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provide both high speed and high force at different points in the cycle when required.
They are actuated either by hydraulic cylinders or ball screws driven by electric
motors. Toggle-clamp units include various designs like V toggle, 5 point toggles,
Side toggles and others.
Hydraulic clamps are used on higher-tonnage injection moulding machines. The
clamping force is focused in the center providing even force distribution. They are
more flexible than toggle clamps in terms of setting the tonnage at given positions
during the stroke and also provide better mould protection.
Hydro mechanical clamps: Used for very large tonnages machines. Utilise
hydraulic cylinders for mould close, mechanical locking and high pressure
hydraulics for clamping tonnage.
Considerations for choosing right Injection Moulding Machine:
An injection moulding machine will be referred to by its shot capacity in Grams (from
10 gms to few kilograms) which is the maximum grams of material that can be
injected in one shot and its clamping force rated by tonnage (varying from less than
5 tons to 6000 tons) which represents the amount of clamping force that the machine
can exert. An example would be a 90 Gms and 60-ton machine.
a) Shot weight capacity of machine should be more than total weight of articles
plus runner (Multi cavities)
b) Injection pressure should be sufficient
c) Clamping tonnage be higher than Injection pressure
d) Screw design should be suitable for material to be processed
e) Daylight opening be higher than mould size plus article height plus space
required for ejection of article
f) Distance between the tie rods should be more than mould size
Hydraulic vs. Electric vs. Hybrid Machines
The initial cost of a moulding machine is less than the cost of the energy used during
its lifetime. Energy efficient machines will save money in the long term and the initial
purchase cost should not be the dominant factor in the decision making process.
Hydraulic Machines
l Hydraulic drives normally require continuous operation with minimum start-ups
and shut downs making it difficult to improve energy savings.
l Machine control is vulnerable to hydraulic ?uid temperature.
l Hydraulic system ?ow and pressure requirements vary throughout the cycle and in
many cases excess ?uid that is not required by the process is throttled back to the
reservoir, wasting motor energy and producing additional thermal load on the
cooling system.
All-electric Injection Moulding Machines
l All-electric machines have lower power consumption at start up leading to lower
maximum demand requirements and have the potential to reduce the energy usage

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