Definition: Temperature required to dry polymer in advance to ensure quality of molding
Function: 1. Remove moisture in raw material. 2. Ensure quality of finished product
Setting principles: 1. Polymer will not decompose or agglomerate (polymerization) 2. Drying time is as short as possible, drying temperature is as low as possible without affecting its drying effect. 3. Drying temperature and time vary with different raw materials.
Note: 1, A means hot air dryer.
2, D means dehumidifying dryer.

 

Definition: Temperature added to material tube is set to ensure smooth progress of molding.
Function: Ensure good polymer plasticization (melt glue), smooth filling and molding.
Setting principles: (1) It will not cause plastic to decompose and carbonize. (2) From feeding break to nozzle rise sequentially. (3) Nozzle temperature should be slightly lower than barrel break temperature. (4) Required temperature depends on type of material Different. (5) It will not have a bad quality impact on product.

Definition: Surface temperature of mold cavity that product touches
Function: Control affects cooling rate of product in cavity and apparent quality of product.
Setting principles: (1) Consider properties of polymer. (2) Consider size and shape of product. (3) Consider structure of mold runner system.

Definition: Under a certain pressure, speed at which melt is injected from nozzle into mold.
Function: (1) Increase of injection speed will increase filling pressure. (2) Increase of injection speed can increase flow length and make quality uniform. (3) Viscosity is high during high-speed injection, and cooling speed is fast, which is suitable for long-process products. (4) Flow is stable at low speed, and product size is stable.
Setting principles: (1) Prevent mold support and avoid edge overflow. (2) Prevent excessive speed from causing scorching. (3) Under premise of ensuring product quality, choose high-speed filling as much as possible to shorten molding cycle.

Definition: Speed of screw melt during plasticization process.
Function: It is an important parameter that affects plasticizing ability and quality of plasticizing. The higher speed, the higher melt temperature and the stronger plasticizing ability.
Setting principles: (1) When adjusting melt speed, it is generally adjusted from low to high. (2) Speed of machine with a screw diameter greater than 50MM should be controlled below 50RPM, and machine with a screw diameter of less than 50MM should be controlled below 100RPM.

Definition: Maximum pressure that occurs at the tip of screw at injection port is closely related to oil pressure generated in injection cylinder.
Function: It is used to overcome pressure loss of melt from nozzle-runner-gate-cavity, so that cavity is filled with Quebec to obtain required products.
Setting principle: (1) Must be within rated pressure range of injection molding machine. (2) Try to use low pressure when setting. (3) Try to avoid using high pressure at high speed to avoid abnormal conditions

Definition: Pressure established in melting cavity during plasticization process of plastic.
Function: (1) Increase specific gravity of melt. (2) Make melt plasticize uniform. (3) Reduce gas content in melt, improve quality of plasticization
Setting principles: (1) Adjustment of back pressure should consider nature of plastic material. (2) Adjustment of back pressure should refer to apparent quality and size accuracy of product.

Definition: Clamping system exerts closing force on mold to overcome expansion force that separates mold during injection and holding pressure stages.
Function: (1) Ensure that mold will not be expanded during injection and pressure holding. (2) Ensure apparent quality of product. (3) Ensure dimensional accuracy of product.
Setting principle: (1) Size of clamping force depends on size of product and size of machine. (2) Generally speaking, in the case of ensuring that product does not have burrs, the smaller clamping force is, the better (3) Clamping force setting should not exceed rated pressure of machine.

Definition: From filling mold cavity with plastic, and continuing to apply injection pressure on mold cavity plastic, until gate is completely cooled and closed for a period of time, it depends on a relatively high pressure support technique, this pressure is called holding pressure.
Function: (1) Replenish amount of material close to gate position, prevent unhardened plastic in the cavity from flowing back under residual pressure before gate is cooled and closed, prevent shrinkage of part, avoid shrinkage, and reduce vacuum bubbles. (2) Reduce parts that are prone to bursting or bending due to excessive injection pressure.
Setting principles: (1) Holding pressure and speed are usually set to 50~60% of the highest pressure and speed when plastic fills mold cavity. (2) Length of pressure holding time is related to material temperature. High temperature gate has a long sealing time and a long pressure holding time. (3) Holding pressure is related to projected area and wall thickness of product, thicker and larger ones require a longer time. (4) Holding pressure is related to gate size, shape and size. Holding pressure switching position, metering length and loosening stroke setting

Definition: After plasticization begins, screw will retreat under force of plastic melt from injection end position during rotation process until limit switch is retracted. This process is called metering stroke.
Function: Ensure that there is enough plastic to fill mold cavity to obtain desired appearance and size of product.
Setting principles: (1) Metering stroke should be set according to size of product and size of machine. (2) Metering stroke should not be too large, so as to avoid injection of excess plastic staying in barrel for too long and causing carbonization. (3) Metering stroke should not be too small to ensure that filling has sufficient metering and to avoid mechanical damage to screw and nozzle. There should be a buffer of 3~5mm.

 

Definition: Position change of screw during injection process
Function: Combine speed and pressure to control flow state of plastic
Setting principle: (1) Measuring position is determined by filling amount of finished product. Usually, 3~5mm cogwheel impulse is added to this value to determine final setting. (2) Switching point to second speed is usually switched to full hot runner and sprue position. (3) Switching point to the third speed, 90% filling degree of molded product is used to set switching position. (4) Holding pressure switching point is generally set at 90% filling of finished product. (Note: Above four sections are taken as an example)

Definition: After screw is pre-plasticized (measured) in place, it retreats a distance in a straight line. This retreat action is called back loosening, distance of loosening is called loosening amount or anti-extending amount.
Function: Function of back loosening is to increase specific volume of melt in metering chamber, decrease internal pressure to prevent melt from flowing out of metering chamber.
Setting principle: (1) It can be set according to viscosity of plastic raw material, relative density and actual situation of product. A larger amount of loosening will cause melt to mix with bubbles and affect quality of product. (2) Setting of loosening amount should be compatible with screw speed and back pressure. (3) There is no need to set loosening amount for materials with high viscosity, such as PC materials.

Definition: After screw has been injection molded, I do not want to inject all melt in head of screw, but also want to keep some. Form a sacrifice amount, which is buffer amount.
Functions: (1) Prevent screw head from contacting nozzle and cause mechanical damage accidents. (2) Control repeatability of injection volume
Setting principles: (1) Amount of buffering should not be too large or too small. Too large will cause too much residual material, causing pressure loss and raw material degradation. If it is too small, it will not achieve purpose of buffering. (2) To determine amount of buffering, generally 3~5mm is appropriate.

Definition: Time from end of mold opening to end of mold opening after next injection cooling is completed
Function: to ensure that product is formed, completely cooled and shaped
Setting principles: (1) Cycle is as short as possible. (2) Cycle must be shortened under premise of ensuring product quality

Definition: Time it takes for product to cool and solidify without being deformed after being demolded
Function: (1) Let product solidify (2) Prevent product from deforming
Setting principles: (1) Cooling time is an important part of cycle time, and it should be as short as possible under premise of ensuring quality of product. (2) Cooling time is determined by temperature of melt, temperature of mold, size and thickness of product .

Definition: In order to prevent plastic from flowing back after injection, cooling, feeding, pressure continued to be applied after injection
Function: (1) Prevent melt from flowing back after injection. (2) Feeding effect of cooling shrinkage.
Setting principles: (1) Holding time varies with thickness of product. (2) Pressure holding time varies depending on temperature of melt. The higher temperature takes longer, and the lower temperature takes shorter. (3) In order to improve production efficiency, pressure holding time should be as short as possible under premise of ensuring quality of system.

Definition: Time it takes for melt to fill entire cavity.
Function: Injection time is determined by factors such as injection pressure, injection speed and product size
Setting principle: (1) Make injection time as short as possible under condition of ensuring molding of product. (2) Injection time is affected by factors such as material temperature and mold temperature.

Definition: After injection is terminated, time required for screw to reach end of metering position.
Role: to ensure sufficient melt glue.
Setting principle: (1) Screw speed and back pressure are mutually controlled. (2) Do not let molten plastic body stay in screw for too long, so as not to cause plastic to decompose and carbonize under a long-term high temperature state.

Definition: Time required to dry raw materials in advance using drying equipment
Functions: (1) Improve surface gloss, increase bending resistance and tensile strength, avoid internal cracks and bubbles. (2) Improve plasticizing ability and shorten molding cycle. (3) Reduce moisture and humidity in raw materials.
Setting principles: (1) Drying time varies with different raw materials. (2) Setting of drying time should be appropriate. Too long will reduce drying efficiency and even cause raw materials to agglomerate. If it is too short, drying effect will be poor.