Technology / product information

For those facing short shot issues in injection molding

For those facing short shot issues in injection molding

– Supporting fundamental improvement of insufficient flowability through mold maintenance services –

In injection molding, short shots (insufficient resin filling) are typical defects that not only cause appearance issues and functional degradation, but also destabilize production conditions.
They are especially likely to recur in connectors and thin-walled parts, leading to production stoppages, scrap losses, and difficulty in process control.

■ What is a short shot?

A short shot is a defect in which molten resin does not completely fill the mold cavity, resulting in missing features or insufficient dimensions in the final product.
It occurs primarily due to insufficient resin flowability and is influenced by multiple factors, including material temperature, mold temperature, gate design, and venting condition.

■ Typical parts and applications

Short shots frequently occur in:

Electronic components

Automotive electrical and electronic parts

Precision connectors

Parts with fine features, thin walls, or complex geometries

For products requiring micron-level accuracy, even minor incomplete filling can lead to significant performance degradation, making early root-cause identification and mold-side optimization essential.

■ Benefits of improvement and key considerations

Proper short shot improvement provides:

Stabilized molding conditions

Improved productivity through shorter cycle times

Extended mold life

Significant reduction in defect rates

However, simply increasing material or mold temperature is only a temporary measure and may lead to recurrence. Comprehensive countermeasures, including mold maintenance and design review, are indispensable.

■ Technical approaches to improve molding stability

The following technical measures are effective for short shot improvement:

Optimizing material and mold temperatures: ensuring sufficient flowability, especially in fine features

Improving and enlarging gate geometry: allowing smooth resin flow and sufficient filling pressure

Enhancing venting mechanisms: preventing gas accumulation that obstructs resin flow

Utilizing flow simulation: evaluating moldability in advance through high-accuracy CAE analysis

Maintaining proper mold condition directly contributes to stable molding accuracy.

■ Information required from customers

To facilitate smooth improvement, please clarify the following:

Detailed defect locations (photos, drawings)

Resin type and flowability index (MFI)

Current molding conditions (temperature, pressure, speed)

Mold specifications (number of cavities, gate location, vent structure)

Expected production volume and target cycle time

For injection molding machines under 100 tons, even slight flow resistance directly affects molding results, making mold-side optimization especially critical.

■ Features of SHINKO PRECISION VIETNAM’s mold maintenance services

SHINKO PRECISION VIETNAM supports fundamental short shot improvement by leveraging the following strengths:

Advanced micro-machining expertise for precision molds under 100 tons

Mold design and repair proposals focused on extending mold life

Strong support network spanning Japan, China, Taiwan, and Vietnam

High-precision mold component manufacturing with short lead times through partner factories

Mold design consulting to prevent recurrence

If molding is unstable due to short shots, resin does not fully flow, or defects frequently occur on small injection machines, mold maintenance and optimization can bring significant improvement.
Please share the molding phenomena and product specifications, and we will propose the most suitable solution.