Page 67 - Plastics News October 2024
P. 67
TECHNOLOGY NEWS
Why Use Hot Runner Systems for Injection Mold-
ing?
thermoplastics and crosslinking plastics (elas-
tomers and thermosets). They allow for pre-
cise flow control, reducing waste, shorter cycle
times, and improved part quality.
A Brief History of Hot Runner Systems
The hot runner system’s development began
in the mid-20th century as industries sought to
improve the efficiency of injection molding pro-
cesses. In the 1960s and 1970s, the early ver-
ot runner systems involve a specially sions of hot runner systems emerged with the
designed manifold that maintains the company Mold-Masters. Husky Injection Molding
Htemperature of the plastic melt, allowing Systems was another significant player in the
continuous flow through the runners to the mold early development of hot runner systems. Husky
cavities without solidification. This technology, focused on improving hot runner technology to
which differs significantly from traditional cold meet the needs of industries requiring precision
runner systems, has transformed how plastic molding. In the 1980s, companies like Incoe Cor-
parts are manufactured, offering a range of ad- poration, also contributed by introducing new
vantages in various industries. designs that improved temperature control and
reliability.
What is a Hot Runner System?
Advantages
- The key economic advantage of hot run-
ner systems is the elimination of material waste.
Unlike cold runner systems, where plastic solidi-
fies in the runners and must be removed and
reprocessed, hot runners keep the material
molten, reducing scrap and the need to regrind
the runner. This is particularly beneficial when
using expensive or technical thermoplastics, as
A hot runner system consists of a heated mani- it minimizes raw material costs.
fold and nozzles in plastics injection molds that ♦ Additionally, hot runner systems allow for
keep the thermoplastic material in a molten state
shorter cycle times. Since there is no need to
throughout the molding process. This system is
wait for runners to cool, production is faster.
thermally isolated from the rest of the mold, en-
Furthermore, machines can be smaller, as
suring the plastic stays liquid until it reaches the
the absence of large, solid runners reduces
mold cavities. Hot runners are used for molding
the required shot volume and clamping forc-
October 2024 PLASTICS NEWS 67
