Small Worm Gear Titanium Alloy Lost-wax Casting

● Mold Design and Manufacturing: Based on the size, shape, and precision requirements of the small worm gear, a mold for pressing the wax model is designed and manufactured. The mold needs to have a high-precision cavity to ensure that the wax model accurately replicates the shape of the worm gear.

● Wax Material Selection and Treatment: Select a suitable wax material for lost-waste casting. Generally, the wax material should have good fluidity, low shrinkage, and moderate strength. The wax material is heated and melted to remove impurities and gases, ensuring its purity.

● Wax Model Pressing: The molten wax material is poured into the mold cavity. Under certain pressure and temperature conditions, the wax material fills the cavity. After the wax material cools and solidifies, the mold is opened, and the wax model is removed. The wax models are trimmed, removing burrs, flash, and other excess material to ensure dimensional accuracy and surface quality.

● Wax Model Welding: Multiple wax models are welded to the sprue bar to form a wax model assembly. During welding, ensure the connections between wax models are secure and accurately positioned to allow molten metal to smoothly fill each wax model cavity during subsequent casting.

● Model Assembly Inspection: A comprehensive inspection of the assembled wax model assembly is conducted, including dimensional accuracy, surface quality, and connection strength. Any wax models that do not meet requirements are repaired or replaced promptly.

● Coating: The wax model assembly is immersed in coating material, ensuring the coating evenly covers the surface. The coating typically consists of refractory materials, binders, and additives, and its performance directly affects the quality of the shell. Depending on different process requirements, multiple coating applications may be necessary, with sanding performed after each application to increase the shell's thickness and strength.

● Drying and Hardening: After coating and sanding, the shell is placed in a drying chamber for drying and hardening. During the drying process, temperature, humidity, and ventilation must be carefully controlled to ensure uniform drying of the mold shell and prevent defects such as cracks and deformation.

● Dewaxing: The dried and hardened mold shell is placed in a dewaxing device. Heating melts the wax model, causing it to flow out of the mold shell and forming a cavity inside the shell that resembles the shape of a small worm gear. Temperature and time must be carefully controlled during dewaxing to prevent damage to the mold shell due to excessive heat.

● Titanium Alloy Smelting: Select suitable titanium alloy raw materials and prepare the batches according to alloy composition requirements. Add the batches to a vacuum induction melting furnace and melt under vacuum or inert gas protection to ensure uniform alloy composition, remove impurities and gases, and guarantee the quality of the titanium alloy.

● Casting: Once the titanium alloy has reached the appropriate temperature and fluidity, it is quickly poured into the preheated mold shell. The pouring process requires careful control of pouring speed, pouring temperature, and pouring pressure to ensure the molten metal completely fills the mold shell cavity and prevents defects such as incomplete filling and cold shuts.

● Shell Cleaning: After the casting has cooled and solidified, the shell is removed using methods such as mechanical vibration and sandblasting. Care must be taken to avoid damaging the casting surface during cleaning.

● Heat Treatment: The cleaned small worm gear titanium alloy casting undergoes heat treatment to improve its microstructure and properties. Common heat treatment processes include solution treatment and aging treatment; specific process parameters are determined based on the titanium alloy composition and application requirements.

● Machining and Inspection: The casting is machined according to the final dimensions and precision requirements of the small worm gear, using methods such as turning and grinding. After machining, a comprehensive inspection of the worm gear is performed, including dimensional accuracy, surface roughness, hardness, and metallographic structure, to ensure the product meets quality standards.

Titanium alloys are chemically reactive and easily react with elements such as oxygen and nitrogen in the air, leading to a decline in alloy properties. The solution is to employ advanced melting technologies such as vacuum induction melting, and strictly control the atmosphere during the melting process to ensure the quality of the titanium alloy.

The quality of the mold shell directly affects the quality of the casting. Defects such as cracks and deformation are prone to occur during the mold shell manufacturing process. The solution is to optimize the coating formula and coating process, control drying and hardening conditions, and improve the strength and stability of the mold shell.