Share the common problems, causes and solutions of die casting moulds

Fisrt. Thimble

Problem: ejector pin jamming, broken ejector pin, ejector pin bit batch front, ejector pin bit multi-material, ejector pin print recessed into the product surface too deep, ejector pin print protruding out of the product surface too high.

Cause analysis: 1. ejector hole processing hole diameter is small or ejector hole inner surface rough, ejector assembly too tight. 2. the ejector hole sealing bit is too deep or not made to avoid empty bit. 3. The hole diameter of the ejector hole is too large when processing, or processed into a shaped hole, and the ejector pin assembly is too loose. 4. When the mould is produced, the ejector pin is not well maintained, the surface of the ejector pin is oiled, the ejector pin is not oiled; the ejector pin hole is worn. 5. Die production, die castings are not taken out to close the mold, pressing bad ejector pin. 6. ejector pin processing, assembly, ejector pin countersunk head position has a false position, ejector pin protruding out of the mold meat surface is not consistent, the ejector pin did not do positioning. 7. The ejector cup head and the ejector plate are not marked, the ejector pin is installed wrong. 8. The trash pins on the ejector plate are too high or too low. 9. The ejector plate is too thin, not strong enough, the ejector plate has not been added to the middle toast, resulting in deformation of the ejector plate. 10. The thimble is not of good quality, not strong enough, not using Cosmos standard heat-resistant thimbles, or the thimble exceeds its service life. 11. The material of the die kernel is not good and strong enough, and the ejector hole is worn. 12. The ejector pin with diameter below Φ3mm is not selected with standard specifications of the ejector pin.

Solution: 1. When processing the ejector hole, the clearance of the ejector hole should be controlled within 0.015mm on one side (e.g. for ejectors with Φ6mm, the corresponding ejector hole should be Φ6mm+0.03/0) to ensure smooth ejecting after assembly of the ejector. 2. The depth of the ejector hole on the die is 25~30mm, and the ejector pin is processed to avoid empty space. 3. When processing the ejector countersunk hole, no taper plane is allowed, and the ejector pin is controlled to be 0~0.05mm higher than the surface of the die insert after assembly. 4. Use ejector pins with a diameter of Φ3mm or less, and use Cosmos standard heat-resistant ejector pins. 5. When producing moulds, pay attention to the maintenance of ejector pins and maintenance. 6. When the mould is in production, stop in time when abnormal situation occurs. 7. When replacing the ejector pin, be careful not to damage the die cavity, and when the ejector pin is stuck, knock it out gently, otherwise, send it to the mould factory for wire cutting or electrical discharge machining to take it out. 8. When assembling the ejector pin, do not make a mistake and check it after completion.

Second. Inserting pins/inserts

Problem: Needle/inset broken, needle/inset bent, needle/inset worn, needle/inset crushed.

Causes: 1. Needle/inset material problem, too high or too low hardness, or needle/inset exceeding service life. 2. 2. needles/inserts with too small a slope or too long a size. 3. Needle/inlay not left clear of the pin/inlay in the touch-through position. 4. Improper handling of the mould during production and uneven spraying of the release agent (too little or too much). 5. The die is closed before the die is taken out and the pin/insert is crushed. 6. During the production of the mould, the mould is stuck and the thimble is used to break the pins/inserts. 7. When the mould is being produced, the die is sticking and the pins/inserts are soaked with hydrochloric acid.

Solution: 1. Use good materials for the needles/inserts, requiring a hardness of HRC 48-52° after surface heat treatment of the needles/inserts, or nitriding or titanium plating of the needles/inserts. 2. 2. the pin/insert has a draw slope of ≥1 degree/side (rear die), a draw slope of ≥1.5 degree/side (front die), a length of ≤10~15mm, and a rounded R angle on the head of the pin/insert. 3. leave a gap of 0.05-0.10 mm between the pins/inserts in the touch-through position. 4. During the production of the mould, pay attention to the maintenance and care of the pins/inserts. 5. Stop the mould in case of abnormalities during production. 6. 6. When replacing pins/inserts: be careful not to damage the cavity of the die, and when the pins/inserts are stuck, knock them out gently; otherwise, send them to the mould factory for wire cutting or electrical discharge machining to remove them. 7. It is forbidden to soak the pins/inserts with hydrochloric acid. 8. When assembling pins/inserts, do not make any mistakes and check them after completion.

Third. Mould kernel

Problems: cavity surface not smooth, burned mould, cavity surface into water erosion, cavity surface corrosion, cavity surface boom, cavity surface cracks, cavity surface crush bad, mold kernel pressure deformation, mold flying material, mold kernel oil leakage.

Solution: 1. Die cavity surface knife pattern or spark pattern is not in place or the die is not saved. 2. Die material or heat treatment problem, die surface hardness is too high or too low. 3. The die material exceeds its service life. 4. Improper handling during mould production, uneven spraying of release agent (too little or too much). 5. The mould is not well maintained during production, the surface of the die is not cleaned up in time, there are foreign objects on the surface of the die. 6. When the mould is in production, the ejector pin is closed before it is returned (broken or stuck ejector pin), or the die casting is closed before it is taken out and the die kernel is crushed. 7. When the mould is being produced, the mould sticks and the ejector pin is used to break the surface of the mould cavity. 8. When the mould is being produced and the mould is sticking, soak the surface of the cavity with hydrochloric acid. 9. The ejector pin, insert or insert touches the oil circuit or the oil circuit is not properly blocked during the machining of the mould insert. 10. The threads of the oil pipe joint are worn, and the raw material is not wrapped and tightened when connecting the oil pipe.

Handling method: 1. The surface of the mould cavity of the mould insert is saved in place. 2. 2. Use a good material of the mould insert, require the hardness of the surface of the insert to reach HRC46~50° after heat treatment, or nitride or titanium plating the surface of the insert. 3. When the mould is produced to the left or right of 10,000 beers, temper the mould kernel. 4. Pay attention to the maintenance of the die kernel during the production of the mould. 5. When the mould is produced, stop the mould in time when there is an abnormal situation. 6. 6. When dismantling and assembling the die insert: be careful not to damage the surface of the die insert cavity. 7. Do not soak the cavity surface with hydrochloric acid. 8. check that the oil pipe is clear and that there are no oil leaks after the mould insert has been assembled. 4.

Fourth. Gate sleeve/splitter cone

Problems: pressure injury between the mouth of the gate sleeve and the mating position of the injection nozzle, sticking of the water outlet to the front of the mould, phi-front of the gate sleeve, strain on the inner hole of the gate sleeve, card head, water leakage from the gate sleeve (oil leakage), water leakage from the manifold cone, crushing of the gate sleeve or manifold cone.

Causes: 1. the material or heat treatment of the gate sleeve/splitting cone, the surface hardness is not enough. 2. the surface of the inner hole of the gate sleeve is not smooth. 3. the clearance between the gate sleeve and the spreading cone is too large, the mould is not in place. 4. the size of the inner hole of the gate sleeve is too large (or too small) when processing. 5. 5. Wear of the bore of the sprue. 6. 6. Worn threads in the joint of the gate sleeve/splitting cone cooling water circuit, or raw material tape not wrapped and tightened when connecting the oil pipe. 7. Improper handling during mould production, uneven spraying of release agent (too little or too much). 8. During the production of the mould, the die casting is closed before it is taken out and the surface of the gate sleeve/splitter cone is crushed.

Solution: 1. Use good material of gate sleeve/splitter cone, require the hardness of the surface of the gate sleeve/splitter cone to reach HRC48~52° after heat treatment, or nitride and titanium plating of the inner hole of the gate sleeve. 2. The surface of the inner hole of the gate sleeve should be mould saving in place. 3. The size of the inner hole of the gate sleeve is within the tolerance requirement. 4. The maintenance of the gate sleeve/splitter cone should be taken care of during the production of the mould. 5. When the mould is in production, stop the mould in case of abnormal conditions. 6. 6. When dismantling the gate sleeve/splitting cone, knock it out gently and be careful not to damage the inner hole surface of the gate sleeve. 7. When the mould is in production, check that the oil circuit of the gate sleeve/splitter cone is clear and that there is no oil (water) leakage. 8. When the mould is in production, check if there is any strain on the clock head, otherwise, replace the clock head in time.

5. Line position

Problem: Flying material in the line position (product batching), jammed slider, bad line position, water erosion in the core of the line position.

Analysis of the causes: 1. the strength of the front die sliding wedge is not enough (or the front die sliding wedge is not hardened), the sliding wedge surface wear. 2. 2. The shape size of the line position slider is small, or the line position slider sealing material is not enough, collapse. 3. the line position slider and guide slide surface (or line position slider sealing material position) with too loose or too tight, wear. 4. The line position slider and the T-slot position of the guide sliding surface with too loose or too tight, or the line position slider pressure bar strength is not enough, wear. 5、Insufficient strength of the inclined guide pillar, or the inclined guide pillar is not balanced. 6. When the mould is being produced, the ejector pin is not returned to its position and the mould is closed (broken ejector pin, jammed ejector pin, unfitted tie bar), or the die casting is not taken out and the mould is closed. 7. When the mould is being produced, the operation method is not appropriate and the release agent is not sprayed evenly (too little or too much). 8. When the mould production, maintenance is not good, not timely clean up the magnesium chips on the line position, the guide slots in the accumulation of magnesium chips, too much oil. 9. When the mould is processed, the line position is not in place with the mould. 10. Wrongly installed line position. 11. Missing to install the tie rod, or tie rod stroke is not well adjusted.

Solution: 1. Ensure sufficient strength when designing and processing the front mould sliding wedge, and the front mould sliding wedge must be equipped with hardening blocks. 2. When designing and processing the line slider, ensure that the outline size of the line slider is sufficient and the width distance of the line slider is more than 25mm. 3、Ensure that the clearance between the sliding block and the guide surface is reasonable. 4. ensure the width and height of the T-slot position when designing and processing the line position slider, and the line position slider pressure bar has sufficient strength. 5. The design and processing of the inclined guide column requires the use of the standard inclined guide column. 6. Marking and error-proofing measures for line sliders. 7. When assembling the mould, check carefully whether the tie bar assembly and adjustment are in place. 8. When the mould is produced, the magnesium pin on the line position should be cleared in time and the line position maintained in place. 9. When the mould is in production, stop in time when abnormal conditions occur.