Material Insights: Understanding the Working Principle, Structure, and Classification of Thermoforming Machines

A thermoforming machine is a device used to heat thermoplastic sheets and form them into specific shapes using a mold. The molded plastic becomes the final component after cooling and trimming. Modern thermoforming machines typically feature functions such as heating, stretching, forming, trimming, and cutting, while the cooling and trimming processes in traditional equipment are often completed externally.

This equipment is widely used in the packaging production of products such as food, agricultural products, pharmaceuticals, daily necessities, consumer goods, and household appliances. It is also suitable for the manufacturing of durable components such as aircraft parts, material handling equipment, automotive interiors, and medical devices.

The core process principle of a thermoforming machine is thermoplastic forming, which mainly includes two basic steps: heating and forming. First, the heating device composed of radiant heaters heats the plastic sheet, softening it to a pliable state. When the sheet is sufficiently flexible, it is drawn into the mold by vacuum pressure, and under this pressure, the sheet takes on the shape of the mold. After solidification, the desired shape of the product is obtained.

Automatic feeding system: Responsible for conveying raw materials such as plastic rolls to the machine's processing position, ensuring continuous supply of materials. Common automatic unwinding devices can provide sheets for subsequent processing according to the set speed and length.

Heating system: Common heating devices include infrared heaters, etc. The heating zone is usually divided into multiple independently controlled areas, allowing for zoned temperature control based on the shape and thickness variations of the sheet material to ensure uniform heating.

Clamping device: In a continuous sheet-drawing thermoforming machine, the clamping action relies on the coordinated operation of the chains on both sides and the front and rear gates, ensuring that the sheet remains stably positioned during high-speed operation for subsequent heating and forming processes.

Vacuum system: composed of a vacuum pump, air storage tank, control valves, connecting pipelines, and vacuum pressure gauges, its function is to rapidly suction the heated and softened plastic sheet onto the mold surface to achieve precise forming.

The compressed air system plays an important role in certain specific processes, such as assisting in demolding and cooling the molded products.

Mold and forming system: including the upper mold assembly, lower mold plate, etc., is the key part that determines the final shape and size of the product. By changing different molds, products of various shapes and specifications can be produced.

Cutting mechanism: Used to cut the formed products from the sheet, typically utilizing a die-cutting system, which can perform precise cutting according to the shape and size of the product.

Control System: Utilizing a pneumatic system as the primary power source, combined with electric drives, reduction devices, time relays, intermediate relays, and limit switches, to build a highly efficient and stable fully automatic control system capable of precisely controlling the sheet pulling length, heating time, forming cycle, and cutting actions.

Classified by the number of workstations

Single-station thermoforming machine: The structure is relatively simple, and only one forming operation can be completed in a single work cycle. It is suitable for the production of small batches or products with simple shapes, or for prototyping and testing of new products.

Multi-station thermoforming machine: capable of efficiently completing multiple processes such as forming, punching, and cutting simultaneously. It offers high production efficiency, significantly improves work efficiency, reduces labor and production costs, and is widely used in industries such as hardware, food packaging, medical packaging, and cosmetics.

Classification by drive type

Hydraulic-driven thermoforming machine: A hydraulic pump pressurizes hydraulic oil, which is then delivered through pipelines into a hydraulic cylinder to drive the movement of the piston, thereby applying and releasing pressure on the mold. The pressure and flow can be precisely controlled, ensuring the stability of the forming process and the quality of the product. It is commonly used in situations where high forming precision and pressure requirements are needed.

Servo-driven thermoforming machine: adopts advanced servo motor drive, featuring digital operation and high precision. The entire machine has no cam or hydraulic cylinder, avoiding the issues of cam wear and difficult maintenance, as well as the hygiene and control problems of hydraulic presses. It enables more accurate motion control and higher production efficiency.

Classification by forming method

Vacuum thermoforming machine: It mainly relies on vacuum negative pressure to adsorb the heated and softened plastic sheet onto the surface of the mold for forming, suitable for products with relatively shallow forming depth and simple shapes.

Positive and negative pressure thermoforming machines: In addition to utilizing vacuum negative pressure, compressed air can also be applied to exert positive pressure, allowing the plastic sheet to be subjected to bidirectional pressure within the mold. This enables the forming of deeper and more complex shapes, improving product quality and forming effectiveness.