In injection molding, temperature setting and temperature fluctuations are often reflected in the appearance and internal quality of the product. Spray lines, burning, cold insulation, warping, shrinkage marks, silver lines, bubbles, black lines and other issues may be related to plasticizing temperature, mold temperature, cooling conditions or material state.
This article takes 8 common defects as examples to sort out their judgment ideas and common adjustment directions related to temperature, providing reference for on-site inspection in production.
01
Eight temperature related injection molding defects
And common coping strategies
Spray pattern:The molten material failed to adhere to the wall and spread out in a timely manner after being injected into the mold cavity at high speed.
nowelephantSerpentine, strip-shaped, or wavy marks extending from the vicinity of the sprue.
causeThe mold temperature and melting temperature are too low, the material viscosity is too high, or the parameters such as firing rate and pressure are set improperly.
countermeasureSet the recommended temperature according to the material (e.g
PC1050 melt at 280-320 ℃); The recommended temperature setting for mold temperature (such as 90-120 ℃ for PC1050 material) adopts a three-stage injection speed of "slow fast slow".
Burning/Carbonization: Trapped Gas and Overheating Decomposition
nowelephantCoking or carbonization black spots appear on the surface or inside of the product.
cause：
moldTrapped gas is injected and compressed to increase temperature (Diesel effect); The material temperature is too high, the screw speed is too fast, or the material stays in the barrel for too long.
countermeasureAdd mold exhaust; Reduce material temperature; Shorten the molding cycle and reduce the retention time of materials in the material barrel and hot runner; Check for temperature control abnormalities, material retention, or dead corners in the hot runner.
Cold insulation/cold material line: nozzle temperature out of control (too low)
nowelephantSurface lines without fused patterns, randomly distributed.
causeThe cold material head at the nozzle or hot runner enters the mold cavity.
countermeasureIncrease the material temperature and mold temperature; Increase injection/holding pressure; Optimize the gate; Raise the temperature of the nozzle and mold; Increase the nozzle aperture; Set up a cold material well; Check for screw wear.
Warping deformation: loss of control due to uneven cooling
nowelephantLifting, bending, twisting, wave deformation or angular deviation.
causeDifferences in cooling/holding pressure/molecular orientation among different regions result in uneven shrinkage.
countermeasurePartition dynamic temperature control (Tg ± 5 ℃); Optimize the conformal cooling water channel; Implement gradient pressure maintenance (high pressure → medium pressure → low pressure stress relief).
harvestShrinkage mark: thick and thin wallUnbalanced cooling rate
nowelephantThe surface of the thick walled or reinforced base is concave.
causeThe cooling in the thick walled area is slow, the shrinkage rate varies greatly, and the pressure compensation is insufficient.
countermeasureReasonably set the ratio of reinforcement thickness to wall thickness; Multi stage pressure maintenance; Adjust the melting temperature/mold temperature/cooling time.
Silver/water patterns: interference from volatile gases
nowelephantSilver white stripes on the surface, especially on transparent parts.
causeHigh moisture content in the material, poor melt decomposition or exhaust.
countermeasure: Fully dry
raw material(Recommended drying temperature according to the raw material properties table); Reduce the melting temperature appropriately; Improve exhaust.
Bubbles/air pockets: internal cavities with uneven cooling
nowelephantThick walled components are hollow inside, with visible voids on the cut surface.
causeInsufficient external solidification and internal melting materials; Insufficient pressure retention; The itinerary is too short; Raw materials contain water; Improper gate.
countermeasureExtend the holding pressure and optimize the holding pressure curve; Reduce the temperature gradient of the mold; Improve wall thickness; Fully dry the raw materials; Increase back pressure; Adjust the gate.
Black stripe: Accumulation of material, carbonization, contamination of melt
nowelephantBlack stripes on the surface.
causeScrew dead corner material carbonization, high material temperature, and too fast firing rate.
countermeasureRegularly clean the screw of the material cylinder; Reduce material temperature; Reduce the firing rate appropriately; Clean the materials before stopping the machine.
The above measures have clear theoretical directions, but in practical production, mastering the methods does not equate to long-term stable mass production. The real challenge lies in whether enterprises can timely perceive anomalies, accurately locate root causes, quickly complete adjustments, and replicate and promote effective experiences among different machines, shifts, and batches when variables such as environmental temperature fluctuations, changes in raw material batches, and equipment status drift occur.
02
From experience judgment to data tracking
Improve the efficiency of defect investigation
For injection molding sites, defect judgment still relies on experience. But if experience only stays in an individual's mind, it is difficult to settle and reuse.iChen ™ Smart Family Zhenxiong Intelligent Industry SolutionThrough device data collection, key parameter recording, and process optimization, it can help enterprises precipitate effective process solutions and provide more basis for the investigation of temperature related defects.
Understanding defects is the first step. Recording and reusing the judgment process is the key to long-term stable production.
iChen ™ AI Molder (Intelligent Injection Molding Assistant)Deep integration of AI algorithms and injection molding process knowledge graph, intelligent recommendation of molding parameters during new mold trial production stage, significantly reducing debugging cycles; When quality defects occur, automatically associate the graph for root cause diagnosis and provide adjustment suggestions. During the mass production process, key parameters such as switching position and pressure are continuously monitored, and any abnormalities are promptly alerted, effectively reducing troubleshooting time and significantly improving production yield.
iChen ™ Cloud (Zhenxiong Zhiyun)Unify the collection and storage of equipment status, process parameters, and production records, and establish a traceable production archive throughout the entire lifecycle. When quality fluctuations occur, they can be quickly traced back and the cause can be identified; The validated mature process can serve as a reference for subsequent production, reducing repetitive debugging. At the same time, the connected auxiliary equipment (such as dryers, mold temperature machines, etc.) can achieve synchronous monitoring, which can significantly reduce the quality risks caused by abnormal auxiliary equipment.
Stable temperature control is the foundation for reducing molding defects. Zhenxiong utilizes equipment temperature control capability and iChen ™ Smart Family Zhenxiong Intelligent Industry Solution helps customers record key process parameters, track abnormal changes in the production process, and provide more basis for the investigation of temperature related defects.
Understanding the manifestation of defects, finding temperature clues, and continuously optimizing process conditions are the key to reducing temperature related molding defects.
