Reaching for the Best

Often viewed as completely separate technologies is medical injection molding and medical extrusion. However, there are many similarities and overlaps in the two fields – especially in regards to machine design – that can lead to better products, features, and solutions for molders and extruders alike.

Machine manufacturers who have deep resources and experience building both injection and extrusion machines are able to use aspects of the one to improve the other, and vice versa.

Built from stainless steel, the Milacron MPAK incorporates a low profile, modular design, and smaller capacity hopper to fit better into cleanrooms.

Intricacies of Medical Production
Manufacturers who specialize in both injection and extrusion have a better understanding of overall machine technology and the complexities of medical production. They are able to draw on engineering experience and proficiency to enhance machines for optimal performance in medical part production.

There are many intricacies to producing medical plastic products: understanding highly engineered medical resins, accommodating tight tolerances, eliminating contaminants, managing cleanroom compliance issues, etc.

Medical products must meet stringent FDA sterilization requirements, which demand high production cleanliness and often various levels of cleanroom certification. Additionally, all instrumentation and components must be FDA compliant to eliminate mercury and other potential contaminants. The best machines will be conducive to these important needs.

Machines with hoppers, barrel guards, and other parts made from stainless steel are much easier to sanitize than those made from other materials. Medical machines require design for flexibility, so that they can easily accommodate cleanrooms, and they must have the wear resistance to process tough, newly engineered resins.
 

Enhancements to Machine Technology
Single-screw extruders are the industry workhorse, processing a wide variety of materials in many different applications. While it is possible to produce medical tubing on almost any of these machines that have a small-diameter screw (generally 1.5" or smaller), some are much better suited for medical applications than others.

The Milacron MPAK is one example of a machine designed specifically for medical extrusion. Built from stainless steel, it incorporates a low profile, modular design, and smaller capacity hopper to fit better into cleanrooms. Additionally, it is powered by a direct drive system via AC vector motor and gearbox or energy efficient gearless torque drive motor, as opposed to a belt drive, preventing belt dust that can easily contaminate medical products.

This simpler drive system derives heavily from the engineering expertise Milacron applied to create the PowerPak line of all-electric injection molding machines. The elimination of oil, valves, hoses, etc. in these machines enhances cleanroom compatibility, requiring less housekeeping because of the avoidance of leaks.
 

The Milacron MPAK is one example of a machine designed specifically for medical extrusion.

Universal Control Software
Another benefit of choosing a manufacturer who produces both injection and extrusion machines is the ability to use universal, integrated control software.

Control software such as Milacron’s MOSAIC control system provides ways to improve consistency and quality, as well as achieve higher production capacity in both injection and extrusion machines. In essence, they can serve as the brain of the entire operation, monitoring and adjusting processes to ensure quality output.

Today’s best software can provide full production control, including:

• SPC monitoring and analysis
• Process alarms
• Slaved co-extruder speed control
• Process recipe storage with call- up capability
• Export process data to customer’s data collection system

Because control systems offer many ways to improve efficiencies, it is important to fully understand the capabilities of your software and know how to operate it effectively. Milacron and other manufacturers often provide comprehensive technical training to support extrusion machinery and processes, including control systems. Classroom and hands-on training can help ensure your system is being used to its fullest potential.

Understanding your control software will also help you link it into other operations, such as melt pumps and downstream equipment, in order to optimize, fully, the production process.
 

Integration
Multifaceted machine manufacturers are better able to integrate extrusion machines with downstream equipment to achieve the highest levels of precision. It is because of this integration that the entire system works together to accommodate any necessary adjustments in the process and maintain consistent quality.

For medical tubing, downstream equipment usually consists of a vacuum sizing tank, a cooling tank, and various types of pulling, cutting, and collection equipment. After extrusion, the tube pulls through the vacuum tank, which creates suction to form the tube and maintain its size. From there, it enters the cooling tank, and then into any auxiliary cutting or collection equipment.

Usually, extruders use laser or ultrasonic measuring devices to monitor variances in wall thickness, diameter, and other dimensions. By integrating these measurement signals with the other equipment, the control system can adjust different parts of the operation, as necessary, to ensure the meeting of specifications.

For example, consider a system that links its downstream equipment to an ultrasonic device in the vacuum tank that monitors wall thickness variations and a laser that measures O.D. variations. If those measurements deviates toward the high or low end of the tolerance, the control system can either speed up or slow down the puller to make corrections and change the diameter.

By monitoring signals coming from the different devices, the control system can usually adjust the process in real time, accommodating for any variances that occur, ensuring consistent, precise production, and reduced waste.
 

Finding the Right Partner
As the medical industry demands more advanced products, it is important for manufacturers to have the best technology – whether they are using injection machines or extrusion.

Machine manufacturers with broad engineering expertise in both injection and extrusion can help medical molders and extruders optimize their process, achieving the highest levels of precision. In today’s marketplace, you cannot look for a machine; you need to look for a manufacturing partner with the experience, technology, and technical support to help you meet even the most challenging demands both today and for years to come.

Milacron LLC
Cincinnati, OH
milacron.com