with appropriate tightness before loosening nut, removing bolt pressure plate, and manually opening mold plate. When lifting mold out, pay strict attention to safety of people, equipment, and molds.
5.5 Check whether cooling water of mold is cleaned thoroughly. After confirming that it is clean, wipe surrounding area and put it into storage.
5.6 It is strictly forbidden to hang mold that has not been blown into warehouse.
5.7 It is strictly forbidden to disassemble accessories of mold at will, especially mold for storage.