Hello and welcome to a new blog post. Today I present to you a metal replacement roadmap which contains five major steps and when all steps are followed, success in metal replacement will be secured.
Why Change from Metal to Plastic?
There are many reasons to consider changing from metal to plastic. Some of the most important benefits include:
Part consolidation and function integration: Plastic parts can be designed to integrate multiple functions into a single part, which can save on manufacturing and assembly costs.
Weight saving: Polymer have a lower density compared to metals, so switching to plastic can help to reduce the weight of products.
Lower processing costs: Plastic parts can be manufactured using a variety of processes, such as injection moulding, which can be less expensive than metal forming processes.
Fewer or no secondary operations: Plastic parts often do not require secondary operations, such as painting or finishing, which can save on manufacturing costs.
Freedom and flexibility of design: Plastic can be molded into a variety of shapes and sizes, which gives designers more freedom to create innovative products.
Corrosion resistance: Plastic is resistant to corrosion, so it is a good choice for products that will be used in harsh environments.
Surface aesthetics, color aspects, markability: Plastic can be easily colored and marked, which makes it a good choice for products where aesthetics are important.
NVH reduction: Plastic can help to reduce noise, vibration, and harshness (NVH) in products.
Possibility to reduce the product carbon footprint; lead free material solutions
Metal to plastic conversion roadmap
As outlined before, replacing metal components with plastic ones offers several benefits, including reduced weight, lower costs, and improved design flexibility. However, the process requires careful planning and execution to ensure optimal results. This roadmap (Figure 1) outlines the key steps involved in efficient metal replacement:
1. Metal Part Identification
2. Polymer Material Selection
3. Design and Engineering
4. Prototyping
5. Production
Figure 1: 5 Step Metal to Plastic Conversion Roadmap.
What are the 5 steps leading to successful metal to plastic replacement?
1. Metal Part Identification
Identify the specific metal components targeted for replacement.
Define the objectives and required outcomes for the replacement.
Outline the preliminary requirements and boundary conditions for the new plastic component.
2. Polymer Material Selection
Choose the most suitable polymer material based on the application requirements.
Consider factors such as mechanical properties, chemical resistance, and thermal stability.
3. Design and Engineering
Develop a detailed CAD design for the plastic component.
Conduct CAE virtual testing and simulations to evaluate the design's performance.
Refine the design based on the simulation results.
4. Prototyping
Create a prototype tool for the plastic component.
Produce molded parts using the selected polymer material.
Perform thorough testing on the parts to ensure they meet the required specifications.
5. Production
Release the final part design for serial production.
Manufacture the plastic components at scale.
By following this roadmap, you can ensure a smooth and successful transition from metal to plastic components.
How a metal replacement project can look like
Example Medical Device Metal replacement
The following example explains the replacement of surgical retractors (Figure 2), used in total hip replacement replacement (THR) surgeries as a case study for metal-to-plastic conversion. In general, replacing metal with plastic can improve performance and reduce costs in medical devices. High-performance polymers such as PEEK, Polysulfones, and PARA offer similar strength and stiffness to metals, with added benefits.
Figure 2: Surgical hip retractor as an example of metal-to-plastics conversion [1].
1. Metal Part Identification
Orthopedic surgery retractors are traditionally made from metal due to the high strength and stiffness required. The document provides a comprehensive account of converting both single-use and reusable retractors to polymer-based designs using polyarylamide (PARA) and polyaryletherketone (PAEK), respectively.
2. Polymer Material Selection
For medical devices, essential performance requirements include chemical resistance and the ability to withstand sterilization processes, such as steam autoclaving or gamma radiation.
Material selection for both single-use and reusable retractors involves aligning with boundary conditions related to sterilization requirements and usage cycles.
PARA (Ixef GS-1022), reinforced with 50% glass fiber, is selected for single-use retractors due to its exceptional strength, compatibility with gamma radiation sterilization, and superior surface finish. It delivers performance levels comparable to stainless steel (in this case 17-4 steel) and can be injection molded, eliminating machining processes and reducing costs.
For reusable retractors, PAEK (AvaSpire AV-651 GF30) is the material of choice, offering a high stiffness-to-weight ratio, hydrolytic stability at elevated temperatures, chemical resistance, and durability even after repeated exposure to disinfectants and steam sterilization. Its ease of processing through injection molding and design versatility further highlight its suitability.
3. Design and Engineering
To replicate the stiffness of metal counterparts in plastics, adjusting the area moment of inertia through design modifications, such as using rectangular geometries or adding ribs was needed. Advanced design using computer-aided engineering (CAE) leverages plastic’s inherent advantages to enhance aesthetics and ergonomics, improving the overall device performance and user experience. A notable design modification for the hip retractor includes optimizing the handle for improved grip and stiffness.
4. Prototyping
Prototyping is crucial in evaluating the feel and functionality of new designs, with 3D printing techniques like selective laser sintering (SLS) employed to create initial prototypes. Validation processes for single-use and reusable plastic retractors involve testing to ensure performance metrics match or surpass those of the original steel retractors. Both plastic versions offer significant weight reduction, decreasing the overall weight of surgical equipment. Additionally, transitioning to plastic reduces the cost of reusable retractors by half and enables economically viable single-use designs.
5. Production
Manufacturing decisions favor injection molding for its cost-effectiveness in large volumes, design flexibility, and quick production turnaround, particularly given the estimated demand for hip retractors over three years.
Metal replacements with high-performance polymers in the medical industry are expanding. Plastic material suppliers, manufacturers, and designers are increasingly focusing their efforts on integrating plastics into medical device designs. Through this transition, the industry aims to meet the dual objectives of enhancing device performance and reducing costs in response to the evolving landscape of healthcare and technology.
Conclusion
Replacing metal components with plastic ones offers several benefits, including reduced weight, lower costs, and improved design flexibility. However, the process requires careful planning and execution to ensure optimal results. The discussed 5-step roadmap outlines the key steps involved in efficient metal replacement.
Interested in assessing the feasibility of metal replacement in one of your components?
No comments:
Post a Comment