PVC injection molding is one type of plastic injection molding. If you are considering utilizing PVC injection molding, you may be wondering about the process, applications, cost, etc. This article will give you comprehensive knowledge.
Processing
If you’re planning to do your own PVC injection molding, you may be wondering how to properly do it. The first thing you should know is that PVC is an industrial thermoplastic. Its great strength and weather resistance make it an excellent choice for many types of projects. To help you make the most of this material, you should consult with a knowledgeable manufacturer. Listed below are some tips to keep in mind. After reading these tips, you’ll know how to do PVC injection molding and why you should be careful when choosing your own supplier.
One of the major challenges with PVC is that its high viscosity and small flow length to thickness ratio make it difficult to process. Thin-walled products may result in the insufficient filling. When designing a PVC mold, consider its size and gate. You should choose one with the least amount of dead space. Ideally, your mold should be between 30 and 45 degrees Fahrenheit. While the temperature may be low, it’s better to use a higher pressure than a lower one, as this reduces shrinkage and allows the product to fill the cavity faster.
Applications
During the process of plastic injection molding, raw material is injected under high pressure into a mould to produce a specific shape. A mould can have multiple cavities or a single cavity to produce the same object in varying geometries. Typically, tool steel moulds are used for the process, though aluminum and stainless steel are sometimes used for certain applications. Depending on the type of application, plastic injection molding can be used to create complex shapes and large volumes of a single object.
The process begins with granules or pellets of PVC. This process is more efficient as it helps in distributing heat evenly and preventing overheating, which could lead to undesirable outcomes. During the injection process, the PVC pellets are fed into the barrel of the injection molding machine via a hopper. Feed rates are controlled to avoid accumulation and ensure an even blend. Next, the injection process is completed by forcing the PVC through a sprue, runner, or mold.
Properties
Among the most commonly used thermoplastics, PP is particularly suitable for injection molding. Its properties include chemical resistance, dimensional stability, elasticity, strength, and resistance to warping. Some manufacturers also make blends of PP and glass fibers. Among these blends, high crystalline polypropylene (HCP) has greater stiffness than regular polypro. This type is compounded with butadiene rubber, which results in a rigid material with low mold shrinkage. It is also good for potable water applications.
The most important considerations when utilizing PVC for injection molding are its poor fluidity and the low temperature of the plastic. High temperatures may result in decomposition of the product, which can lead to yellow spots on the product and erode the mold cavity. In addition to these concerns, PVC can also be harmful for the human body. To avoid these problems, mold temperature should be kept between 30 and 45°F. To reduce post-ejection deformation, use a shrinkage controller to control the temperature and mold runner.
Costs
There are many factors that contribute to the costs of a molded part. For starters, molds are expensive, especially if you plan to manufacture a large quantity of parts. Additionally, larger molds typically need more material to inject. This makes the overall mold cost higher. The good news is that you can reduce the mold cost by focusing on the basics or performance features. By removing these features, the final product is less expensive but may lack the appeal or functionality you’re looking for.
The cost of a mold can range anywhere from $12,000 to $100,000. The cost of steel can be very high, but market indicators predict that costs will decline dramatically in 2021. For smaller, low volume parts, it may be more cost effective to use aluminum. Another aspect that affects mold cost is the amount of machining needed to produce the parts. While lower quality molds may require more machining, they last longer and are less likely to break.
Production speed
One of the key factors for optimizing production speed in pvc injection molding is the use of on-site finishing services. While some customers simply want molded parts, others require unique detailing and basic assembly. Sending parts out to a third party to add these finishing services can slow down the shipping of finished products. Having in-house detailing services will help reduce this time. Several factors affect cycle-time. Here are some tips for optimizing your PP injection molding process.
Injection speed can affect three major aspects of a molded component: molecular orientation, shrinkage, and joint line development. High injection speeds increase the percentage of solidification near the insert and result in a high degree of molecular orientation. High injection speeds improve joint line strength and surface quality, reducing the chance of stress peaks and notch. High speeds also reduce the risk of delamination and cracking.