What should we do when the mold encounters these problems?

1. Gate stripping is difficult

During the injection molding process, the gate is stuck in the gate sleeve and is not easy to come out. When the mold was opened, the finished product showed crack damage. In addition, it is necessary for the operator to knock out the top of the copper rod from the nozzle, so that it can be demoulded after loosening, which seriously affects the production power.
The main factor of this shortcoming is the poor brightness of the gate cone hole and the knife mark in the circumference of the inner hole. Secondly, the data is too soft, the small end of the cone hole is deformed or damaged after a period of use, and the spherical arc of the nozzle is too small, resulting in the gate material rivet here. The cone hole of the gate cover is more difficult to process, and standard parts should be selected as far as possible. If you need to process it by yourself, you should also deny yourself or buy special reamer. The taper hole should be ground to Ra0.4 or more. In addition, it is necessary to set the gate pulling bar or gate ejection.

2. Large mold dynamic fixed mold deviation

Due to the different charging rate of the large mold, and the influence of the die weight during mold loading, the dynamic and fixed mold deviation occurs. In the above cases, the lateral deflection force will be added to the guide column during injection, the guide column appearance is strained and damaged when the mold is opened, and the guide column is zigzagged or blocked when the mold is severe, and even the mold cannot be opened.
In order to deal with the above questions, a high-strength positioning key is added to the four sides of the mold parting surface, and the most concise and useful is the selection of cylindrical keys. The straightness of the guide column hole and the parting die surface is crucial. After clamping the orientation of the moving and fixed die during processing, the boring machine is completed at one time, so as to ensure the concentricity of the moving and fixed die holes and minimize the straightness error.

3. The guide post is damaged

The guide column mainly plays a guiding role in the mold to ensure that the forming surface of the core and the cavity do not touch each other under any circumstances, and the guide column cannot be used as a force or positioning part.
In several cases, the dynamic and fixed die will have infinite lateral deflection force during injection. When the wall thickness of plastic parts is not uniform, the rate of material flow through the thick wall is large, and the greater pressure occurs here. The side surface of the plastic part is not symmetrical, such as the reverse pressure on the opposite two side surfaces of the step parting surface of the mold is not equal.

4. Move the template to bend

When the mold is injected, the molten plastic in the mold cavity has infinite reverse pressure, usually in the range of 600~1000 kg/cm. Mold makers sometimes do not pay attention to this question, usually change the original program standard, perhaps replace the moving template with low-strength steel plate, in the mold with the top rod, due to the large span of both sides of the seat, forming the template bending when the injection.
Therefore, the moving template is necessary to choose excellent steel, to meet the thickness, and can not cut low-strength steel plates such as A3. When necessary, support columns or support blocks should be set under the moving template to reduce the thickness of the template and adjust the forward load.

5. Top rod zigzag, cracking or leakage

The quality of the top rod is better, that is, the processing cost is too high, and now standard parts are usually used, and the quality is worse. If the gap between the ejector rod and the hole is assumed to be too large, there will be material leakage, but if the gap is too small, the ejector rod will expand and get stuck due to the increase in mold temperature during injection.
What is more risky is that sometimes the ejector rod is ejector, usually the ejector rod does not move at intervals and breaks, and the exposed ejector rod cannot be restored when the mold is closed once and the concave mold is damaged. In order to deal with this problem, the top rod is ground from the beginning, and the collaborating section of 10 to 15 mm is saved in the front end of the top rod, and some of the base is ground 0.2 mm smaller. After all the ejector rods are installed, it is necessary to strictly check the coordination gap, usually within 0.05~0.08 mm, to ensure that all ejector arrangements can advance and retreat.

6. Poor cooling or water leakage

The cooling effect of the mold directly affects the quality and production power of the finished product, such as poor cooling, large shortening of the finished product, or uneven shortening and warping deformation. On the other hand, all or some of the mold is overheated, so that the mold can not be formed normally and stop production, and the mobile parts such as the top rod are severely damaged by thermal expansion and stuck.
The cooling system program, processing to the shape of the commodity, do not omit this individual system because of the mold structure clutter or difficult processing, especially large and medium-sized molds must be fully considered cooling questions.

7. The slider is tilted and the reset is not smooth

Some molds are bound by the template area, the length of the guide groove is too small, and the slide block is exposed outside the guide groove after the core pulling action, so that the slide block tilt is simply formed in the period after the core pulling and the initial restoration of the mold, especially in the closing of the mold, the slide block reset is not smooth, so that the slide block damage, and even bending damage. According to experience, after the slider ends the core-pulling action, the length left in the chute should not be less than 2/3 of the total length of the guide groove.

8. The spacing tension arrangement fails

The fixed distance tension arrangement such as the swing hook and the buckle is usually used in the fixed mold core-pulling or some secondary demoulding molds, because this arrangement is set in pairs on the two sides of the mold, and its action is necessary to synchronize, that is, the mold is clasped together, and the mold is unhooked together in a certain orientation.
Once the synchronization is lost, the template of the pulled die must be tilted and damaged, the parts of these arrangements must have higher stiffness and wear resistance, and the adjustment is also difficult, the arrangement life is short, and the use can be prevented as far as possible.
In the case of small suction force ratio, the spring can be used to push out the fixed mold method, in the case of large core pulling force ratio, the core sliding can be used when the dynamic mold is withdrawn, the core is finished after the core pulling action and then the mold structure, and the hydraulic cylinder can be used to pull the core on the large mold. The inclined pin slider core-pulling arrangement is damaged.
The disadvantages of this arrangement are mostly that the processing is not in place and the material is too small, and the following two questions are the first:
A large inclination of the bevel pin has the advantage that a large core-pulling distance can occur in a short die opening stroke. However, if the inclination Angle A is too large, when the pulling force F is a certain value, the zigzag force P=F/COSA encountered by the inclined pin in the core pulling process is larger, and it is easy to present the inclined pin deformation and inclined hole wear.
At the same time, the upward thrust N=FTGA produced by the inclined pin on the slider is also larger, and this force increases the positive pressure of the slider on the guide surface in the guide groove, and then increases the resistance of the slider when sliding. Easy to form sliding, guide wear. According to experience, inclination A should not be greater than 25°.

9. The exhaust in the injection mold is not smooth

Gas often occurs in injection molds. What causes this?

The air in the pouring system and the mold cavity; Some materials are rich in moisture that has not been swept away by boredom, and they will vaporize into steam at high temperatures; Because the temperature is too high during injection molding, some unstable plastics will differentiate and gas will occur; Certain additives in plastic materials transports gases that may chemically react with each other.

The causes of poor exhaust gas also need to be found quickly. The poor exhaust of injection mold will bring a series of damage to the quality of plastic parts and many other aspects, mainly reflected: in the injection process, the melt will replace the gas in the mold cavity, assuming that the gas is not discharged in time will constitute the melt filling difficult, resulting in a short injection amount and can not fill the mold cavity; The cleaning of the bad gas will constitute high pressure in the cavity, and enter the interior of the plastic under a certain degree of contraction, forming quality defects such as emptiness, porosity, sparse arrangement and silver pattern;

Because the gas is highly compressed, the temperature in the cavity rises sharply, which causes the surrounding melt to differentiate and roast, so that the plastic parts show some carbonization and burning. It mainly appears at the confluence of the two melts and the flange of the gate; The gas cleaning is not smooth, so that the melt speed into each cavity is not the same, so it is easy to form active marks and fusion marks, and the mechanical function of plastic parts is reduced; Due to the obstruction of the gas in the cavity, the filling speed will be reduced, the molding cycle will be affected, and the tax power will be reduced.

The spread of bubbles in the plastic parts and the bubbles caused by the accumulated air in the mold cavity are often scattered on the opposite part of the gate; The bubbles of differentiation or chemical reaction in the plastic material are dispersed along the thickness of the plastic part; The remaining bubbles of water gasification in the plastic material are erratically scattered on all plastic parts.