Mold Tech

Cold Runner Molding

• 2021-08-13

Cold Runner Mold: Plastic injection molding, Simple Part Design, Limited Production Runs, Low Maintenance, Change Production Color, Low-Cost Mold

SINCERE TECH (plasticmold.net) provides plastic injection mold solutions to industries of all types and sizes.

Our state-of-the-art mold building facilities include high-speed CNC Milling and mirror EDM Machining for many types of complex specialty injection molds, including insert molds, gas-assist injection molding, 2K mold, multiple cavities mold and unscrewing molds. We can build molds from small to big (25 ton) for both hot runner mold systems and cold runner mold systems.

Cold Runner Molds: Efficient and Economical

Each system has it’s 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

Cold runner systems are best used:

• When the parts produced are of simple design,

• For limited production runs, or

• When a rapid change in production colour is needed

In a cold runner mold, the runner (excess material retained in the feed channels) is cooled and ejected with the part. Every cycle, apart, and a runner is produced.

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 Mold Systems: The advantages & disadvantages

There are many significant advantages to using a cold runner mold system:

• Simple, lower-cost mold design and construction

• Considerably less expensive than a hot runner system

• Moulds require less maintenance

• Easier to set up and operate

• Colour changes are easy – all plastic in the mould is ejected with each cycle

While it is a less expensive process that hot runner systems, there are a few disadvantages to cold runner systems that need to be considered, 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 characteristics and mechanical properties

Is your project ready for molding parts yet? Welcome to send us your requirement for quotation, we will provide you with the best solution base on your part design?

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