How to set the injection speed, position and pressure during plastic injection molding?
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- Unsolveddestoon
- 2021-08-20 11:04
How to determine the holding pressure?
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- 1Flooranonymity
- 2021-08-25 12:38
1. Pressure
The action pressure provided by the pressure system (oil pump) of the injection molding machine or the servo motor is mainly used in the injection device, the glue melting device, the mold opening and clamping device, the ejection device, the injection device, the core pulling device and other action programs. After the control panel of the injection molding machine inputs the relevant parameters, the processor converts them into the signals of each program action, thereby controlling the pressure required for the execution of each action program.
The principle of pressure setting is: the corresponding strength to overcome the resistance of the action, but the parameter value needs to be adjusted accordingly to match the speed of the action.
2. Speed
Cooperate with the above pressure to complete the required movement speed (system hydraulic oil flow) for each action program. The basic speed levels are divided into: slow flow 0.1-10, slow speed 11-30, medium speed 31-60, high speed 61-99.
1. The injection speed control is applied to different product structures and materials to set the size and value. There is no difference here (engineering/general plastics, crystalline/amorphous plastics, high/low temperature plastics, soft/hard plastics) ) It is easy to confuse the audio and video, and make a relatively easy-to-understand explanation. The injection speed is a process element that is difficult to control in injection molding. Unlike other process elements, there are standard data for reference (detailed introduction will be given later).
The numerical setting of the injection speed mainly follows the following points:
According to the fluidity of the material, such as PP, LDPE, TPE, TPR, TPU, PVC and other soft plastics, the fluidity is better, and the cavity resistance is small when filling. Generally, a lower injection speed can be used to fill the type. Cavity.
Commonly used medium viscosity plastics such as ABS, HIPS, GPPS, POM, PMMA, PC+ABS, Q glue, K glue, HDPE, etc. In the case of wall thickness or bone thickness above 1.5mm), the injection speed can be filled at a medium speed. On the contrary, the filling speed should be appropriately increased according to the product structure or appearance requirements.
Engineering plastics such as PC, PA+GF, PBT+GF, LCP and other engineering plastics have poor fluidity and generally require high-speed injection during filling, especially for materials with increased GF (glass fiber). If the injection speed is too slow, it will cause the surface of the product. The floating fiber (silver pattern on the surface) is serious.
2. Control of melting speed
This parameter is one of the most easily overlooked processes in daily work, because most colleagues think that the process has little effect on molding, and the parameters can be adjusted at random to make products, but the melt parameters in injection molding are the same. Gluing speed is just as important, melting speed can directly affect the melt mixing effect, molding cycle and other important links
3. Control of opening and clamping speed
Different parameters are mainly set for different mold structures. For example, two-platen flat molds can adjust high-speed mold clamping before starting clamping and low pressure and adjust to rapid mold opening after the product leaves the mold cavity, which can effectively improve production efficiency.
However, when adjusting the speed of mold opening and locking for molds with row positions, the speed of mold opening and locking needs to be switched according to the height and structure of the row position. Due to the complex structure of the special mold structure and core-pulling mold, an explanation will be given in the following chapters.
4. Control of thimble speed
It mainly depends on the demolding condition of the product. In principle, it should be as fast as possible under the premise of ensuring that the product does not appear top white, top height, or deformation. The true speed should be medium and low speed (15%-35%), which can effectively extend the life of the thimble and the thimble cylinder.
3. Location
The switching point between the fast and slow speed, high and low pressure of each action
1. Control of the injection position;
In the adjustment of injection molding parameters, the injection position needs to be adjusted according to the product unit weight and structure. Adjust the position after considering the product unit weight, which is how much glue is needed for the product.
For example, the unit weight of a product is about 50G, and it is produced by a 90T injection molding machine. The theoretical injection volume of this model is 120G, and the melt stroke is 130MM. About each MM melt weight is the theoretical injection volume 120G÷the melt stroke 130MM =0.92G, that is, the injection distance of the product is 50×0.92=46MM. If the melting end position is set at 60MM, the quality of the product is basically OK when the injection reaches 14MM.
(Of course, the above is an empirical talk, it is somewhat deviated, because it did not follow the screw compression ratio calculation formula in the book, it is too complicated, I believe most of my colleagues can't count it), as for how to use the injection position to control various moldings The bad phenomenon of the product will be explained in detail in the following chapters.
2. Control of the glue position;
Generally understood as setting the melt distance in response to the required injection volume of the molded product. Most colleagues ignore the three-stage switch position of the melt and only pay attention to the end point of the melt;
Generally difficult molding products do not need to switch between fast and slow speed or high and low back pressure when adjusting the melting position. The required product quality can still be achieved, but the melting speed should be appropriately switched in the production of color masterbatches and high heat-sensitive plastics. And the adjustment position of back pressure can better control the product quality.
The action pressure provided by the pressure system (oil pump) of the injection molding machine or the servo motor is mainly used in the injection device, the glue melting device, the mold opening and clamping device, the ejection device, the injection device, the core pulling device and other action programs. After the control panel of the injection molding machine inputs the relevant parameters, the processor converts them into the signals of each program action, thereby controlling the pressure required for the execution of each action program.
The principle of pressure setting is: the corresponding strength to overcome the resistance of the action, but the parameter value needs to be adjusted accordingly to match the speed of the action.
2. Speed
Cooperate with the above pressure to complete the required movement speed (system hydraulic oil flow) for each action program. The basic speed levels are divided into: slow flow 0.1-10, slow speed 11-30, medium speed 31-60, high speed 61-99.
1. The injection speed control is applied to different product structures and materials to set the size and value. There is no difference here (engineering/general plastics, crystalline/amorphous plastics, high/low temperature plastics, soft/hard plastics) ) It is easy to confuse the audio and video, and make a relatively easy-to-understand explanation. The injection speed is a process element that is difficult to control in injection molding. Unlike other process elements, there are standard data for reference (detailed introduction will be given later).
The numerical setting of the injection speed mainly follows the following points:
According to the fluidity of the material, such as PP, LDPE, TPE, TPR, TPU, PVC and other soft plastics, the fluidity is better, and the cavity resistance is small when filling. Generally, a lower injection speed can be used to fill the type. Cavity.
Commonly used medium viscosity plastics such as ABS, HIPS, GPPS, POM, PMMA, PC+ABS, Q glue, K glue, HDPE, etc. In the case of wall thickness or bone thickness above 1.5mm), the injection speed can be filled at a medium speed. On the contrary, the filling speed should be appropriately increased according to the product structure or appearance requirements.
Engineering plastics such as PC, PA+GF, PBT+GF, LCP and other engineering plastics have poor fluidity and generally require high-speed injection during filling, especially for materials with increased GF (glass fiber). If the injection speed is too slow, it will cause the surface of the product. The floating fiber (silver pattern on the surface) is serious.
2. Control of melting speed
This parameter is one of the most easily overlooked processes in daily work, because most colleagues think that the process has little effect on molding, and the parameters can be adjusted at random to make products, but the melt parameters in injection molding are the same. Gluing speed is just as important, melting speed can directly affect the melt mixing effect, molding cycle and other important links
3. Control of opening and clamping speed
Different parameters are mainly set for different mold structures. For example, two-platen flat molds can adjust high-speed mold clamping before starting clamping and low pressure and adjust to rapid mold opening after the product leaves the mold cavity, which can effectively improve production efficiency.
However, when adjusting the speed of mold opening and locking for molds with row positions, the speed of mold opening and locking needs to be switched according to the height and structure of the row position. Due to the complex structure of the special mold structure and core-pulling mold, an explanation will be given in the following chapters.
4. Control of thimble speed
It mainly depends on the demolding condition of the product. In principle, it should be as fast as possible under the premise of ensuring that the product does not appear top white, top height, or deformation. The true speed should be medium and low speed (15%-35%), which can effectively extend the life of the thimble and the thimble cylinder.
3. Location
The switching point between the fast and slow speed, high and low pressure of each action
1. Control of the injection position;
In the adjustment of injection molding parameters, the injection position needs to be adjusted according to the product unit weight and structure. Adjust the position after considering the product unit weight, which is how much glue is needed for the product.
For example, the unit weight of a product is about 50G, and it is produced by a 90T injection molding machine. The theoretical injection volume of this model is 120G, and the melt stroke is 130MM. About each MM melt weight is the theoretical injection volume 120G÷the melt stroke 130MM =0.92G, that is, the injection distance of the product is 50×0.92=46MM. If the melting end position is set at 60MM, the quality of the product is basically OK when the injection reaches 14MM.
(Of course, the above is an empirical talk, it is somewhat deviated, because it did not follow the screw compression ratio calculation formula in the book, it is too complicated, I believe most of my colleagues can't count it), as for how to use the injection position to control various moldings The bad phenomenon of the product will be explained in detail in the following chapters.
2. Control of the glue position;
Generally understood as setting the melt distance in response to the required injection volume of the molded product. Most colleagues ignore the three-stage switch position of the melt and only pay attention to the end point of the melt;
Generally difficult molding products do not need to switch between fast and slow speed or high and low back pressure when adjusting the melting position. The required product quality can still be achieved, but the melting speed should be appropriately switched in the production of color masterbatches and high heat-sensitive plastics. And the adjustment position of back pressure can better control the product quality.