Guide to the Working Principle of vertical Injection Molding ...

MIN-HUI Injection molding machines are also known as injection molding machine or injection machine. It is the key molding equipment for making thermosetting plastic or thermoplastic into many shapes of plastic products via plastic molding molds including horizontal, vertical, and all electric. The vertical injection molding machine can heat the plastic and use high force to the molten plastic to inject it to fill the mold cavity.

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The masterpiece of the vertical injection molding machine

Vertical injection molding machine is generally composed of clamping system, injection system, electrical control system, transmission system, heating and cooling system, lubrication system, safety monitoring system, etc.

• Injection system

The injection system is one of the most vital parts of the injection molding machine. Generally, there are 2 main types: screw type, plunger type, and screw pre-plastic plunger injection type. The screw type is presently the most largely used. Its work is that in a cycle of the plastic injection molding machine, a certain amount of plastic can be warmed and plasticized within a specified time.

• Hydraulic system

The work of the hydraulic transmission system is to realize the injection molding machine to give power according to the many actions needed by the process, and to meet the needs of the speed, pressure, temperature, etc, needed by each part of the injection molding machine. It is largely composed of many hydraulic parts and hydraulic auxiliary parts, among which is motor and the oil pump are the power source of the injection molding machine. Many valves control the oil force and flow rate to meet the needs of the vertical injection molding process.

• Cooling/heating system

The warming system is used to heat the barrel and the injection nozzle. The barrel of the injection molding machine usually uses an electric ring as a warming device, which is fixed on the outside of the barrel and is detected in sections with a thermocouple. The heat conducts warm conduction via the cylinder wall to give a warm source for the plasticization of the material; the chilling system is largely used to chill the oil temperature. High oil temperature will cause a range of faults, so the oil temperature must be managed. The other place that needs to be chilled is near the feeding port of the feed pipe to stop the raw material from melting at the feeding port, causing the raw stuff to fail to be fed usually.

• Electrical control system

The hydraulic system and electric control system are reasonably coordinated to realize the process needs and many program actions of the injection machine. Largely composed of electrical components, electric meters, sensors, heaters, etc. There are generally 4 control modes.

• Lubrication system

The lubrication system is a circuit that gives lubrication conditions for the relative moving parts of the injection molding machines movable template, connecting rod hinge, and plastic mould adjustment device, so as to decrease power use and increase the life of parts. Lubrication can be automatic electric lubrication or regular manual lubrication.

• Security protection and monitoring system

The safety gadget of the injection molding machine is largely used to save the safety of people and machines. It is largely composed of hydraulic valves, safety doors, photoelectric detection elements, etc. to get electrical-mechanical hydraulic interlock protection. The monitoring system largely monitors the material temperature, oil temperature, system overload and process and equipment of failures of the injection molding machine, alarms or indicates when abnormal situations are found.

Working process

The injection molding machine and the syringe used for injection have a quite similar working principle. It is a process in which the plasticized molten state plastic is injected into the closed mold cavity by the screw thrust and the product is obtained after shaping and solidification.

The injection molding process is a cycle. Plasticizing pressure injection and quantitative feeding melting and cooling mold opening and picking are the key contents of each cycle. After taking out the plastic part, the mold is clogged again for the upcoming cycle. Control 3 aspects including electrical control system operation, keyboard operation, and hydraulic system operation. Respectively adjust the injection force and back force, check the temperature of each section of the barrel, and pick the injection process action, injection pressure, feeding action, ejection type, injection speed, etc.

First, include powered or granular plastic into the barrel. The plastic is melted by the rotation of the screw and the outside wall of the barrel. Then the machine closes the mold and moves the injection seat forward, nearer the nozzle at the gate of the mold, and then press the oil is passed into the injection cylinder and the screw is pushed forward, so injecting the melt into the closed mold with a lower temperature at a top pressure and a quicker speed. After a certain period of time and force holding, cooling, and solidifying it, the item can be opened and taken out. 

Injection, plasticization, and molding are the general needs of injection molding. The prerequisite for realizing and ensuring the standard products is plasticization. At the same time, because there is a high injection force, there is a high force correspondingly produced in the cavity. So there must be an important clamping force. This shows that the important components of the injection device and the mold clamping device.

Notes

• The thermoplastic molten liquid has low viscosity and so it can flow simply.
• In the case of thermoset liquids, the high viscosity and so it is hard to flow
• From the nozzle and that is the reason, thermoplastics will be used in vertical injection moulding machine.

MIN-HUI vertical injection molding machine process advantages:

• The flexibility of design is very high and it works as a benefit to the producers to create many products irrespective of design.
• The scrap is almost zero in this kind of machine.
• Different products can be produced by replacing the dies of mold.
• The color of the products can be managed during the creation of parts.
• Different items can be produced by changing the dies of mold.

Vertical injection moulding process applications

The applications of injection moulding process are as follows:

• Agriculture products
• Kitchen products
• Plastic plates
• Water cooler parts
• Industrial pump impeller
• Medical products

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Prepare the vertical injection molding machine before starting

Check whether each lubrication part is fully lubricated; Check whether the oil pump has abnormal noise; Install and tighten the mold carefully, and pay attention to safety when loading and unloading the mold; Adjust pressure at all levels; Set all levels of temperature.

Manual operation and adjustment of vertical injection molding machine

Adjust the position of each switch manually to ensure the safety of the die. Set the manual button ON the electronic control panel to ON(open). When the machine is operated manually, each action button ON the electronic control operation panel can only be operated when the button is pressed (ON), and the action disappears when it is released. Mold adjustment:

First adjust the die close high voltage proximity switch travel block to the lowest point, then install the die in the center between the upper and lower die, and then press the die adjustment (pull out) button on the electronic control panel. At this point, the upper form begins to close the mold at low pressure and slow speed. After the die is sealed, adjust the close die close high pressure close pull stop block to a position that can raise the high pressure. At this point, the high pressure is turned off to increase the pressure when the manual die close button is pressed.

Close the vertical injection molding machine mold:

When semi-automatic, both hands hold down the two automatic start buttons on the operating table, then the machine closes the mold. At the beginning, the mold is closed quickly. When the closing mold is in contact with the lower closing mold entering switch block, the closing mold is closed slowly until the closing mold is completed. High voltage mode locking is produced when the high voltage proximity switch block is contacted.

Seat entry: used when mold alignment, that is, to control the forward use of the nozzle cylinder table.

Injection: According to the product material, shape and size, adjust the injection pressure, maintain the pressure and cure the injection time and position, then press the injection button to complete the injection. (Note: When the temperature reaches the set value, the shooting action can be performed).

Screw feeding: After pressing the feed button, the screw rotates the rubber, and the stirring compression screw rises (the rising speed is determined by the adjustment of the back pressure regulating valve). When the rising action of the screw contacts the feed contact switch block, the feeding action stops. The size of the feeding stroke depends on the amount of feeding required by the product.

Loose: When manually pressing the loose button, the screw moves upward, and the shooting action can be performed.

Before starting

1. Before the operation of the injection molding machine, check whether there is water and oil in the electrical control box. If the electrical equipment is damp, do not start the machine. There should be maintenance personnel to blow dry electrical parts before starting.

2. Before the operation of injection molding machine, check whether the supply voltage is in line with it. Generally, it should not exceed ±6%.

3. Check whether the emergency stop switch and front and rear safety door switches are normal. Verify the motor and oil pump rotation direction is consistent.

4. Check whether the cooling pipes are unimpeded for long distance, and pass cooling water into the cooling water jacket of the oil cooler and the end of the barrel.

5. Before operation of injection molding machine, check whether there is lubricating oil in each moving part, and add enough lubricating oil.

6. Turn on the electric heat and heat each section of the cylinder. When the temperature of each section reaches the requirements, heat preservation for a period of time to make the temperature of the machine stable. The holding time varies according to the requirements of different equipment and plastic raw materials.

7. Add enough plastic to the hopper. According to the requirements of injection molding different plastics, some raw materials are best after drying.

8. Cover the heat shield on the barrel, which can save electricity and prolong the life of the electric heating ring and current contactor

1. Do not cancel the role of the safety door for convenience.

2. Pay attention to the temperature of the pressure oil, and the oil temperature should not exceed the prescribed range. The ideal working temperature of hydraulic oil should be kept between 45-50', generally in the range of 35-60' is more appropriate

3. Pay attention to adjust the switch of each stroke to avoid the impact of the machine during operation.

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