Thermoforming is a method of manufacturing products using thermoplastic sheets as raw materials. The typical forming process is as follows: first, a certain size and shape of sheet material is clamped on the frame of the mold, heated to a high elastic state of Tg~Tf, the sheet material is heated while extending, and then pressure is applied to make it closely adhere to the surface of the mold, thereby obtaining a shape similar to the surface. After cooling, shaping, and trimming, the product is obtained. During hot forming, the applied pressure is mainly achieved by vacuuming and introducing compressed air to form a pressure difference on both sides of the sheet, which can also be achieved through mechanical pressure and hydraulic pressure.
With the continuous development of production technology, hot forming equipment has gradually moved away from being just an independent plastic sheet forming system, and has begun to combine with other production equipment to form a complete production line that meets specific needs, thereby further improving production efficiency and reducing the production cost of the final product.
Injection molding, also known as injection molding, is a basic injection molding method that involves adding polymer pellets or powders into the barrel of an injection molding machine, heating, compressing, shearing, mixing, and conveying them to homogenize and melt them. Then, with the help of a plunger or screw, pressure is applied to the melted polymer melt, and the high-temperature melt is injected into the pre locked mold cavity through the nozzle in front of the barrel and the gating system of the mold. After cooling and shaping, the mold is opened and ejected to obtain plastic products with a certain geometric shape and accuracy.
Injection molding is one of the most important plastic processing methods.
In recent years, injection molding technology has increasingly introduced the concept of system integration, integrating material processing before injection molding, as well as product inspection, assembly, packaging, and other processes after injection molding into the production process with a systematic and intelligent manufacturing approach, forming a set of modular manufacturing systems.
Hot forming vs. injection molding
cost
Usually, people first consider costs, and there are some related factors involved in costs.
Hot forming has low mold costs;
The cost of hot forming molds is significantly lower than that of injection molding molds.
Hot forming, especially pressure forming, has significant cost efficiency in forming large parts, especially when mold cost may be the biggest obstacle to injection molding. Although the cost of pressure forming is low, it does not sacrifice the quality of the product. Plastic thermoforming can achieve an extremely elegant appearance similar to cosmetics, and both the appearance and feel can meet the expectations of end users.
The size of plastic parts is also a consideration factor for mold cost. As the size increases, the difference between the cost of hot forming molds and injection molding molds becomes greater. As the size of the parts increases, the economy of hot forming becomes better. When forming very large products, the advantages of hot forming are prominent. For example, parts as large as 1200 * 2400mm can be formed.
Injection molding has the advantage of single piece cost in very high batches.
Injection molding has great advantages for extremely large batches of small parts. Of course, there are exceptions. When a small component has a very thin wall thickness, hot forming exhibits its special advantages.
Material costs are also an important factor that cannot be ignored.
Due to the need for high-quality plastic sheets, the raw material cost of hot forming may be 50% higher than other methods.
The energy consumption during the manufacturing process needs to be considered.
During the processing, plastic sheets are in a flexible state and may break due to excessive stretching at a certain temperature, which can lead to waste and increase processing costs.
efficiency
For the manufacturing industry, efficiency is an important factor that cannot be ignored. This involves specific production efficiency, but what cannot be ignored is the efficiency of product development and market launch.
When product launch time is an important consideration, hot forming has significant advantages.
Hot forming often achieves the best delivery speed. Once the design is confirmed, hot formed products can usually be submitted within a month, which is generally not possible for injection molding.
During the design phase, product validation and adjustment are more efficient and flexible.
Pressure forming and hot forming molds are easier to modify than injection molds because the vast majority of edge trimming is directly modified using a 5-axis machining center, and many secondary trimming adjustments only need to be completed by modifying the program. In addition, the modification of aluminum hot forming molds is easier than the adjustment of steel injection molds.
If you need design assistance or want to verify different options, hot forming is a more flexible and cost-effective design option. This is particularly suitable for situations where there is no previous manufacturing experience to refer to, and it is more beneficial for modifying future designs.
Hot forming can usually achieve faster product launch requirements. The typical delivery time for hot forming molds and samples is usually within 6-8 weeks.
Thermoforming makes it easier to achieve a variety of choices in appearance, fabrics, patterns, and more.
The stability of the production system in the mass production process is crucial.
This requires specific product analysis. Both molding methods can achieve very high manufacturing efficiency.
