Watch Buckle Made Of Titanium Alloy Lost-wax Casting

Lost-wax casting, also known as investment casting, is a precision casting method. Its basic principle is to first create a wax model with the same shape as the watch clasp, then coat the surface of the wax model with multiple layers of refractory material to form a monolithic shell. Next, the shell is heated, causing the wax model to melt and flow out, leaving a cavity inside the shell that matches the shape of the watch clasp. Finally, molten titanium alloy is poured into this cavity, and after it cools and solidifies, the shell is broken to obtain the desired watch clasp. This process can manufacture parts with complex shapes and high precision, making it ideal for products like watch clasps that require high dimensional accuracy and appearance quality.

Titanium alloy is an alloy composed of titanium as a base and other alloying elements. For watch clasps, titanium alloy has many advantages. First, its density is low, only about 60% of that of steel, making the watch lighter and reducing wrist strain. Second, titanium alloy has extremely high strength, capable of withstanding various external forces in daily use, ensuring the durability and reliability of the clasp. Furthermore, titanium alloys possess excellent corrosion resistance, making them less prone to rust and corrosion in humid or sweaty environments, thus extending the lifespan of the watch clasp. In addition, titanium alloys are biocompatible, skin-friendly, and suitable for people of all skin types, reducing the occurrence of allergic reactions.

Before the lost-wax casting of the watch clasp, careful design is required. The design process must fully consider the overall style of the watch, wearing comfort, and the functionality of the clasp. For example, the opening and closing mechanism of the clasp should be convenient while ensuring a secure closure. Based on the design drawings, a wax model of the watch clasp is made using wax material. The precision of the wax model directly affects the quality of the final product; therefore, high-precision machining equipment and skilled technicians are required. CNC machining and engraving methods can be used to create the wax model, ensuring that the dimensional accuracy and surface finish meet the requirements.

The completed wax model is fixed onto the sprue bar to form the mold assembly. The mold is then immersed in refractory coating, ensuring a uniform coating layer. A layer of refractory sand is then sprinkled on top, and this process is repeated several times to form a shell of a certain thickness. The quality of the shell is crucial to the casting quality, requiring sufficient strength, thermal stability, and permeability. Different combinations of coatings and sands affect the shell's performance and must be selected based on the characteristics of the titanium alloy and casting process requirements. During coating and sand application, careful control of the thickness and uniformity of each layer is essential to avoid defects such as bubbles and cracks.

Dewaxing and Firing: The mold with the shell is placed in a dewaxing device, where heating melts and removes the wax pattern. The dewaxing temperature and time must be carefully controlled based on the characteristics of the wax material and the shell thickness to ensure complete melting and removal of the wax pattern. After dewaxing, the shell is placed in a firing furnace for high-temperature firing. Firing removes residual wax and moisture from the shell, improving its strength and thermal stability. The firing temperature is generally between 800 and 1200℃, with the specific temperature and time determined based on the material of the mold and the casting process.

Titanium Alloy Melting and Casting: The titanium alloy raw material is heated and melted using a vacuum induction melting furnace. During the melting process, the melting temperature, time, and furnace atmosphere must be strictly controlled to ensure the chemical composition and purity of the titanium alloy. Because titanium alloys are highly chemically reactive and easily react with elements such as oxygen and nitrogen in the air, the melting process must be carried out under vacuum or inert gas protection. Once the titanium alloy is completely melted and reaches the appropriate casting temperature, it is quickly poured into the preheated mold. The casting process should be smooth and rapid to avoid defects such as incomplete filling or cold shuts.

Post-processing: After the titanium alloy cools and solidifies, the mold is broken, and the watch clasp is removed. The clasp is cleaned to remove mold residue and oxide scale from the surface. Sandblasting and polishing can be used for cleaning to achieve a smooth surface. Then, the clasp is dimensionally and visually inspected to ensure it meets design requirements. If dimensional deviations or surface defects are found, appropriate adjustments and repairs can be made. Finally, the end buckle can be surface-treated as needed, such as anodizing or electroplating, to improve its wear resistance, corrosion resistance, and aesthetics.