The Advantages of Hot Runner Systems vs. Cold Runner Systems in Custom Injection Molding

Hot runner systems have become an essential tool for many manufacturers across various industries. By leveraging this technology, businesses can enhance their production processes, deliver superior products, and stay ahead in the competitive manufacturing landscape.

So how are hot runner systems different from cold runner systems? The main difference lies in how they handle the plastic material during the injection molding process. In a hot runner system, the plastic is kept in a molten state throughout the entire process. This is achieved by using heated components, such as heated nozzles and manifold systems, to maintain the desired temperature of the plastic.

So how does this create an advantage over cold runner systems? Let’s explore the many benefits:

Complex Designs

The use of a hot runner system allows for more complex and intricate designs, as there are no restrictions imposed by the presence of runners. Additionally, some hot runner systems will do two shot molding enabling the injection of multiple materials or colors simultaneously, without the risk of cross-contamination. This versatility opens up a wide range of possibilities for manufacturers, allowing them to create multi-component parts or products with intricate designs and color patterns.

Part Quality

Using a hot runner system also helps to prevent material degradation and ensures optimal part quality. By closely monitoring and controlling the temperature of the plastic, hot runner systems can produce parts with superior surface finish and dimensional accuracy for a clean and finished product.

Material Savings

In cold runner systems, these runners solidify along with the plastic, resulting in material waste that needs to be trimmed or regrinded. In contrast, hot runner systems ensure a smoother flow of plastic, without the need for runners. This not only reduces waste but also speeds up the production cycle.

By reducing material waste, manufacturers can optimize their material usage and reduce overall costs. This also results in environmental benefits. By eliminating plastic waste, they contribute to a more sustainable production process. This aspect is particularly crucial in today’s manufacturing landscape, where businesses are under increasing pressure to minimize their environmental footprint.

Efficiency

The absence of runners and sprues in hot runner systems results in faster production cycles. With no waiting time for the plastic to cool and solidify, manufacturers can produce parts at a higher rate, increasing overall productivity.

Cost Savings

A common misconception about injection molding is that it is an expensive process. However, as we’ve discussed, by reducing waste, speeding up production, and minimizing the need for labor-intensive processes such as trimming and regrinding, hot runner systems can lead to substantial savings for the customer.

The upfront cost of these systems might be higher than their cold runner counterparts for the company who owns the mold however, the actual per-unit cost of production is lower—making the production cost for their customers lower as well. This is especially true for high-volume production runs due to the high efficiency and repeatability of the process.