【Popular Science】Addressing shrinkage of the plastic housing to strengthen the foundational quality of terminal connectors
- Categories:Company News
- Author:Guangdong Deke Electric Co., Ltd.
- Origin:https://www.de-ke.cn/
- Time of issue:2026-06-03 11:46
- Views:
【Popular Science】Addressing shrinkage of the plastic housing to strengthen the foundational quality of terminal connectors
- Categories:Company News
- Author:Guangdong Deke Electric Co., Ltd.
- Origin:https://www.de-ke.cn/
- Time of issue:2026-06-03 11:46
- Views:
As an old industry saying goes: Countless plastic part shrinkage defects mostly stem from uneven wall thickness!
Terminal connector plastic housings feature thin walls, numerous buckles and intricate structures, making them prone to injection molding sink mark defects. Such flaws not only spoil appearance but trigger dimensional deviation and loose buckles, further causing assembly malfunction and higher production costs. This article analyzes root causes of shrinkage and shares practical improvement solutions.
I.Definition of Injection Molding Shrinkage
Shrinkage, also known as sink mark or surface dent, commonly occurs at uneven wall sections, rib positions, boss posts and root parts of buckles. Insufficient resin feeding during plastic cooling and contraction leads to surface depressions. Given the precise and sophisticated structure of connector housings, shrinkage happens frequently on these products.
II.Core Causes of Injection Shrinkage
Repeated housing shrinkage in many manufacturers rarely results from a single factor; it arises from combined drawbacks in mold design, raw material, processing temperature, molding parameters, packing setup, cooling system, gate design and production environment. Below is a detailed breakdown of eight common shrinkage triggers:
1.Mold Design Defects
Terminal housings are generally thin-walled with dense ribs and buckles. Uneven wall thickness in mold design brings inconsistent cooling speed of molded parts. Thick-wall areas feature drastic plastic shrinkage without enough melt replenishment, directly resulting in sink marks and dents, the top cause of industry-wide shrinkage issues.
2.Raw Material Properties
Different plastic materials carry distinct shrinkage rates. In general, rigid materials deliver low shrinkage while flexible materials come with high shrinkage ratios.
3.Processing Temperature Issues
Excessively high processing temperature accelerates plastic melting and flow to raise shrinkage rate; overly low temperature leads to incomplete raw material fusion and internal air voids that alter shrinkage performance.
4.Injection Molding Parameter Settings
Key parameters including injection speed, packing duration and cooling time change plastic melting and flowing status, hence impacting the final shrinkage rate.
5.Production Environment
Ambient temperature and humidity exert influences on plastic shrinkage. High ambient humidity causes raw material moisture absorption and aggravated shrinkage.
6.Packing Pressure & Holding Time
Insufficient packing pressure or inadequate holding time fails to supply enough molten plastic to fill voids generated during cooling and creates sink marks. Higher packing pressure and extended holding time effectively mitigate shrinkage.
7.Improper Cooling System
Poorly configured mold cooling circuits cause uneven cooling, resulting in uneven shrinkage across different product sections.
8.Improper Gate Design
Unreasonable gate location and dimension obstruct melt flow during cavity filling and negatively affect shrinkage control.

III.Targeted Improvement Solutions
1.Optimize Mold Design
Optimize mold structure to realize uniform product wall thickness; apply material removal or transitional thickening at thick-wall sections to reduce wall thickness discrepancies.
2.Rational Raw Material Selection
Select qualified raw materials matching product specifications; prioritize grades with stable shrinkage performance and adjust molding processes in advance for flexible high-shrinkage plastics.
3.Standardize Processing Temperature
Set molding temperature per material specifications to avoid overheating; moderately raise low temperature for complete plastic fusion and void prevention.
4.Adjust General Injection Parameters
Modify injection speed and multi-stage velocity to ensure smooth melt flow and full cavity filling.
5.Upgrade Packing Pressure & Duration
Increase packing pressure and prolong holding time to sustain continuous melt feeding for shrinkage void compensation during cooling.
6.Upgrade Mold Cooling Layout
Rearrange cooling channels for homogeneous part cooling and enhance cooling layout at thick-wall and shrinkage-prone positions.
7.Revise Gate Configuration
Readjust gate position and size to smooth melt feeding toward ribs, buckles and boss posts.
8.Control Production Conditions
Stable workshop temperature and thorough raw material pre-drying prevent excessive shrinkage caused by material moisture absorption.
Closing Remarks
Tiny as terminal connectors are, they function like blood vessels for electronic equipment. Minor surface dents on plastic housings may trigger loose fitting of contact components or overheating and burnout under heavy current.
In the fiercely competitive connector market, qualified product yield determines enterprise survival. Shrinkage defects require systematic rectification instead of makeshift fixes.
Deke Electric has long engaged in terminal connector manufacturing with self-owned full-set injection molding workshop and precision mold maintenance center. We master every detail of plastic housing molding besides terminal production.
We never compromise on common industry defects including shrinkage, short shot and deformation. Equipped with high-precision injection machines and full-process mold flow analysis, Deke Electric delivers zero-defect and perfectly matched connector solutions for clients. Professional problem-solving and reliable quality make Deke your trustworthy and efficient partner.
Guangdong DEKE Electric Co., Ltd.
Specializing in R&D and Manufacturing of Connectors & Terminals · High-Tech Enterprise · Pioneer in Domestic Substitution
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