This document discusses rapid heating and cooling mold (RHCM) technology for injection molding. RHCM aims to improve plastic part surface quality without increasing cycle times. It works by heating the mold cavity surface before injection to a high temperature using various heating methods. The mold is then rapidly cooled after filling to solidify the plastic melt and eject the part. RHCM offers benefits like better surface quality and reduced defects, but has disadvantages such as high energy consumption and maintenance costs.

1. Guided By :
Mr. JINESH P
Lecturer
GIT, Kangazha
Presented By :
Mr. JERIN JOSEPH
17110316
TD S5
GIT, Kangazha

2. CONTENTS
o INTRODUCTION
o INJECTION MOULDING MACHINE
o HISTORY
o PURPOSE OF RHCM
o CYCLE TIME IN INJECTION MOULDING
o RAPID HEATING AND COOLING MOLD TECHNOLOGY
o TYPES OF MOULD HEATING METHODS
o COOLING METHODS IN RHCM
o ADVANTAGES
o DISADVANTAGES
o CONCLUSION
o REFERENCE

3. INTRODUCTION
 Injection molding is the most important industrial processes
in the production of plastic parts.
 The main phases in an injection molding process are filling,
cooling and ejection.
 The cost-efficiency of the process is dependent on the time
spent in the molding cycle.
 Reducing the cooling time spent on cooling the part before it
is ejected increase the production rate, hence reduce costs.

4. INJECTION MOULDING MACHINE
Injection molding process :
Feeding Plastic granules Hopper
Heating Coil
Compressing Barrel Screw
Heating Coil
Metering Melting Injection

5. HISTORY
 American inventor John Wesley Hyatt, together with his brother
Isaiah, patented the first injection moulding machine in 1872.
 it worked like a large hypodermic needle, using a plunger to
inject plastic through a heated cylinder into a mould.
 The German chemists Arthur Eichengrün developed the first
injection moulding press in 1919.
 In 1946, American inventor James Watson Hendry built the first
screw injection machine, which allowed much more precise
control over the speed of injection and the quality of articles
produced.

6. PURPOSE OF RHCM
 In plastic injection molding the cooling stage is most important
because it greatly affects the productivity, cost and the quality of
the product.
 the use of low temperature cooling water and rapid passage
of cooling water through the cooling system helps to reduce
the cycle time in injection moulding.
 An efficient cooling system design of the cooling channels
minimizes undesired defects such as sink marks, thermal
residual stress, differential shrinkage, and part warpage .

7. CYCLE TIME IN INJECTION MOULDING

8. RAPID HEATING AND COOLING MOLD
TECHNOLOGY
 Rapid heating and cooling mold (RHCM) is a new injection
molding technology, which improves surface quality of the plastic
parts without increasing the cycle time of process.
 In the RHCM, the mold cavity surface is heated by various types
of heating methods to a high mold temperature before melt
injection.
 The high temperature during filling and packing stages, and finally
the mold is cooled down rapidly to solidify the plastic melt in
cavity for ejecting the part .

10. TYPES OF MOLD HEATING METHODS
 Exterior Heating
 The heat source or heating
device installed outside mold
base.
 Infrared heating, flame
heating, and induction
heating, surface resistance
heating.
 Internal heating
 In inner mold heating, the heat
source is located inside the
mold.
 Hot medium like air, steam,
oil and electric heating.
 steam heating method and
electric heating method;
have been widely used in
RHCM.
The rapid mold heating methods include resistance heating, high-
frequency proximity heating, gas-assisted heating, induction
heating, infrared heating, and convection heating using hot fluids
such as oil, water and steam .

12. COOLING METHODS IN RHCM
 In rapid mold cooling methods, the conventional method by
circulating water in mold cooling channels.
 To shorten molding cycle, mold temperature need to be kept
much lower than the frozen temperature of the polymer melt.
 Ideally, the mold wall temperature should be equal to the melt
temperature during filling, and equal with the room temperature
on the cooling stage.

13.  By reducing the mold wall temperature during the cooling stage,
the part will more quickly solidify and significantly increase the
productivity.
 Formation of warpage and sink marks.

14. COOLING PROCESS

17. ADVANTAGE
 Due to the high mold temperature during filling, the molten plastic has
good flow ability and can be easily transformed into the geometry of the
cavity. The surface of injected plastic parts has extra-high gloss if the
surface of mold cavity is glossy.
 The mold surface temperature is very crucial in the plastic injection
molding.
 If the mold surface temperature is high then surface quality of the part
will be better, but the cooling time will increase and thus the cycle time
will increase.
 If the mold surface temperature is reduced the cooling time will also
reduce.
 Weld marks and other defects on the part can be reduced

18. DISADVANTAGE
 High energy consumption.
 Maintenance cost is high.
 Shortage of machine and shops.
 Large floor space necessary.

19. CONCLUSION
 The injection molding process including rapid heating and cooling
methods, conforming cooling channels, hot runner mold. There
are various methods of mold heating and each method has its
own advantages and disadvantages.In particular, there are three
primary areas of cost savings: reduction in wall thickness and
reduction in cycle time. One drawback of rapidly cooling the mold
surface is the large thermal stresses induced in the surrounding
material.

20. REFERENCE
1. Mihăilă, S., Chira, D., Horge, I., Muşet, V., Study
regarding the determination of the cooling time in to the
product plan shape from plastical materials processing by
injection. Annals of the Oradea University Fascicle of
Management of Technological Engineering, Vol. VI (XVI),
2007.
2. Saifullah, A.,B., M., Masood, S., H., Cycle Time
Reduction in Injection Molding with Conformal Cooling
Channels, Conference Proceedings of the International
Conference on Mechanical Engineering 2007 pp. 29- 31,
2007.
3. Autodesk Inventor 2010. Professional. Plastic Part
Design.