Pinpointing and Solving Short Shots in Injection Molding

Short shots in injection molding can lead to significant production inefficiencies and compromised product integrity, posing a technical challenge for manufacturers. Addressing this issue requires a comprehensive understanding of its various causes, which can range from mold design flaws to suboptimal processing conditions. This article delves into the multifaceted origins of short shots, laying out the potential reasons categorized under mold-related issues, process inadequacies, design oversights, equipment malfunctions, and material deficiencies. 

Cause Analysis (Basis for Machine Adjustment: Reference Control Parameters)Mold Causes

1. The water inlet is too small, does not fill the mold with enough plastic.
2. Poor venting, air traps causing short shots.
3. Mold misalignment.
4. Nozzle, gate channel too small.
5. Local air traps, need to set exhaust pins.
6. The encapsulated metal does not match the mold properly.
7. Hot runner blocked.
8. Hot runner leaking.

Process Causes

1. Injection pressure too low.
2. Injection speed too slow.
3. Mold temperature too low.
4. Not enough melt.
5. Injection transfer position set unreasonably.
6. Barrel temperature too low.
7. Nozzle blocked.
8. Mold clamped too tight, unable to vent.
9. Leakage.

Design Causes

1. Improper gate location.
2. Bone position designed too thin.
3. Product corners too sharp.

Equipment Causes

1. Machine too small, insufficient pressure.
2. The three small parts, barrel damaged, not sealing.
3. Injection cylinder oil seal leaking oil, unstable pressure.
4. Pump damaged, pressure unstable.
5. Barrel temperature abnormal (one does not rise, raised by the side).
6. Barrel cooling water effect not good, resulting in material degradation.
7. Machine screw model not matching with the plastic material.
8. Inappropriate voltage output, unstable.

Material Causes

1. Poor flowability of the material.
2. Material, sprue not mixed evenly.
3. Material particles too large, uneven distribution.

The phenomenon of short shots in injection molding is a complex interplay of various factors that demand attention to detail and rigorous process control. By meticulously analyzing and rectifying each contributing factor, from precise mold design to optimal material characteristics, manufacturers can significantly reduce the incidence of short shots. Effective troubleshooting guided by the insights provided can not only enhance production efficiency but also ensure the delivery of high-quality injection molded products.