The plastic processing industry is one of the world's fastest
growing industries. The two major plastic processing methods are
injection moulding and extrusion. Approximately 40percent of all
plastics processed goes through injection moulding machines. The
advantages of injection moulding machines is that the moulded
parts can be produced economically in unlimited quantities with
little or no finishing operations.
As a result of the perpetual changes in the standard
of living and new products required by the market, the demands
placed on the processors are arising with each passing day. This
drives machinery manufacturer to develop innovative machinery
upgrading their machinery. This new generation injection-moulding
machines are expected to meet the processor's requirements because
of consistency, accuracy, repeatability, energy efficiency and
productivity, which will yield maximum returns.
Since 1872 when the first injection moulding
machine (Plunger type stuffing machines) was used, the machinery
has come a long way. The changing needs reflect the dynamic growth
of the industry. Apart from its own normal growth, the injection
moulding machinery technology has been influenced by the advancement
of other technologies like hydraulics, electronics, computers,
robotics and the demands of modern, engineering-grade moulding
When we consider the developments in injection
mouldings, two distinct areas are very evident. While one is the
machine, the other is the process, and though these are separate,
both are closely inter-related. Developments in process might
require changes/modifications in the machinery. Changes in machine
design might require different process settings when compared
with conventional methods.
Although the needs of the customers are satisfied,
there are a few needs which are difficult to satisfy, and machine
manufacturers striver hard to meet these needs.
Some of them are:
||Large mould area to accommodate different sizes and shapes
||Ease to setting and retrieving of process parameters.
||Consistency and repeatability of the process.
||Ease of mould loading.
||Ease of maintenance.
||Low cost of maintenance.
||Less power consumption.
||Lower cost of the machine.
It is very difficult to satisfy all these demands
in a single machine. Hence, we find different types of machines
being offered by machine manufacturers. Also, raw material suppliers
try to blend different materials to achieve the desired properties
if the end product. There are others who work on innovative ideas
and various processes and come out with new concepts of moulding.
Innovations in the injection moulding process
have products and special processes such as:
HIGH Technology Fully Closed Loop Machine
||Fully closed loop high tech injection moulding machines.
||Tiebarless injection moulding machines.
||Tiebarless injection moulding machines.
||All electric injection moulding machines.
||Co-injection moulding machines.
||Vertical insert injection moulding machines
||Two Platen injection moulding machines
||Structural foam / web injection moulding
||The gas pressure process
||The mono sandwich process
These machines are equipped with user-friendly,
modern processors for faster data processing. The machine and process
functions are software-driven. The proportionally acting hydraulic
systems control the closed loop velocity and pressure parameters.
This results in precise moulding and minimal part rejections.
The hydraulic systems incorporated in these machines
make use of integrated hydraulic components comprising multiple
variable volume pumps/servo pumps with extensive usage of cartridge
and proportional valves.
Finite element analysis of casting, special feed
screw designs and integrated hydraulics contribute to reducing energy
consumption through reduced weight control and improved performances.
The options available among injection units used to plasticize the
materials optimise the machine for specific requirements. These
machines are frequently used in electronics, automobile, furniture
and container industries.
Tiebarless Injection Moulding Machine
The practice of loading bigger/bulkier moulds into
smaller machines along with the necessity of frequent mould changes
to meet just in time (JIT) production needs led to the origin of
Tiebarless machines. Tiebarless designs have the advantage of providing
maximum platen mounting surface access to minimise the hassles of
contending with interference from strainrods during mould installation
and machine operation. Moulds with projection cores and unusual
dimensions can be easily loaded on to the platen mounting surfaces.
Innovative designs of linear deflection platens, compensating cylinders
and advanced sculptured cast frames control platen deflection during
tonnage. These machines are basically closed-loop machines used
in specific applications.
Tiebarless machines offer several advantages for
processors; moulds of all configurations are easier to load and
unload by crane from the top or by forklift from the side; easy
integration of peripherals and auxiliaries (including robots, parts
removal and secondary operation system); quick die change systems
and other automated systems. The machine operator also has easier
access for part removal.
The machine frame is often more rigid than conventional
machines thereby making the installation easier and simpler.
All Electric Injection Moulding Machine
As energy consumption awareness gained momentum,
innovative ideas for the reduction of energy usage resulted in the
development of all electric machines. These machines have the potential
of reducing energy consumption by 50 percent when compared with
conventional machines. The functions performed by pumps, directional
valves, cylinders and hydraulic motors, which are used to control
and move the machine's axis, are replaced with electrical servomotors,
ballscrews, and track-and-pinions. Since hydraulic oil is not used,
these machines can be termed more eco-friendly than hydraulic equipment.
Electric machines generate and release less heat into the environment
thus reducing the cost of air conditioning and heat build-up in
production buildings. Due to its combination with gear mechanisms,
servomotors make less noise and yet deliver highly precise and quick
operation. These machines are ideal wherever precise and strict
control of the finished part is required.
Co-injection Moulding Machine
Co-injection basically means that two or more plastics
are laminated together during the molding process. The plastics
could be the same material with different coloration or totally
different materials. When different plastics are used, they must
be compatible in order to provide proper adhesion and to meld at
approximately the same temperature. The term co-injection can either
denote different products such as sandwich moulding or two-color
Multi-colour/multi-component machines have opened
up new fields of applications, particularly in injection moulding
of rigid/soft composites. This process is already a well-established
technology. Numerous innovative and revolutionary solutions have
been developed in the last decade. Two melts are layered in a cylinder
and then successively injected into the cavity. The basic machine
can be combined with additional injection units of different sizes
to give even more versatility. The mould determines the parameters
required for injection units. These are also specific application
Vertical Insert Moulding Machine
This is a substitute for horizontal insert moulding
machines where time is lost during the cycle at the operator's station.
In vertical insert moulding machine with rotary/shuttle tables,
productivity increases through the use of a loading station while
another mould is being processed in the machine.
Vertical machines are used when processes utilise
insertion methods for medium lot sizes to very complex insertion
processes for which a special handling system is required. The use
of a rotary shuttle table with multiple moulds enables higher productivity
as the inserts are placed in the mould while the moulding of another
shot is taking place thus saving time. The Tiebarless frames facilitate
faster placing of inserts. These machines are used for specific
applications like encapsulating, metal insets etc.
Two Platen Injection Moulding Machine
These machines have some important benefits over
the conventional benefits over the conventional design. The inherent
design characteristics permit:
||Larger clamp strokes compared with conventional machine
||70-80 percent reductions in tonnage build time
||faster clamp movements
The typical applications of this machine is in
the household sector. The household moulds are generally deep cavity
moulds that require longer clamp strokes. The payback period of
these machines is less since productivity is generally higher.
Foam / Web moulding
This moulding concept has originated mainly for
the moulding of large parts with ribs.
Structural Foam (SF) injection moulded plastic
parts have a cellular foamed core surrounded by integral skins forming
an indivisible structure. In this process, a foaming agent (N2 or
CBA-Chemical Blowing Agent) is mixed with the polymer melt and injected
through multiple nozzles into the mould in smaller volumes than
required to mould a solid part. Both injection pressure and the
expanding gas/polymer mixture act to fill the mould.
The melt, after coming in contact with the cool
surface of the mould, forms and almost-solid skin. In the inner
core, the foaming gas expands to form a cellular structure.
Structural Foam, with is rigid skin and foam core,
is lighter, stronger, more durable and less expensive than other
conventionally processed plastics, metal wood or fiberglass.
This process has greatly extended the range of
product types and sizes that can be produced and offers significant
advantages that include:
||15-30 percent less part weight than solid plastics.
||Larger parts with high degree of rigidity.
||Low part stress and warpage.
||Complex parts without sink marks.
||Multiple parts can be moulded in a single cycle.
||Most thermoplastic resins can be moulded.
||Excellent part-to-part repeatability and dimensional stability.
||Low cavity pressure permits use of lower cost aluminum molds.
Structural Web (SW)
moulding is closely
related to SF moulding but uses injection of solid (non-foamed)
polymers to create parts with other desirable characteristics. Parts
moulded by the SW process are producers with a solid (non-cellular)
plastic skin and a hollow cross section. The polymer melt is injected
into the mould.
The inert gas is injected into the mould, packaging
the melt against the mould walls forming solid web sections with
hollow areas such as ribs. The exact configuration of these solid
and hollow sections depends on the product's design and the moulding
The process can produce parts with three main different
characteristics: products with a uniform wall thickness with a webbed
interior; products with thin, solid walls and thick, hollow ribs;
and thick-walled tubular products. Other beneficial characteristics
||The SW process eliminates the structural foam surface swirl
and permits smooth, solid-colour finishes in a cold mould.
||Reduced cycle time due to shorter cooling time and ability to
be painted immediately after removal. (SF requires up to 24 hours
to de-gas before paint can be applied.)
||Uniform surface replication - surface swirl and cavity pressure
gradients found with SF are eliminated.
||15-30 percent less part weight than solid plastics.
||High stiffness-to-weight ratio.
||Thicker parts and tubular shapes without sink marks - internal
gas pressure packs out the polymer against the mould wall during
||Transparent parts can be produced using clear polymers.
Airpress III - the perfect internal gas pressure process
When the Airpress III process is used, gas is directly
taken into the molten plastic mass via injection needles in the
mould. The gas then displaces, the excessive molten mass either
into a separate side capacity or back into the plasticizing cylinder
Gas moulding saves material, reduces the required
clamping force and avoids unwanted markers. Completely new fields
of application are conceivable wherever a plastic part includes
both thick and thin-walled areas.
The Mono Sandwich Process
The mono sandwich process allows for a simple production
of sandwich structures form reclaimed (re-grind) material with minimum
The two melts are simply layered in a standard
cylinder that are spatially separate and are then injected one after
another into the cavity.
This process can save 40-60 percent of new material
usage; has identical process control as used in conventional injection
moulding and provides for simple colour changes.
Milacron Inc. has been successful in anticipating
and developing new ideas for customers. Whether it is designing
new products, developing new sequencing options or incorporating
new feed screw profiles, Milacron's Plastics Technologies Group
is continually seeking customer satisfaction and delight.
Complementary to innovative developments is the global manufacturing
strategy. Global manufacturing helps Milacron to customise its technologies
to local needs. Milacron's involvement in all the key areas of plastics
processing and its worldwide coverage gives it a unique ability
to transfer technology rapidly from different parts of the world
and from different parts of the industry.