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Short shot / Incomplete filling
The molten resin cannot completely fill the mold cavity.
| Causes (1.1) | Solutions (1.2) |
|---|---|
| 1.1.1 Injection volume insufficient; not enough material added. | 1.2.1 Increase the material feed. |
| 1.1.2 Inadequate plasticizing capacity or insufficient residual material. | 1.2.2 Replace the machine or adjust process parameters to increase residual material. |
| 1.1.3 Plastic particle size inconsistent, causing uneven plasticization. | 1.2.3 Replace material (if using regrind, reprocess to uniform particle size). |
| 1.1.4 Bridging in hopper; particles too large or clumped, causing poor feed and uneven plasticization. | 1.2.4 Remove large particles from regrind; control hopper temperature to prevent clumping; check thermocouples. |
| 1.1.5 Excess lubricant in material; large screw-barrel clearance; excessive melt backflow. | 1.2.5 Repair equipment if screw or barrel is worn; replace barrel and screw if necessary. |
| 1.1.6 Poor balance of feed in multi-cavity molds; small gates or far-away cavities receive insufficient material. | 1.2.6 Modify gate size for distant cavities; repair gates as needed. |
| 1.1.7 Nozzle or barrel temperature too low. | 1.2.7 Adjust barrel and nozzle temperature. |
| 1.1.8 Nozzle blocked or too small. | 1.2.8 Clean nozzle blockage or replace nozzle with larger diameter. |
| 1.1.9 Low injection pressure, short injection or holding time, premature screw retraction. | 1.2.9 Adjust injection pressure, injection and holding time. |
| 1.1.10 Injection speed too fast causing air entrapment, or too slow causing incomplete filling before material solidifies; foreign objects in blind holes. | 1.2.10 Reduce injection speed or add vents if too fast; increase speed if too slow; clean foreign objects in blind holes. |
| 1.1.11 Poor flowability of plastic. | 1.2.11 Use material with higher melt flow index or adjust process conditions. |
| 1.1.12 Excess flash. | 1.2.12 Increase clamping force; adjust or repair nozzle to match mold gate insert. |
| 1.1.13 Low mold temperature causing rapid cooling/solidification. | 1.2.13 Increase mold temperature so melt fills cavity before solidifying. |
| 1.1.14 High flow resistance in mold gating system; improper gate location; small cross-section; long, winding flow path. | 1.2.14 Polish mold runners or modify gating system structure and gate size. |
| 1.1.15 Poor venting; no cold slug well or improper cold slug well. | 1.2.15 Increase venting; add cold slug well. |
| 1.1.16 Excess mold release agent; moisture in cavity. | 1.2.16 Reduce or avoid mold release; wipe excess release agent and moisture. |
| 1.1.17 Thin wall, complex shape, large area; melt solidifies during flow. | 1.2.17 Increase mold temperature or adjust runner system to improve melt flow. |
| 1.1.18 High moisture or volatiles in material. | 1.2.18 Properly dry material to meet moisture requirements. |
| 1.1.19 Low back pressure; air enters melt during preplasticizing. | 1.2.19 Increase back pressure and reduce screw speed to prevent air inclusion. |
| 1.1.20 Faulty hot runner heating ring or thermocouple. | 1.2.20 Replace faulty components. |
| 1.1.21 Hot runner nozzle too small or blocked. | 1.2.21 Replace or clean nozzle. |
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