[silence] [music] [siren wailing] This is a medical emergency. A 42-year-old manwith a massive gastrointestinal hemorrhage. His blood pressure has already droppeddangerously low and every second counts. Each year, millions of peopleenter our hospitals for some form of treatment. We have come to dependon the healthcare team that treats us, and we rely on the drugsand medical devices they use. A defective medical devicewhich finds its way into the hospital can have some important consequences. If the device fails,it may seriously impair the treatment of the patient. As a result, the morale and confidenceof the healthcare specialist and their patientscan be severely damaged, and hospitals and doctors can becomethe targets of massive malpractice suits. The confidence patients havein their doctors and hospitals must be actively protected byhealthcare practices that are as reliable and as safe as we can make them. This means educatingand licensing the hospital staff as well as maintaining high standardsin the production of the things they use. Many of the devices used in today's hospitalsare made of plastic. Often, they are disposable. These devices,like any other manufactured objects, are subject to defects. Some defects affectthe function of the device while others are merely cosmetic in nature. In either case,every attempt is made to eliminate the defective device as well asthe manufacturing conditions which gave rise to them. Defects in plastic medical devicescan occur at various stages of manufacture. For this reason,strict quality assurance procedures must be followedduring the entire process. These procedures begin at the timeraw materials or components enter the plant at the receiving dock. A unique code number is assignedto the incoming material, providing a means of tracing itthroughout all phases of manufacture. Another important way to ensure qualityis to keep untested materials physically isolated from the stock supplyused to fill work orders. This isolation is maintaineduntil initial physical tests show that the raw materials or componentsmeet the required specifications. In this case, rubber plunger tips suppliedas a component from another company are being sampled. First, they are giventhe required physical tests, which in this case measures theconcentricity or circularity of the part. If they successfully pass this test,the device history record is signed accordingly. If they don't pass the test,they may be either rejected and returned to the vendor,or the specifications will be reviewed by some established review panel to decidewhether or not the variation will make a difference in the product's usability. If they decide the variationwill not affect the product, a written exception will be includedin the device history record. If the initial physical test fordimensional, visual, and mechanical properties indicate acceptability,the materials are then tested biologically to determineif any soluble toxic substances or fever-producing agentsknown as pyrogens are present. The materials are measured and autoclavedwith a sterile saline solution. Then the extracted liquid is injectedinto test mice. The mice are weighedand logged before injection. They are then watched carefullyand their reactions logged. The record isnotated with these observations. Having passedthe crucial physical and biological tests, the components are labeled accordinglyand are transferred from the quarantined areainto the warehouse until they are used. The basic quality assurance proceduresfor handling plastic pellets or resins are pretty muchthe same as those four components. However, in the case of these raw materials,chemical tests may be carried out to determine the presenceof chemical adulteration and to verify adherenceto chemical specifications. This infrared spectrophotometer is usedto produce spectrographs of new materials for comparison with the spectrographsof control materials. Ultraviolet tests are also conductedin this laboratory. All these tests are conducted to checkthe medical usability of the materials before they are acceptedby the manufacturer of the devices. If acceptable,they are signed off by the lab technician. Production of a plastic devicefrom the pellets involves melting the plasticand forming it into the desired shape. The plastics usedare generally of two types. Thermoplastics are wax-like substanceswhich soften when heated and harden when they are cooled. The others are the thermosetswhich undergo chemical reactions when heated causing themto set up into a solid. The properties of plasticsare often tailored to meet particular needsthrough the addition of additives. Antioxidants retard oxidationand eventual degradation of the product. Anti-static agents minimizethe buildup of electrical charges during the production stages. Flame retardants minimize fire hazards. Lubricants improvethe processability and appearance of the plastic products. Plasticizers improvesoftness and processability. Stabilizers preventthe degradation of materials. Fillers may reduce costs, provide body,speed the cure or hardening, minimize shrinkage,improve thermal endurance, or provide special electrical,mechanical, and chemical properties. Catalysts induce chemical reaction. Colorants colorthe plastic such as dyes, which usually supply brilliant,transparent color, organic pigments, which are discrete solidparticles of dyes and inorganic pigments made of salts and oxides of metals. When pigments are added,tumblers like these are used for mixing the dry colorswith the pellets. There are a variety of means by whichplastics or their compounded mixtures can be formed into useful objects. The two typesof injection molding machines and the extrusion machines commonly usedall start out in the same way. Pellets are placed in the hopper,in this case by the vacuum tubes we see hanging from the hoppersinto the barrels of pellets From the hopper,they drop by gravity into the feed system. The feed mechanism in turndrops the pellets through the feed throatleading into the heating cylinder. In the plunger injection molding machine,a ram moves the pellets through the heating cylinderwhile the screw injection molding machine transfers the pellets with a screw. The additional heatgenerated by the shearing of the pellets in the screw machine,results in a quicker melt. Not only can the screw machinemold products faster, but a more homogeneous mix is obtained. The heat in this cylinderconverts the plastic from solid pellets to melt form. The electric heating bandsusually hidden under the cover provide the heat that melts the pellets. The molten plastic is called a melt,which looks like a long squirt of toothpaste. By the time the plastic has reachedthe forward end of the cylinder, it is ready to beinjected through this nozzle into the mold. Moving the softened materialrequires tremendous injection pressure. Injection plungers may exert pressureof more than 20,000 pounds per square inch on the melt to force it through the nozzleinto a channel called a sprue bushing. The mold is then clampedshut with either a toggle or a ram clamp. After the mold is closed,hot plastic is injected through the sprue bushing. From the sprue bushing,it flows through the sprue into the cavity via the runner system. When the parts have set rigidly enoughto withstand ejection without distortion, the mold is openedand the molded parts still attached to the sprue or to the runnersare pushed out of the mold by ejector pins. The entire process is a complicated one,and each step has to work properly for the productionof high-quality molded products. When things don't work properly,a number of defects can occur. Short shots are causedwhen not enough melt enters the cavities resulting in an incomplete molded part,such as we see in this plastic razor handle. Flashing, which is seenas extra material adhering to the part can come about from moldswhich are worn or improperly designed, or which are runat the wrong temperature or pressure. Embedded debris is generally the resultof dirt or some other foreign material getting mixed in with the plasticbefore molding. Surface blemishes may appearas silvery streaks or burn marks. These defects usually resultfrom improper melt temperature, too much release agent,improper compounding of additives, or the mold being too hotand actually burning the surface of the molded part. Sink marks are surface imperfectionslike a dimple or corrugation caused by excess heat or unevenlymixed stabilizers, which usually do not causefunctional problems. The example is seenin the neck of this funnel-shaped part. A warped part usually resultswhen a part is released from the molding cyclebefore it has cooled sufficiently to hold its shape. Cracking is a defect that can resultfrom a part sticking to the mold when the ejection pins in the moldare trying to push it out. Cracking can also occurif the plastic molding resins have not been compoundedor stored properly. Moisture can also be a problem,especially in certain plastics like polycarbonates,which must be dried before introduction to the hopper. Weak weld lines aredifficult to detect with the unaided eye. They occur when the pathof the plastic flow through a mold is divided and then rejoins itself atanother part of the mold forming a weld. A defect can occurif the plastic has cooled before it joins back together,or bubbles are captured in the melt where it joins. Detection of this type of defect is donewith a special polarized light source. Remember, improper control of heat, pressure, molds, and resins can lead to problemsin injection molding. Extrusion isanother plastic-forming process in which careful control of the variablesis necessary. The melt is forcedthrough an orifice called a dye into the shape of the desired product,which is usually tubing. In tubing, the dyewill be a ring-shaped opening for the melted polymer to exit,and the mandrel, which is the post making up the solid center of the dyewill be drilled out so that forced air can enter the tubingas it is extruded. In some cases, there is a mandrel wire,which takes the place of the solid mandrel in the dye. The polymer is extruded on this wirewhich is later removed leaving a hollow tube. The extrudate is still moltenas it enters the dye. It must be cooled and conveyedso that its shape is not distorted. For tubing such as catheters or airways,this is done by pumping air through the tubing,keeping it at a constant pressure as it moves throughthe water-filled cooling trough to the far endwhere it is pulled through these rollers. This hard-walled tubing is being cutto predetermined lengths. It is checked for concentricity, diameter, length, and consistency. At this air-driven take-up rollused for pliable tubing, there is a constant watch of the take-up speed. If the extrudate is pulledfaster or slower than indicated in the manufacturing procedures,the product may not meet specifications. Common defects in extruded tubinginclude surface blemishes or dye streaks, which are causedby incomplete melt or oil and grease on the dye and are consideredmostly cosmetic in nature. Another common defect is a variation inthe inner and outer diameters of the tubing. This defect is caused byimproper adjustment of the polar rollers or the rate of melt extrusion. Both extrusion and injection moldingare subject to certain common problems. These problems occur from contaminationof the plastic used to produce the melt. Contamination may occurwhen the runners and scrap from a plastic fabricating operationare ground for reuse. An operator may inadvertently mixtwo types of plastic scrap together. Such a mix mayonly cause cosmetic problems in the products produced from such a mix,but in some cases, physical properties of the mixmay be altered to such an extent that the function of the form devicewould be impaired. Contamination by the grinding machinescan also occur. This is best avoidedby using grinding machines, which are color-codedfor use with specific plastic types. There are also sources of contaminationnear the plastic forming machines themselves. Paint scale, oil, dust,insects, and other vermin can fall into the hopper or drumof pellets which are fed into the machine. This form of contaminationcan be controlled by using covered drums and hoppers and vacuum hosesfor the transfer of pellets to the machines. Common sense and good housekeepinghelps too. We have followed the flowof materials from receiving through the various fabricating processes. We have seen how defects can arisein a host of different ways. Now, one last processing step remainsbefore the plastic medical devices are ready for shipment from the plant,they must be sterilized. Like every other stepin making a high-quality product, the sterilization must be carried outunder exacting conditions. There are two major methodsof sterilization of plastic devices, radiation, and ethylene oxide. This sequence shows some phasesof a typical ethylene oxide sterilization. After the itemshave been packaged and labeled, small boxes containingthe biological indicators are attached. The biological indicators containliving microorganisms whose failure to grow in a suitable culture mediumafter sterilization indicates that sterilization has been complete. The pellets are then movedto a pre-conditioning room where humidity and temperatureare rigidly controlled for a specified periodin order to humidify the devices and packing material. This practice has been found to makethe subsequent sterilization more effective. From this pre-conditioning room,the pellets will go into large sterilization chambers. These pellets are rolled into the chamber,making sure that the indicators are systematically placedthroughout the chamber to ensure thorough effectivenessof the sterilization cycle. It is importantthat the manufacturer has qualified a cycle for thingslike the specific load configuration, product, and material. This automated system monitorsand documents the temperature, humidity, pressure, time,and the concentration of ethylene oxide gasused during the cycle. The circular graph is also usedas backup documentation of the sterilization cycle. Once the gas has been drawn offand scrubbed, usually through water filters,the chamber is opened and the pellets are aeratedand removed to a quarantined area. The biological indicators are removedfrom the pellets and taken to the sterilization laboratorywhere the indicators are tested. This facility is a clean room,which prevents contamination. The spore strips are removed hereand added to a culture broth. This broth is then incubated. After about 10 days,the broth culture is examined. If the sterilization has been effectiveunder the programmed conditions, the devices may then bespot checked for proper performance before being released for distribution. [siren wailing][music] We're going to need an IV [?] Now, have you hadany swelling at all up in here. No. Quality medical products areessential for quality medical care. [music]