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In medical injection molding projects, many risks often begin with material selection. Choosing the wrong material may lead to sterilization issues, yellowing, cracking, warpage, unstable dimensions, or assembly problems during mass production. This guide will help you understand common medical-grade plastic materials, their typical applications, and the key factors to consider before starting a mold project, helping you make a better material decision at the early stage of product development.
| Table of Contents |
1. What Are Medical-grade Plastics? |
2. 11 Types of Common Medical-grade Plastics |
3. How to Select Materials for Medical Injection Molded Part |
4. Medical Plastics Selection and Mold Design Considerations |
5. In conclusion |
6. FAQ |
Medical-grade plastics are polymer materials that are specifically selected, tested, and qualified for use in medical and healthcare applications. They are commonly used in medical devices, diagnostic equipment, disposable medical consumables, surgical instruments, drug delivery components, and healthcare products.
Compared with metal or glass, medical-grade plastics are lighter, more impact-resistant, easier to mold, and more suitable for complex part design and mass production. If your product requires complex geometries, precision assembly, or consistent high-volume manufacturing, injection molding enables the production of various medical plastic components, including connectors, housings, transparent covers, clips, handles, and precision structural parts.
In medical injection molding, different plastic materials are suited to different types of medical products. Material selection is typically based on factors such as intended use, operating environment, sterilization method, strength requirements, transparency, dimensional stability, and chemical resistance. Common medical-grade plastics include PP, PE, PC, ABS, PMMA, POM, PA,PVC, PEEK, PSU, and PEI.
Characteristics: PP is a very common material in medical injection molding, characterized by good chemical resistance, low weight, relatively low cost, and ease of processing.
Applications: Suitable for disposable medical consumables, syringe components, bottle caps, connectors, clips, and similar products, etc.
Characteristics: PE offers good flexibility and chemical resistance; it has a relatively soft feel, making it suitable for medical plastic parts that do not require high structural strength. It comes in various forms—including LDPE, HDPE, and UHMWPE—with different types suited to specific medical applications.
Applications: Commonly used for medical containers, hose connectors, bottle bodies, caps, catheter components, and other medical plastic parts requiring flexibility or chemical resistance, etc.
Characteristics: PC offers high transparency, impact resistance, and dimensional stability; however, specific sterilization methods and chemical resistance requirements must be considered during selection.
Applications: Suitable for transparent medical housings, protective shields, viewing windows, testing equipment components, and similar products.
Characteristics: ABS offers good processability, strength, and aesthetic qualities, making it suitable for non-implantable medical plastic parts that require specific aesthetic and structural stability.
Applications: Commonly used for medical equipment housings, instrument casings, handheld device housings, and similar products, etc.
Characteristics: PMMA offers high transparency and excellent surface gloss, though its impact resistance is lower than that of PC; structural strength must be considered during product design.
Applications: Suitable for transparent covers, viewing windows, optical medical components, etc.
Characteristics: POM features good wear resistance, rigidity, and dimensional stability, making it ideal for small, precision structural components.
Applications: Commonly used for gears, sliding parts, connectors, and small precision structural components in medical equipment.
Characteristics: PA offers good mechanical strength, toughness, and wear resistance. However, it is prone to moisture absorption, which can affect dimensional stability; therefore, material selection and processing control require special attention for precision medical parts.
Applications: Suitable for medical structural components, functional parts, and connectors that require strength and toughness.
Characteristics: PVC offers good flexibility, chemical resistance, and processability, and can be formulated as either soft or rigid material depending on product requirements. However, when used in medical products, special attention must be paid to the material grade, type of plasticizer, biocompatibility, and sterilization method.
Applications: Commonly used for medical tubing, IV lines, drainage tubes, respiratory masks, medical bags, catheter connectors, etc.
Characteristics: PEEK is a high-performance engineering plastic offering excellent high-temperature resistance, chemical resistance, and mechanical properties; however, material costs and processing requirements are relatively high.
Applications: Commonly used for demanding medical components, surgical instrument parts, precision structural components, and similar products.
Characteristics: PSU and PPSU exhibit good high-temperature resistance, hydrolysis resistance, and resistance to repeated sterilization, making them suitable for medical plastic parts requiring high-temperature steam sterilization.
Applications: Commonly used for sterilization trays, medical instrument handles, connectors, high-temperature resistant medical components, and similar products.
Characteristics: PEI offers high strength, heat resistance, and dimensional stability, making it suitable for medical plastic parts with high-performance and high-temperature requirements.
Applications: Suitable for high-performance medical equipment components, high-temperature resistant structural parts, and precision medical plastic components.
It is important to note that not all grades of PP, PC, ABS, or PEEK are suitable for direct use in medical products. medical plastic molding projects typically require the selection of medical-grade materials that meet specific application requirements, alongside a comprehensive evaluation considering product functionality, regulatory standards, sterilization methods, and mass production conditions.
The data below serves as a preliminary reference for material selection. Properties vary depending on the specific medical-grade material grade, additives, filler content, and testing standards; for actual projects, the Technical Data Sheet (TDS) provided by the material supplier should be consulted.
Material | Tensile Strength | Hardness | Melting Point / Tg | Density |
PP | 25–40 MPa | Rockwell R80–R100 | 160–170°C | 0.90–0.91 g/cm³ |
PE | 10–35 MPa | Shore D 45–70 | 110–135°C | 0.91–0.96 g/cm³ |
PC | 55–75 MPa | Rockwell M70–M80 | Tg 145–150°C | 1.20–1.22 g/cm³ |
ABS | 35–50 MPa | Rockwell R90–R110 | Tg 100–110°C | 1.03–1.08 g/cm³ |
PMMA | 50–75 MPa | Rockwell M80–M100 | Tg 100–110°C | 1.17–1.20 g/cm³ |
POM | 55–70 MPa | Rockwell M80–M90 | 165–175°C | 1.40–1.42 g/cm³ |
PA | 50–85 MPa | Rockwell R100–R120 | 220–265°C | 1.12–1.15 g/cm³ |
PVC | 10–60 MPa | Shore A 60–95 / Shore D 65–85 | Tg 70–90°C | 1.10–1.45 g/cm³ |
PEEK | 90–116 MPa | Rockwell M95–M105 | 341–343°C | 1.30–1.32 g/cm³ |
PSU / PPSU | 65–85 MPa | Rockwell M80–M100 | Tg 185–220°C | 1.24–1.29 g/cm³ |
When selecting materials for medical injection-molded parts, you cannot simply look at the price or ask, "Which material is the best?" A more rational approach involves a comprehensive assessment based on factors such as the product's intended use, sterilization method, performance requirements, and dimensional stability. Different medical plastic parts operate in different environments, and consequently, the material requirements vary significantly.
First, you need to clarify the product's actual application. Is it, for example, a disposable medical consumable, a medical device housing, a transparent viewing window, a connector, a clip, or a precision structural component? Different products impose different demands on material properties.
If the product is a disposable medical consumable—such as syringe components, catheter connectors, clips, or bottle caps—priorities typically include material cost, molding efficiency, basic strength, and the ability to maintain stable mass production. Materials like PP and PE are commonly used for such products.
If the product is a housing for medical equipment or a handheld instrument, you must consider aesthetics, strength, assembly structure, and long-term stability; materials such as ABS, PC, or PC/ABS may be more suitable.
If the product requires transparency—such as viewing windows, transparent covers, or components for diagnostic equipment—you should focus on transparent materials like PC or PMMA.
Sterilization method is also an important factor in material selection. You need to confirm in advance whether the product requires EO sterilization, gamma sterilization, high-temperature steam sterilization, or only general chemical disinfection.
Different materials have different resistance to sterilization methods. If the wrong material is selected, the product may experience yellowing, brittleness, deformation, cracking, or dimensional changes.
For example, products that require high-temperature steam sterilization usually need to consider heat-resistant materials such as PSU, PPSU, PEI, and PEEK. For disposable medical consumables, PP is commonly used in many projects, but it still needs to be confirmed based on the specific sterilization method and material grade.
You also need to choose the material based on how the product will be stressed during use. If the part is only a simple housing or protective cover, the strength requirement may not be very high. However, if it is a clip, connector, gear, sliding component, or a structural part that needs to withstand assembly force, you need to consider the material’s strength, toughness, wear resistance, and fatigue resistance.
For example, POM is suitable for some wear-resistant sliding components, PA is suitable for structural parts that require strength and toughness, while PEEK is more suitable for high-performance medical parts with higher requirements.
If your product has transparency requirements, you need to further confirm whether it only needs to be “visible,” or whether it requires high transparency, low haze, or good optical performance.
PC has better impact resistance and is suitable for transparent parts that require higher strength. PMMA offers excellent transparency and surface gloss, but its impact resistance is relatively weaker than PC. If the product needs to meet transparency, strength, and sterilization requirements at the same time, you should not only consider whether the material is transparent, but also evaluate it together with the actual application environment.
Chemical resistance should not be ignored. Many medical plastic parts may come into contact with alcohol, medicines, cleaning agents, disinfectants, or other chemical substances.
If the material does not have enough chemical resistance, the product may experience stress cracking, surface whitening, brittleness, or reduced strength during use. Therefore, when selecting a material, you need to confirm in advance what liquids or chemicals the product may contact, and ask the material supplier to confirm whether the specific material grade is suitable.
For medical plastic parts with assembly requirements, dimensional stability is very important. For example, connectors, clips, threaded parts, sealing components, and precision structural parts may have problems such as tight assembly, loose assembly, poor sealing, or out-of-tolerance dimensions if the material has high shrinkage, high water absorption, or is prone to deformation.
For example, although PA has good strength, it has relatively obvious water absorption. Therefore, dimensional changes should be carefully considered when PA is used for precision medical parts.
To help you make an initial judgment at the early stage of your project, you can refer to the table below to quickly compare the key questions to confirm and the common material options for each selection factor.
Selection Factor | Questions You Need to Confirm | Common Material Options |
Product Application | Is it a disposable consumable, equipment housing, transparent part, or precision structural component? | PP, PE, ABS, PC, PMMA, POM, PA |
Sterilization Method | Does the product require EO sterilization, gamma sterilization, high-temperature steam sterilization, or chemical disinfection? | PP, PC, PSU, PPSU, PEI, PEEK |
Strength Requirement | Does the part need to withstand assembly force, impact, pressure, or long-term use? | PC, PA, POM, PEEK, PEI |
Transparency Requirement | Does the part need transparent observation, a viewing window, or optical performance? | PC, PMMA |
Chemical Resistance | Will the product come into contact with alcohol, medicines, cleaning agents, or disinfectants? | PP, PE, POM, PEEK, PSU / PPSU |
Dimensional Accuracy | Are there clips, threads, sealing areas, or assembly tolerance requirements? | POM, PC, PEI, PEEK |
Molding Stability | Is the material prone to shrinkage, deformation, air traps, or demolding difficulty? | Needs to be evaluated together with material flowability and mold design |
Project Cost | Is it a disposable mass-production part or a high-performance small-batch component? | PP and PE are relatively low-cost; PEEK, PEI, and PPSU are higher-cost |
Finally, you also need to confirm whether the material has relevant documentation for medical applications, such as medical-grade resin information, material data sheets, compliance documents, or biocompatibility test data.
For medical products, material selection not only affects product performance, but also influences later certification, mold design, mold trial results, and mass production stability. Confirming the material direction before mold manufacturing can help reduce the risk of mold modification, material re-testing, and project delays.
Material selection for medical plastics should not be considered separately from mold design. Different materials have different shrinkage rates, flowability, molding temperatures, demolding behavior, and surface requirements, all of which directly affect the mold structure. If these factors are not considered before mold manufacturing, issues such as unstable shrinkage, warpage, air traps, weld lines, demolding difficulty, surface defects, or out-of-tolerance dimensions may occur later.
Different materials have very different shrinkage rates. During mold design, dimensional compensation should be made in advance according to the material characteristics. For example, PP and PE usually have higher shrinkage rates, while PC, ABS, and PMMA have relatively lower shrinkage rates. For precision medical parts such as connectors, clips, threaded parts, and sealing components, inaccurate shrinkage estimation may lead to tight assembly, loose assembly, or poor sealing during mass production.
Material | Common Shrinkage Reference |
PP | 1.0%–2.5% |
PE | 1.5%–4.0% |
ABS | 0.4%–0.8% |
PC | 0.5%–0.7% |
PMMA | 0.2%–0.8% |
POM | 1.5%–2.5% |
PA | 0.8%–1.8% |
PA + GF | 0.2%–0.8% |
PEEK | 1.0%–1.3% |
PSU / PPSU | 0.5%–0.8% |
PEI | 0.5%–0.7% |
For precision medical parts, it is recommended to evaluate deformation risks before mold manufacturing by combining material shrinkage, product structure, and Moldflow analysis.
For precision medical parts, it is recommended to evaluate deformation risks before mold manufacturing by combining material shrinkage, product structure, and Moldflow analysis.
Medical plastic parts usually require stable dimensions, clean appearance, and consistent molding quality, so wall thickness design is very important. In general, many medical injection molded parts have a wall thickness of around 1.0–3.0 mm. Small precision parts may be around 0.5–1.0 mm, while housing parts commonly have a wall thickness of about 1.5–2.5 mm.
The wall thickness should be kept as uniform as possible. If some areas are too thick, shrinkage marks, bubbles, warpage, and longer cooling time may occur. If some areas are too thin, short shots, filling difficulty, or insufficient strength may occur. Rib thickness is generally recommended to be around 40%–60% of the main wall thickness to avoid obvious sink marks on the opposite side of the ribs.
Gate location affects material flow direction, weld lines, air traps, appearance, and dimensional stability. For transparent or cosmetic medical parts, the gate should be placed away from visible surfaces, sealing surfaces, and key assembly areas as much as possible. For connectors, threaded parts, or precision structural parts, the gate location should also avoid affecting critical dimensions and fitting areas.
Common design references:
Item | Reference Suggestion |
Gate location | Preferably in a thicker area or a position that does not affect appearance |
Edge gate thickness | Usually about 40%–70% of the product wall thickness |
Multi-cavity mold | Runner balance is required to avoid differences in part weight and dimensions between cavities |
Transparent parts | Avoid weld lines in viewing windows or high-transparency areas |
Precision parts | The gate should not affect clips, threads, sealing surfaces, or assembly areas |
For medical parts, gate design is not only about whether the product can be filled. It also needs to consider weld line location, shear stress, appearance, and later assembly stability.
Cooling design directly affects product dimensional stability and molding cycle time. If mold cooling is uneven, the product may suffer from warpage, inconsistent shrinkage, dimensional variation, and unstable cycle time.
Common cooling design references:
Item | Reference Range |
Cooling channel diameter | Usually 6–12 mm |
Distance from cooling channel to cavity surface | Usually 2–3 times the cooling channel diameter |
Distance between cooling channels | Usually 3–5 times the cooling channel diameter |
Precision medical parts | More uniform cooling is needed to reduce dimensional variation |
Transparent parts / high-temperature materials | More stable mold temperature control is required |
Different materials require different mold temperatures. For example, PC commonly uses a mold temperature of about 80–120°C, PMMA about 60–90°C, while high-performance materials such as PPSU, PEI, and PEEK require higher mold temperatures. Unstable mold temperature may affect product dimensions, surface quality, and internal stress.
If medical plastic parts have clips, threads, undercuts, sealing edges, or thin-wall structures, demolding design must be considered in advance. Poor demolding design may cause scratches, whitening, deformation, breakage, or visible ejector marks on transparent parts.
Common design references:
Item | Reference Suggestion |
Draft angle for ordinary smooth surfaces | Usually 0.5°–1° |
Deep ribs or deep cavities | Recommended 1°–2° or more |
Textured surfaces | Usually require a larger draft angle |
Appearance surface of transparent parts | Avoid ejector marks in visible areas as much as possible |
Threaded parts | Slides, lifters, or automatic unscrewing structures can be considered |
For medical cosmetic parts and transparent parts, ejector location should be carefully considered. It is not enough to only ensure that the part can be ejected; you also need to consider whether it will affect appearance, transparency, or assembly surfaces.
Medical products often have high requirements for surface cleanliness, appearance, and touch feel. For transparent medical parts such as viewing windows, transparent covers, and protective shields, the mold cavity needs a higher level of polishing to ensure transparency and surface quality.
Common surface requirement references:
Surface Requirement | Common Application | Mold Consideration |
High gloss / transparent | PC and PMMA transparent covers, viewing windows | High-level polishing is required to avoid tool marks, EDM marks, and scratches |
Matte finish | Medical equipment housings, handheld devices | Texture uniformity needs to be controlled |
Textured surface | Housings, handles, anti-slip structures | A larger draft angle is required |
Sealing surface | Connectors, caps, liquid-contact parts | Flatness and machining accuracy must be ensured |
For transparent parts, mold steel, polishing level, and injection molding process are all important. Poor mold surface quality may cause haze, flow marks, scratches, or insufficient transparency.
Mold steel should be selected according to the material, product appearance, mold life, and mass production requirements. Different materials have different requirements for mold steel, especially glass-filled materials, high-temperature materials, and transparent materials.
Common selection references:
Application | Common Mold Steel Options |
Ordinary medical housings | P20, 718H, NAK80 |
Transparent medical parts / high-gloss parts | S136, S136H |
Long mold life | H13, S136, 1.2344 |
Glass-filled materials, such as PA+GF and PBT+GF | More wear-resistant steel is required |
High-temperature materials, such as PEEK, PPSU, and PEI | Steel with good heat resistance, wear resistance, and thermal stability is required |
In conclusion, material selection for medical injection molding should not be based only on material name or cost. It needs to be evaluated together with product application, strength requirements, transparency, chemical resistance, sterilization method, and mass production needs. At the same time, material shrinkage, flowability, wall thickness, gate location, cooling system, demolding method, polishing requirements, and mold steel selection should also be considered before mold manufacturing to reduce mold trial modifications and production risks.
With over 25 years of experience in medical injection molds and injection molding, Alpine Mold can provide material suggestions, DFM analysis, mold design, and mold manufacturing solutions based on your product application, structure requirements, and production needs. If you are developing medical plastic parts, feel free to contact us to discuss a suitable material and mold solution for your project.
Q: What types of injection molding are used in medical devices?
A: Common types of injection molding used in medical devices include standard injection molding, precision injection molding, insert molding, overmolding, two-shot molding, micro injection molding, and cleanroom injection molding.
Q: Is medical grade plastic safe?
A: Yes. Medical-grade plastic is generally safe when it meets the required material specifications, testing standards, and application requirements.
Q: Can medical plastics be recycled?
A: Yes, some medical plastics can be recycled, but it depends on the material type, contamination level, and regulatory requirements. For medical products, recycled plastic is usually used only when it meets safety and compliance standards.
Q: What is the difference between medical-grade plastic and regular plastic?
A: Medical-grade plastic is designed and tested for medical applications, with stricter requirements for safety, biocompatibility, chemical resistance, sterilization compatibility, and material traceability.
Regular plastic may not meet these medical standards, so it is not suitable for medical devices or healthcare products unless properly tested and approved.
Q: Why is the demand for medical-grade plastics increasing?
A: The demand for medical-grade plastics is increasing because of advancements in medical technology, an aging population, and the growing need for innovative healthcare solutions. These materials are commonly used in wearable medical devices, disposable medical supplies, diagnostic products, drug delivery components, and other medical applications.
Q: How large is the global medical plastics market?
A: The global medical plastics market was valued at around USD 61.35 billion in 2025. It is expected to grow from about USD 66.0 billion in 2026 to approximately USD 83.3 billion by 2030, based on a CAGR of 6.0%. This indicates strong and continuous demand for medical plastic materials across medical devices, diagnostics, disposable consumables, drug delivery systems, and healthcare applications.
