As most of modern devices are either getting smaller or requiring tinier components, the demand for plastic micro molding continues growing. Thus it is easy to guess - this presentation is going to dive us in peculiarities of micro injection molding technology. This was SlideShare adapted from our companies blog post: https://www.micromolds.eu/micromolding-in-depth-insights

1. Micromolding-inDepth
Insights
2020-01-26

2. TableofContents
Micro molding in medicine
Micro molding in electronics
Micro molding in automotive
What is plastic micro molding and its features?
Could micro injection molding replace conventional injection
molding?
How extensively µIM is used across industries?
How far could thin wall molding go?
What materials are the best for micromolding?
What are the future of micro injection molding technology?
Challenges in micromolding: micro assembly and packaging.

3. As most of modern devices are either getting smaller or requiring tinier components, the demand for plastic
micro molding continues growing. Thus it is easy to guess - this article is going to dive us in peculiarities of
micro injection molding technology – analysis of its features as well as materials used with it, packaging
challenges, design for manufacturability and the future horizons of micro molding.
Whatisplasticmicro
moldingandwhat
areitsfeatures?
Micro molding is a highly specialized process where micro-structured steel or aluminum molds are CNC and
EDM machined within micron or even submicron scale tolerances. Usually, when molded part weighs fraction of
a gram or its micro features range from 50µm to 5µm or less in largest side micro molding world reveals.The
main difference between micro molding and traditional molding technologies is the shot size and the precision
of injection machines. Micromolding machines can inject fraction of a gram with high precision as they have
higher resolution feed options which results in even pressure distribution inside the cavity. In micro injection
molding smaller molds are used too. Micro molds are machined with smaller cores and cavities and micro
features inside with precision CNC and EDM tools. In conventional molding things like packaging and quality
management can be viewed as secondary operations, however, micro molding process demands extensive
attention to packaging and quality control details, since molded parts are very small.

4. COULD MICRO INJECTION MOLDING REPLACE
CONVENTIONAL INJECTION MOLDING?
The answer is: YES. Micromolding sometimes can be ‘small’ but
not ‘micro’. In a vast variety of demanded plastic parts many of
them might be small enough to fit in micro mold projected area (e.
g. of ⌀~100mm circle perimeter) and not to exceed micro injection
shot volume (e. g. ~15-30cm3). Moreover, innovating companies
often seek for resilience and low-risk market entrance with pilot
launches with manufacturing volumes up to 100k pcs.

5. In these conditions there will be no better way than
using micromolding technology. A significant cost and
time reduction is possible compared to traditional
injection molding. It is possible to save up to 3-4x on
tooling costs and enter the market with finished
products in less than 3 weeks:
Low machine operating expenses, since there are
smaller machines used and lower clamping force is
exerted.
Waste minimization due to shorter runner systems
required. Since there are shorter runners needed to
fill in the cavities, there is a dramatic difference in
the volumes of cut and disposed runners, in
comparison to traditional injection molding.
Easy and flexible modification is possible due to the
fast and low cost mold machining.
Fewer mold cavities and aluminum used results in
faster and cheaper machining.

6. How extensively µIM is
used across industries?

7. MedicalandHealthcare
industries
Undoubtedly, the field of medicine as such requires an extreme accuracy in
most of the processes. Therefore, in many cases, the medical instruments
used must be small and highly sophisticated. Thus, micro molding is
widely used in medical devices manufacturing: drug delivery devices,
catheters, diagnostic systems, optical and hearing aid components, etc.
and is highly applicable for the instruments of minimally invasive
surgeries. For instance, neurosurgeries, aortic treatments, etc.It might
also be stressed that new types of microfluidic systems are becoming more
and more popular and widely applicable in various medical performances
(including Point-Of-Care applications). No surprise that medical
industries capture approximately a quarter of the global market share of
micro injection molding, according to 'Mordor Intelligence'

8. Automotiveindustries
Micro injection molding is quite widely used for manufacturing
automobiles’ components which frequently require light and small
components. Micro molding is used for under the hood parts (e.g.,
engine or breaks) of a car and for various other components relevant
for automotive industry, such as different clips, washers, door
locking mechanism parts, various buttons, switches and even for
micro plastic gear manufacturing. Since the whole automotive
industry is huge and requires many micro parts, no wonder why this
sector captures the most value (almost a third) from micro molding
(ibid).

9. Since modern electronic devices are getting smaller, there is a growing
need of high precision and complexity for this sector, too. Micro molding
benefits may be exploited in various electronics components
manufacturing. Micro-optics might be one of some examples (e.g.,
manufacturing laser-based devices, smart phones, lenses, prisms, etc.). As
well as microelectronic components: such as connectors, switches, plugs,
computer chips, etc. for computers, communication technologies, musical
devices and other microelectronics fields.Microelectromechanical systems
(MEMS) often require micro molding manufacturing, too. Since the
industry itself is in the growth stage, the demand for innovative micro
molding in manufacturing processes is increasing as well. For instance,
BioMEMS (Biomedical Micro-Electro-Mechanical Systems) are now being
widely investigated and potential Next Generation Sequencing (NGS) and
Point-of-Care diagnosing opportunities already applied which significantly
increases the demand for MEMS.The rapid development of modern
technologies leads to a dramatic growth in electronic industries and this
might be represented by the fact that electronic sector holds a little bit
more than a fifth of the global micro injection molding market share (ibid).
Electronicindustries

10. Howfarcouldthinwall
moldinggo?
ABS: 170/1
SAN: 120/1
PA: 150/1
PC: 100/1
HDPE: 225/1
LDPE: 275/1
PP: 250/1
PMMA: 130/1
POM: 150/1
PS: 200/1
Firstly, to discuss thin wall molding, the concept itself should be
clarified. Thin wall molding can be classified according the ratio of flow
length and wall thickness: L/t ratio. As different plastics have different
flow rates their maximums of the ratios will vary accordingly. Here are
the maximums of L/t ratios for 10 of the most widely used
thermoplastics:

11. Timely cycles, since thicker walls cool longer than the thin ones;
Too thin a wall might be too fragile and in addition, may cause
flow rate (the speed of flowing into cavities) errors. The latter
issue may result in voids if material does not fill all the features
before it cools;
Uneven walls cool and solidify differently, and this factor is
usually a reason why there might exist any unintended
permanent warps or sink marks on the molded part surfaces.
The quality of the molded part is highly dependent on correct design
of wall thickness. By highlighting ‘correct’ design it is meant to
choose compatible ranges of wall thickness for various
thermoplastics and to maintain similar aspect ratios throughout
whole part design process. Failing in this design for
manufacturability stage may lead to:

12. Since thin wall molding is primarily dependent on resins choice it is
good to refer on some experimental data. The table below
demonstrates the most widely used plastic materials with minimum
and maximum wall ranges for injection molding:
MATERIAL APPLICATION WALL THICKNESS
ABS - Mostly for plumbing or automotive industry - 0.143 mm – 3.556
mm
ACETAL - May replace some parts that used to be metallic - 0.762 mm
– 3.048 mm
ACRYLIC - Mostly replacing glass for beauty, fashion or even art
industries - 0.635 mm – 12.70 mm
NYLON (POLYAMIDE) - Various industrial and mechanical uses -
0.762 mm – 2.921 mm
POLYCARBONATE - Used in a wide range of markets - 1.016 mm –
3.810 mm
POLYESTER - Used in a wide range of markets - 0.635 mm – 3.175 mm
POLYETHYLENE - Perfect for disposable and recyclable products -
0.762 mm – 5.080 mm
POLYPROPYLENE - Various application possibilities, however,
frequently used in food industries, since it does not leach chemicals -
0.635 mm – 3.810 mm
POLYSTYRENE - Applicable in various industries - 0.889 mm – 3.810
mm
POLYURETHANE - Applicable in various industries - 2.032 mm – 19.05
mm
When resin material is chosen some other
requirements must be met for thin wall molding.
Since thin walls cool faster than thick walls, thin wall
molding requires the higher speed of cavity-filling (fill
time indicates the time required for the material to
flow into cavities). For instance, a 25% drop in wall
thickness needs a 50% drop in time of injection. Thin
wall manufacturing requires specialized machinery to
process higher speed and pressure. Even though
modern technologies allow standard machinery to fill
thinner and thinner parts, the tiniest parts require
more advanced machines for both, injection and
clamping, cycles.

13. It should also be highlighted that with the rapid technological
development and the growth of demand, there is an increase
in the use of bioabsorbable polymers in micro injection
molding. Bioabsorbable materials are widely applicable in
modern healthcare. Since these polymers may be absorbed
and dissolved by a human organism, the use of them lowers
the number of surgical interventions needed for specific
(most usually, orthopedic) treatments. Along with the
innovations, grows the demand for the applications of these
materials and this is where modern micro molding
technologies are used, too.
There is a high variety of materials that may be used in micro molding. However, there definitely
are some crucial constraints not to forget while choosing materials, such as: mechanical properties
(what are expected operating environment, high-heat situations, hygroscopic properties?)
compatibility (contact with other biological bodies, cosmetic appearance and price. Some of the
most popular materials for micro molding are shown in the table below.
WHAT MATERIALS ARE THE BEST FOR MICRO INJECTION
MOLDING?
MATERIAL APPLICATION
LCP (liquid crystal polymer) - High temperature tolerance; Great chemical and
weathering resistance; Stress cracking resistance)
PMMA (polymethylmethacrylate) - Great transparency; Ultraviolet radiation
resistance; Scratching resistance
COCs (cyclic olefin copolymers) - Great flowability; Heat, chemical, moisture
resistance; High clarity
PEEK (polyether ether ketone) - High chemical resistance; Great heat and pressure
tolerance; Stress-crack resistance and high strength
PLA (polylactic acid) - Biodegradability; High transparency; Great compatibility
PGA (polyglycolic acid) - Biodegradability; High strength; High abrasion and solvent
resistanc
LSR (liquid silicone rubber) - Electrical resistance; Chemical resistance; High
thermal stability and weatherability
Polyethylene - Great chemical resistance; High strength and surface hardness;
Abrasion resistance
Polypropylene - Great chemical and heat resistance; High flexural strength and
fatigue resistance; Electrical insulation
Polycarbonate - High transparency and high dimensional stability; Rigidity and
toughness; Moisture and chemical resistance

14. Whatisthefutureofmicroinjection
moldingtechnology?
Plastic injection molding is used in a majority of industries
across the world. Old manufacturing technologies are
replaced or upgraded by the new ones and the industry 4.0 is
catalysing all of it. Micromolding is not an exception and
thus must to remain innovative and to adapt to the new
market demands where components are getting smaller and
smaller. For this reason, new technologies are being
developed to improve micromolding:

15. Significant progress in substance control. The most visible progress is that
companies are trying to research the recycling of polymers and this research is
associated with environmental considerations;
New innovations depend on customer needs, it’s because sometimes they
require something that companies cannot create. This demand puts a lot of
pressure on manufacturer and for this reason new technologies are being
produced, for example, extreme thin wall molding, 2-shot micro molding and
automatic insert molding, are direct results of the market demands;
New micro molding sensors have been specially adapted to the mould,
previously the sensors were too large. New sensors are very compact, easily
installed, save significant space in the mold and are designed to monitor
temperature, pressure, warpage, shrinkage and others processes;
Runnerless or reduced flow path molds are designed to save expensive
materials and it will allow machine manufacturers redesign to achieve high
accuracy and ultra-small shot sizes. New advances include non-standard
material designs, improved reduced wall thickness filling options, stress
removal and mold annealing, improved mold and material monitoring
systems.
One of the latest innovations are CNC machine tools and micro sinker EDM.
These devices allow molders to inject shots of less than 1 gram with minimal
damage and very high shot accuracy. Advances in shrinking pressure and
temperature sensors hardware allow for better control and real-time
monitoring of the process.

16. CHALLENGES IN MICROMOLDING: MICRO
ASSEMBLY AND PACKAGING

17. Packaging and micro assembly cost is a big portion of the
overall cost of any micro-scaled product and it is an
important part of the development of a microscopic
product. Efficient packaging and assembly is a key for
success products in the marketplace.
The main reason for the cost of packaging and assembly
of micro-scaled products is the lack of automation in
both of these operations. Most micro-assembly requires
the use of operators to manually select and insert small
parts using powerful microscopes and micro-tweezers.
Manual assembly is extremely expensive and takes a lot
of time. Operators who are assembling such a micro-
scaled parts, suffer from the tension on the eye strain,
have strict requirements for the final product, but must
also achieve the required reliability of its quality.

18. Visual system with high-performance stereo microscope, long-
lasting distance and high resolution camera and monitor. The latter
is used to provide instructions and feedback during and after
assembly;
Micro-positioner with a resolution of 40 nm for workpiece control,
microgripper and position management;
Real-time computer vision for controlling servo mechanisms and
motors and assemble parts within micron level accuracy;
High resolution, high precision transfer tool for handling parts and
components.
To make micro-assembly easier and much quicker, several specific tools
and equipment must be available for this process:
If you are making a micro-scaled product and you don’t want to
assemble it under the microscope, there are some methods that helps
to combine different parts together at the design stage:

19. Two-shot micro molding. This method let to inject two
different materials into a mold at two different or in the
same place.
Ultrasonic welding. It is affective when joining
thermoplastics and compatible metals;
Laser welding. This is usually used for joining micro
components, when 3D geometry cannot be combined
through overmolding. Laser welding also can be used to
clean and disassemble materials such as wires quickly and
without breaking them;
Staking. This is a very cheap way for assemble polymer and
metal by using folding of one material into another;
Solvent bonding is known as cheaper and faster way for
joining micro-scaled components. Typically, it is
combining different materials and solvents, using micro
and nano pipettes. Those two components, must be bonded
together, especially if this combination will be used as an
implant.
Packaging of micro components is as important as micro-assembly.
Each micro-scaled part must be delivered to the customer safely.
When sending small, sharp or friction and vibration sensitive parts,
packaging can be a very difficult process, it has to be well thought
out. Micro-packaging requires components to be individually
packed in special packages or pallets. When dealing with clean
room requirements or ISO 13485 quality assurance it is also very
important to ensure an appropriate temperature of machines and
airflow around it. Usually it is a must to have fans generating
filtered airstreams to prevent air contamination and dust attaching
to the molded parts until they are packed.

20. THANKYOU!
Contact us:
info@micromolds.eu
+370 634 44885
Lentvario str. 16, Vilnius, Lithuania, LT-02300
Company Code: 303176864
Micromolds
Micromolds
Micromolds
Social