Injection Molding Blog

Electrical System introduction of Injection Molding Machines – By Zafar Kamal         For better and accurate functions, the injection-molding machine follows a programmed sequence of events for the precise control of heat, the proper timing of injection pressures and cooling, and special machine sequences, and the ever-dominant need for safety of personnel and equipment. Most injection that the operator has the fundamental knowledge of the machine’s electrical circuits.

Hydraulic Fluids and Hydraulic Accessories in Injection Molding Machines – By Zafar Kamal         4.3 Hydraulic Fluids If the heating cylinder of the molding machine can be treated as the heart of the system , then it follows the hydraulic-oil lines are the blood of the process. The selection of the oil is very important factor , therefore serious consideration should be taken while selecting the oil. Please contact your machine`s manufacturer for what exactly kind of hydraulic-oil their machines is best selection. 4.4 Hydraulic Accessories All modern molding-machine are equipped with the necessary filtering systems, and a part of any good maintenance program includes the regular inspection of these systems. Maintaining the hydraulic fluid at the proper tank level, making sure that the injection machine is operated at the proper temperature levels, and assuring that the oil is being cleaned and filtered are all-important to the continued trouble-free operation of the machine. The other type of the system which is very important in case of accuracy acheivement is called an electrical system.

Hydraulic Motors and Cylinders of Injection Molding Machine – By Zafar Kamal         Hydraulic motors are used to convert hydraulic energy (pressure and flow) to mechanical energy. Their operation is reverse of a pump’s. When oil is pushed into one port and discharge from another , the motor rotates in one direction. If the flow is reversed, the direction of the rotation is reversed. Since no centrifugal force exists until the motor begins to rotate, springs are used behind the vanes to hold them in place against the ring. Unlike motors, cylinders are linear actuators which convert hydraulic energy into mechanical energy. Oil forced in the one end of the cylinder causes the piston and rod to move in one direction. If the flow of oil is reversed the movement is reversed.

Operating Valves and Control of Hydraulic System for Injection Molding Machine – By Zafar Kamal         The relief valve limits the maximum pressure in the hydraulic circuit. Since the pump is a positive displacement unit, it continuous to push out oil regardless of the resistance which the flow encounters. The relief valve is needed to bypass excess oil back to the tank and protect the hydraulic system and machine against excessive pressure. An unloading valve is used to dump the flow of oil from one pump, while holding pressure with another pump. This type of pump is generally used with a double pump to conserve power and heat by unloading the large-volume pump while holding pressure with the small-volume pump. A check valve permit flow in one direction and prevents flow in the other direction. A light spring hold the poppet on its seat. When the pressure on the inlet port overcome the spring force, the poppet lifts off its seat and flow passes from the inlet to the outlet port. In the reverse direction, pressure applied

Hydraulic Pump of Injection Molding Machines – By Zafar Kamal         The pump pushes the fluid through the lines. The pumps most commonly used on injection-molding machines are the balanced-vane type. The pumping unit of cartridge includes a cam ring, a slotted rotor, and vanes held between, with a wear plate and pressure plate at the sides. Pockets are formed by each two adjacent vanes, the ring rotor, and the side plates. As the pump rotates, the volume of each pocket become larger or smaller as the contour of the cam ring pushes the vanes in and out of the rotor slots. Ports in the side plates, connected to the pump inlet port, admit oil into the rotating cartridge to fill the pockets as they increase in size. Other ports in the sideplates are connected to the pump discharge port and accept oil discharge from the rotating cartridge when the pocket decrease in volume. Two inlet ports are diametrically opposite each other, as are the two pressure (outlet) ports, to provide the hydraulic balance which eliminates all

Hydraulic System for Injection Molding Machines – By Zafar Kamal         The function of the hydraulic system in injection molding machine is to transmit the power from electric motor to the various moving parts of the machine, and to control the power. An electrical control system regulates the hydraulic system to control the direction, force, speed, and sequence of the machine cycle. The basic components of the hydraulic system are: 1-fluid reservoir 2-pumps 3-valves 4-cylinders 5-hydraulic motors The hydraulic fluids transmits the power throughout the hydraulic system, and lubricates the pumps and valves. It is important to follow the recommendations of the machine manufacturer or the hydraulic-equipment supplier in selecting the fluid to be used. The hydraulic lines form passageways in which the fluid from one component to the other in the circuit. The lines may be seamless steel tubes, hoses, or the hydraulic oil may flow through drilled manifolds. The reservoir is simply a storage tank for the hydraulic fluid. In addition, it helps to keep the fluid clean by allowing contaminants to settle out, and

Opening and Closing System for Mold in Injection Molding Machines – By Zafar Kamal         Opening and Closing System for Mold The function of the clamp end of an injection molding machine is opening and closing of the mold. At the same time it must have a means of keeping the mold tightly closed during the injection cycle. This function is performed by a mechanical or hydraulic device for traversing the movable platen of the machine. Mechanical devices for moving and locking the movable platen consist of toggle systems which can be single or multiple, mounted between the movable platen and the fixed tailstock of the clamp unit. With the toggle in the open or folded position the movable and stationary platens are separated and the mold is open. When the mold is closed the toggle arm form a continuous beam structure that can support the full clamp force of the machine. Clamp systems can be also be direct hydraulically operated. Hydraulic clamp cylinders can develop large clamp forces but they are slow acting as compared with

Efficiency of the Clamp in Injection Molding Machines – By Zafar Kamal         The nominal clamp-force ratings are approached but rarely reached in actual molding machines. A particular unit may be designed for a specific strength factor but more than likely it will not have the exact force indicated. Since, in the course of any design calculation, there are many add-on factors which will indicate the need for more clamp force than the theoretical value, any loss i efficiency can usually be neglected . Also, as the machine is used its efficiency will continue to fall off from its original rating. Therefore, any machine that has been in operation for any length of time should be considered as having a lower clamp force than when it was new. If calculations indicate that the clamp force of a machine may be taxed by a particular job, other avenues should be sought for the running of this job. One approach can be redesign of the mold to require less clamp force by reducing the projected area. The other one