Introduction
The injection molding process has gained traction in recent times. For producing similar products in bulk, injection molding is the primary option. With every successive production, the cost drastically reduces, thus improving the profit. It has diversified applications with metals, polymers, plastic, 3D printing, etc.
Advantages Of Injection Molding
It is undoubtedly a versatile product with a range of advantages. It increases production speed with a decrease in cost, not only in production terms but also in labor due to improved mechanization. It is reliable in producing identical machinery and can go on for multiple rounds without compromising quality.
Issues In Injection Molding And Their Solutions
Injection molding has various issues apart from its fair share of advantages, some of which can be easily resolved. Injection moulding problems and solutions are not something unique or difficult. Some of them are listed as follows:
Warping
It happens during the cooling process when the mold gets disfigured compared to the shape intended, resulting in an uneven shrinkage of different parts.
The prominent cause of warping is due to inappropriate temperature settings. The molding requires gradual cooling, which otherwise can lead to the disfigurement of the product. An abrupt cooling or a higher temperature than is necessary for cooling contributes to the problem. Insufficient injection pressure is another cause of the rapid cooling of the material.
The resolution of this is simple. One should check on the temperature subjected to the process and ensure that the conductivity of the mold material is in sync with the temperature of the process and that injection pressure is adequate.
Another cause is the unsymmetrical walls of the mold, which causes differential heating that leads to warping. One should undertake material redesigning to ensure uniformity of thickness and uniform heating.
Flow Lines
It is the pattern created on the molded component as a consequence of uneven molding and solidification speed of the material. If not rectified on time, these marks appear on the final product in a different shade than the original, leading to poor customer experience.
The causes of these flow lines can be varied:
The insufficient injection speed causes solidification of the component before the injection material reaches the end, which leads to the formation of flow lines. Sub-optimal temperatures have a similar consequence as injection speed, i.e. material cooling down before being smoothly molded. Different wall thickness causes differential melting and creates flow lines. The inadequate gate size lowers the speed of injection flow, and the material cools down before being molded.
The injection nozzle should be of increased diameter to increase flow. One can approach the medical device contract manufacturers for ideal injection designs to improve the molding process.
The chosen material should have higher thermal conduction, such as a Teflon rod, which increases the time it takes to cool down and gives more time to mold. There should be an increase in the gate diameter so that there is an improvement in molding speed due to high injection flow. Thickness uniformity should be maintained, which otherwise causes both warping and flow line issues.
- Vacuum Voids
The voids or air pockets form in the final molded product. It is not a serious issue but if present in high numbers, it can undermine product integrity. It is formed either due to high moisture in the molded material, a high wall thickness, insufficient holding pressure, or incorrect mold alignment.
One needs to dry out the molding component completely to avoid moisture hampering the process. A high wall thickness leads to insufficient heat in the interior of components that creates air pockets and voids. There must be a thorough inspection of the thickness before putting it to use.
One must carry out a proper check in the case of mold that is divided into multiple parts to ensure that they are in alignment and don’t allow any trapping of air that can cause bubbles. The inadequate holding pressure reduces the condensation
capability, which otherwise forces the air out and avoids air bubbles.
- Delamination
It occurs due to unwanted material, creating a thin film on the final component. The film can be peeled off easily, giving the impression that this issue is insignificant, but it reduces the strength of the material in reality and compromises its quality.
The choice of plastic is crucial to rectify this issue as a sub-optimal quality can lead to significant losses in the production process. In the case of two different materials used together, one needs to ensure that they are compatible to avoid one of them forming a separate layer instead of blending naturally. Some other solutions are improving injection speed, maintaining a uniform thickness of walls, increasing the gate size, and keeping a check on melting temperature.
Conclusion
Injection molding is an effective industrial process that makes mass production convenient and inexpensive. However, for a hassle-free production process, precautions are essential in injection molding to give a satisfactory and high-quality final product.
