By Ed Sullivan
When it comes to cases, trays and otherenclosures for medical devices and instruments, off-the-shelf products and thosemade from plastics may not be the best solution. Before ordering or designing your next medical case or system,it could pay major dividends to consider the questions that many experts askthemselves.
Providing unfailing protection for medical devices andequipment a function often performed by cases and other enclosures isnot to be taken for granted. While there is no shortage of medical casefabricators and other suppliers, selecting the right case whether carryingcase, instrument housing, sterilization container or other equipment enclosure can be vital to the successful care of patients.
Because medical cases are often subjected to the stresses ofharsh environments, such as chemical or autoclave sterilization, rugged use andatmospheric pressure, or carry devices that will benefit from special designfeatures, it behooves medical equipment suppliers and practitioners to be highlyselective when specifying case-application requirements.
Many people in the medical community feel that cases, traysand other equipment enclosures are more or less standard items, says DonSaak, business development director for Zero Manufacturing. The fact is that custom cases are not only practical, butare often critical for the protection, performance and efficient use of theequipment they contain.
What criteria should manufacturers and users of medicalequipment consider in the specification of cases for their products? While thatdepends on specific applications and the sensitivity of case contents, Saakidentifies five guidelines for specifying medical cases:
1. Choose appropriate case materials
Thematerials from which cases are fabricated have a direct bearing on protection ofthe case contents and durability of the case itself. Essentially, the choice of case materials is between metal andplastic. Metal cases are usually constructed of aluminum or aluminumalloys, and are typically either deep-drawn or welded. Plastics, ranging fromstandard compositions to space-age composites, are commonly vacuum formed,thermoformed, rotationally molded, blow molded or injection molded.
Metal cases are well known for their protective attributes, asthey offer high resistance to impact, can be sealed tightly, can withstandextreme temperatures and can be made fireproof.
If an aluminum case is subjected to high impact, the shockwill be absorbed by the entire case, explains Saak. Weve receivedletters from customers that told how their metal cases withstood the impact ofauto accidents and buildings collapsing. These cases may be dented, but they will take a beating or gothrough a fire and still protect the contents.
Plastic cases can also offer a good seal and, depending oncomposition, substantial resistance to impact. When plastic cases give, they tend to crush or crack. While metal cases are notcrush-proof or crack-proof, they will usually sustain a wider range of extremeheat or cold. Aluminum becomes harder in extreme cold, whereas plastic becomesbrittle. Aluminum dissipates heat, whereas plastics can deform or melt whensubjected to extreme heat, exposing contents to shock and perhaps functionaldamage.
Sometimes overlooked, case materials can affect the hygiene ofcontents that undergo sterilization. The materials that make up the plasticcase could out-gas during some chemical sterilization processes, Saak explains. While this is not a common problem, it isone that could cause contamination of items such as surgical instruments orimplants that are being sterilized. Also, many plastics are weakened duringautoclave sterilization, and may have a much shorter lifespan than their metalcounterparts. One-piece deep-drawn metal cases also offer the advantage ofhaving no seams or welds, so there are fewer hiding places for bacteriaand other foreign matter.
In some cases, applications require shielding from EMI/RF(electromagnetic interference/radio frequency interference), which will affectchoice of materials. We have a lot of experience in this with aerospace andmilitary cases, Saak says. We know that aluminum provides a naturalEMI/RFI shield, which will prevent stray emissions from affecting instrumentsinside or even outside one of our cases. Plastic must be coated orimpregnated with shielding materials.
Case inserts, such as plastic, metal and foam that aretypically used to hold and protect contents, should also be considered. Theabilities to absorb impact, withstand extreme temperatures and facilitate accesswill be important to many applications. Quality suppliers should be able tooffer a selection and assist with evaluating choices.
2. Consider short-term and future costs
While the choice of case materials has a definite impact oncost, the true economics depend primarily on the manufacturing process involved.To a certain extent, costs will depend on economies of scale. However, total cost is the inevitable concern, and it is herethat some customers are in for a surprise.
Aluminum cases fabricated from the deep-drawing process can befar more affordable than many people realize. Deep drawing is a process used toform metal without seams, rivets or welds. Essentially, a sheet of aluminum,pre-cut to the correct size, is formed around a die in the shape of the caserequired.
Using the deep-draw process, modifications can easily bemade according to customer specifications without creating new tooling. So, ifthe thickness or alloy of the metal needs to be changed to accommodate changesto the case contents, those alterations can be made without starting fromscratch, says Saak. Metal cases fabricated using the deep-draw processprovide an economy of scale, because once a die has been set up production goesvery quickly.
Conversely, metal cases that undergo the welding process donot enjoy economies of scale. These must be fabricated one at a time, regardlessof quantity. Also, welded cases must undergo grinding of the weld seams toprovide a smooth appearance. This process can create voids in the welds thatcould permit the inward or outward penetration of liquid or gas. Whiledeep-drawn aluminum cases can be anodized in the color of choice, welded metalcases must be painted after the grinding operation if the welds are to bedisguised.
Various types of plastic-formed cases all require costlytooling, but none so expensive as injection molding, which can be prohibitive tocustomers exploring a non-standard size. Because injection molding is ahigh-volume process, many case manufacturers offer thermoform- (with relativelyinexpensive mold costs, compared to injection molds), rotational- or blow-moldedcases that are tailored to a customers specifications. However, if these specifications change, new tooling ormodifications to the exiting tooling will be required. Injection- andblow-molding processes permit latches and hinges to be molded into the case,reducing labor costs because only the hinge pins and seals need be installed. But if a latch breaks, the case cannot be repaired.
3. Look for a turnkey solution
Relative to cost, material selection, quality and many otherconsiderations, it is often wise to choose a supplier that offers turnkeyproducts.
There are many quasi-manufacturers who, because of theirsize or limited capacity, job-out various case making operations, Saakexplains. They might make the basic case at their shop, but job-outother tasks such as painting, attaching hardware, or producing foam inserts.There are responsibility and quality issues with this approach, and it createsextra work that will likely affect costs.
Saak explains that when shops outsource secondary operationsthey give up a certain amount of quality control while creating additionalpaperwork. Multiple vendors must be selected; multiple purchase orders issuedand invoices paid, and subsequent inspections must be made. If cases are damagedwhile undergoing operations outside the manufacturers plant, the acceptablequantity delivered will be affected.
This is a difficult position to be in, Saak says. With aturnkey supplier you can be sure that when you order 24 cases youll get 24.But if the cases are sent out for secondary work, you really cant be suretheyll all come back and pass inspection
There are other important reasons for single-sourcing amedical case supplier. Flexibility and experience can be crucial factors. Thereare many types of medical cases needed, from rack-mounted storage systems totrays and small enclosures. A highly experienced and flexible supplier canpartner with customers and give them the benefit of cross-pollinating application experience.
Ultimately, the ideal single-source supplier of cases will beable to provide multiple solutions in both metal and plastic cases. This notonly provides the sophistication to offer a choice, but also ensures that thesupplier will not be motivated by conflict of interest.
Compliance with industry standards may also be important inthe choice of a supplier. For example, manufacturers who are members of theNational Institute of Packaging Handling & Logistics Engineers (NIPHLE) orthe Armed Forces Communications & Electronics Association (AFCEA) may applythe highest operational and quality standards including ethics, guidelinesand equipment that adheres to very high military specifications to all theirproducts. Suppliers who are ISO- (International Standards Organization)certified must comply with manufacturing, documentation and transactionalprocedures that are often beneficial to product quality as well as customersrelationships.
4. Appearance actually matters
Appearance can be important in any industry, and the medicalfield is certainly no exception. Physicians, paramedics, hospitals and otherorganizations have different preferences when it comes to medical cases.Specific colors, logos, warnings and other body graphics may be required on thecase exterior, and specific case handles, feet and other attachments may requireaesthetic as well as functional consideration.
For those who specify drawn aluminum cases, the opportunitiesto create a stylish, custom look are many. For example, manufacturers ofpharmaceuticals may have their sales team carry demo cases that have beenanodized or painted in the companys colors. Their logo can be affixed with alabel, silk-screened or embossed on the side to readily identify who thesalesman represents. The seamless construction and high-tech look of these casescan make a powerful statement.
Typical applications for aluminum medical cases includeoptical and medical scopes, housings for instruments, defibrillators,aspirators, wound and IV care, blood analyzers, and surgical instrument cases.
Form and functionality can also be gracefully combined inplastic cases, which can be produced in special colors, with silk-screened orembossed graphics and a wide choice of handles and attaching hardware.
5. Weigh after-sale support needs
You may need a supplier who offers engineering support thatcontinues after the initial sale, Saak advises. Medical instruments andother devices change over time, as do kits and systems that are transported orstored in cases. So it is often beneficial to have a supplier who canreconfigure or even re-engineer your case without having to go back to squareone.
In some instances, customers may have problems due to productchanges that affect case performance. If a customer is experiencing recurringperformance problems with their medical case, its important that the supplierhave troubleshooting capabilities and the test facilities necessary to correctthe problem, Saak says. Its also important to have a relationship witha supplier who has the ability to meet changing FDA requirements and has thenecessary awareness of changing materials and compliances that will keep you upto date with industry standards.
Other important after-sale supports include case repair,hardware replacement, redesign or replacement of foam and other case inserts.
Ed Sullivan is a technical writer based in Hermosa Beach,Calif.