Micro Moulding – Designing Medical Devices for MIS

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Micro Moulding:
Meeting Design Challenges of Medical Devices for (MIS)

In his second contribution to Micro Manufacturing magazine, John Whynott analyses the use of micro moulding technology in the manufacture of medical products. Are you looking for new technologies to help reduce the complexity of minimally invasive surgical devices? Micro moulding technology can provide the technological edge you need.

John Whynott
Technical Product Manager
Mikrotech, Division of ASYST Technologies LLC
Kenosha, WI, USA

The rising cost of healthcare continues to be a concern for individuals, employers and benefit providers. Pressure to decrease the cost of medical treatment provides opportunities for medical device designers and manufacturers to develop lower cost products.

For over two decades, minimally invasive surgery (MIS) has made successful inroads reducing the costs of healthcare by permitting selected surgeries to be performed through small ports rather than large incisions, often resulting in shorter recovery times, fewer complications and reduced hospitalization costs. (MIS) has been widely adopted for certain surgical procedures, but it has not been widely adopted within complex surgical procedures. It is estimated that only 25% of all surgical procedures are performed minimally invasively. Manufacturers are seeking to design new devices that will allow open surgeries to be converted to minimally invasive procedures. These devices are highly complex yet they need to be cost-effective enough to be widely adopted.

One of the main contributors to the price of (MIS) devices is the cost to manufacture them. A large percentage of (MIS) devices are still manufactured using a microscope. The manufacturing of these devices requires highly skilled labor (artisans). To establish qualified personnel to perform these operations requires a long training period and a trained qualitative eye to determine if a completed process meets specifications.

A majority of the components used in (MIS) devices are machined from stainless steel, ceramic, plastic or glass and require secondary operations such as gluing, welding or surface coating to assemble the device. Many in manufacturing battle the complexity of assembling these miniature devices into a finished product. Obtaining an acceptable yield can often be a long and challenging battle. Machined components and the utilization of secondary operations place limitations on the size, complexity, and the material selection of (MIS) devices. As a result, manufacturing low to moderate volume (MIS) devices has been a costly challenge for (MIS) manufacturers.

The design and manufacturing of (MIS) devices, like all other products, is limited by the technology capable of producing them. Machining, molding and assembly limitations coupled with the trend toward miniaturization of medical devices provide an excellent opportunity to develop alternative manufacturing processes. We believe micro moulding technology is the solution. Advances in micro moulding technology and material science now make possible a range of cost-effective alternatives for components that are miniature, complex and require high precision tolerances.

Micro moulding technology has the potential to change the landscape of minimally invasive surgery. Micro moulding technology is still in the introductory stage of its product life cycle, therefore it is what I would like to call a disruptive technology. Medical device designers and manufacturers are just beginning to realize that there is a need for this technology and are looking to fill this technology gap. It will change the way designers and buyers look at developing new products and re-designing existing products. Micro moulding technology coupled with the trend toward miniaturization of medical devices and less invasive procedures will provide ample opportunity for designers to develop new and innovative products.

Advantages of using micro moulding technology
for (MIS) devices and instruments

There are a number of benefits that can be achieved using micro moulding technology for designing minimally invasive devices and instruments. In addition to the cost savings. Micro moulding technology can also provide (MIS) designers and manufacturers one or more of the following benefits:

Table 1. Benefits of using micro moulding for (MIS) devices
Benefits
Decrease the overall size of their products
Incorporate additional complex features
Reduce complexity of assembling the product
Reduce the number of components
Identify design and process innovations that lead to converting open surgical procedures
Dimensionally stable production process
No particle contamination
Use alternate resins or fillers to improve mechanical and/or electrical properties
Better surface finish
Likely reduction in part cost compared with other forming techniques

There are a number of ways micro moulding technology can be effectively incorporated into (MIS) devices. Here are a few examples of how micro moulding technology can offer solutions to some common manufacturing issues.

1. Medical devices that require visibility under an x-ray are typically made from metal. The density of the material provides the contrast needed to accurately locate the position of the device inside the body during the procedure. Plastic resins filled with radiopaque compounds can be visible under x-ray imaging and can be used to replace metal components. Materials typically added to base resins to add radiopacity are barium, bismuth and tungsten.

2. Medical devices that carry current (amperes) need to be isolated from the main body of the instrument. This additional component increases the diameter of the product. Moving to a molded plastic component can remove the need to add isolation to metal components thereby reducing the size of the device.

3. Plastic with metal or ceramic filler can be a suitable replacement for metal injection molding (MIM). It eliminates the need for secondary operations associated with metal injection molding (MIM).

4. Micro moulding can be suitably vertically integrated into an entire manufacturing assembly process that may include stamping, insert molding, bonding or conventional molding.

5. Ceramic is traditionally very brittle. If a device is dropped it could break rendering the entire device unusable. Substituting ceramic for a plastic resin with ceramic filler for ceramic can increase the toughness.

micro moulding technology can provide a significant impact to both existing and new (MIS) designs.

Existing (MIS) Devices.

For devices already in production micro molding technology can prolong product life with cost-effective upgrades, enhancements and other value-adding features providing a better defense to existing competitors products. This is accomplished by eliminating secondary operations that are extremely difficult to control such as gluing, coating and welding to name a few. Many of these secondary operations place limitations on material selection, size, complexity and quality of the device. Removing these secondary operations creates a more robust assembly. It also improves quality by reducing the reliance on artisans to manufacture product.

Attempting to convert existing products to micro moulding may appear to be difficult due to the nature of the undertaking. It can require a number of actions depending on the significance of the change. It may require as little as a 30 day notice for a process change or as much as a 90 day 510k submission that may require further information, including clinical data. Action items may include a cost and investment analysis, assistance from several functional departments, capital investment, testing and FDA approval. However, the benefits might far outweigh the undertaking required to convert to micro molding. Obviously not all potential conversions will have the same impact, however, it might behoove (MIS) manufacturers to review existing product lines and perform a cost and capital investment analysis to determine which products are good candidates for conversion. The cost savings might well justify placing strategic resources to those products that present a significant cost savings (benefit).

It may take a lot of effort to remove resistance to change once a product design is frozen and in production due to the amount of time and resources that were required to get there. If converting existing devices seems like an insurmountable task then taking the path of least resistance and switching over to micro moulding technology on new designs may be the best alternative.

New (MIS) Devices.

Micro moulding technology can provide a significant impact to new (MIS) products in the design and development stage. It can help produce the next generation product that can drive market leadership from within in your organization. It can help in getting the product right the first time and getting it to market on-time by reducing the number of start-up problems associated with manufacturing complexity.

micro moulding technology gives designers flexibility to design smaller more complex devices while not compromising manufacturability thereby enhancing their ability to create new and more innovative products and establish product leadership. If designers can enhance the performance of the device and/or add more features (benefits) to allow doctors to utilize the devices more effectively and lessen the trauma to the patient, the doctor will be more inclined to use the device again. It can also potentially increase the growth of the (MIS) market by creating products leading to the conversion of open surgical procedures to (MIS) procedures.

The next section will provide three case studies demonstrating how micro moulding technology can be utilized to produce more sophisticated (MIS) devices. The case studies will identify how existing manufacturing processes can be converted to micro moulding resulting in improved devices as well as cost savings.

Case Studies

Illustrated below are three examples currently under development that provide insight into the possibility of using micro moulding technology. The first example shows a direct conversion from machining to micro moulding while the following two examples show a conversion and the elimination of secondary operations. Please note that the illustrations of the components depicted in these case studies have been altered to protect the confidentiality of the customer.

Example 1

Example 1. This example illustrates a potential cost savings project we are currently working on with a medical device original equipment manufacturer (OEM). The component is part of a medical device used for a cardiology procedure. The device is currently in production. The component is machined from beryllium copper. We are proposing to convert to liquid crystal polymer (LCP). It is currently in production and has a life expectancy of another five years. The estimated annual usage (EAU) is 30,000. The company is paying $12.49. The equivalent cost for a micro molded component would be approximately $4.75.

This example uses net present value (NPV) for the cost and capital investment analysis. The NPV is based on a minimum 5 year life expectancy and a required internal rate of return of 10% (IRR). The project will have an immediate outlay of $39,000 for mould and inspection tooling and an estimated cost of $35,000 for product re-validation. The re-validation cost includes samples of the component, manufacturing product assemblies, performing design verification and submitting a 510(k) submission. A large commitment from the OEM is needed since it will draw a number of resources from functional departments such as purchasing, engineering and quality to complete the conversion. Figure 2 illustrates the potential cost savings for the project.

Figure 2 Part Description: Optical Ring - Beryllium Copper-LCPCash inflows (savings) are expected to be $232,200 for years 1 through 5. The net present value for the sum of the years is $806,221. That savings would double if the life reached ten years. Since the NPV is greater than zero the company should invest in this conversion project. The results show that the total savings would be enough to offset the costs associated with re-validation and seeking regulatory approval.

Example 2

Example 2 illustrates a potential cost savings project we are currently working on with a contract design house for a new device. The three components are part of a medical device used for a laparoscopic procedure. This device is currently in development but is a replacement for a device currently in production. Figure 3 Part Description: Process Flow w/InsulatorThe Body is metal injection molded, the Insulator is plastic injection molded and the Plate is stamped stainless steel. In the current process the Plate is glued to the Insulator and then the Plate/Insulator is glued to the Body. Figure 3 identifies the current process flow diagram. It has five process steps.

It is proposed to combine the body and insulator into one component and convert to LCP and simul– taneously insert mould the plate. Figure 4 Part Description: Proposed Process FlowFigure 4 exhibits what the process flow diagram would look like if micro moulding was introduced to the design and manu– facturing of the assembly. The proposed solution eliminates cost contributors such as ordering, carrying, assembly and design. The revised process flow eliminates four steps or 80% of the work. There would be one part to order vs. three, therefore only one part to carry and inventory. It eliminates the gluing operation entirely and simplifies the assembly of the device.

This new design is in the early stage of development, however, this approach will undoubtedly offer significant cost savings and drastically reduce the number of operations required to assemble.

Example 3 illustrates a potential cost savings project we are currently working on with a medical device original equipment manufacturer (OEM). The two components are part of a medical device used for a urology procedure. The device is currently in production. The Aperture is machined out of nickel and the Spacer is machined out of stainless steel. Figure 5 Part Description: Current Process Flow It is currently in production and has a life expectancy of another five years. The estimated annual usage (EAU) is 10,000. The company is paying approximately $12.00 for both components. The equivalent cost for a micro molded component would be approximately $2.85. Figure 5 identifies the current process flow diagram. It has five process steps.

Figure 6 Part Description: Micro Moulded Process FlowWe are proposing to combine the Spacer and Aperture into one component and convert to liquid crystal polymer (LCP). Figure 6 exhibits what the process flow diagram would look like if micro moulding was introduced to the manufacturing of the assembly. The proposed solution eliminates cost contributors such as ordering, carrying and assembly. The revised process flow eliminates two steps or 40% of the work. There would be one part to order vs. two, therefore only one part to carry and inventory. It eliminates the gluing operation entirely and simplifies the assembly of the device.

This example uses net present value (NPV) for the cost and capital investment analysis. The NPV is based on a minimum 5 year life expectancy and a required internal rate of return of 10% (IRR). The project will have an immediate outlay of $17,750 for mould and part removal/inspection tooling and an estimated cost of $30,000 for product re-validation. The re-validation cost includes samples of the component, manufacturing product assemblies, Figure 7 Part Description: Aperature Spacer Savings performing design verification and submitting a 510(k) submission. A large commitment from the OEM is needed since it will draw a number of resources from functional departments such as purchasing, engineering and quality to complete the conversion. Figure 7 illustrates the potential cost savings for the project.

Cash inflows (savings) are expected to be $91,500 for years 1 through 5. The net present value for the sum of the years is $299,107. That savings would double if the life reached ten years. Since the NPV is greater than zero the company should invest in this conversion project. The results show that the total savings would be enough to offset the costs associated with re-validation and seeking regulatory approval.

How to Get Started

Figure 8 So how do you get started? provides a simple six step process to help establish potential opportunities and allow you to make an informed decision on whether or not to utilize micro moulding technology for you (MIS) devices. Figure 8 Conversion Guidelines for (MIS) DesignersThe process flow chart and the net present value calculation are tools that can assist you with understanding the impact of converting to micro moulding and obtaining capital budget approval. The internal rate of return (IRR) is optional capital budgeting method that can be used.

Every company has a different internal rate of return (IRR). Contact your accounting department to find the value they find to be acceptable. Cost contributors may include non-value added activities, such as, material movements, inventory transactions, in-process inspection, labor reporting, labeling, etc. For simplicity these activities were not included in the examples but are very important to consider and collectively can add significant cost to the device.

Conclusion

Micro moulding technology can be an excellent lower-cost alternative to designing and manufacturing (MIS) devices. The technology can be utilised for both new and existing (MIS) devices, providing a solution to common hurdles now present in designing and manufacturing them. It may also provide the catalyst to move additional complex open surgical procedures to minimally invasive procedures.

As with any new technology there is scepticism as to whether or not it can work, and micro moulding technology is no exception. Since this technology is in its infancy, many designers and buyers have little or no experience with it. There is always an element of risk with any new technology and not all projects will be successful. However, to maintain product leadership, (MIS) designers and manufacturers need to stretch the limits of technology, both in products and processes. That is a company's chief strategic means of remaining a product innovation leader. Micro moulding technology allows (MIS) device designers and manufacturers the catalyst to innovate and create breakthrough products. Consider the benefits your company can achieve by utilising micro moulding technology in your (MIS) devices.

John Whynott is Technical Product Manager of Mikrotech a division of ASYST Technologies LLC. He was appointed to his current role in January 2004. Previously, he served as Engineering Manager and Project Engineer. John has six years experience in micro moulding and a combined 20 years experience in engineering and management. He earned a Bachelor's degree in mechanical engineering technology from the University of Wisconsin-Parkside and a Master's degree in engineering management from the Milwaukee School of Engineering.

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Mikrotech, LLC
9900 58th Place
Kenosha, WI

Tel 262.577.0232