Injection Molding
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ABS injection short shot (lack of material)
Problem Phenomenon
The product is locally unfilled, commonly seen at thin-wall ends far from the gate and at rib ends; the short shot edge is rounded and repeats at the same position.
Cause Analysis
The melt stops flowing before reaching the end of the cavity due to temperature drop, pressure loss, or trapped air back pressure; insufficient injection pressure/speed, low melt and mold temperature, poor venting, and too thin wall thickness all can cause it, and need to be checked one by one.
Solution
①Prioritize increasing injection pressure and speed; ②appropriately increase melt temperature and mold temperature; ③enlarge the gate and runner and shorten the flow length; ④improve venting at the ends; ⑤thicken too-thin structures when allowed; ⑥use the short shot method to locate the last filling point.
Key Takeaway
Check ABS short shots in the order of 'pressure and speed→temperature→venting→structure': first increase pressure and speed, then keep warm, then vent, and finally evaluate the wall thickness; the short shot method is a sharp tool for locating the last filling point.
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