For general and simple small products, you can first set a period of high speed and high pressure, use position switching, and adjust the position to produce a product with about 90% integrity. The pressure maintaining speed is also used at high speed. The pressure maintaining pressure is set at about half of the injection pressure or slightly higher, and the pressure maintaining time is added from 1 second to more. Select the time when the unit weight of the product is stable as the pressure maintaining time. The back pressure can be selected as an empirical value based on the machine. Simple products are generally OK after a period of high-speed molding, but there are relatively high requirements for molds and equipment.

Generally, it is necessary to adjust the second or multi stage process based on this. If mold opening does not take into account product deformation or poor exhaust performance, it is also necessary to adjust mold temperature, use low speed, low pressure processes, etc. Mold testing is a process of debugging, and specific issues need to be analyzed in detail.

Generally, it is required to hit 90% of the product, and then add and maintain the pressure. This requires you to find the switching position on the premise of knowing the measurement of this product. As for the speed, it depends on the product's material. ABS material should be low speed and low pressure, while nylon material should be high speed and high pressure. In short, it is necessary to consider the fluidity of the material and the amount of bone position of the product. Of course, it is best to use a mold temperature machine to improve the mold temperature when necessary, The fluidity of the material in the mold cavity is improved.

The function of pressure retaining is to adjust the local size while ensuring the beauty of the product. As the saying goes, "one protection, two pressure, and three stability" is the principle. The first section of the product is protected, and the last section is protected.

Some products have too many or too deep bone positions, which requires accurate knowledge of which section of the tube is here, and adjusting the position and speed to fill it! Actually, it all requires experience.

1、 Pressure

The action pressure provided by the pressure system (oil pump) or servo motor of an injection molding machine is mainly used in various action programs such as injection devices, glue melting devices, mold opening and locking devices, ejection devices, ejection devices, and core pulling devices. After inputting relevant parameters into the control panel of the injection molding machine, the processor converts them into signals for each program action, thereby controlling the pressure required for the execution of each action program.

The pressure setting principle 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

The required movement speed (flow of system hydraulic oil) for completing each action program with the above pressure is divided into three basic levels: slow flow 0.1-10, slow speed 11-30, medium speed 31-60, and high speed 61-99.

"The control of glue injection speed should be applied to different product structures and materials to set size values. It is not necessary to distinguish (engineering/general purpose plastics, crystalline/amorphous plastics, high-temperature/low-temperature plastics, soft/hard plastic) here, which can easily confuse the public. For a more understandable explanation, glue injection speed is a relatively difficult process element to control in injection molding.", Unlike other process elements, standard data is available for reference (detailed description will be provided later).

The numerical setting of glue injection speed mainly follows the following points:

According to the fluidity of materials, such as PP, LDPE, TPE, TPR, TPU, PVC, and other soft plastics, their fluidity is good, and their cavity resistance is small when filling. Generally, a lower injection speed can be used to fill the cavity.

· Commonly used medium viscosity plastics such as ABS, HIPS, GPPS, POM, PMMA, PC+ABS, Q glue, K glue, HDPE, and so on have slightly poor fluidity. When the requirements for product appearance glossiness are not high or the product flesh thickness is moderate (the product wall thickness or bone thickness reaches 1.5 mm or above), the injection speed can be used to fill at medium speed. Conversely, it is necessary to appropriately improve the filling speed according to the product structure or appearance requirements.

Engineering plastics such as PC, PA+GF, PBT+GF, and LCP have poor fluidity, and generally require high-speed glue injection during filling, especially for materials that increase GF (glass fiber). If the glue injection speed is too slow, it can cause serious surface fiber floatation (surface craze) on the product.

2. Control of glue melting speed

This parameter is one of the most easily overlooked processes in daily work, as most colleagues believe that this process has little impact on molding, and products can be made by randomly adjusting parameters. However, in injection molding, the melt parameter is as important as the injection speed, which can directly affect important links such as melt mixing effect and molding cycle

3. Control of mold opening and locking speed

Different parameters are mainly set for different die structures. For example, the production efficiency can be effectively improved by adjusting the high-speed clamping of the two plate plane die before starting the clamping low pressure and adjusting the high-speed clamping after the product is separated from the mold cavity.

However, when adjusting the speed of mold opening and locking for molds with row positions, it is necessary to adjust the speed of mold opening and locking based on the height and structure of the row positions.

4. Control of ejector pin speed

It mainly depends on the mold release status of the product. In principle, it is necessary to ensure that the product does not appear top white, top height, or deformation as soon as possible, otherwise, it is necessary to adjust the parameters appropriately according to the actual situation, of course; In general, when adjusting the true speed for the first time, it is better to use a medium and low speed (15% - 35%), which can effectively extend the service life of the ejector pin and the ejector pin cylinder.

3、 Location

Switching point between fast and slow speed, high and low pressure of each action

1. Control of glue injection position;

During the debugging of injection molding parameters, the injection position needs to be adjusted according to the unit weight and structure of the product. When adjusting the position based on the unit weight of the product, it is often said that how much glue is required for the product,

2. Control of glue melting position;

3. Generally speaking, it is understood that the melt distance should be set according to the required injection amount of molded products. Most colleagues ignore the three-stage switch position of the melt and only focus on the end point position of the melt;

Generally difficult molded products do not need to switch between fast and slow speeds or high and low back pressure when adjusting the melt position, and can still achieve the desired product quality. However, when producing color masterbatches and heat sensitive plastics, appropriately switching the melt speed and back pressure adjustment positions can better control product quality.

3. Position control of mold opening and locking

· Set switching points mainly to meet the needs of mold opening and locking speed

Generally, the switching point for mold opening speed is the slow speed before the molded product leaves the mold cavity (about 5-15MM), and the fast speed after turning, which can effectively shorten the time required for mold opening. Finally, the slow speed (i.e., the mold opening buffer position, generally 20-40MM from the desired mold opening end position, is the best starting point for switching. (The end position depends on the product structure and whether a manipulator is used), which can effectively extend the service life of the hinge of the injection molding machine and stabilize the mold opening action).

The structural factors of some special molds, such as three-plate molds or core-pulling molds, need to be determined based on the actual situation. For example, due to the fact that the product cavity is on the middle plate, the three-plate mold first acts on the nozzle plate during mold opening, and it is necessary to separate the nozzle runner from the product before separating the male and female molds. Therefore, it is necessary to add 1-2 switching points on the mold opening position, which are medium speed - slow speed - high speed - slow speed, For machines with large tonnage, several switching points can be added as needed. In short, the quality of molded products is not affected and the action process is stable during the mold opening process.

· The setting of the mold locking position mainly depends on the mold structure

For example, in a planar mold structure (i.e., the parting surfaces of both the front and rear molds are planar, with no slider/core pulling, and no insertion structure), when switching the mold locking speed, it is possible to directly use the 4-segment position for "fast medium speed low pressure high pressure",

The principle for switching its position is:

The fast stroke for mold locking is preferably about 70% of the mold opening stroke. (The fast end position of the three-plate mold depends on the structural size of the mold.) Its main function is to shorten the mold locking cycle. Turn back to medium speed, which acts as a deceleration buffer for high-speed mold locking (as the low pressure protection function will be switched after medium speed)

The end position of the medium speed of mold locking is very important, which determines the starting position of mold locking low voltage protection. Some senior colleagues are very vague about mold locking low voltage, and believe that mold locking can be set arbitrarily, but in fact, it is not. If the mold locking low pressure is improperly set, the protection function will be completely lost, which is fatal to fully automated mold production. How to correctly set the low pressure protection function will be described in detail in the following chapters.

4. Control of ejector pin position;

In theory, the ejection length of the ejector pin is twice the height of the mold cavity (i.e., the mold core) behind the mold, but in actual operation, it is not necessary to set the position completely according to this method, specifically to facilitate the removal of the product. However, when adjusting the ejector pin position for the first time, it is necessary to gradually lengthen it, first ejecting 50% of the ejector pin stroke of the mold, and then depending on the withdrawal status of the product during the production process.

4、 Temperature

Necessary conditions for plastic melting and mold heating

1. Control of material pipe temperature;

Generally, there are relatively standard molding temperatures for plastics with different properties, such as:

· ABS=(distinguish between high impact material 230-260 and low impact material 190-230)

· SAN=180-220、

· HIPS=180-220、

· POM=170-200、

· PC=240-300、

· ABS/PC=230-260、

· PMMA=200-230、

· PVC=(distinguish between high density 160-200 and low density 140-180)

· PP=180-230、

· PE=(distinguish between high density 240-300 and low density 180-230)

· TPE=(distinguish between high density 170-200 and low density 140-180)

· TPR=(distinguish between high density 170-200 and low density 140-180),

· TPU=(distinguish between high density 160-200 and low density 120-160)

· PA=230-270、

· PA+fiber=250-300

· PBT=200-240、

· PBT+fiber=240-280, and the molding temperature for adding flame retardant (i.e., fireproof material) should be 20-30 degrees lower than that for ordinary materials.

The specific use temperature depends on the production situation, as the molding temperature directly affects the fluidity, viscosity, mold temperature, color, shrinkage, product deformation, etc. of the plastic.

2. Control of mold temperature;

The mold temperature is mainly determined based on different plastic fluidity, which can be understood simply as the key process to overcome poor fluidity. For example, if the fluidity of PC and PA+fiber materials is poor, and their flow resistance during the filling process is large, a faster injection speed is required for filling.

In addition, when producing PC transparent rubber parts, it is necessary to have a higher mold temperature in order to improve the surface air marks, rainbow marks, and internal bubbles of the product. When producing fiber reinforced materials, if the mold temperature is lower, silver threads (floating fibers) will appear on the surface. In general, the mold temperature can be adjusted by referring to the following data:

· ABS=30-50 (products with high surface quality requirements or requiring controlled deformation can be increased to 60-110 degrees)

· PC=50-80 (products with high surface quality requirements or thin walls can be improved to 85-140 degrees)

· HIPS=30-50 (transparent PS and products with high surface quality requirements can be increased to 60-80 degrees)

· PMMA=60-80 (thin-walled products and products with high surface quality requirements can be increased to 80-120 degrees)

· PP=10-50, PE=10-50 (high-density or thin-walled products can appropriately increase mold temperature)

· Rubber (TPE, TPR, TPU)=10-50,

· PA, PBT=30-60 (high surface quality requirements and glass fiber reinforced materials can be increased to 70-100)

5、 Time

The execution time of each action

1. Control of filling time, including glue injection time and pressure holding time

· Injection time

Generally, products with acceptable quality should be as short as possible, as the glue injection time directly affects the internal stress and production cycle of the product. In principle, the thinner the glue position of the product, the shorter the glue injection time. Conversely, for thick wall products, it is necessary to extend the glue injection time as appropriate to control their shrinkage.

In addition, using products with multiple stages and large switching ranges between fast and slow speeds requires a longer injection time. The setting of the injection time also needs to be based on the volume of the product (the larger the product, the longer the injection time is required). Here, it is also necessary to consider the properties of the plastic used in production, such as the general plastic ABS. When the product wall thickness is 2.0MM, the injection speed is moderate, and the material pipe temperature is moderate, the flow rate is about 65mm/s in the longitudinal direction (different mold structures or processes have different flow rates).

· Pressure holding time

In principle, the pressure holding time mainly controls the surface shrinkage of the product and the structural dimensions of the product. However, after fully mastering the control method of the pressure holding time, it can also be used to adjust the deformation degree of the product (therefore, the adjustment process is a precision machine adjustment process, and the adjustment method will be described in detail in the following chapters).

Here, we will briefly explain how to use pressure maintaining to control product shrinkage. Generally, the choice of using pressure maintaining to control product shrinkage depends on the shrinkage position of the product. Not all shrinkage can be solved using pressure maintaining. For example, if the shrinkage position is at the end of the melt filling, using pressure maintaining to control shrinkage can cause excessive stress near the nozzle position, resulting in top whitening, mold sticking, or causing product warpage and deformation.

2. Ejector delay time

It mainly controls the dwell time when the ejector pin is ejected, facilitating the robot to pick up the product.

3. Core pulling time

Control the action time of the core pulling device of the injection molding machine (mainly used to control the action stroke with time). If the core pulling stroke is controlled with an inductive switch, the core pulling time may not be set.

4. Low-voltage time and setting method of mold locking, etc.