How can we extend the service life of injection molds for medical plastic products ?

• How can we extend the service life of injection molds for medical plastic products ?
  • What are injection molds for medical plastic products ?
  • How long can medical injection molds be used?
  • Types of steel commonly used in medical injection molds
  • affecting the life cycle of molds for medical plastic products
  • Defects that shorten the expected lifespan of medical injection molds
  • Strategies for efficiently maintaining the lifespan of medical injection molds
  • Precautions for maintaining the healthy lifespan of medical injection molds
  • How to choose the right material for medical injection molds?
  • Collaboration with Elimold on injection molds and molding projects for medical plastic products
  • Summarize
  • Frequently Asked Questions

In the healthcare industry , injection molds for medical plastic products are highly valued for their repeatability and high performance. These molds enable the efficient production of sterile and consistently high-quality products for a wide range of medical applications. Regardless of the type of medical products and devices to be manufactured , medical injection molds play a crucial role in the production of custom parts. Therefore, extending the lifespan of these molds is essential for a stable and cost-effective supply of these products .

Generally speaking, the exact lifespan of injection molds for medical plastic products cannot be predicted. However, by following basic standard operating procedures (SOP) for maintenance, the lifespan of injection molds can be extended. This article will provide valuable insights into injection mold maintenance to help various individuals maintain their molds, ensuring optimal performance and extending their service life.

What are injection molds for medical plastic products ?

Medical injection molds are essentially no different from those used to produce ordinary plastic products. The only difference is that medical injection molds must meet relevant industry standards. Medical injection molds are primarily used for the mass production of various medical plastic parts to meet the broad demands of the global medical market . According to Elimold’s experience, injection molds can withstand an average of 250,000 cycles, but in actual use, they may only be used around 180,000 times. This significant decrease in the number of cycles could be due to improper mold use or inefficiency caused by the mold’s design itself .

molds used to produce medical plastic products must strictly adhere to FDA standards , whether for producing high-quality medical prototype parts or for mass production . These molds are made from medical-grade thermoplastics such as ABS, nylon, polyethylene, acrylates, and polyoxymethylene (Delrin). Medical professionals can utilize medical injection molds to produce high-quality, antimicrobial devices for implants and orthopedics. Therefore, maintaining mold hygiene and optimal performance is crucial for extending their lifespan.

How long can medical injection molds be used?

One of the most important factors affecting the lifespan of injection molds is their mold grade. The Plastics Industries Association (SPI) defines the characteristics of each category and maintains control over the standards. The SPI Injection Mold Standard Classification is a set of standards introduced by the SPI to help the manufacturing industry identify mold types, cycle performance, and hardness resistance. Below are some of the standards:

SPI Class	Capabilities	Hardness Values	Life Cycle Expectancy
101	Low cost mold, suitable for extremely high volumes	28 RC, for tool components, and 48 RC, for cavities	1 million
102	Moderate cost, suitable for high production volumes	50-55 HRC	500,000 to 1 million
103	Suitable for medium production volumes	18 RC for tools, and 28 RC for cavities, and cores	500,000 cycles
104	For low volume manufacturing projects	60-65 RC	100,000 cycles
105	Molds reserved for prototype production	65 – HRC	500 cycles

Types of steel commonly used in medical injection molds

Injection molds made from different types of steel have varying lifespans, which is a key factor affecting the number of times a mold can be manufactured. Therefore, it’s essential to understand the types of steel commonly used in mold making. Below are some material types commonly used in manufacturing FDA-compliant medical molds.

P20 steel	P20 steel is a high-quality mold steel with high strength and hardness, as well as excellent wear and corrosion resistance. Therefore, P20 steel is widely used in the manufacture of high-quality injection molds for medical plastic products.
718 steel	718 steel is a hot-work die steel, characterized by high hardness, high tensile strength, and high heat resistance. It is suitable for manufacturing injection molds for large and complex medical plastic products.
NAK80 steel	NAK80 steel is a high-strength, high-hardness steel with excellent wear resistance and corrosion resistance, making it particularly suitable for mold manufacturing requiring high precision and long service life. This steel is widely used in the medical device industry.
S136 steel	S136 steel is a corrosion-resistant mold steel with excellent corrosion resistance and good polishing properties. It is suitable for manufacturing molds that come into contact with corrosive plastics, such as medical equipment molds and medical product packaging molds.
FS139 and FS636ESR steel	FS139 and FS636ESR are high-grade mold steels produced by Fushun Special Steel. They possess a variety of properties, including high corrosion resistance, high polishability, high wear resistance, and stable heat treatment, making them ideal materials for injection molds. These steels are particularly suitable for producing high-precision, high-hygiene-standard medical plastic parts.

affecting the life cycle of molds for medical plastic products

Many factors influence the overall lifespan of medical injection molds. The lifespan of an injection mold depends on its maintenance. Preventative maintenance and attention to materials, time, and other environmental factors throughout the tool’s lifecycle can significantly improve the overall expected lifespan of the injection mold. Below, we summarize the most important factors that can affect the lifespan of injection molds. Let’s briefly assess these factors in detail:

environment	The lifespan of a mold is greatly influenced by the surrounding environment. It directly affects the final molded product part. Highly acidic and harsh environments can lead to low molding efficiency and significantly reduce the mold’s lifespan. Conversely, a clean and dust-free environment can extend the mold’s lifespan, allowing it to be used for decades.
Mold material	The mold material determines the mold’s lifespan and durability. Typically, OEM designers use hard materials to manufacture molds, such as aluminum, while steel is a commonly used metal for medical molds. These molds may wear down due to the plastic materials used to mold medical products. The hardness of the material determines the mold’s lifespan. For example, aluminum is softer than steel, so aluminum molds have a longer lifespan than hard steel molds. Furthermore, impurities in the mold can sometimes significantly affect its lifespan.
Proper maintenance	Proper maintenance helps extend the life and durability of molds. This is a proactive approach to keeping the mold in good condition and extending its service life by ensuring it is always operating normally. Therefore, giving the mold rest time during operating intervals is crucial, as this helps improve its durability. After each cycle, the mold should be allowed to cool down to reduce the temperature of the heat-generating elements. Continuous use of the equipment can lead to potential damage and degrade mold performance.
Mold maintenance	To avoid overheating and cracking, attention should be paid to smooth transitions and grinding techniques during mold cutting. To obtain a smooth, uniform surface, the quality of the plastic, demolding requirements, and corrosion and rust resistance must be carefully considered.
Reasonable mold design	Mold design can achieve a variety of functions, such as engraving or marking, which is crucial for the traceability of medical devices. Good mold design contributes to product success. Optimal design can reduce stress input, thereby extending the lifespan of the instrument.
Maintain smooth demolding	Certain part design features often result in higher ejection forces. Polishing the cavity features would be beneficial because it reduces the coefficient of friction, thereby reducing ejection forces, making it a more desirable option.
Preventive maintenance	To prevent product defects and malfunctions, equipment must be properly maintained to ensure it is in good working order. Good equipment condition, combined with preventative maintenance, can extend the lifespan of tools.

Defects that shorten the expected lifespan of medical injection molds

Even the cleanest environments, adhering to every protocol to ensure the longest possible lifespan for medical injection molds, can handle common defects. Some of the most common mold defects occur due to a mismatch between the appropriate material and mold type, or due to operator inexperience. In both cases, these defects can have a significant impact on mold production and its expected lifespan. Below are some of the various causes we have summarized.

Streamline	Streamlines are a result of changes in the cooling rate of plastic, caused by impurities and other factors such as variations in part thickness.
Shrinkage	This defect is extremely common in parts with edges or gaps. Shrink marks are a result of rapid cooling of a portion of the mold during the flow process, causing pits or small depressions on the part. Such parts become very difficult to eject and may damage the mold in the process.
burn marks	This is a common defect in high-speed production. Burn marks are caused by overheating in certain parts of the mold, and in some extreme cases, this can render both the part and the mold unusable.
Layering	Delamination occurs when a part is separated into several layers during the manufacturing process. This defect creates a worn surface that can damage the cavity or other parts of the mold during demolding.
Flash	Flash refers to excess plastic flowing out of the mold through both sides of the parting line. Generally, the sides of the mold remain fragile and easily damaged because plastic can stick to them, and if it contains corrosive elements, it can cause problems.

Strategies for efficiently maintaining the lifespan of medical injection molds

Many factors can affect the proper maintenance of molds, thus impacting their service life.

Mold structure and dimensions	Choosing the best design is crucial because it plays a vital role in product management. A high-quality design includes elements such as reasonable runner length and minimal clamping force requirements.
Surface treatment and processing	This includes machining the mold to the required structure and dimensions to prevent overheating and cracking. This will improve the mold’s efficiency and lifespan by increasing its strength and rigidity.
Cleaning and inspection	Regular cleaning is a fundamental part of maintaining mold equipment. Timely removal of contaminants and toxins from the mold surface can extend its service life. An inspection should be performed after each use or production run to identify any damage or wear. This will reduce potential errors and malfunctions in the equipment.
lubricating	Ensure regular lubrication of mold equipment to reduce thermal stress. Silicone-based lubricants are commonly used in the medical field because they minimize friction. Choosing the right lubricant for your tools is crucial; once selected, it will be highly effective.
Temperature and humidity management	Maintaining an ideal environment for medical molded equipment is as important as its manufacturing process. Fluctuations in temperature and humidity can cause significant changes in its dimensions and operational capabilities. Controlling the environment under appropriate conditions can reduce environmental stress and maximize its performance and lifespan.
Training and Education	Because these devices are highly sophisticated and critical, they should be operated by qualified professionals. A training program, including proper operating techniques, procedures, and safety precautions, should be provided before they are put into use.
Regular maintenance	Regular maintenance should be a routine task for mold equipment users. A maintenance plan should include cleaning, lubrication, parts maintenance, and inspection. This will improve equipment productivity and ensure patient safety.

Precautions for maintaining the healthy lifespan of medical injection molds

● Use products recommended for cleaning tools, such as CLR Mold Cleaner or RMR-86 Pro Fast Mold Stain Remover.

● When not using the tool, ensure it is stored at the optimal temperature, which ranges from 50°C to 200°C, depending on the mold type.

● A check-up is performed approximately every five days.

● Avoid using harsh chemicals, as they can cause corrosion.

Common defects that affect durability:

● Surface marks are minor deformations on the mold surface caused by temperature changes.

●Warping refers to the deformation that occurs after demolding.

●Flash refers to excess material protruding and affecting normal operation.

● Severe overheating in specific areas of the mold can cause burn marks, thereby reducing its durability.

● Air bubbles and voids are cavities that remain on the surface of the mold and reduce its performance.

How to choose the right material for medical injection molds?

When selecting the appropriate injection mold material for a specific medical plastic product application, several factors should be considered, including the type of plastic resin, part complexity, production volume, expected mold life, cost factors, and environmental conditions. The following are general guidelines for selecting mold materials for common medical plastic product injection applications:

General medical plastic products	For general medical plastic applications using common thermoplastics such as polypropylene (PP), polystyrene (PS), or polyethylene (PE), materials such as P20 or 420 stainless steel are generally suitable. These materials offer a good balance between hardness, toughness, and cost-effectiveness, making them suitable for medium-volume production.
High-performance medical products	For molding engineering plastics such as ABS, PC, or nylon, consider using high-performance mold materials such as H13 tool steel or beryllium copper. These materials offer better heat resistance, wear resistance, and dimensional stability, and can withstand the high temperatures and stresses associated with engineering resins.
Medical products in corrosive environments	If the injection molding resin is corrosive, such as PVC (polyvinyl chloride) or a filled resin, it is recommended to use corrosion-resistant mold materials, such as stainless steel (e.g., 420 or 440) or beryllium copper. These materials have excellent corrosion resistance and can prevent premature mold failure.
Mass production of medical plastic products	For mass production where molds need to be used for extended periods and have rapid cycle times, materials with good wear resistance and thermal conductivity, such as H13 tool steel, are recommended. H13 steel is known for its ability to handle high-volume production and is often used in medical products that are consumed frequently.
Medical products with thin-wall design	When forming thin-walled parts, materials with good thermal conductivity help achieve rapid heat transfer and efficient cooling. Aluminum molds are often used due to their lightweight and excellent thermal conductivity, which can shorten cycle time and improve part quality.
High-precision and optical medical products	For medical applications requiring high surface finish, optical transparency, or precision, stainless steel or nickel-chromium alloy tool steel mold materials with excellent polishing properties are recommended. These materials help achieve the desired surface aesthetics and reduce defects, and are commonly used in lenses, light guides, or medical electronics.

Collaboration with Elimold on injection molds and molding projects for medical plastic products

Molds are typically the most expensive part of any injection molding project and require the highest consistency, precision, and durability. Elimold is a manufacturer providing professional mold making and injection molding services, and we are a partner that can deliver all these services in the shortest time and at the most competitive prices on the market.

Currently, Elimold’s team collaborates with numerous manufacturers worldwide, providing physical injection molds tailored to project requirements. Want to start your project? Send your mold design details and other information to our official email address: [email protected]. Our dedicated pre-sales engineers will respond quickly and provide a prompt quote and other detailed information.

Summarize

Medical injection molds play a vital role in the medical field, making their maintenance crucial. Neglecting maintenance reduces tool performance, durability, and effectiveness. Proper maintenance helps improve equipment safety and minimize mold-related defects. Ultimately, investing in tool maintenance is a worthwhile investment, protecting not only its integrity but also enhancing its functional performance.

Frequently Asked Questions