High Quality Injection Molded Electronics From AAA MOULD

In the injection molding production process, blooming is a common defect that affects product quality. It is characterized by white powdery, foggy deposits or waxy layers appearing on the surface of plastic parts. This not only seriously affects the appearance of the product but also may reduce the mechanical properties, surface adhesion, and service durability of the plastic parts, bringing troubles to enterprises such as increased production costs and delayed delivery. To help industry partners accurately identify and efficiently solve this problem, this article comprehensively analyzes the core causes of blooming problems based on years of practical experience in injection molding processes, and provides implementable and replicable solutions to help enterprises improve product qualification rates and reduce production losses.



I. Core Definition and Hazards of Blooming in Injection Molding
Blooming in injection molding, also commonly referred to as "whitening" or "powdering" in the industry, is essentially a phenomenon where additives inside the plastic (such as lubricants, plasticizers, stabilizers, vulcanizing agents, etc.) reach saturation in the resin and cannot be stably accommodated by the resin matrix. During production, processing, finished product storage, or use, these additives slowly diffuse and precipitate from the inside of the plastic part to the surface, forming visible deposits.

The hazards of blooming problems are mainly reflected in three aspects: first, affecting the appearance, causing the surface of the plastic part to turn white, foggy, and lose luster, failing to meet the quality requirements of appearance parts and being directly judged as unqualified products; second, damaging performance, the precipitated additives will destroy the integrity of the plastic part surface, reduce its wear resistance, weather resistance, and bonding performance with other components, and shorten the product service life; third, increasing costs, the rework and scrapping of unqualified products, as well as the loss of materials and time in the process of troubleshooting problems, will lead to an increase in enterprise production costs and affect production efficiency.

It should be particularly noted that blooming is easily confused with plastic part aging "whitening" and surface contamination, which can be distinguished by a simple method: the deposits from blooming can temporarily restore the original color of the plastic part after wiping with a clean cloth, and there will be powder or oily residues after wiping; while aging "whitening" cannot be restored after wiping, and there are no obvious residues.



II. Analysis of Core Causes of Blooming Problems in Injection Molding
The occurrence of blooming problems is not caused by a single factor, but by the combined effect of various factors such as formula, process, raw materials, and environment. Combining industry practice and technical research, the core causes can be summarized into four categories to accurately locate the root cause of the problem.

(1) Formula Factors: Unreasonable Selection and Proportion of Additives
The formula is the core root cause of blooming problems. Most blooming phenomena are directly related to the improper selection and proportion of additives, which is also the most easily overlooked link:

1.Excessive additive dosage: Each type of additive has an upper limit of solubility in the resin. If the addition amount of lubricants, plasticizers, stabilizers, etc., exceeds their saturated solubility in the resin, the excess additives cannot be fully wrapped by resin molecules and will gradually precipitate in the subsequent process to form blooming. For example, the solubility of sulfur in natural rubber is about 2%, and excessive addition is likely to cause powdering blooming; excessive use of stearic acid and paraffin is likely to cause wax blooming.
2.Poor compatibility of additives: The mismatch between the polarity of the resin and the additives will lead to insufficient compatibility between the two. Even if the additive dosage does not exceed the standard, migration and precipitation will occur because they cannot be stably dispersed in the resin matrix. For example, using polar plasticizers for non-polar resins or non-polar paraffin for polar resins is likely to cause blooming; some accelerators have extremely low solubility in specific resins, and a slightly larger dosage may cause blooming. For example, TMTD and TMTM have very low solubility in BR, IIR, and EPDM, but a slightly larger dosage in NBR is not easy to cause blooming.
3. Abnormal interaction between additives: Some additives will undergo chemical reactions to form insoluble substances, or the precipitation of one additive will drive other additives to precipitate together. For example, if the amount of antioxidant is too high (mostly p-phenylenediamine type), its precipitation will drive the residual sulfur and accelerators to spray out together; the reaction between accelerator M and antioxidant MB generates insoluble salts, which will also precipitate to form blooming.

(2) Process Factors: Improper Control of Injection Molding Process Parameters
The precise control of injection molding process parameters is the key to avoiding blooming. Deviations in parameters such as temperature, pressure, and time during the production process will directly lead to blooming problems, which is also the most easily adjustable link in front-line production:

1.Unreasonable temperature control: Both too high and too low temperatures can cause blooming. If the barrel temperature is too high, it will accelerate the volatilization and migration of additives, and some additives will precipitate in advance at high temperatures and attach to the surface of the plastic part; if the mold temperature is too low, the cooling speed of the plastic part is too fast, and the additives inside the resin cannot diffuse evenly, which will crystallize and precipitate on the surface to form foggy blooming. In addition, if the temperature of the rubber compound is too high during mixing, it will also lead to local high concentration of additives, laying hidden dangers for blooming.
2.Improper pressure and holding pressure parameters: Insufficient injection pressure and too short holding time will lead to insufficient compactness inside the plastic part with tiny gaps, and additives are likely to migrate to the surface along the gaps; on the contrary, too high pressure and too long holding time will over-compress the resin molecules, and additives will be squeezed out to the surface to form blooming.
3.Improper mixing and feeding process: If the equipment speed is too low, the mixing time is insufficient, or the feeding order is messy during mixing, the additives will not be evenly dispersed in the resin, and the local concentration of additives will be too high, forming saturated precipitation conditions; if additives such as sulfur are damp and agglomerated due to improper storage and are put into use without crushing, it will also lead to local high concentration and cause blooming.
4. Improper storage of rubber compound and plastic parts: If the mixed rubber compound does not enter the injection molding process in time and is stored for too long, the additives will slowly diffuse inside the resin and eventually precipitate; if the plastic parts are not cooled to room temperature in time after molding, or are placed in a high-temperature and high-humidity environment after cooling, it will also accelerate the precipitation of additives and cause blooming.

(3) Raw Material Factors: Insufficient Raw Material Quality and Processing
The quality of raw materials and the effect of pre-treatment directly affect the quality of injection molding, and are also important incentives for blooming problems:

1.Insufficient raw material purity: The resin raw material contains too many impurities, low molecular volatile substances, or the proportion of recycled materials added is too high. These impurities and low molecular substances will be precipitated during injection molding, forming a phenomenon similar to blooming, which is easily misjudged as blooming.

2.Insufficient drying of raw materials: Resin raw materials (especially hygroscopic resins such as PA and PC) are not fully dried before injection molding and contain moisture inside. During injection molding, the moisture evaporates, which will drive the additives to precipitate together to form foggy blooming; some fillers have high water content, which will be higher in humid weather. During high-temperature injection molding, they will dissolve out with the evaporation of moisture, and white powder will be left after the moisture evaporates, forming powdering blooming.

3. Poor quality of additives: The used lubricants, plasticizers and other additives have insufficient purity or contain volatile components, which are easy to volatilize and precipitate during injection molding to form blooming; some fillers (such as alkaline precipitated silica) are unstable in nature and are also easy to cause powdering.

(4) Environmental Factors: Improper Control of Production and Storage Environment
The temperature, humidity, cleanliness, etc., of the production and storage environment will indirectly affect the occurrence of blooming problems, which are easily overlooked:

1.Temperature and humidity fluctuations: High temperature and high humidity in the production environment will accelerate the migration and precipitation of additives; drastic temperature fluctuations in the storage environment, the solubility of additives increases at high temperatures, and drops sharply at low temperatures, the excess components precipitate, and repeated alternation of high and low temperatures will further accelerate blooming.

2. Poor environmental cleanliness: Excessive dust and oil stains in the production workshop will attach to the surface of plastic parts, forming an illusion similar to blooming. At the same time, dust may mix into the raw materials, affecting the dispersion of additives and indirectly causing blooming.

3. Light exposure and medium contact: During the storage or use of plastic parts, long-term exposure to sunlight, ultraviolet rays will damage the resin structure and promote the migration of additives; contact with acid-base media, alcohol and other solvents will also accelerate the precipitation of additives and cause blooming.

III. Targeted Solutions to Blooming Problems in Injection Molding
In view of the above causes of blooming, combined with industry practical experience, the idea of "accurately locating the root cause + targeted rectification + long-term prevention" is adopted to formulate implementable solutions. No complex testing equipment is needed, and front-line operators can directly refer to and apply them to quickly solve the blooming problem.

(1) Optimize the Formula: Reduce Blooming Hidden Dangers from the Root
Formula optimization is the core of solving blooming problems. It is necessary to scientifically select additives and adjust the proportion according to the resin characteristics to avoid additive precipitation from the root:

1.Reasonably adjust the additive dosage: According to the type of resin, strictly control the addition amount of various additives to ensure that it does not exceed their saturated solubility in the resin. For example, for products with silica as the main filler, the amount of PEG can be reduced to 5% to 6% of the amount of silica to avoid wax blooming; the dosage of sulfur and accelerators needs to be determined through experiments to avoid excessive addition.
2. Select additives with good compatibility: Prioritize additives that match the polarity of the resin and have good compatibility to reduce the risk of migration and precipitation. For example, use non-polar lubricants for non-polar resins and polar plasticizers for polar resins; select accelerators with strong reactivity with the resin as the main accelerator to reduce the residue of free additives; add plasticizers or homogenizers such as coumarone resin and phenolic resin to improve the dispersion stability of additives in the resin by using their solubilizing effect.

In the injection molding production process, part and gate adhesion is one of the common process defects. This problem not only leads to difficult demolding and reduced production efficiency, but also may cause surface scratches, gate residues, and even part damage, directly affecting product quality and production efficiency, and bringing unnecessary cost losses to enterprises. Combining years of practical experience in the injection molding industry, this article systematically analyzes the core causes of part and gate adhesion, and provides actionable and highly adaptable solutions to help enterprises efficiently solve production pain points and improve the stability of injection molding production.

I. Core Causes of Part and Gate Adhesion in Injection Molding
The essence of part and gate adhesion is that after the plastic melt at the gate cools and solidifies, the bonding force between the melt and the part, as well as the mold gate structure, is greater than the demolding force, resulting in failure to separate smoothly during demolding. Combined with actual production, the main causes can be divided into three categories: mold design, process parameters, and raw material characteristics, which are detailed as follows:



(1) Unreasonable Mold Design
The mold is the foundation of injection molding, and improper design of gate-related structures is the primary cause of adhesion problems. Firstly, the gate size and shape are unreasonable. For example, an excessively thick or short gate, or an irregular cross-sectional shape of the gate, will cause the melt to bond too tightly with the mold wall after solidifying at the gate, increasing demolding resistance. Secondly, the gate position is improperly selected. If the gate is set at a position with uneven part wall thickness or a corner, it will lead to unsmooth melt flow and inconsistent cooling speed, resulting in insufficient solidification at the connection between the gate and the part and forming adhesion. Thirdly, poor mold ventilation. The residual gas at the gate cannot be discharged in time, which will cause insufficient melt filling, generate internal stress after cooling, and aggravate the adhesion phenomenon. In addition, the absence of a demolding slope and insufficient surface roughness at the mold gate will also increase the friction between the plastic and the mold, leading to adhesion.

(2) Improper Setting of Injection Molding Process Parameters
The rationality of injection molding process parameters directly affects the filling, cooling and solidification process of the melt, and parameter deviations are likely to cause adhesion problems. Firstly, the melt temperature is too high, which will prolong the cooling and solidification time of the plastic melt, make the melt bond more closely with the mold and the part at the gate, and at the same time, the excessively high temperature may cause plastic degradation, generate viscous substances, and aggravate adhesion. Secondly, the mold temperature is too high. The excessively high temperature of the mold cavity and the gate will slow down the cooling speed of the plastic melt, resulting in incomplete solidification at the gate and easy adhesion to the part during demolding. Thirdly, the holding pressure is too high and the holding time is too long, which will cause the melt to be overfilled into the gate, increase the bonding force between the gate and the part, and at the same time, excessive holding pressure will generate internal stress, leading to difficult demolding. Fourthly, the demolding speed is too fast or too slow. Too fast will cause uneven force at the gate, which is easy to cause adhesion and tearing; too slow will make the gate contact the mold for a long time, aggravating adhesion.

(3) Improper Raw Material Characteristics and Handling
The inherent characteristics of raw materials and the quality of pre-treatment also have an important impact on gate adhesion. Firstly, the addition of additives in raw materials is unreasonable. For example, insufficient addition of lubricants and mold release agents will reduce the demolding performance of plastics and increase the friction with the mold and gate; if the addition of lubricants is excessive, it may cause surface defects of the part and affect the bonding stability at the gate. Secondly, the water content of raw materials is too high and they are not fully dried. During the injection molding process, the water will vaporize when heated, generating bubbles, leading to insufficient filling at the gate and loose adhesion after cooling. Thirdly, the raw materials themselves are highly viscous. For example, engineering plastics such as PA and PC have large intermolecular forces. If the formula or process is not reasonably adjusted, adhesion is likely to occur at the gate.

II. Targeted Solutions to Part and Gate Adhesion Problems
In view of the above causes, combined with the actual production scenarios, actionable solutions are provided from three dimensions: mold optimization, process adjustment, and raw material handling, which are both practical and economical, helping enterprises quickly solve adhesion problems.



(1) Optimize Mold Design to Reduce Adhesion Hidden Dangers
Mold optimization is the key to solving adhesion problems from the root, focusing on adjusting the gate structure, ventilation system, and surface treatment:



1.Adjust gate size and shape: According to the part size, wall thickness and raw material characteristics, reasonably design the gate size. Generally, the gate thickness is recommended to be 1/3-1/2 of the part wall thickness, and the length is controlled at 1-3mm to avoid being too thick or too short. Prioritize the use of regular cross-sectional gates such as circular and trapezoidal to reduce melt flow resistance and facilitate cooling and demolding. For easily adherent plastics (such as PA and PC), point gates and submarine gates can be used to shorten the contact area between the gate and the part and reduce the risk of adhesion.


2.Optimize gate position: Avoid positions with uneven part wall thickness and corners, and prioritize setting the gate at a position with a thicker part wall and a flat structure to ensure smooth melt filling and uniform cooling. If the part structure is special, a multi-gate design can be adopted to disperse the filling pressure and reduce the force and bonding force of a single gate.


3.Improve the mold ventilation system: Set ventilation grooves near the gate and at the end of melt flow. The width of the ventilation groove is recommended to be 0.02-0.05mm, and the depth is 0.01-0.03mm to ensure that the gas is discharged in time during the injection molding process, avoid the generation of bubbles, and improve the filling density at the gate. At the same time, clean the sundries and accumulated materials in the mold cavity and gate to avoid adhesion caused by foreign objects.


4.Optimize mold surface treatment: Set a reasonable demolding slope (generally 1°-3°) at the gate to facilitate demolding. Polish the mold cavity and gate to reduce surface roughness and the friction between plastic and mold. If necessary, spray a special mold release agent at the mold gate to improve demolding performance, but the spray amount must be controlled to avoid affecting the surface quality of the part.
(2) Adjust Injection Molding Process Parameters to Optimize the Molding Process
By adjusting the process parameters, optimize the filling, cooling and solidification process of the melt, and reduce the bonding force between the gate and the part. The specific adjustment directions are as follows:



1.Control melt temperature: According to the raw material characteristics, appropriately reduce the melt temperature, generally by 5-10℃, to shorten the cooling and solidification time of the melt and reduce the bonding time between the melt and the mold and part. At the same time, avoid the melt temperature being too low to prevent insufficient melt fluidity, which may lead to new defects due to insufficient filling.



2.Adjust mold temperature: Appropriately reduce the mold temperature, especially the mold temperature at the gate, it is recommended to reduce by 10-15℃ to accelerate the cooling and solidification speed of the melt at the gate and reduce adhesion. For crystalline plastics (such as PP and PA), the mold temperature can be reasonably controlled to avoid adhesion caused by incomplete crystallization.


3.Optimize holding pressure parameters: Reduce the holding pressure (generally by 10%-20%) and shorten the holding time (by 2-5s) to avoid overfilling of the melt into the gate and reduce the bonding force between the gate and the part. At the same time, adjust the holding pressure switching time to avoid excessive extrusion on the gate during the holding stage.


4.Adjust demolding parameters: Control the demolding speed to maintain stable and uniform demolding, avoiding being too fast or too slow. For large parts or easily adherent parts, a segmented demolding method can be adopted to gradually separate the gate and the part, reducing adhesion and tearing caused by uneven force. At the same time, check the demolding mechanism to ensure that the ejector pins and ejector sleeves move flexibly and are evenly stressed, avoiding adhesion caused by jamming of the demolding mechanism.

(3) Standardize Raw Material Handling to Improve Demolding Performance
Do a good job in the pre-treatment and formula adjustment of raw materials to improve the demolding performance of plastics and reduce adhesion problems from the root:



1.Standardize raw material pre-treatment: For raw materials with high water content (such as PA and PET), dry them in advance. The drying temperature is controlled at 80-120℃, and the drying time is 2-4h to ensure that the water content of raw materials is less than 0.2%, avoiding the generation of bubbles during injection molding and leading to gate adhesion. For moisture-absorbing raw materials, they should be sealed and stored after drying to prevent re-absorption of moisture.

2.Adjust raw material formula: Reasonably add lubricants and mold release agents to raw materials, with the addition amount controlled at 0.5%-2%, to improve the demolding performance of plastics and reduce the friction with the mold and gate. Select raw materials with moderate viscosity. If it is necessary to use highly viscous engineering plastics, an appropriate amount of modifier can be added to reduce their viscosity. At the same time, avoid using degraded and deteriorated raw materials to prevent the generation of viscous substances.


3.Optimize raw material mixing: Fully mix raw materials with lubricants and mold release agents to ensure uniform dispersion of additives, avoiding adhesion problems caused by insufficient local additives. Avoid mixing impurities and foreign objects during the mixing process to prevent affecting the molding quality of the part.

III. Preventive Measures for Adhesion Problems
The core of solving adhesion problems is "prevention first, treatment second". By establishing a sound production control system, potential adhesion hazards are avoided in advance, and production stability is improved:



1.Daily mold maintenance: Regularly inspect and clean the mold, clean the accumulated materials and sundries at the gate, check whether the demolding mechanism and ventilation system are normal, timely repair mold wear and scratches, and keep the mold surface smooth. Regularly perform anti-rust and lubrication treatment on the mold to extend the service life of the mold and reduce potential adhesion hazards.


2.Standardization of process parameters: According to the part model and raw material characteristics, formulate standardized injection molding process parameters, clarify the melt temperature, mold temperature, holding pressure parameters, demolding parameters, etc., to avoid random adjustment of parameters. Regularly verify and optimize the process parameters, and fine-tune them according to the actual production situation to ensure parameter adaptability.


3.Raw material quality control: Establish a raw material incoming inspection system, strictly inspect indicators such as water content, purity, and additive content of raw materials, and eliminate the use of unqualified raw materials. Standardize the storage, drying and mixing processes of raw materials to ensure stable performance of raw materials.


4.Operator training: Strengthen professional training for operators to make them familiar with the mold structure and process parameter adjustment methods, master the emergency handling skills of adhesion problems, and be able to timely find and handle abnormal situations in the production process to avoid the expansion of problems.

IV. Conclusion
The problem of part and gate adhesion in injection molding is the result of the combined action of multiple factors such as mold design, process parameters, and raw material characteristics. In the production process, enterprises should first find the core causes of adhesion through investigation, then take targeted measures such as mold optimization, process adjustment, and standardized raw material handling, and establish a sound preventive control system to avoid potential adhesion hazards from the root.

In injection molding production, injection volume is a core parameter for matching injection molding machines, optimizing molding processes, and ensuring product quality. It directly determines the maximum volume of molten plastic that can be melted and injected by the injection molding machine in a single cycle, and controls common product defects such as insufficient filling, shrinkage, flash, and material burning. Accurate calculation of injection volume is a fundamental task for mold design, machine model selection, and process debugging. Combining universal industrial standards and on-site practical experience, this paper systematically introduces the definition, calculation formulas, parameter values, correction methods, and practical application key points of injection volume.



1. Core Definition of Injection Volume

The rated injection volume of an injection molding machine refers to the volume of molten plastic discharged in a single injection cycle under the maximum effective injection stroke of the screw, with the common unit of cubic centimeter (cm³). In the industry, it is divided into theoretical injection volume and actual injection volume, which serve as the core basis for molding calculation. The differences are as follows:




Theoretical Injection Volume: An ideal maximum injection volume calculated based on screw structural parameters, ignoring melt compression, screw clearance, pressure loss and other factors. It is the benchmark data for equipment parameter labeling and mold selection.




Actual Injection Volume: The effective injection volume corrected according to actual working conditions such as the compression characteristics of molten plastic, molding pressure and equipment loss, representing the real available volume in production practice.



2. Standard Calculation Formula for Theoretical Injection Volume

The theoretical injection volume is only related to the screw diameter and maximum effective injection stroke of the injection molding machine. As a universal basic formula applicable to all screw-type injection molding machines, it is defined as follows:



V = π × (D/2)² × S

Parameter Explanations:

- V: Theoretical injection volume, unit: cm³;

- π: Pi, conventionally valued at 3.1416;

- D: Screw diameter, unit: cm, subject to the nameplate parameters of the injection molding machine;

- S: Maximum effective injection stroke, unit: cm, referring to the maximum effective moving distance of the screw.

Example: For an injection molding machine with a screw diameter of 30mm (3cm) and a maximum injection stroke of 120mm (12cm), the calculation is as follows: V=3.1416×(3/2)²×12≈84.82cm³, which means the theoretical maximum injection volume of the equipment is 84.82cm³.



3. Calculation of Actual Injection Volume (Practical Production Formula)

In actual injection molding production, molten plastic is compressible under high temperature and high pressure. In addition, tiny clearance leakage exists between the screw and barrel, resulting in melt conveying loss. Therefore, the actual available injection volume is always lower than the theoretical value. The universal practical calculation formula in the industry is:

V = V × η



Parameter Explanations:

- V: Actual effective injection volume, unit: cm³;

- η: Injection efficiency coefficient, ranging from 0.80 to 0.95 based on plastic material type, molding pressure and equipment aging condition.

Precise Value Rules of Efficiency Coefficient η:


General plastics (PP, PE, ABS), new equipment, conventional molding pressure (80~120MPa): η = 0.90~0.95;




Engineering plastics (PA, PC, POM), moderately aged equipment, medium and high pressure molding (120~160MPa): η = 0.85~0.90;




High-viscosity and high-compressibility plastics, severely aged equipment, high-speed and high-pressure molding: η = 0.80~0.85.



4. Calculation of Required Product Injection Volume (Core of Machine Matching)

In the mold selection stage, it is necessary to calculate the total injection volume required for single-cycle product molding first, and then match it with the actual injection volume of the injection molding machine, which is the key to avoid inappropriate machine model selection (over-sized or under-sized). The total single-cycle injection volume includes the weight of molded products, the weight of runner and gate sprue, and a safety margin. The calculation formula is as follows:

V = (W + W) / ρ × (1 + 10%~20%)

Parameter Explanations:

- V: Injection volume required for product molding, unit: cm³;

- W: Total weight of all products in a single mold, unit: g; sum the weight of all cavity products for multi-cavity molds;

- W: Total weight of condensed materials such as gates, runners and sprue bushes, unit: g;

- ρ: Melt density of plastic, unit: g/cm³; solid-state density at room temperature can be used for approximate calculation, while melt density is required for high-precision calculation;

- 10%~20%: Safety margin coefficient; 20% for complex-structured and thin-walled products, 10% for simple thick-walled products.



5. Industrial Standards for Injection Volume Matching (Core Prohibitions)

After calculating the actual injection volume of the injection molding machine and the required product injection volume, strict industrial matching specifications must be followed to avoid molding defects and equipment loss. The standards are as follows:



1. Minimum Usage Limit: The required product injection volume shall not be less than 20% of the actual injection volume of the machine. Excessively small usage will lead to long melt residence time in the barrel, causing material decomposition, yellowing and burning, and reducing product performance.

2. Maximum Usage Limit: The required product injection volume shall not exceed 80% of the actual injection volume of the machine. A 20% margin ensures stable melt filling and balanced pressure, and prevents flash, overflow and equipment overload caused by high-speed and high-pressure injection.

3. Optimal Molding Range: The product injection volume is controlled within 40%~70% of the actual machine capacity. This range features the best molding stability, the largest process adjustable range and the highest product qualification rate.



6. Common Calculation Errors and Correction Key Points

1. Matching production directly with theoretical volume: Ignoring melt compression and equipment loss will result in insufficient actual injection volume and product short shot. Corrected actual volume must be adopted for verification.

2. Ignoring the weight of runner condensed materials: Calculating only the weight of products will cause insufficient injection volume, and the error is particularly prominent for multi-cavity molds and thin-runner molds.

3. Fixed safety margin value: Thin-walled, deep-cavity and complex-textured products have high melt flow resistance and require an increased safety margin to avoid insufficient filling and sink marks.

4. Universal parameters for new and old equipment: Aged injection molding machines have worn screws and increased clearance, leading to reduced injection efficiency. The efficiency coefficient η needs to be reduced by 0.03~0.05 to ensure calculation accuracy.



7. Conclusion

The calculation of injection volume follows three core logics: first, calculate the theoretical volume through screw diameter and stroke; second, correct it into the actual available volume according to material characteristics and equipment working conditions; finally, calculate the required molding volume based on product and runner weight to complete machine matching. Accurate volume calculation can avoid production waste caused by mismatched machine and mold sizes, and fundamentally prevent problems such as insufficient filling, material decomposition and unstable molding. It is an essential basic skill for mold design, machine selection and standardized injection production. In actual production, parameters should be adjusted flexibly according to plastic characteristics, equipment status and product structure to achieve efficient and high-quality molding.