How to avoid product cavity problems when pouring molds?

Solution: 1. Increase the temperature gradient of the solidification of the casting, that is, to ensure the bottom-up solidification sequence of the casting, which can effectively reduce the generation of gas shrinkage holes.

2. Reduce the gas generation of the casting cavity, if the cavity is too large, it will also make the casting have a lot of cavities.

Problems that should be paid attention to when pouring molds:

1.The accuracy of the product is closely related to the mold temperature of the plastic mold. Therefore, it is necessary to ensure that the melt flows through the gating system at a constant temperature, so it is essential to arrange a cold and hot temperature control system in the accessories of the gating system.

2.The channel through which the melt flows through the gating system is as short as possible to avoid pressure and temperature reduction under the requirements of exhaust and pouring.

3.The structural design of the gating system of the plastic mold should ensure that there is no turbulence or eddy current phenomenon from the melt to the mold cavity, otherwise the molding quality of the plastic product will be affected.

4.The structural design of the precision plastic mold gating system not only needs to consider the shape and material of the product, but also refers to the injection pressure, model and other parameters of the injection machine.

5.The pouring quality of the gating system of precision plastic mold is also related to the number of mold cavities, generally not more than 4 mold cavities, and the size difference of the mold cavity should not be placed in a mold.

6.The inlay design is a common design form in precision plastic molds, and if there are inserts in the gating system, the inlay accuracy must be ensured.

7.If the precision of precision plastic products is very high, and the gate of a certain part of the gating system shrinks due to the material, temperature and other factors, there is a margin design for subsequent processing and repair.

This kind of problem is best to ask a professional master to guide on site, however, you can provide a little experience to you, a small amount of phosphorus (sodium) in the molten iron can solve the problem of insufficient fluidity, but I personally think that you should ponder and ponder by changing the position of the casting port, and reasonably arrange the ventilation port to solve, because this kind of casting with uncomplicated structure should generally not occur in this situation (I can't see your diagram, for reference only).

Then you need to vibrate hard. Let the air inside be exhausted as much as possible, and of course don't forget to add a defoamer. It's impossible to be completely free of bubbles, and the most important thing is that there are no bubbles on the surface, right? Then focus on the surface. And the finished product.

First of all, pay attention to the exhaust problem of the mold, depending on the situation of the product, and then you are afraid of the early solidification, you can make a fuss about the insulation of the mold!

Increase pouring temperature and improve runner design.

The scorching of the product is mainly caused by poor exhaust gas, which can be solved in several ways:

1. Increase the mold exhaust duct and reduce the mold temperature.

2. Don't adjust the mold too tightly when adjusting the mold, and try to adjust it loosely when ensuring that there is no burr.

3. Reduce the injection speed.

4. Check whether it is due to the scorching caused by the high temperature of the barrel.

The main reason for the black spots caused by the discoloration and coking of injection molded products is that the plastic or the added ultraviolet absorber and antistatic agent are overheated and decomposed in the barrel, or they stay in the barrel for too long and decompose and coke, and then form with the melt injected into the cavity. The analysis is as follows:

1.In terms of machines:

1) Due to the loss of control of the heating control system, the barrel is overheated and causes decomposition and blackening.

2) Due to the defects of the screw or barrel, the melt is stuck in and hoarded, and it is decomposed due to long-term fixed heating. The tip kit should be inspected for wear or metal foreign objects inside.

3) Some plastics such as ABS are cross-linked and coking under high heat in the barrel, which is difficult to melt under the condition that the original particle shape is almost maintained, and is crushed by the screw and then entrained into the workpiece.

2 Mold aspect:

1) The mold exhaust is not smooth, it is easy to burn, or the size of the gating system is too small, and the shear is too strong, resulting in coking.

2) There are inappropriate oil lubricants and release agents in the mold.

3 Plastics:

Excessive volatiles in plastics, excessive humidity, too many impurities, too much recycled materials, and pollution.

4 Processing:

1) Too much pressure, too high speed, too much back pressure, too fast speed will decompose the material temperature.

2) The barrel should be cleaned regularly to remove additives that are worse than plastic resistance.

That's not called burning, it's called lack of glue. One is that the molding parameters are not adjusted well, which can increase the injection pressure and reduce the injection speed. The second is the mold problem, generally the relatively high bone position must be exhausted, cut an insert, do a pin.

The following expert analysis said that it may be a gas accumulation problem, if it is gas accumulation, it should be solved with a cleaning agent that traps the gas in the mold, so that there should be no scratches and gas lines on the sub-product. I know that there is a ligth stopper that removes the trapped gas of the mold, you can, go and search for the cleaning agent of the mold trapped gas.

Since it is an old mold, I thought that the exhaust had been designed at the beginning, and I guess it was scorched, and the exhaust should have been sealed. It is recommended to take it out for cleaning.

Hehe, I'm still not familiar with some of the terms on the product. Char. Try adjusting the pressure.

It should be a gas accumulation problem, call the mold master to take a look

One method is to increase the temperature gradient of the solidification of the casting, that is, Wusen ensures the bottom-up solidification sequence of the casting, which can effectively reduce the generation of gas shrinkage holes.

Another way is to reduce the gas generation of the casting cavity, if the cavity is too large, it will also make the casting have a lot of trembling cavities.

Increase the sprue and pay attention to the exhaust at the same time.

It should be that the wall thickness of the casting is uneven, and it is very easy to produce defects such as shrinkage holes, and the available solution can increase the shrinkage channel of the casting at the thickness change, that is, increase the casting fillet, because the shape with vertical angles should be avoided as much as possible in casting.

Another method is to increase the temperature gradient of the casting when solidifying, that is, to ensure the bottom-up solidification sequence of the casting, which can effectively reduce the generation of gas shrinkage holes.

Another way is to reduce the gas generation of the casting cavity, if the cavity is too large, the casting will also have a lot of cavities.

In the process of injection molding, shrinkage and depression of the product are a relatively common phenomenon. The main reasons for this are:

1 Machine:

1) The nozzle hole is too large, which causes the melt to reflux and shrinks, and the resistance is too small, and the material is insufficient.

2) If the clamping force is insufficient, the flash will also shrink, and the clamping system should be checked for problems.

3) If the plasticization amount is insufficient, a machine with a large plasticization amount should be selected to check whether the screw and barrel are worn.

2 Mold aspect:

1) The design of the workpiece should make the wall thickness uniform and ensure that the shrinkage is consistent.

2) The cooling and heating system of the mold should ensure that the temperature of all parts is consistent.

3) The gating system should be unobstructed, and the resistance should not be too large, such as the size of the sprue, runner and gate should be appropriate, the finish should be sufficient, and the transition area should be circular and arc transition.

4) The temperature should be increased for thin parts to ensure the smooth flow of materials, and the mold temperature should be reduced for thick-walled parts.

5) The gate should be opened symmetrically, and the thick-walled part of the workpiece should be opened as much as possible, and the volume of the cold material well should be increased.

3 Plastics:

Crystalline plastics are more shrinkage than amorphous plastics, and the amount of material should be increased appropriately during processing, or a replacement agent should be added to the plastic to accelerate crystallization and reduce shrinkage depression.

4 Processing:

1) The temperature of the barrel is too high, and the volume changes greatly, especially the temperature of the front furnace, and the temperature should be appropriately increased to ensure smooth flow of plastics with poor fluidity.

2) The injection pressure, speed, back pressure is too low, and the injection time is too short, so that the amount or density is insufficient and the shrinkage pressure, speed, back pressure is too large, and the time is too long, resulting in flash and shrinkage.

3) The amount of feeding is that the injection pressure is consumed when the buffer pad is too large, and the amount of material is insufficient if it is too small.

4) For the workpiece that does not require precision, after the injection pressure is completed, the outer layer is basically condensed and hardened, and the sandwich part is still soft and can be ejected, the mold should be released as soon as possible, and it can be cooled slowly in air or hot water, which can make the shrinkage and depression smooth and not so conspicuous without affecting the use.

Increase the holding time and pressure to prolong the cooling and reduce or increase the material temperature.

Reduce material temperature, increase holding time, increase injection speed, and expand gates.

Those few small holes can be made directly when making die-casting molds, and a few cores can be made directly. However, the core should have a relatively large demoulding slope, otherwise it will affect the demoulding. However, it is not a big problem, if it affects the use, you only need to use a standard drill bit to ream, which is much less troublesome than drilling.

This seems to be a brake disc, which is machined by a drilling machine, and the hole is a threaded hole.

If it is made directly on the mold, the edge is not good to be molded into a right angle, and the die-casting mold is not like a plastic mold, and the exhaust should be good;

Lack of plastic parts:

1. The supply of plastic is insufficient, the temperature is low, and the injection volume is insufficient.

2. The injection pressure is small, the injection time is short, and the pressure holding time is short.

3. The injection speed is too fast or too slow.

4. The nozzle temperature is low, the blockage or the aperture is too small, and the temperature of the barrel is low.

Dimensionally unstable:

1. The molding conditions (temperature, pressure, time) are unstable, and the molding cycle is inconsistent.

2. The performance of the injection molding machine is poor or uneven plasticization.

3. The electrical or hydraulic system of the machine is unstable.

There are bubbles: 1. The material temperature is too high and the heating time is too long.

2. The injection pressure is small.

3. The injection speed is too fast.

Collapse or dent:

1. The material temperature is high, the mold temperature is high, and the cooling time is short.

2. The injection pressure is small and the speed is slow.

3. Short injection and holding time.

4. The amount of feeding is not enough, the supply is insufficient, and the remaining material is not enough.

You're stealing business from the injection molding master, you can't do this, leave a way for people to live. Hehe, give it a look.

First draw the shape of the product, then design the mold, then process the mold, and then load the processed mold on the injection molding machine, and the injection molding can get the product. How to make molds? There are many kinds of processing methods, such as milling blanks, EDM slow wire, polishing, etc., many more.

The mold made of resin is also an external mold at the time of resin pouring

This is a question that requires you to spend three to five years of study, and a few years of work practice for college graduates.