Injection molded parts can undergo a variety of post-processing operations, such as assembly, machining, laser marking, pad printing or surface finishing, to meet the exact requirements of the medical device.

Process validation is the best way to ensure the production of safe parts, to reduce rejection rates, to prevent part failures in the field and to ensure the part meets with application, specification and regulatory obligations.

A large tonnage injection molding machine requires a large amount of resources.  The footprint of a large tonnage machine is approximately 40’ x 8’ x 8’.  The capital cost of a large machine can start at $250,000 and can exceed $1MM.  The injection molds that are processed in these machines exceed 10,000# and require special lifting equipment.  The facility foundations must be suitable for machines exceeding 100,000 lbs.  The utilities required to operate a large machine are great and are expensive to bring to the building.  Large tonnage machines typically run larger parts.  Handling and storing large quantities of large parts requires considerable space for staging, packaging and storing parts.  As a result of these considerations, there are fewer companies that choose to offer machines >500 tons.

PTI Engineered Plastics provides medical device manufacturers with full-service advanced product development delivered in a compressed timeframe. With superior design for manufacturability, tooling, and molding capabilities, PTI turns product visions into reality and gets your product to market first.

The injection molding process generates minimal material waste compared to other manufacturing methods. This not only contributes to cost savings but also aligns with the increasing focus on sustainable and environmentally friendly manufacturing practices.

Mold Design is a crucial step in the injection molding process.  Once you’ve finalized your part in CAD software for fit and function, it must then be transformed into a design for molding to ensure the capture of all the specified details.  In some cases, certain features of the part design may not be manufacturable via the injection molding process.

Injection molding offers unmatched precision and consistency in the production of medical device components. The process allows for intricate designs and tight tolerances, ensuring that each part is identical to the next. This uniformity is crucial in the medical field, where reliability and precision are paramount.

Some of the most common materials used in medical devices are: Polypropylene, ABS, Polyurethane, Polyvinylchloride, Polycarbonate, Polystyrene, Polysulfone, Acetal and Polyethylene.

Many medical devices must be in direct contact with the human body. Injection molding allows manufacturers to choose biocompatible materials, ensuring patient safety. These materials can be sterilized without affecting their properties, making them suitable for a wide range of medical applications.

There are many different grades of plastic resin.  Plastic resins are generally specified by the physical, environmental and chemical resistance properties required of the finished parts.  Each grade of resin has an ideal processing temperature range without degrading the properties during manufacturing.  Each different grade of resin will have different rate at which the plastic melt flows.  The Melt Flow Index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer.  It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.  Thermoplastic resin manufacturers can formulate the thermoplastic resin to have a range of MFI within a specific grade. The higher the MFI, the easier the melt flows.  The higher the MFI the less injection pressure is required to fill the cavity and less clamp tonnage required by the molding machine.

The high initial tooling costs can be a barrier to entry for some manufacturers. However, once the molds are in place, injection molding is incredibly cost-effective for large production runs. The ability to produce a large number of parts in a short time reduces unit costs significantly, making it an ideal choice for mass production.

Process Validation as defined by the FDA is “The collection and evaluation of data, from the process design stage throughout production, which establishes scientific evidence that a process is capable of consistently delivering quality products.”

Injection molding produces parts with a high level of structural integrity, ensuring they can withstand the rigors of their intended application. These parts are less prone to defects and offer superior performance over their lifecycle.

During the injection molding process hydraulic cylinders push the screw forward injecting melted plastic resin into the cavity of the mold at extremely high pressures.  Pressures exceeding 20,000 p.s.i. during injection push the two halves of the mold apart.  Injection molding machines are rated by “clamping force” in tonnage.  The tonnage of force clamping the two halves of the mold together.  The larger the surface area of the molded part, the greater the tonnage is required.  Generally “large tonnage” machines are machines rated with 500 or more tons of clamping force.

In many cases, our medical device customers look to process validation to ensure quality parts.  After all, patients lives depend on PTI to deliver high quality parts each and every time.

With streamlined production processes, injection molding can significantly reduce time-to-market for medical devices. This is crucial in a rapidly evolving industry where innovations can make a significant impact on patient care and outcomes.

Furthermore, we have over 5,000 square feet of controlled environment space.  This segregated area is temperature controlled and pressurized, and can accommodate part decorating, assembly and packaging needs.

We have been serving the medical industry for nearly 40 years, specializing in handling complex, multi-part programs and medical device molding for a variety of customers. Our direct contact with doctors and other medical professionals gives us insight into their needs and helps define and assist with final product solutions.

Injection molding for medical devices represents the perfect synergy of precision engineering and advanced manufacturing technology. Its benefits, from precision and consistency to cost-efficiency and regulatory compliance, make it a top choice for design engineers and medical device manufacturers. The process empowers engineers to innovate, create intricate components, and bring lifesaving devices to market faster than ever before. The future of medical device manufacturing is being molded with precision, and injection molding is at the forefront of this revolution.

Having served the medical industry for nearly 40 years, we understand medical device manufacturing.   Plastic Injection Molding remains one of the best manufacturing methods for achieving precision and cost-efficiency as well as maintaining patient safety.

Thicker wall sections provide more volume for the plastic melt to flow.  As plastic melt travels to the end of the mold cavity, the steel is removing heat.  Thicker wall sections provide insulation for the melt and allow it to travel further with less pressure.  Similarly, the thinner the wall the faster heat is transferred from the plastic melt and more pressure is required to push the melt flow into thin sections.

At PTI, we have over 16,000 square feet of ISO Class 8 cleanroom space that we utilize in our injection molding process to ensure as little contamination as possible.  We adhere to strict protocols that meet the demands the medical industry requiring ISO 14644 Cleanroom specifications, including bioburden and electrostatic discharge (ESD).

Meeting stringent regulatory requirements is a non-negotiable in the medical device industry. Injection molding excels in this regard. The ability to use FDA-approved materials and consistently produce parts that meet these standards ensures compliance from the outset.

Injection molding is scalable, which means it can cater to a variety of production volumes, from small-scale prototypes to mass production. This scalability offers manufacturers the flexibility to meet different market demands.

A general rule of thumb is 2-8 tons per square inch.  For example, a 10” x 10” part (100 square inches x 2 tons/sq. in.) = 200 tons.  The larger the part the more clamp force is required to hold the two halves of the mold together during the injection process.  There are several factors that influence the amount of clamping force required including wall thickness, geometry, gating of part, viscosity of resin and temperature of injection mold.

The more tortuous the path and further the distance the plastic melt travels, the greater volume of melt is being pushed and greater transfer of heat from the melt flow to the steel cooling the plastic.  The additional material and resistance to flow as travel distance increases requires additional injection pressure and clamp tonnage.

At PTI, we collaborate with you to achieve the best possible design for manufacturability.  In fact, we have a FREE guide to help you with this.

Injection pressure is a measure of pounds per square inch (PSI) required to inject the melted plastic resin to displace the air and fill the cavity under adequate pressure for form a quality part.  The clamp on an injection molding machine “clamps” the two halves of the mold together during injection, packing and cooling process of manufacturing a plastic part.  The greater the injection pressure pushing plastic melt into the cavities the greater the clamp force required to hold the mold together.

Injection molding allows medical design engineers the freedom to design complex or intricate parts, a vast selection of suitable materials and the consistency to produce both low and high volumes of devices.

In this article, we have not listed every factor, but these represent the main considerations for selecting the proper injection molding machine clamp tonnage.  Texas Injection Molding is one of the largest custom injection molding companies in Texas and has made the strategic decision to position our company to offer a broad range of capabilities at a single location.   Texas Injection Molding works closely with our customers during initial stages of product development to ensure part performance and efficient manufacturing. We are certified to the standards of ISO 9001-2015 and have a full-service tool and die shop to complete routine maintenance, engineering changes and repairs in a cost-effective and timely manner.  In addition to our fleet of small to medium tonnage machines, we have several large tonnage machines and have planned our building, utilities, material handling and lifting capabilities to meet these broad manufacturing requirements.

Careful selection of materials is extremely important within the medical industry. Materials must meet FDA and other regulatory standards, ensuring patient safety, biocompatibility, sterilizability and durability.  As Injection molding allows for a vast selection of both thermoplastic and thermoset materials to choose from, there is certain to be a material suitable for just about any application.

As plastic melt is injected into the steel cavity of the mold, heat is transferred into the steel and the plastic begins to cool.  If the resin cools (“freezes off”) before reaching end of fill for the cavity, you will have a “short shot”.  Increasing the temperature of the mold will help the plastic material flow better and require less pressure and thereby less clamping force to hold the mold closed during fill.

One of the most significant advantages of injection molding is its design flexibility. Engineers can create complex, customized components with minimal tooling changes. This adaptability is essential in a field where the demand for innovative and unique medical devices is ever-expanding.