Plastic injection molding pressures are classified based on the clamping pressure that the molding presses exert. This is the reason why it’s important to check the size of the press, which is often referred to as the tonnage. The clamping pressure exerted by the press can range anywhere from 5 tons to more than 4,000 tons. (more…)
Why should you choose a hot-runner mold system over a cold-runner mold system (or vice versa)? Each type of molding system has unique features that help determine exactly which one is best for you.
Called a cold-runner mold system because the runners are the same temperature as the molds, there are two types of cold-runner systems: a three-plate system and a two-plate system.
Three-plate systems allow the part to be ejected from the runner without an ejection system, but are a little more complicated than a two-plate system, which does require an ejection system to remove the part and the runner from the mold. Two-plate systems can handle most molds, however a three-plate system is friendlier when it comes to complex designs.
In a cold-runner mold system, the runner has to be larger than the part. Otherwise, you run the risk of underfilling the mold. One big advantage over a hot-runner system is the ability to use more types of polymers without concern for heat sensitivity.
Cold runners are less expensive than hot runners and are easily maintained as well, but they can create waste unless you can recycle or melt down the extra material.
There are two types of hot-runner mold systems, both of which use two plates heated by a manifold system. Externally heated molds allow you to use more heat-sensitive polymers while internally heated molds generate better flow control. Depending on your materials and applications, you may prefer (or need) one type over the other.
Hot runners are more expensive than cold runners (in initial investment and maintenance), but they can handle higher volumes and larger parts and also don’t generate any waste. In some cases, the lack of waste balances with the higher maintenance cost to actually be about the same net cost as a cold-runner system.
Overall, hot-runner molds produce parts with more consistent quality and do so with faster cycle times, but it’s not as easy to change colors nor can hot runners accommodate some heat-sensitive polymers.
Depending on exactly what you’re doing with your molds—materials, applications, size, volume, etc.—you may have a clear answer as to the best mold system or it may be more complicated. For instance, if you’re only working with heat-sensitive polymers, a cold-runner mold system is probably your best choice. If you’re producing large volumes and need faster cycle times, you’re probably looking for a hot-runner mold system.
However, those aren’t definite answers and shouldn’t be taken as such. You need to consider every facet of what you’re doing to determine the best system for you. Feel free to contact us if you’d like to talk about which type of mold system is your best option.
When you’re buying molded parts made from different types of plastics, it’s crucial you know about some of parts defects that can lower the quality of the molded plastic parts. If you know the sources of the defects and flaws they can cause, you can work in conjunction with your plastic injection molding company to maintain the highest standard of quality during production. (more…)
In the plastic injection molding industry, the quality of plastic parts is paramount. Plastics can be precisely molded, but many companies end up with flawed parts because they get one contractor to construct the mold and another to use the mold to create the parts. As a result, quality is often compromised. Companies can now achieve the perfect plastic parts by taking into consideration the following four steps. (more…)
Very interesting article from Plastics Technology: “Researchers from Harvard University’s Wyss Institute have developed a fully-degradable bioplastic isolated from shrimp shells which they report can be molded into products such as cell phones, food containers and toys…”
The team is developing a new way to process the chitin to be able to fabricate it into larger 3D, complex shapes using traditional casting or injection molding techniques.
Read the rest of the article HERE.
The injection molding industry is extremely competitive because of the need to respond quickly to a customer’s requests while keeping production costs low. Unfortunately, both are not always possible, and that’s why many manufacturers have been opting for off-shoring in order to cut production costs. However, the recent trends show manufacturing companies are now looking to re-shore their plastic injection molding manufacturing, and they have very good reasons for doing so. (more…)
