In complex world of injection molding production, every detail affects final product quality and production efficiency. For injection molding professionals, mastering an effective machine adjustment method is like possessing a key to success. Below, I will analyze key points of injection molding machine adjustment in detail to help you work with ease, improve product quality and production efficiency.

 

Injection molding production involves five core elements, which are interconnected and mutually influential, jointly determining molding effect of product.
Temperature: This includes barrel temperature, mold temperature, drying temperature, hydraulic oil temperature, and ambient temperature. Different plastics have different temperature requirements. Precisely controlling temperature at each stage ensures that plastic melts, flows, and cools in optimal conditions. For example, excessively high barrel temperature can cause plastic decomposition, resulting in defects such as bubbles and discoloration; while improper mold temperature can affect shrinkage rate and surface finish of product.
Pressure: This includes injection pressure, holding pressure, back pressure, ejector pin pressure, mold opening pressure, and mold closing pressure. Magnitude and duration of pressure directly affect filling, compaction, and molding of plastic. Insufficient injection pressure may lead to incomplete filling; improper holding pressure can cause shrinkage or dimensional instability.
Time: Injection time, holding time, cooling time, drying time, metering delay time, etc., each time parameter must be precisely set. Insufficient injection time will prevent plastic from fully filling mold; insufficient cooling time will cause product deformation, affecting dimensional accuracy.
Speed: Injection speed, melt speed, mold opening and closing speed, demolding speed, etc. A proper combination of speeds is crucial for product's appearance and internal structure. Excessively high injection speed may produce jetting marks and air bubbles; improper melt speed will affect plasticizing quality.
Positioning: Precise settings for positions such as metering, ejection, mold opening ensure production stability and product consistency. Inaccurate metering can lead to inconsistent plastic injection volumes, affecting product weight and dimensions; improper ejection can cause whitening or mold damage.

Accurate Root Cause Analysis: When encountering quality anomalies, use 5M1E (Man, Machine, Material, Method, Measurement, Environment) analysis method to comprehensively investigate possible causes. After confirming root cause, perform targeted machine adjustments. For example, surface scratches on product could be due to mold surface damage (machine) or incorrect insert placement by operator (person); each possibility must be checked.
Single Parameter Adjustment Principle: During machine adjustment, only one parameter should be changed at a time, observing condition of 2 to 3 batches. By analyzing feedback from machine, mold, and materials, assess adjustment effect before deciding whether further modifications are necessary. This cautious adjustment approach avoids complicating problem and making it difficult to determine true cause due to simultaneous changes in multiple parameters.
Prioritize Problems: Approximately 70%-80% of injection molding defects originate from mold malfunctions, 10%-20% are related to materials or other factors, and only 10% are due to machine adjustment issues. Therefore, when troubleshooting, prioritize checking mold condition to ensure it is in good working order. Avoid using temporary special processes to address production issues; instead, address root cause to ensure long-term stable production.
Continuously Optimize Production Cycles: After the first piece has been in normal production for 2 hours, try shortening cycle time by 2-3 seconds; after half a shift of normal production, optimize cycle time again. Through continuous improvement, gradually achieve optimal balance between efficiency and quality. However, it is important to note that cycle time reduction should be done while ensuring product quality, and speed should not be blindly pursued.
Regular Machine Inspections: Inspect machine every 2 hours, carefully confirming that all parameters are normal, mold temperature and barrel temperature are within set range, nozzle and sprue heating, mold condition, and peripheral equipment are functioning properly. Promptly identify and address potential problems to ensure continuity and stability of production process.

 

Mold-related issues: Insufficient water inlet size prevents effective pressure holding; poor venting prevents gas from escaping; inadequate mold cooling leads to localized overheating; mold misalignment causes uneven shrinkage of different parts of product; mold sticking causes dents; broken needles or inserts affect plastic flow; insufficient nozzles and runners restrict plastic entry; hot runner blockage or leakage affects pressure holding.
Process-related issues: Insufficient holding pressure and time fail to fully compact product; insufficient melt volume leads to incomplete filling; excessively high mold temperature increases shrinkage; excessively low mold temperature causes uneven filling and internal stress concentration; overly tight mold lock hinders venting; improper injection position, pressure, and speed settings affect plastic filling and compaction; blocked nozzles affect plastic flow; excessively high barrel temperature causes plastic decomposition; leakage leads to pressure loss.
Design-related issues: Improper water inlet placement leads to uneven plastic filling; uneven thickness results in inconsistent shrinkage; excessively thick glue layer causes large shrinkage; inappropriate shrinkage rate value does not match actual plastic properties; excessively thick rib design hinders cooling; improper cooling location and insufficient cooling channels affect cooling effect.
Equipment-related issues: Machine is too small, resulting in insufficient pressure; damage to three small parts and barrel prevents sealing; oil leakage from injection cylinder oil seal and damage to oil pump cause unstable pressure; abnormal barrel temperature, one section fails to rise or cooling water is ineffective, resulting in backflow; machine screw model is incompatible with the plastic, affecting plasticizing quality; improper and unstable voltage output affects normal equipment operation.
Material-related issues: Inadequate curing of material results in excessive moisture content; uneven mixing of material and sprue leads to inconsistent composition; material particles are too large or uneven, affecting flow and filling; excessive material shrinkage rate leads to severe shrinkage after molding.

Mold-related issues: Insufficient sprue size prevents full injection; poor venting leads to air trapping and insufficient glue; mold misalignment prevents even plastic filling; insufficient nozzle/sprue channel restricts plastic flow; localized air trapping requires venting pins; improper fit between overmolding hardware and mold affects plastic flow; hot runner blockage or leakage affects plastic supply.
Process-related issues: Injection pressure and speed are too low, failing to fully inject plastic into mold; mold temperature is too low, reducing plastic flowability; insufficient melt volume results in incomplete filling; improper injection transition position setting affects filling effect; low barrel temperature leads to poor plasticization; nozzle blockage affects plastic flow; overly tight mold lock hinders venting; leakage leads to pressure loss.
Design-related issues: Improper sprue placement makes plastic filling difficult; thin ribs result in insufficient strength and insufficient glue; sharp corners obstruct plastic flow.
Equipment-related issues: Similar to equipment-related issues in shrinkage problems, insufficient machine pressure, damaged equipment parts, and abnormal temperatures can all affect plastic filling.
Material-related issues: Poor material flowability makes it difficult to fill mold; uneven mixing of material and sprue results in inconsistent composition; excessively large or uneven material particles affect flowability.

Mold-related issues: Insufficient sprue size causes spraying and material curdling; poor venting traps air, leading to curdling; residual plastic at sharp corners causes curdling; insufficient sprue or nozzle size affects plastic flow; dead zones in hot runner cause residual plastic decomposition and curdling; improper hot runner temperature sensor location or abnormal wiring affects temperature control; partial blockage of hot runner hinders plastic flow; mold seepage causes plastic to decompose due to moisture; excessively high hot runner temperature causes plastic decomposition and curdling.
Process-related issues: Inappropriate back pressure settings affect plasticizing quality; excessive injection speed causes injection defects; improper front-end injection parameters lead to injection defects; excessively fast melt speed causes plastic decomposition and material defects; insufficient slow-end finishing of injection phase causes trapped air and material defects; partial nozzle blockage affects plastic flow; mold temperature too low results in poor plastic flowability; blocked venting at parting line requires regular cleaning; excessively long injection time causes plastic to remain in barrel for too long, leading to decomposition and material defects; excessively high barrel temperature causes plastic decomposition.
Design-related issues: Non-smooth gate design results in residual plastic and material defects; improper venting location or insufficient quantity affects venting effectiveness; improper gate entry methods, such as incorrect selection of pin points, square, round, or fan shapes, affect plastic flow.
Equipment-related issues: Three small parts and barrel are damaged, resulting in poor pre-plasticizing quality; nozzle and mold nozzle R are not aligned, causing air to mix in and produce spray patterns; material barrel overheats abnormally, fan is damaged, affecting plastic drying; barrel temperature is abnormal, one section does not rise or cooling water effect is poor, resulting in sizing.
Material-related issues: Material is not properly baked, baking temperature is improperly set, and moisture content is too high; there are foreign objects or foreign materials in material, affecting plastic properties; material particles are too large or uneven, affecting flow and plasticization; material and sprue are not mixed evenly, resulting in inconsistent composition; granulated material is abnormal, not baked dry, and contains moisture.

 

Mold-related issues: Sprue is too small, producing spray air marks; confluence point after impact point is not vented, and gas cannot be discharged; poor venting causes trapped air and air marks; hot runner is partially blocked, hindering plastic flow; venting is too concentrated, requiring more venting channels.
Process-related issues: Improperly set injection parameters in the front section can cause injection marks; unreasonable injection transition position and speed settings affect plastic filling; failure to slow down injection tail section can cause air trapping and air marks; partial nozzle blockage affects plastic flow; improper back pressure settings affect plastic plasticizing; excessive pumping time causes plastic to remain in barrel for too long, decomposing and generating gas; low mold temperature results in poor plastic flowability.
Design-related issues: Improper gating methods, such as inappropriate selection of pin points, square, round, or fan shapes, affect plastic flow; improper gating position leads to uneven plastic filling; failure to set venting according to mold flow analysis prevents gas from escaping.
Equipment-related issues: Similar to the equipment-related causes mentioned above, equipment malfunctions and abnormal temperatures can affect plastic filling and molding, resulting in air marks.
Injection molding machine setup is a comprehensive technology that requires operators to possess extensive knowledge, keen observation skills, and a meticulous work attitude. By mastering core elements, following key work points, and deeply analyzing causes of common defects, we can quickly solve problems in actual production, continuously improve product quality and production efficiency, and contribute to development of injection molding industry. We hope this machine setup guide will be a valuable tool for injection molding professionals, helping everyone achieve even greater success in the field.