When you need to consider the selection of materials for a new product, or when you need to change the design of a product due to unforeseen circumstances, you may choose plastic instead of metal. Compared with metal materials, plastic can provide a better solution for many reasons. Plastic replacement of metal means using high-performance engineering plastic parts to replace traditional metal parts without sacrificing product quality and performance, so as to simplify product structure, reduce product costs and achieve product lightweighting. The demand for lightweight, high strength, corrosion resistance and long life is increasing. Metal parts are often gradually replaced by plastic parts due to their high cost, long manufacturing cycle and difficulty in meeting the needs of complex shapes.
Advantages of replacing metal parts with plastic parts
When selecting a material for a part that requires strength, durability, and the ability to withstand a variety of stresses (impact, shear, tensile, and warping stresses), metal was once the primary solution. With modern technological advances in finite element analysis (FEA), composite engineering, and precision injection molding processes, converting parts from metal to plastic has become a viable, economical, and popular solution.
Using plastics not only reduces part weight and manufacturing costs, but also increases design flexibility by reducing manufacturing operations. Using scientific methods to manufacture plastic parts comparable to metal parts can produce parts with the same structural integrity, with additional advantages such as chemical resistance and electromagnetic (EM) and radio frequency (RF) shielding.
There are studies that show that by using engineering-grade materials with proper structural design, plastic parts can actually be stronger than metal parts. The ability to shape structural strength features such as ribs, bosses, and gussets at the time of initial production (rather than later fastening, welding, and bonding) increases the overall strength of the assembled part and reduces additional costs.
Why can engineering plastics replace metals?
Engineering plastics are a rising star. They not only retain the excellent properties of ordinary plastics, but also have better high temperature resistance and mechanical strength than ordinary plastics.
- High performance: Modified plastics are one of the best varieties of engineering plastics with high temperature resistance, and their heat deformation temperature is generally above 260°C. In addition, it also has the advantages of small molding shrinkage, low water absorption, excellent fire resistance, vibration fatigue resistance, and strong arc resistance. Especially in high temperature and high humidity environments, it still has excellent electrical insulation, so it can replace metal as an engineering material in many application fields.
- Light product quality: The specific gravity of ordinary engineering plastics is about 1.34~2.0, which is only 1/9~1/4 of steel and about 1/2 of aluminum. This characteristic of engineering plastics is especially important for mechanical equipment such as vehicles, ships, and aircraft that need to reduce weight.
- High strength: For the same volume of materials, the strength of engineering plastics is usually lower than that of metals, but because plastics are much lighter than metals, when compared with metals, engineering plastics are much stronger than ordinary metals. Among existing structural materials, its strength is the highest.
- Convenient processing: Plastic products can be formed in one step, while metal products may have to go through several, dozens, or even dozens of processes to complete. This feature of plastics is very important for saving working time and improving production efficiency. In addition, it is relatively simple to use CNC machining or injection molding for plastics.
Issues to consider when replacing metal parts with plastic parts
Metal and plastic materials have their own advantages and disadvantages, and the right material needs to be selected according to the specific application requirements. Research and development of technologies that can achieve mutual conversion between metal and plastic in the industry will bring broader ideas for future development. Therefore, there are several basic issues to consider when using plastic materials to replace metal materials.
Performance issues
Compared with metal parts, plastic parts are usually 50% lighter. Although plastics can provide certain performance properties that metals cannot surpass, in some parts that need to withstand considerable pressure or meet very specific performance requirements, it is necessary to test whether parts made of plastic materials can really replace metal parts. For example, applications that need to absorb shock and withstand corrosive elements and heat resistance are very important.
Multi-component merging
Although plastic materials can produce parts with complex geometries through processes such as injection molding, including bosses, ribs, holes, threads, bottom cuts and ports, which have strict tolerances. However, many applications on the market currently require multiple parts to be merged or assembled to meet the requirements. Therefore, it is necessary to consider whether the overall performance of the parts made of plastic materials after assembly can meet the design requirements.
Design flexibility
It is difficult to create complex designs in metal without complex injection molds that require a lot of development time. For example, when you want to create a part with narrow corners or thin-walled designs, you also need to consider whether the part can meet the performance requirements using plastic.
Legality
Although the corrosion resistance and environmental protection of engineering plastics have been improved, in some areas, plastics or additives in manufacturing may cause environmental problems. Another problem may be related to regulated materials. Even if plastics are not processed, they may bring other restrictions. Exporting to areas that restrict easy pollutants may be troublesome. You can replace the part with metal and the regulatory restrictions will not be too great.
Ultrasonic Seamless Welding of High-Performance Plastic Parts
Many of Elimold’s customers are interested in reducing the cost of producing parts, especially those made from thermoplastics. Applying full heat is not an option because it causes the plastic to warp and deform along the weld. Using our ultrasonic welding service, safe, effective and very durable welds are provided without direct heat. The following is a summary of questions for ultrasonic welding services.
- Does the base plastic melt to form the weld?
No. With ultrasonic welding, small bumps are formed into the parts to be joined, directing the energy into place. These points are heated and form the joint under applied pressure. The plastic base material does not melt and therefore does not deform. Small spikes are carefully placed along the edges to provide a complete seal.
- Is ultrasonic welding better than glue?
With our ultrasonic welding service, the end result is a plastic joint that is not only stronger than glue, but also lasts longer without deteriorating. Not only is it more durable, but the process is faster: the parts are completely welded together in less than a second. The process can also be fully automated, making the process more efficient.
- Can ultrasonic welding be used for all plastics?
In general, ultrasonic welding can be used for all thermoplastics from thin to medium thickness. To avoid heating the substrate, the weld must be made very quickly, which makes thick plastics a problem.
However, ultrasonic welding can be used for two different types of plastics. However, the characteristics of the two plastics must be carefully considered to ensure that the process can produce the necessary weld strength.
Summary
Plastic parts are usually made of excellent engineering plastics. With its advantages of low cost, light weight, high strength, corrosion resistance and long life, it is gradually becoming a perfect substitute for metal parts. It is widely used in industries such as automobiles, electronics, aerospace, medical devices and construction. With the continuous development of technology, we have reason to believe that engineering plastic parts will play a more important role in the future manufacturing industry. Whether you need metal or plastic parts, you can contact Elimold to serve you.