Simple Mold Design, Inexpensive Alternative to Hot Runner System, Low Maintenance, Easy Set-Up / Operation, Easy Color Changes
GC MOLD provides plastic injection molding solutions to industries of all types and sizes. Our production capacity provides manufacturing facilities for many types of specialty injection molds, including insert molds and unscrewing molds. We can manufacture plastic parts from both hot runner molds and cold runner molds.
Each system has its advantages and disadvantages. Choosing the correct system depends on the requirements of the part to be produced. A few of the considerations include:
- Part complexity
- Color requirements
- Physical characteristics of the material
- Type of material – virgin or “regrind”
- Color changes during the production run
There are two major types of cold runner molds:
- A two plate cold runner mold is the easiest and least expensive type of mold to produce. Two plate molds have a single parting plane, and the mold splits into two halves at the plane. Because the runner system must be in line with the parting plane, the part can only be gated on its perimeter.
- A three-plate cold runner mold differs from a two plate in that it has two parting planes, and the mold splits into three sections every time the part is ejected. This feature provides greater flexibility of design, allowing gating to be placed in the most efficient locations. Since the mold has two parting planes, the runner system can be located on one, and the part on the other, for easier separation.
Cold Runner Molding: The Pros and Cons
In a cold runner mold, the runner (excess material retained in the feed channels) is cooled and ejected with the part. Every cycle, a part, and a runner are produced.
While it is a less expensive process that hot runner systems, there are a few disadvantages to cold runner systems, including:
- Waste plastic generated
- Runner material must be either disposed of or
reground and reprocessed - Additional steps in the manufacturing process
- Regrind will increase variations in the injection
molding process - Regrinding could decrease the plastic’s strength
and mechanical properties
Despite these disadvantages, there are many significant advantages to using a cold runner mold:
- Simple mold design
- Considerably less expensive than a hot runner system
- Molds require less maintenance
- Less skill required to set up and operate
- Color changes are easy – all plastic in the mold is ejected with each cycle
