The short answer
For housings that are wiped with hospital disinfectants, use a healthcare grade chosen for chemical resistance: healthcare PC/ABS, a PC/PBT or PC/PET blend, or copolyester. Avoid standard PC and PC/ABS on parts that are wiped often, because they are prone to stress cracking. Use PSU, PPSU or PEI where the part must be steam sterilized or needs the highest heat and chemical resistance. Check the flame rating for powered equipment, and biocompatibility only where the housing contacts the patient.
This page covers housings and enclosures for monitors, handheld devices, diagnostic and lab equipment, pump covers and carts. ResinBridge supplies resins for non-implant applications only. We do not supply materials for implantable or in-body devices. See FDA and medical compliant materials.
Disinfectants are the main design load
Hospital infection control means housings are wiped often, sometimes many times a day, with strong products and long wet contact times. The common chemistries are:
- Quaternary ammonium compounds, often blended with alcohol
- Alcohols (isopropyl and ethyl)
- Sodium hypochlorite (bleach)
- Hydrogen peroxide, including accelerated (stabilized) formulations
The failure is usually environmental stress cracking: the disinfectant soaks into areas under stress, such as screw bosses, snap fits, inserts and gates, and cracks appear weeks or months later. Standard PC and PC/ABS are especially vulnerable. On some resins, bleach and peroxide are more likely to cause discoloration or loss of gloss than cracking.
Resin producers now offer healthcare grades of PC/ABS, PC copolymers, PC/polyester blends and copolyester formulated and tested against lists of common hospital disinfectants. Their published results are a useful screen, but test conditions differ between producers, so test your own molded parts.
Resins for medical device housings
| Resin | Disinfectant resistance | Impact | Sterilization options | Notes |
|---|---|---|---|---|
| Polycarbonate (standard) | Poor to fair; stress-cracks with many disinfectants | Very high | EtO; gamma with stabilized, color-corrected grades; limited steam cycles | Clear and tough; fine for parts that are rarely wiped |
| PC/ABS (standard) | Poor to fair | High | EtO; gamma possible but yellows; not for steam | Easy to mold and paint, but a frequent source of cracked housings |
| PC/ABS, healthcare grades | Improved; grade-specific | High | EtO; gamma depends on grade; not for steam | Formulated for disinfectant resistance; FR grades available |
| PC/PBT and PC/PET blends | Generally better than standard PC/ABS | High | EtO; gamma depends on grade; not for steam | Polyester phase adds chemical resistance; FR grades exist |
| Copolyester, healthcare grades | Good with many disinfectants | Good to high | EtO and gamma; not for steam | Clear options; good color retention after gamma on many grades |
| Polysulfone (PSU) | Good; some solvents attack it | Moderate | Steam, EtO, gamma | Transparent amber; repeated steam sterilization |
| PPSU | Very good | Very high | Steam (more than 1,000 cycles on many grades), EtO, gamma | The toughest of the sulfones; high cost |
| PEI | Good to very good | Moderate; notch-sensitive | Steam, EtO, gamma | Inherently flame resistant; high heat; high cost |
Typical behavior; results depend on the grade, the disinfectant, contact time, temperature and molded-in stress. Sterilization compatibility is grade- and cycle-specific. Confirm with the producer's data for your grade and test finished parts.
How to choose
Wiped, not sterilized
- Healthcare PC/ABS: the closest swap for a standard PC/ABS housing. See PC/ABS.
- PC/PBT or PC/PET: more chemical resistance, with somewhat different shrinkage and molding.
- Copolyester: good disinfectant resistance and clear options.
Sterilized or hot
- PSU: repeated steam sterilization at the lowest cost of these three. See PSU and PPSU.
- PPSU: the most steam cycles and the most toughness.
- PEI: high heat, inherently flame resistant. See PEI.
Design and molding against cracking
- Keep molded-in stress low: correct mold temperature, enough packing without overpacking, and generous radii at corners and boss roots.
- Control assembly stress: use bosses and screws designed for the resin, limit press-fit interference, and avoid thread-locking compounds that attack the resin.
- Test the way the device will be cleaned: strained specimens or real parts, wiped or wrapped with each disinfectant over days to weeks, then inspected and impact tested.
Sterilization, if the part needs it
Many housings are cleaned, not sterilized. Where sterilization is needed:
- Ethylene oxide: compatible with the common housing resins; high molded-in stress can still cause crazing.
- Gamma: yellows standard PC and, to varying degrees, other resins. Use gamma-stabilized, color-corrected grades and check color after the parts have rested, because some of the color fades over time.
- Steam: PC tolerates only a limited number of cycles; PSU, PPSU and PEI are the usual choices for repeated autoclaving.
Biocompatibility, flame rating and color
- Biocompatibility: ISO 10993 evaluation applies to parts that contact the patient or user in a way the risk assessment covers, and it is judged on the finished device. Medical grades often come with ISO 10993 or USP Class VI data on the resin and with change notification. That data applies only to the named grade and color, and the device maker remains responsible for the device.
- Flame rating: for powered equipment, IEC 60601-1 can call for V-1 or better on fire enclosures and on materials supporting some circuits, depending on the construction route. Many makers specify V-0 or V-1 grades. See best plastic for electrical housings.
- Color and gloss: light colors show yellowing and staining, and some disinfectants dull high-gloss surfaces. A light texture hides wear and wipe marks. Lock the color to a named grade and colorant, because a change can affect test data.
What to send us for a quote
- The device and housing part, and the grade you run now, if any
- The disinfectants used and any sterilization method
- Flame rating, color and any biocompatibility data you need on the resin
- Annual volume and ship-to location
Common questions
What plastic is best for medical device housings?
For housings wiped with hospital disinfectants, healthcare grades of PC/ABS, PC/polyester blends (PC/PBT, PC/PET) and copolyester are common choices because they resist stress cracking better than standard PC and PC/ABS. PSU, PPSU and PEI cover parts that must be steam sterilized or need the highest chemical and heat resistance.
Why do medical device housings crack?
Usually environmental stress cracking: a disinfectant soaks into areas under molded-in or assembly stress, such as screw bosses and snap fits, and cracks form weeks or months later. Standard PC and PC/ABS are especially vulnerable to many hospital disinfectants.
Which hospital disinfectants are hardest on plastics?
It depends on the resin, but quaternary ammonium cleaners blended with alcohol are frequently cited as hard on PC and PC/ABS. Hydrogen peroxide (including accelerated formulations) and bleach can also crack, discolor or dull some plastics, so test with the products the hospitals in your market actually use.
Does gamma sterilization affect polycarbonate?
Yes. Gamma radiation yellows standard PC and can reduce some properties, so gamma-stabilized, color-corrected PC grades are used for parts that will be irradiated. PC handles ethylene oxide well but tolerates only a limited number of steam cycles.
Do medical device housings need biocompatibility testing?
Biocompatibility evaluation under ISO 10993 applies to parts that contact the patient or user in a way the risk assessment covers, and it is judged on the finished device. Many producers offer medical grades with ISO 10993 or USP Class VI data on the resin, which helps, but that data applies only to the named grade and does not replace evaluation of the device.
What flame rating does a medical device housing need?
It depends on the device and the construction route taken under IEC 60601-1 (and its U.S. adoption). V-1 or better comes up for fire enclosures and for materials supporting some circuits, and many makers specify V-0 or V-1 grades for powered equipment housings. The test lab and the applicable standard decide.
Does ResinBridge supply materials for implants?
No. We supply resins for non-implant applications only, such as housings, carts, diagnostic equipment and labware. We do not supply materials for implantable or in-body devices.
Tell us the device and how it is cleaned
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province