WEBVTT

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[silence]

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[music]

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[siren wailing]

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This is a medical emergency.

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A 42-year-old man
with a massive gastrointestinal hemorrhage.

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His blood pressure has already dropped
dangerously low and every second counts.

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Each year, millions of people
enter our hospitals

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for some form of treatment.

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We have come to depend
on the healthcare team that treats us,

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and we rely on the drugs
and medical devices they use.

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A defective medical device
which finds its way into the hospital

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can have some important consequences.

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If the device fails,
it may seriously impair

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the treatment of the patient.

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As a result, the morale and confidence
of the healthcare specialist

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and their patients
can be severely damaged,

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and hospitals and doctors can become
the targets of massive malpractice suits.

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The confidence patients have
in their doctors and hospitals

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must be actively protected by
healthcare practices that are as reliable

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and as safe as we can make them.

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This means  educating
and licensing the hospital staff

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as well as maintaining high standards
in the production of the things they use.

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Many of the devices used in today's hospitals
are made of plastic.

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Often, they are disposable.

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These devices,
like any other manufactured objects,

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are subject to defects.

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Some defects affect
the function of the device

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while others are merely cosmetic in nature.

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In either case,
every attempt is made to eliminate

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the defective device as well as
the manufacturing conditions

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which gave rise to them.

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Defects in plastic medical devices
can occur at various stages of manufacture.

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For this reason,
strict quality assurance procedures

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must be followed
during the entire process.

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These procedures begin at the time
raw materials or components

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enter the plant at the receiving dock.

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A unique code number is assigned
to the incoming material,

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providing a means of tracing it
throughout all phases of manufacture.

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Another important way to ensure quality
is to keep untested materials

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physically isolated from the stock supply
used to fill work orders.

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This isolation is maintained
until initial physical tests show

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that the raw materials or components
meet the required specifications.

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In this case, rubber plunger tips supplied
as a component from another company

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are being sampled.

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First, they are given
the required physical tests,

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which in this case measures the
concentricity or circularity of the part.

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If they successfully pass this test,
the device history record

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is signed accordingly.

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If they don't pass the test,
they may be either rejected

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and returned to the vendor,
or the specifications will be reviewed

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by some established review panel to decide
whether or not the variation will make

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a difference in the product's usability.

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If they decide the variation
will not affect the product,

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a written exception will be included
in the device history record.

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If the initial physical test for
dimensional, visual, and mechanical

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properties indicate acceptability,
the materials

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are then tested biologically to determine
if any soluble toxic substances

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or fever-producing agents
known as pyrogens are present.

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The materials are measured and autoclaved
with a sterile saline solution.

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Then the extracted liquid is injected
into test mice.

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The mice are weighed
and logged before injection.

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They are then watched carefully
and their reactions logged.

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The record is
notated with these observations.

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Having passed
the crucial physical and biological tests,

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the components are labeled accordingly
and are transferred

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from the quarantined area
into the warehouse until they are used.

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The basic quality assurance procedures
for handling plastic pellets or resins

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are pretty much
the same as those four components.

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However, in the case of these raw materials,
chemical tests may be carried out

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to determine the presence
of chemical adulteration

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and to verify adherence
to chemical specifications.

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This infrared spectrophotometer is used
to produce spectrographs of new materials

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for comparison with the spectrographs
of control materials.

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Ultraviolet tests are also conducted
in this laboratory.

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All these tests are conducted to check
the medical usability of the materials

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before they are accepted
by the manufacturer of the devices.

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If acceptable,
they are signed off by the lab technician.

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Production of a plastic device
from the pellets

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involves melting the plastic
and forming it into the desired shape.

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The plastics used
are generally of two types.

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Thermoplastics are wax-like substances
which soften when heated and harden

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when they are cooled.

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The others are the thermosets
which undergo chemical reactions

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when heated causing them
to set up into a solid.

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The properties of plastics
are often tailored

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to meet particular needs
through the addition of additives.

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Antioxidants retard oxidation
and eventual degradation of the product.

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Anti-static agents minimize
the buildup of electrical charges

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during the production stages.

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Flame retardants minimize fire hazards.

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Lubricants improve
the processability and appearance

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of the plastic products.

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Plasticizers  improve
softness and processability.

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Stabilizers prevent
the degradation of materials.

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Fillers may reduce costs, provide body,
speed the cure or hardening,

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minimize shrinkage,
improve thermal endurance,

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or provide special electrical,
mechanical, and chemical properties.

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Catalysts induce chemical reaction.

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Colorants  color
the plastic such as dyes,

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which usually supply brilliant,
transparent color, organic pigments,

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which are discrete solid
particles of dyes and inorganic pigments

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made of salts and oxides of metals.

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When pigments are added,
tumblers like these

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are used for mixing the dry colors
with the pellets.

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There are a variety of means by which
plastics or their compounded mixtures

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can be formed into useful objects.

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The two types
of injection molding machines

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and the extrusion machines commonly used
all start out in the same way.

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Pellets are placed in the hopper,
in this case by the vacuum tubes

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we see hanging from the hoppers
into the barrels of pellets

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From the hopper,
they drop by gravity into the feed system.

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The feed mechanism in turn
drops the pellets

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through the feed throat
leading into the heating cylinder.

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In the plunger injection molding machine,
a ram moves the pellets

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through the heating cylinder
while the screw injection molding machine

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transfers the pellets with a screw.

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The additional heat
generated by the shearing of the pellets

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in the screw machine,
results in a quicker melt.

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Not only can the  screw machine
mold products faster,

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but a more homogeneous mix is obtained.

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The heat in this cylinder
converts the plastic from solid pellets

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to melt form.

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The electric heating bands
usually hidden under the cover

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provide the heat that melts the pellets.

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The molten plastic is called a melt,
which looks like

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a long squirt of toothpaste.

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By the time the plastic has reached
the forward end of the cylinder,

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it is ready to be
injected through this nozzle into the mold.

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Moving the softened material
requires tremendous injection pressure.

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Injection plungers may exert pressure
of more than 20,000 pounds per square inch

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on the melt to force it through the nozzle
into a channel called a sprue bushing.

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The mold is then clamped
shut with either a toggle or a ram clamp.

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After the mold is closed,
hot plastic is injected

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through the sprue bushing.

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From the sprue bushing,
it flows through the sprue into the cavity

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via the runner system.

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When the parts have set rigidly enough
to withstand ejection without distortion,

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the mold is opened
and the molded parts still attached

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to the sprue or to the runners
are pushed out of the mold

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by ejector pins.

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The entire process is a complicated one,
and each step has

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to work properly for the production
of high-quality molded products.

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When things don't work properly,
a number of defects can occur.

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Short shots are caused
when not enough melt enters the cavities

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resulting in an incomplete molded part,
such as we see

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in this plastic razor handle.

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Flashing, which is seen
as extra material adhering to the part

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can come about from molds
which are worn or improperly designed,

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or which are run
at the wrong temperature or pressure.

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Embedded debris is generally the result
of dirt or some other foreign material

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getting mixed in with the plastic
before molding.

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Surface blemishes may appear
as silvery streaks or burn marks.

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These defects usually result
from improper melt temperature,

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too much release agent,
improper compounding of additives,

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or the mold being too hot
and actually burning

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the surface of the molded part.

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Sink marks are surface imperfections
like a dimple or corrugation

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caused by excess heat or unevenly
mixed stabilizers,

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which usually do not cause
functional problems.

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The example is seen
in the neck of this funnel-shaped part.

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A warped part usually results
when a part is released

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from the molding cycle
before it has cooled sufficiently

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to hold its shape.

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Cracking is a defect that can result
from a part sticking to the mold

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when the ejection pins in the mold
are trying to push it out.

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Cracking can also occur
if the plastic molding resins

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have not been compounded
or stored properly.

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Moisture can also be a problem,
especially in certain plastics

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like polycarbonates,
which must be dried

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before introduction to the hopper.

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Weak weld lines are
difficult to detect with the unaided eye.

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They occur when the path
of the plastic flow through a mold

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is divided and then rejoins itself at
another part of the mold forming a weld.

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A defect can occur
if the plastic has cooled

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before it joins back together,
or bubbles are captured

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in the melt where it joins.

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Detection of this type of defect is done
with a special polarized light source.

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Remember, improper control of heat,

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pressure, molds, and resins

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can lead  to problems
in injection molding.

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Extrusion is
another plastic-forming process

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in which careful control of the variables
is necessary.

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The melt is forced
through an orifice called a dye

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into the shape of the desired product,
which is usually tubing.

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In tubing, the dye
will be a ring-shaped opening

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for the melted polymer to exit,
and the mandrel, which is the post

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making up the solid center of the dye
will be drilled out

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so that forced air can enter the tubing
as it is extruded.

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In some cases, there is a mandrel wire,
which takes the place

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of the solid mandrel in the dye.

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The polymer is extruded on this wire
which is later removed

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leaving a hollow tube.

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The extrudate  is still molten
as it enters the dye.

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It must be cooled and conveyed
so that its shape is not distorted.

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For tubing such as catheters or airways,
this is done

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by pumping air through the tubing,
keeping it at a constant pressure

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as it moves through
the water-filled cooling trough

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to the far end
where it is pulled through these rollers.

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This hard-walled tubing is being cut
to predetermined lengths.

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It is checked for concentricity,

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diameter, length, and consistency.

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At this air-driven take-up roll
used for pliable tubing, there is

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a constant watch of the take-up speed.

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If the extrudate is  pulled
faster or slower than indicated

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in the manufacturing procedures,
the product may not meet specifications.

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Common defects in extruded tubing
include surface blemishes or dye streaks,

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which are caused
by incomplete melt or oil and grease

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on the dye and are considered
mostly cosmetic in nature.

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Another common defect is a variation in
the inner and outer

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diameters of the tubing.

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This defect is caused by
improper adjustment of the polar rollers

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or the rate of melt extrusion.

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Both extrusion and injection molding
are subject to certain common problems.

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These problems occur from contamination
of the plastic used to produce the melt.

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Contamination may occur
when the runners and scrap

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from a plastic fabricating operation
are ground for reuse.

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An operator may inadvertently mix
two types of plastic scrap together.

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Such a mix may
only cause cosmetic problems

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in the products produced from such a mix,
but in some cases,

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physical properties of the mix
may be altered to such an extent

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that the function of the form device
would be impaired.

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Contamination by the grinding machines
can also occur.

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This is  best avoided
by using grinding machines,

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which are color-coded
for use with specific plastic types.

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There are also sources of contamination
near the plastic forming machines themselves.

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Paint scale, oil, dust,
insects, and other vermin

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can fall into the hopper or drum
of pellets which are fed into the machine.

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This form of contamination
can be controlled by using covered drums

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and hoppers and vacuum hoses
for the transfer of pellets

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to the machines.

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Common sense and good housekeeping
helps too.

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We have followed the  flow
of materials from receiving

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through the various fabricating processes.

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We have seen how defects can arise
in a host of different ways.

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Now, one last processing step remains
before the plastic medical devices are

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ready for shipment from the plant,
they must be sterilized.

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Like every other step
in making a high-quality product,

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the sterilization must be carried out
under exacting conditions.

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There are two major methods
of sterilization of plastic devices,

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radiation, and ethylene oxide.

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This sequence shows some phases
of a typical ethylene oxide sterilization.

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After the items
have been packaged and labeled,

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small boxes containing
the biological indicators are attached.

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The biological indicators contain
living microorganisms whose failure

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to grow in a suitable culture medium
after sterilization indicates

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that sterilization has been complete.

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The pellets are then moved
to a pre-conditioning room

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where humidity and temperature
are rigidly controlled

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for a specified period
in order to humidify

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the devices and packing material.

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This practice has been found to make
the subsequent sterilization more effective.

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From this pre-conditioning room,
the pellets will go

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into large sterilization chambers.

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These pellets are rolled into the chamber,
making sure that the indicators

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are systematically placed
throughout the chamber to

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ensure thorough effectiveness
of the sterilization cycle.

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It is important
that the manufacturer has qualified

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a cycle for things
like the specific load configuration,

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product, and material.

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This automated system monitors
and documents the temperature,

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humidity, pressure, time,
and the concentration

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of ethylene oxide gas
used during the cycle.

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The circular graph is also used
as backup documentation

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of the sterilization cycle.

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Once the gas has been drawn off
and scrubbed,

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usually through water filters,
the chamber is opened

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and the pellets are aerated
and removed to a quarantined area.

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The biological indicators are removed
from the pellets

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and taken to the sterilization laboratory
where the indicators are tested.

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This facility is a clean room,
which prevents contamination.

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The spore strips are removed here
and added to a culture broth.

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This broth is then incubated.

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After about 10 days,
the broth culture is examined.

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If the sterilization has been effective
under the programmed conditions,

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the devices may then be
spot checked for proper performance

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before being released for distribution.

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[siren wailing]
[music]

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We're going to need an IV [?]

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Now, have you had
any swelling at all up in here.

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No.

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Quality medical products are
essential for quality medical care.

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[music]