Lost Wax Castings
Many casting techniques permit manufacturers to duplicate metal parts. Lost wax castings provide a way to obtain finely detailed cast replicas of original works of art, jewelry, and prototypes.
Archaeologists today believe lost wax casting as a manufacturing process dates back thousands of years, possibly to the Bronze Age. Some of the world’s most famous artists, including the French sculptor Francois Auguste Rodin (1840-1917), frequently used this method of casting to create celebrated works of art.
The time-consuming and labor-intensive aspects of this form of casting caused it to fall out of favor as a primary industrial casting technique in modern mass production environments. However, manufacturers do still sometimes rely on lost wax casting today to replicate works of fine art and to create prototypes.
Lost Wax Casting Process
Lost wax casting enables a manufacturer to reproduce models in exact detail. Essentially, it involves duplicating an item in wax, then “losing” the wax to create a space for molten metal.
“Lost wax” casting occurs in two basic forms: solid core or hollow-core reproduction. The manufacturer creates either a solid wax model (for solid core patterns) or a wax copy of a clay model (for hollow core patterns).
steps used in casting
Lost wax casting requires multiple steps to complete. First, a manufacturer produces a model for reproduction. This item may consist of stone, metal, wood, plaster or clay.
Artisans create an impression of a non-wax model by placing it inside a hard gated outer mold filled with soft, easily compressed material. This mold may consist of two halves, one for the front and the other for the rear of the object. Workers press fireproof clay into the depression(s), re-creating the outlines of an original three-dimensional model.
Next, the manufacturer selectively removes a thin layer of material from the exterior of the newly-formed clay mold. When placed within the original impression of elastic material, a slight gap appears between the original impression and the now-reduced clay mold. The manufacturer then closes both sections of the hard outer mold around the clay model, completely enclosing it inside before pouring hot molten wax into the closed mold. The mold usually rests upside down during this process.
Wax congeals around the clay, creating a wax model for a hollow core pattern reproduction. (Using a solid wax model directly permits solid core pattern reproductions.)
Craftsmen construct a detailed structure of gates and vents called “sprues” along the exterior. (These channels will permit the exit of melted wax later.) The manufacturer coats this assembly with fine plaster or ceramic material before applying heat, usually by placing the mold in a kiln. Rising temperatures melt the wax, causing this material to flow from the model through the attached sprue channels.
The manufacturer subsequently applies a thin metal layer of cladding to the mold (excluding the gate). This material when dried will protect the outline of the mold.
Finally, workers pour a hot molten metal slurry into the mold through the gate, filling the space formerly occupied by wax. After this substance cools, the manufacturer cuts (or sandblasts) away from both the cladding and the ceramic or plaster covering to reveal a finely detailed “lost wax” casting. A process called “metal-chasing” involves completing the removal of any remaining sprues and gates from the workpiece.
Lost Wax and Investment Casting
Conventional lost wax casting holds disadvantages in modern mass production settings. This form of casting requires a significant commitment of labor and time, factors which increase production costs.
Possibly, for this reason, the more streamlined process of investment casting utilizing expendable ceramic molds today takes precedence over lost wax casting in generating high volumes of detailed metal parts and components for industrial purposes. Xinwo Ltd possesses the capabilities to use both lost wax casting and investment casting, offering more available options to customers.
For example, a designer may request the use of lost wax casting to create several prototype models of a product. Once a customer decides to proceed with a specific design, investment casting may help generate high-quality ceramic molds for use in the production of the model in larger quantities. By choosing Xinwo Ltd to assist your firm in the fabrication of prototypes and final product lines, you’ll gain flexibility and access to the most cost-effective fabrication processes.
Lost wax casting retains popularity as a way to create jewelry, as well as small decorative metal items e.g. custom-designed belt buckles, brooches, accent logos or sculpture reproductions. Variations of lost wax casting techniques also sometimes assist companies in completing dental restorations.
Advantages of Lost Wax Casting
The advantages of lost wax casting include the ability to replicate highly intricate and detailed patterns in metal, that are reliable and durable. Additionally, manufacturers can employ this form of casting using a variety of different mold making materials. Lost wax casting offers both flexibility and design freedom.
This casting technique does require extensive time to perform correctly. An error at any point in the process of creating a lost wax casting may require the repetition of previous production stages. For this reason, this casting technique remains labor-intensive. It requires skilled production personnel.
Yet despite its potential drawbacks, in some situations lost wax casting has become the manufacturing technique of choice. It sometimes proves particularly useful in cases involving limited production volumes or prototype construction. Manufacturers can employ lost wax casting to reproduce very fine details in metal dependably. Jewelry makers and artists still rely extensively on this ancient casting process.