How We Avoid Plastic Injection Molding Defects

When it comes to manufacturing quality plastic injection moulded products, we are experts in our field. From the smallest, intricate part to large, mass-produced plastic moulded projects, we have experience and skills to perfect your products. When it comes to plastic injection moulding, there will always be risks of defects in the finished product. Here are just some of the ways we avoid injection molding defects in our injection moulding process using high-tech machinery and skills to create your perfect product.

Avoiding Air Pockets and Vacuum Voids During the Plastic Injection Moulding Process

When creating bespoke products using plastic injection moulding, it is extremely important to avoid the creation of air pockets during the process. A bubble defect in injection molding can be the result of volatiles from the resin, the decomposition of gases from polymers or additives or moisture vapour. This can inadvertently distort the shape and use of the finished product. As experts in our field, we have a number of processes in place to avoid this in our plastics mould manufacturing process. We also have high-tech machinery to optimise the process and ensure adequate moulding pressure forces any excess air out of the moulding cavity. Our high-tech plastic injection moulding machinery also ensures premature cooling does not happen, another cause of air pockets in the moulding process.

Preventing Burn Marks in Our Plastic Injection Moulding Process

In some cases when creating plastic injection moulded products, burning can appear. In many cases, this can be due to air or even resin becoming trapped in an air cavity and overheating. This then results in the scorched material. Here at Fern Plastics, our skilled team members prevent burn marks in injection molding by loosely monitoring the temperature of our plastic injection mouldings and the speed of our injection mouldings to ensure this doesn’t happen to our products. We take pride in ensuring each of the products that leave us are fit for purpose and look visually as expected..

Avoiding Plastic Injection Mould Warping

As with any materials, when treating plastics and using them during the plastic injection moulding process, there is a risk of warping the materials. A warping defect in injection molding has a range of side effects including excessive space produced between components and misshaped products. Warping as an effect of the injection moulding process can be caused during the cooling process when uneven shrinkage can put stress on different parts of the plastic product. Often, the materials used can be prone to developing warping defects. Materials with semi-crystalline structures are more likely to be subject to warping. We combat this through strategic selection of materials and expert mould design to avoid this. We also ensure an even and gradual cooling process to avoid warping of the plastic injection moulded product.

Jetting During the Plastic Moulding Process

A jetting defect in injection molding can occur when the solidification process happens unevenly. In order to create a smooth, streamlined plastic injection moulding without any jetting, it is important to use the perfect injection pressure for your product to avoid initial streams solidifying before the product is finished. We have years of experience perfecting the plastic injection moulding process so make it our priority to provide an exceptional product and service each and every time. Our innovative machinery calculates the exact pressure needed for every moulding whilst our mould designs optimise for a smooth finish.

Preventing Sink Marks in Injection Molding

Sink marks are common defects in injection moulding often found in thick-walled sections. One of the main causes of sink mark defects relates to incorrect melt temperatures. We are able to prevent the formation of this defect by understanding the importance of staying within the temperature range recommended by the resin manufacturer. Since thick sections contain more plastic, failing to verify the temperature can result in the part taking longer to cool which will lead to the formation of sink marks. As well as verifying the correct temperature during the injection moulding process, we make sure the correct second-stage pressure and pack and hold times are maintained. The ideal second-stage pressure (or pack and hold pressure) not only helps to prevent shrinkage but when combined with the proper pack and hold times, ensures the part is efficiently sealed which can prevent sink marks from forming. Where applicable, we apply gas-assist injection moulding processes to help reduce the appearance of sink marks.

Avoiding Short Shots in Injection Molding

During the injection molding process, partially formed parts known as short shots occur when the resin hasn’t entirely filled the mold cavity. The result is a plastic part that is visibly incomplete and often unusable. We prevent short shots in injection molding by ensuring a consistent flow within the mold cavity which can be affected by blocked or narrowed gates. We also avoid short shots by adjusting the mold temperature and maintaining the correct injection pressure so that the entire mold cavity is filled during mould injection. 

Weld Lines in Injection Molding

A weld line defect is formed when two flows of injected resin material meet within the mould cavity. Also called a “knit line”, these marks usually form around holes as the plastic flows around either side. When the temperature of the resin is incorrect, the two flows fail to bond together properly which results in a visible weld line. Weld line defects reduce the durability, strength and aesthetic quality of the plastic component. To combat the formation of a weld line defect in injection molding, we can make adjustments to the mould design as well as raise the temperature of the molten resin which prevents it from solidifying too fast. Low-viscosity resins with lower melting points are often less prone to developing weld line defects. We also adjust the injection speed and pressure where necessary which also prevents early solidification and the formation of knit lines. 

Our experienced and highly trained team are fully equipped to deal with the nuances of plastic injection moulding to ensure an industry-leading product each and every time. If you are looking for state-of-the-art plastic injection mouldings from a source you can trust, get in touch with the team here at Fern Plastics and find out more about what we can offer you. Get in touch online or call 01902 758282 for more.