In a broad sense, automotive molds are a general term for molds used to manufacture all parts of a car. Examples include injection molds, stamping molds, forging molds, casting wax molds, and glass molds. When people talk about cars, the first thing that comes to mind is the car body. In other words, the car body is the iconic assembly of a car. The car body represents the image of the car. In a narrow sense, automotive molds are a general term for molds used to stamp all stamped parts on a car body, specifically "car body stamping molds." Examples include roof flanging molds and crossbeam stiffening plate stamping molds.
I. Classification of Automotive Plastic Molds
There are many ways to classify automotive plastic molds. Based on the different molding and processing methods of plastic parts, they can be divided into the following categories:
Injection Molds
Injection molds, also known as injection molding, are characterized by placing the plastic raw material in the heating cylinder of the injection molding machine. The plastic is heated and melted by the screw or plunger of the injection molding machine, and enters the mold cavity through the nozzle and mold gating system. Within the mold cavity, the plastic solidifies through heat preservation, pressure holding, and cooling. Because heating and pressurizing devices can function in stages, injection molding can not only form complex plastic parts but also boasts high production efficiency and quality. Therefore, injection molding accounts for a large proportion of plastic part molding, and injection molds make up more than half of all plastic molds. This injection molding machine is mainly used for molding thermoplastics, but in recent years it has also been increasingly used for molding thermosetting plastics.
Compression Mold
Compression molds, also known as compression molds or press molds, involve directly adding plastic raw materials into the mold cavity, followed by mold closing. Under heat and pressure, the plastic melts, filling the cavity with pressure. At this point, the plastic's molecular structure undergoes a chemical cross-linking reaction, gradually hardening. Compression molds are mainly used for thermosetting plastics, and their injection molded parts are primarily used for electrical switch housings and daily necessities.
Transfer Module
Transfer molds, also known as injection molds or extrusion molds, involve adding plastic raw materials to a preheated feeding chamber, then applying pressure to the plastic material in the feeding chamber using a pressing column. The plastic melts under high temperature and pressure and enters the mold cavity through the mold's gating system. Then chemical cross-linking occurs, and it gradually solidifies. Transfer molding is mainly used for thermosetting plastics and can be used to mold plastic parts with complex shapes.
Extrusion Dies
Extrusion dies are also called extruders. These dies can continuously produce plastics with the same cross-sectional shape, such as plastic pipes, rods, and sheets. The heating and pressurizing devices of the extruder are the same as those of the injection molding machine. Molten plastic forms continuous plastic parts after passing through the die head, resulting in high production efficiency.
In addition to the types of plastic molds listed above, there are also vacuum forming dies, compressed air dies, blow molding dies, and low-foaming plastic molds.
Stamped parts on automobile bodies are generally divided into body panels, frame parts, and general stamped parts. Automobile body panels are stamped parts that clearly express the image characteristics of the automobile. Therefore, a more specific automobile mold can be called an "automobile body panel stamping die," or simply an automobile body panel stamping die. Examples include front door outer panel trimming dies and front door inner panel blanking dies.
II. Classification of Automobile Stamping Dies
Of course, stamped parts on automobile bodies are not the only type. The molds used for all stamped parts on automobiles are called "automotive stamping dies." In summary, they are:
1. Automotive molds are the general term for molds used to manufacture all automobile parts.
2. Automotive stamping dies are the molds used to stamp all stamped parts on automobiles.
3. Body stamping dies are the molds used to stamp all stamped parts on the car body.
4. Automotive body panel stamping dies are the molds used to stamp all body panels on the car body.
III. Classification of Automotive Tire Molds
1. Activated molds consist of a mold ring, mold sleeve, and upper and lower side plates.
Difference between tapered guide dies and inclined guide dies
2. The two halves of a mold consist of an upper mold and a lower mold.
IV. High-Speed Cutting Technology for Automotive Molds
High-speed cutting technology has been widely used in the automotive mold manufacturing industry both domestically and internationally, achieving significant benefits. However, the mechanism and related theories of high-speed cutting are still incomplete. A database for high-speed cutting of automotive molds has not yet been established. Domestic and international companies still primarily rely on traditional trial-and-error methods and empirical approaches to select high-speed tool parameters and high-speed cutting parameters. When machining a new material, repeated cutting tests with various tools are often necessary. Researching and analyzing the methods and causes of tool wear and breakage to find an optimal set of tool materials and machining parameters is a repetitive, blind, and wasteful process involving significant human, financial, and material resources. For high-speed cutting of special materials such as alloy cast iron, high-strength alloy steel, and high-temperature alloys (e.g., titanium alloys), how to select suitable tools based on material characteristics and how to design reasonable cutting parameters remains under research and development.
High-speed machining technology is an advanced manufacturing technology of the 21st century, possessing strong vitality and broad application prospects. High-speed cutting technology can solve a series of problems that plague conventional cutting of automotive molds. In recent years, high-speed machining technology has been widely applied in most mold companies in industrialized countries such as the United States, Germany, and Japan, with approximately 85% of mold electrical discharge machining processes replaced by high-speed machining. High-speed machining technology, integrating high efficiency, high quality, and low consumption, has become the mainstream of international mold manufacturing technology.
Through practical applications in the domestic and international automotive mold manufacturing industry, high-speed cutting technology offers the following advantages:
1. Increased Processing Speed: High-speed cutting on automotive molds achieves speeds approximately 10 times faster than conventional cutting. Because the excitation frequency of the high-speed machine tool spindle far exceeds the inherent frequency range of the machine tool-workpiece system, the automotive mold processing is smooth and impact-free.
2. High Production Efficiency: Using high-speed machining centers or high-speed milling machines, roughing and finishing of the mold surface and the processing of other automotive mold parts can be completed in a single setup-a process known as one-time machining. The application of high-speed cutting technology significantly accelerates the development of automotive molds.
3. High-Quality Machining Achieves High-Quality Machined Surfaces: Due to the extremely small number of steps and cutting depth, high-speed cutting can achieve high surface quality, even eliminating the need for manual polishing.
4. Simplified Process Flow: Conventional milling can only be performed before quenching, and deformation caused by quenching must be manually corrected or ultimately shaped by electrical discharge machining (EDM). This can now be accomplished through high-speed machining without the surface hardening caused by EDM. Furthermore, due to the reduced cutting volume, high-speed machining allows for the use of smaller diameter tools to process smaller corner radii and mold details, eliminating some machining or manual trimming steps and thus shortening the production cycle.
5. High-speed cutting makes automotive mold repair more convenient.
Automotive molds often require multiple repairs during use to extend their service life. High-speed cutting allows for faster completion of tasks, achieving a grinding-instead-of-grinding effect. The original NC program can be used without reprogramming, and it maintains high precision.
6. High-speed cutting can process complex-shaped hard automotive molds.
The mechanism of high-speed cutting shows that the cutting force is greatly reduced during high-speed cutting, making the cutting process easier. High-speed cutting has significant advantages in cutting high-strength, high-hardness materials, and can process materials with complex shapes and relatively high hardness.