Summary:
When designing a hot runner mould, you have to consider its function and balance of operation. An unbalanced mould can ...
When designing a hot runner mould, you have to consider its function and balance of operation. An unbalanced mould can lead to overfilled parts, wide flash, and residual tension. Unbalanced operation also reduces part quality. Consider the function and balance of a multi-cavity mold when determining the right hot runner mould for your application.
Cold runner vs hot runner system
The main difference between hot runner and cold
runner mould systems is in the heating system. Hot runner molds have a heated runner system that is fixed throughout the molding process. They have the advantage of being able to handle large volumes and smaller parts with ease. These systems also offer a lower cost of ownership and maintenance. In general, hot runner moulds yield better quality parts and shorter cycle times. However, they cannot handle certain types of polymers that are sensitive to heat.
Cold runner mould systems have two or three plates that are separated by a stripper plate. This stripper plate delivers plastic to the runners, which are connected in separate cavities. The third plate then forms the final molded part. This system allows for greater design flexibility and gate installation. However, the disadvantages of cold runner molds are that the runners need to be recycled and reground after use. The cold runner mould system also requires more polymers and a longer cycle time.
The advantages of hot runner systems include faster cycle times and less waste. Hot runner moulds can also be used for larger components. However, they are more expensive than cold runner systems, as the cost of the moulding process is higher than the cost of a cold runner system. Besides, hot runner systems require more complex design, which results in higher upfront costs. The added complexity of the mold also results in higher maintenance and inspection needs.
Cost
The main difference between a hot runner mould and a cold runner mould is the method of molding. With a hot runner mould, the molten plastic is forced into the mould cavity while a cold runner mould is not heated. A hot runner mould makes it possible to produce larger parts. It also requires more power for its heating system. However, this system is more expensive.
The benefits of a hot runner mould are obvious. It improves cycle time, which translates into higher profits on high volume jobs. Even the smallest improvement can produce thousands of dollars in returns. This is a critical factor for most OEMs, which require continuous improvement plans to decrease cycle time and increase automated efficiencies. The cost savings can be significant, especially on multi-cavity high-volume production jobs.
Hot runner moulds have two types of gates. There are insulated runners for specialized polymers, and non-insulated ones for general plastics. They also require large runner channels and open passages in the mould plate. In addition, insulated runners eliminate the need for drops or manifolds. They also make it easier to change the color of the product.
Another difference between hot runner moulds and cold runner moulds is the way in which the molten plastic flows. A hot runner mold is a two-plate mold with a heated runner system within one half. A manifold system consists of two heated plates - one is externally heated and the other is internally heated. The external heating method is better for materials that need to be very hot, while the internal heating method offers better flow control.
Function
Hot runner moulds function by providing molten plastic through channels. These channels have a constant temperature and pressure so the plastic is melted at the correct temperature and consistency. These moulds are beneficial for manufacturing parts with narrow edges. They can be internally or externally heated. The heating system used in these machines affects the quality and consistency of the part, and it's important to select the right technology for your needs.
Before deciding on a hot runner mould, it's important to consider its design and function. The number of cavities is crucial because they must balance the activity of the plastic solution. Two cavities are usually more balanced than three. A mold with four cavities is balanced. Ideally, a mould with two cavities would be a good choice, but a mould with three cavities would require a complex system to keep everything in balance.
Hot runner moulds come in a variety of designs and styles. Valve-gated models are more aesthetic and often feature a mechanical valve. They are more expensive than general-purpose hot runner moulds, but are a good choice for highly aesthetic projects. A well-designed valve-gated hot runner mould is more effective than a cold one.
One of the biggest advantages of using a hot runner mould is that they offer faster cycle times than cold-runner molds. They also cut down on plastic waste. The hot runner method is better for producing multiple products at once.
