Golf Ball Injection Mold Runner System Flow Balance
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Solution Overview
Problem
Conventional golf ball injection molds result in excessive sprue formation and uneven plastic flow, leading to surface imperfections and bubble issues in the final product due to lengthy runner systems and imbalanced material injection.
Innovation Solution
The injection mold design features a primary runner, an annular runner, and a varying number of injecting runners, where the cross-sectional area or count of injecting runners near the primary runner is smaller than those further away, ensuring balanced plastic flow and reduced sprue formation by optimizing the runner system's geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional runner system with extending runners and arched runners is used, then the molten plastic flows evenly into the hemispherical recesses, but the total length of the runners becomes excessively long, resulting in excessive sprue formation
Solution Approach 1:
The runner system is segmented into three distinct components: primary runners that receive molten plastic from the injection molding machine, annular runners that surround the spherical cavity, and injecting runners that connect the annular runners to the spherical cavity. This segmentation allows optimization of each component's function while reducing total runner length and sprue formation.
Solution Approach 2:
The annular runner is designed to surround the spherical cavity in a circular path, transitioning from linear extending runners to a dimensional arrangement that distributes plastic flow more efficiently around the cavity perimeter, reducing the need for long extending runners.
2Loss of substance
If an annular runner with evenly spaced injecting runners is used to reduce sprue volume, then the total runner length is reduced, but the molten plastic flows unevenly, causing surface imperfections and bubble problems
Solution Approach 1:
The injecting runners are designed with non-uniform spacing around the annular runner, with greater spacing in regions where plastic flow pressure is higher and closer spacing where pressure is lower. This local variation in spacing compensates for pressure differences, ensuring uniform plastic flow distribution into the spherical cavity and preventing surface imperfections and bubble formation.
3Ease of manufacture
If injecting runners are evenly spaced around the annular runner, then the runner system is simple to manufacture, but the molten plastic cannot be injected simultaneously and evenly into all hemispherical recesses, leading to thickness inconsistencies and off-center problems
Solution Approach 1:
The injecting runners are positioned at non-uniform intervals around the annular runner, with specific spacing adjustments made in different regions. This maintains relative manufacturing simplicity while achieving uniform plastic flow distribution and consistent injected layer thickness across all hemispherical recesses.
4Manufacturing precision
If the runner system is designed with long extending runners to reach all hemispherical recesses, then complete coverage is achieved, but the injection pressure is insufficient at distant injecting runners, causing incomplete filling
Solution Approach 1:
The runner system is divided into primary runners, annular runners, and injecting runners. The annular runner acts as an intermediate distribution manifold that reduces the distance from the primary runner to each injecting runner, maintaining adequate injection pressure at all cavity locations without requiring excessively long extending runners.
Solution Approach 2:
The annular runner distributes plastic flow in a circular path around the spherical cavity, reducing the radial distance that plastic must travel compared to long extending runners. This dimensional arrangement maintains injection pressure while achieving complete cavity filling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for even plastic distribution, reduces sprue volume, enhances yield rate, and improves the golf ball's surface quality by minimizing bubbles and thickness inconsistencies, thereby increasing the resilience and performance of the golf ball.
Implementation Method 1
The runner system includes a primary runner, an annular runner, and a plurality of injecting runners, wherein the plastic material flows through the primary runner into the annular runner, and the annular runner surrounds the spherical cavity
Data Source
AI summary
An injection mold for golf balls includes a first mold half and a second mold half, which could be removable mated with each other, and a spherical cavity and a runner system are disposed therebetween. The runner system includes a primary runner corresponding to an annular runner surrounding the spherical cavity. Additionally, the injecting runners connect the annular runner and the spherical cavity. A sum of the cross-sectional area of the injecting runners near the primary runner is smaller than a sum of the cross-sectional area of the injecting runners away from the primary runner. Alternatively, a number of the injecting runners near the primary runner is smaller than a number of the injecting runners away from the primary runner. With such design, the plastic material could be evenly injected into the spherical cavity, and the sprue of the product could be reduced. A golf ball manufactured by using the injection mold is provided herewith.