Introducing common plastic product defects, and analyzing any repair molds?

The common defects are: lack of glue, sleepiness, top white, criticism, flow pattern, deformation, shrinkage, etc. Adjust the magnitude of the pressure, 2. Adjust the size of the shot volume, 3. Hit the exhaust,

First, the lack of materials is uneven.

1 The injection pressure is too small.

2 The injection speed is too slow.

3. Poor exhaust of the mold cavity.

4 Clogged inlet.

5 The injection time is too short, 6 The nozzle leaks.

Second, the raw edge of the peak.

1 Too much pressure to inject.

2. The mold clamping is not tight, and the clamping force is too small.

3. The mold combination and sealing are not tight, and there are sundries or template deformation on the mold.

4. Mold bonding defects.

3. Bubbles Plastic raw materials are wet.

1. Plastic raw materials are decomposed.

2. The forming temperature is too low, 3, the welding is poor, 4, the plastic raw material is mixed with impurities.

5 The thickness of the plastic surrounding the insert is not enough.

6 The mold temperature is too low.

7. The design of the inlet position is unreasonable.

8. Plastic raw materials are wet.

Fourth, the temperature of the bonding line 1 is too low, or the temperature of the material is too low, and the temperature of the tomato is too low, and the exhaust of the mold cavity is poor.

Fifth, the material flower 1 plastic raw materials have moisture and lack of volatiles.

2 The drying temperature is too low.

3 The size of the inlet is too large.

6. Black dots (mixed colors).

1. Plastic raw materials are decomposed.

2. Plastic raw material debris is stuck between the plunger and the barrel.

3. Plastic raw materials are contaminated or bring in impurities.

4. The particles of plastic raw materials are uneven.

5. Poor exhaust of the mold cavity.

7. Deformation 1 The temperature of the mold is too high and the cooling time is not enough.

2. There is a huge difference in the thickness of the wall of the product.

3. The thimble is not properly pushed out, and the force of the product is uneven, 4. The mold cavity is not smooth, the demoulding is not smooth, and the friction force is too much.

There are three reasons for this:

1. In the injection molding process, if it is found that the geometry of the plastic product is unstable and the dimensional error is large, it may be that the compression of the inner cavity of the mold is relatively small; The length and size of the qualitative part of the mold mouth mold are small, the sizing sleeve is deformed, or the temperature of the mold body is uneven.

2. If you see that the surface of the product is yellowish and the phenomenon of scorch spots often appears, the expansion angle of the classification cone in the mold is larger. This results in high melt flow resistance.

3. If the longitudinal flow pattern on the surface is uninterrupted, it is very likely that there will be foreign objects stuck in a certain part of the runner cavity, and there will be scratch marks, burrs or serious wear in the shaping part.

Then it depends on what is wrong with the plastic parts!

How to find it? Do it for a few more years and you'll understand!

The quality of plastic products is divided into appearance and structural problems, and the surface treatment of injection molds, injection molding water and materials, design, mold temperature, molding temperature, etc., are related to specific analysis.

How to reduce defects in plastic product mold processing: reduce the quenching stress after bending at the thermal source to a minimum, because the quenching stress and the reticulated carbonization structure are under the action of grinding force, and the phase change of the structure is very easy to cause cracks in the workpiece. Rational use of cooling lubricating fluid, play the three major functions of cooling, washing and lubrication, keep the cooling lubrication clean, so as to control the grinding heat within the allowable range, so as to prevent the thermal deformation of the workpiece.

1. Improve the cooling conditions during grinding, such as using oil-soaked grinding wheels or hail-filled internal cooling grinding wheels. By introducing the cutting fluid into the center of the grinding wheel, the cutting fluid can enter the grinding zone directly, providing an effective cooling effect and preventing burns on the surface of the workpiece. Rational use of cooling lubricating fluid, play the three major functions of cooling, washing and lubrication, keep the cooling lubrication clean, so as to control the grinding heat within the allowable range, so as to prevent the thermal deformation of the workpiece.

2. Reduce the quenching stress after heat treatment to a minimum, because the quenching stress and the reticulated carbonization structure are under the action of grinding force, and the phase change of the structure is very easy to cause cracks in the workpiece. For high-precision molds, in order to eliminate the residual stress of grinding, low-temperature aging treatment should be carried out after grinding to improve toughness. Imitation.

3. To eliminate grinding stress, the mold can also be immersed in a 260 315 salt bath, and then cooled in 30 oil, so that the hardness can be reduced by 1HRC, and the residual stress can be reduced by 40% to 65%.

4. For the precision grinding of precision molds within the dimensional tolerance, it is necessary to pay attention to the influence of ambient temperature, and constant temperature grinding is required. It can be seen from the calculation that when the temperature difference of 300mm long steel parts, the material has a change of left and right, and the influence of this factor needs to be fully considered in each finishing process of every 100mm deformation.

5. Electrolytic grinding is used to improve the accuracy and surface quality of mold manufacturing. During electrolytic grinding, the grinding wheel scrapes off the oxide film: instead of grinding the metal, the grinding force is small, the grinding heat is also small, and there will be no grinding burrs, cracks, burns and other phenomena, and the general surface roughness can be better; In addition, the wear of the grinding wheel is small, such as grinding cemented carbide, the wear amount of silicon carbide grinding wheel is about 400% 600% of the weight of the cemented carbide that is ground off, and the wear of the grinding wheel is only 50% to 100% of the amount of cemented carbide grinding when grinding with electrolytic grinding.