What is Lost wax casting?

Lost wax casting‌ (also known as ‌investment casting‌) is a highly precise ‌metal casting process‌ that produces near-net-shape components with exceptional dimensional accuracy. As one of the oldest ‌metalworking techniques‌, it dates back thousands of years in China and remains a cornerstone of modern ‌precision casting manufacturing‌.

‌The Evolution of Lost Wax Casting Technology‌

Since the 1990s, Chinese ‌foundry engineers‌ have revolutionized ‌lost wax casting processes‌ by integrating advanced technologies from around the world. These innovations have significantly expanded ‌industrial applications of investment casting‌, making it a preferred method for industries requiring ‌high-precision metal parts‌, such as:

  • ‌Aerospace‌ (turbine blades, engine components)
  • ‌Medical‌ (surgical implants, dental prosthetics)
  • ‌Automotive‌ (fuel injection systems, turbochargers)
  • ‌Industrial Machinery‌ (pump housings, valve bodies)

‌Our Expertise in Precision Lost Wax Casting‌

At ‌Sipx Casting Foundry, we specialize in delivering ‌high-quality investment castings‌ through:

✅ ‌Advanced Process Design‌

  • Optimized ‌wax pattern creation‌ for complex geometries
  • Custom ‌ceramic shell molding‌ techniques
  • AI-assisted ‌casting simulation‌ for defect prevention

✅ ‌Strict Quality Control‌

  • ‌Dimensional tolerances‌ as tight as ±0.005mm
  • ‌X-ray & CT scanning‌ for internal defect detection
  • ‌Material testing‌ to ensure superior mechanical properties

✅ ‌Proven Industry Applications‌

  • Over ‌200+ successful casting projects‌ across multiple sectors
  • Case studies demonstrating ‌cost-effective casting solutions‌
  • Continuous R&D to enhance ‌casting efficiency and durability‌

‌Why Choose Lost Wax Casting?‌

Compared to other ‌metal forming processes‌, ‌investment casting‌ offers:
✔ ‌Minimal machining required‌ (near-net-shape production)
✔ ‌Superior surface finish‌ (reducing post-processing costs)
✔ ‌Wide material compatibility‌ (stainless steel, superalloys, titanium)

ss304 Lost Wax Casting faucet

ss304 Lost Wax Casting faucet

Lost wax casting mechanic parts

Lost wax casting mechanic parts

ss304 Lost Wax Casting kitchenware

ss304 Lost Wax Casting handle

 
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Lost wax casting manufacturing processes

Lost wax mold design

Step 1: Lost wax mold design

According to the requirements of the casting parts drawing to design mold.

Lost wax mold

Step2: Manufacturing mold:

According to the mold tooling design drawings to manufacture molds. the mold material normally is iron steel or aluminum.

wax mold

Step3: Manufacturing the lost wax mold

Using a hydraulic wax injection machine or an air-driven wax press, injecting liquid wax into the press to make a wax mold.

Wax assembly module

Step4: Wax assembly module

The wax mold is welded or glued to the precast wax stick to form a module

Degreasing

Step5: Degreasing

Immerse the mold in a special degreasing solution to remove the oil and release agent on the surface of the wax mold, so as to increase the adhesion of the wax mold.

Manufacturing shell

Step6:Manufacturing shell

Apply fire-resistant coating(slurry) on the surface of the module, and sprinkle a layer of sand(zircon sand, corundum sand, silica sand, etc.).

Lost wax casting

Step7: Lost wax casting

Heating the already made mold shell in steam or hot water, melting all the wax molds to obtain a mold shell with internal cavities.

Shell baking

Step8: Shell baking

Placing the shell in a high-temperature oven for high-temperature baking to remove residual wax, various volatile substances and water from the shell.

Liquid metal casting

Step9: Liquid metal casting

Pouring qualified high-temperature metal liquid that has been melted with chemical components into a fully baked hot mold shell

Deburring and cleaning

Step10: Deburring and cleaning

deburring with hand tools or virbratory deburring machines, removing sand, cutting the castings after pouring and gating, followed by other cleaning and post-treatment processes.

Inspection

Step11: Inspection

All lost wax casting parts must be checked then could put into warehouses.

lost wax casting packing

Step12: Packing and transportation

Packed according to client’s needs. Keep safe transportation.

Subsequent processing after casting

Customized Machining Lost Wax Casting Service

Our customized machining lost wax casting service is specifically designed to meet the precise demands of specialized industries such as Medical, Automotive, Aerospace, Elevator, Jewelry, and Optics. After the initial lost wax casting process, these industries often require secondary precision machining to achieve the highest levels of accuracy and quality.
 
With ISO 9001 certification and ITAR registration, we offer high – precision machining services that are tailored to not only meet but also exceed the stringent industry standards. Our state – of – the – art equipment, coupled with our extensive expertise in lost wax casting service, allows us to machine tight – tolerance casting parts with exceptional accuracy.
 
We are committed to ensuring superior quality, rapid production, and cost efficiency, all customized to your unique specifications. Our customized machining lost wax casting service provides the perfect solution for manufacturers seeking to enhance the precision and performance of their cast components.
SS316 Lost Wax Casting auto parts

SS316 Lost Wax Casting auto parts

Lost Wax Casting Machining Quality & Certifications

IAF 16949 / ISO 9001:2015 certified
99.9% on time delivery and Average 7 days turnaround machining time
wide range options of machining materials
Multiple options of machining technology: CNC Machining, Lathing, Drilling, Milling, Grinding and Welding etc.
Specialized in machining precision casting parts.

precision casting-machining service-1

CNC Machining Materials related to lost wax casting service

Aluminum 2024, 5083, 6061, 6063, 7050, 7075, etc.
Copper Alloy brass 360, 101 copper, 110 copper, 932 bronze, zinc, etc.
Titanium Alloy grade 2, grade 5, etc.
Stainless Steel 303, 304, 410, 17-4, 2205 Duplex, 440C, 420, 316, 904L, etc.
Superalloy Kovar,Hastelloy，Inconel,monel,etc
Zinc Alloy 3#,6#,9# etc.,
Engineering Plastic POM (Delrin), ABS (Acrylonitrile Butadiene Styrene), HDPE, Nylon, PLA,
PC (Polycarbonate), PEEK (Polyether Ether Ketone), PMMA (Polymethyl Methacrylate or Acrylic),
PP (Polypropylene), PTFE (Polytetrafluoroethylene), etc.
Other Other CNC machining materials: Graphite, VeroClear

Our Lost Wax Casting Service Machining Capabilities

CNC Lathing and Milling Machine
CNC Swiss Turn by Tsugami
High Speed Drilling-Tapping Machine
MAZAK 5 Axis Turning-Milling Machine
CNC Milling Turning Centers
Multi Spindle Cam Automatics
CNC Swiss Turning Machine 
DMU 5 Axis CNC Machine

Inspection Ability about our Lost Wax Casting Service

Chapter 1

Lost wax casting process has the following advantages and Limitations:

1.1- Lost Wax Casting Advantages

1.1.1-Tolerance

High dimensional accuracy and small surface roughness of lost wax castings. Due to the use of precise and smooth fusible patterns in lost wax casting, it achieves an integral mold shell without parting lines. It also avoids dimensional errors caused by processes like mold release, core removal, and assembly in sand casting. lost wax castings have sharp corners and can achieve dimensional accuracy of CT4~6 grade, with a surface roughness of Rao.8~1.25um. Therefore, castings produced by lost wax casting are closer to the final shape of the parts, reducing the amount of machining required and saving on metal material consumption.

1.1.2-Structure

Lost wax casting, as known as investment casting, is suitable for casting complex and precise structures. It can produce castings that are difficult to produce using other methods, such as various types of turbines, impellers, hollow blades, directionally solidified blades, single crystal blades, etc. It can also cast small components with a wall thickness of 0.5mm, minimum casting hole size of 1mm, weight as small as lg, up to 1000kg, and overall dimensions exceeding 2000mm. Moreover, it allows for the integration of multiple parts into a single casting.

1.1.3-Material

No restrictions on alloy materials. Various alloy materials such as carbon steel, alloy steel, stainless steel, high-temperature alloys, copper alloys, aluminum alloys, magnesium alloys, iron alloys, precious metals, and cast iron can be used in lost wax casting. Especially for alloys that are difficult to machine, lost wax casting is a more suitable process.

1.1.4-Batch Quantity

lost wax casting can be used for both large and small-batch production. Since metal molds are commonly used to produce the lost wax casting patterns, it is suitable for mass production. However, using inexpensive gypsum molds, low melting point alloy molds, or silicone rubber molds (commonly used for art and jewelry casting) can also make it applicable for small batch

1.2-lost wax casting has the following limitations:

It is most suitable for producing medium to small castings with a maximum through-hole diameter of 3-5mm, maximum blind hole diameter of 5mm, minimum casting slot width of 2.5mm, and minimum groove depth of 5mm.

  • The production cycle is relatively long.
  • The cooling rate of the castings is slow, which can lead to coarse grain structure in the castings and surface decarburization in carbon steel castings.
  • Requirements for Mold Materials in Lost wax Casting(1) Melting Point: The melting point and solidification temperature range of the mold material should be moderate, with a melting point generally ranging from 50 to 80° The solidification temperature of the mold material is usually selected between 5 and 10°C to facilitate the preparation of the mold material, mold making, and wax removal processes.
  • Thermal Stability: Thermal stability refers to the ability of the mold material to resist softening and deformation as the temperature increases. The thermal stability of wax-based mold materials is often expressed by the softening point. It is the temperature at which the deformation (deflection) of a standard cantilever specimen reaches 2mm after heating and insulation for 2 hours. The softening point of the mold material should generally be at least 10°C higher than the temperature of the mold-making workshop.
  • Shrinkage: To ensure that the lost wax casting achieves the required dimensional accuracy, the mold material should have low shrinkage, generally less than 1%. High-quality mold materials can have linear shrinkage rates below 0.5%. A small shrinkage rate corresponds to a small expansion coefficient, which also helps prevent cracking of the shell during wax removal.
  • Strength: The mold material should have sufficient strength at room temperature to ensure that the lost wax casting does not deform during the mold-making and shell-making processes. 
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Chapter 2

Lost Wax Casting Wax Mold

2.1-Requirements of Wax Mold Materials for lost wax Casting

2.1.1-Wax Mold Material Melting Point:

In the realm of lost wax casting, the selection of appropriate wax mold materials is crucial for the success of the process. The melting point and solidification temperature range of the mold material should be moderate. Generally, the melting point should fall between 50 to 80°C, while the solidification temperature range is typically from 5 to 10°C. These temperature ranges are optimal as they facilitate the preparation of the mold material, simplify the mold making process, and ensure a smooth dewaxing process in lost wax casting.
 
The right wax mold material with these thermal properties guarantees better control during the lost wax casting process. It allows for precise manipulation of the mold, reducing the risk of defects and improving the overall quality of the final cast product. By adhering to these temperature parameters, manufacturers can enhance the efficiency and effectiveness of their lost wax casting operations.

2.1.2-Heat Stability of Wax Mold Materials:

 

Lost wax casting

In the intricate process of lost wax casting, the heat stability of wax mold materials stands as a pivotal factor. Heat stability signifies the mold material’s capacity to resist softening and deformation as temperatures rise. For wax – based mold materials, this attribute is commonly represented by the softening point. The softening point is defined as the temperature at which a standard cantilever test specimen undergoes 2mm of deformation (deflection) following 2 hours of heating and insulation.
To guarantee optimal performance in the lost wax casting process, the mold material’s softening point should typically surpass the mold making workshop temperature by a minimum of 10°C. This temperature buffer ensures that the wax mold retains its structural integrity throughout the various stages of lost wax casting, from mold creation to the critical investment and dewaxing phases.
By adhering to these temperature – related criteria for wax mold materials, manufacturers can significantly diminish the likelihood of defects in the final cast components. This careful consideration of heat stability contributes to the production of high – quality parts that meet the precise specifications demanded by industries utilizing lost wax casting.

2.1.3-Lost Wax Mold Material Shrinkage Rate:

To ensure the dimensional accuracy of lost wax casting, the mold material must have a low shrinkage rate. Typically, this rate should be less than 1%, with high-quality materials achieving a linear shrinkage rate of below 0.5%. A low shrinkage rate directly correlates with a reduced expansion coefficient, which minimizes the risk of shell cracking during the dewaxing phase. This is crucial for maintaining the integrity of the mold and ensuring the precision of the final cast part. By carefully selecting mold materials with these properties, manufacturers can enhance the overall quality and reliability of their lost wax casting processes.

2.1.4-Wax Mold Strength:

Within the context of lost wax casting, the mold material must possess adequate strength at room temperature. This ensures the mold remains intact throughout the mold making and shell building processes, preventing any breakage or fracturing that could compromise the casting’s quality.
For small castings in lost wax casting, the mold material’s tensile strength should exceed 1.4MPa (14kgf/cm²). When dealing with larger castings, this tensile strength should not be lower than 2.5MPa. If flexural strength is assessed, it ought to surpass 2.0MPa, with an optimal range of 5.0 to 8.0MPa. These strength parameters are crucial as they guarantee the mold’s durability during the lost wax casting process.
By meeting these strength requirements for wax mold materials, manufacturers can significantly reduce the risk of mold damage. This, in turn, enhances the overall efficiency and reliability of the lost wax casting process, ensuring the production of high-quality castings that meet precise specifications.

2.1.5- Wax Mold Hardness:

In the lost wax casting process, the mold material’s surface hardness is a critical factor that prevents damage and abrasion during production. The hardness is typically measured by the penetration degree, where 1 degree equals 1/10 mm. High – quality mold materials used in lost wax casting generally achieve a surface hardness of 4 to 6 degrees.
 
However, it’s crucial to note that excessively high hardness can result in poor machinability and increased brittleness of the mold material. This can negatively impact the precision and integrity of the lost wax casting process.
 
For optimal results in your lost wax casting projects, the mold material should balance adequate hardness with machinability. This ensures the mold’s durability while allowing for the precise fabrication required in industries such as aerospace, automotive, and jewelry, which rely on the accuracy and quality that lost wax casting provides.

2.1.6-Wax Mold Material Flowability:

The mold material should have good flowability to facilitate filling the mold cavity under pressure, achieving sharp edges, accurate dimensions, and a smooth and polished surface of the lost wax casting. It also facilitates the flow of the mold material out of the shell during dewaxing.

2.1.7- Material Wetting Property:

The mold material should wet the refractory material well and form a uniform covering layer. The wetting property of the mold material can be measured by the wetting angle between the lost wax casting and the binder.

2.1.8- Ash Content:

A critical consideration for wax mold materials in lost wax casting is the ash content, which is the residue left after the mold material is burned. After the shell is calcined, the residual mold ash in the cavity should be minimal to ensure it does not compromise the surface quality of the casting. Generally, the ash content should be less than 0.05% (mass fraction).
 
Excessive ash content can negatively impact the precision and finish of the final product in lost wax casting. High-quality wax mold materials with low ash content are essential for producing castings that meet the stringent surface quality requirements of industries such as aerospace, automotive, and jewelry.

2.1.9-Weldability:

 Most lost wax casting assemblies are welded, so the mold material should have good weldability to prevent fractures at the welding points during transportation and shell building processes.
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2.2-Lost Wax Casting Mold Materials

2.2.1-Wax-based Mold Material

Wax-based mold materials, commonly used in lost wax casting, are typically a blend of paraffin wax and stearic acid. A typical formulation consists of 50% paraffin wax and 50% stearic acid. The paraffin wax (CnH2n+2) should have a melting point of around 58°C and be either refined or semi-refined. The stearic acid (C17H35COOH) should be of grade one, in block form.
 
In the realm of lost wax casting, paraffin wax serves as the primary component of mold materials. The addition of stearic acid significantly enhances the mold material’s properties. Due to their polar nature, stearic acid molecules exhibit excellent wetting properties in coatings. This characteristic improves the mold material’s coating ability and thermal stability, both crucial factors in the lost wax casting process.
Liquid paraffin wax and stearic acid mix well together, creating a homogeneous blend. This particular type of mold material boasts a low melting point, which facilitates easy preparation, molding, and dewaxing steps in lost wax casting. Moreover, it offers a high wax recovery rate and good reusability, making it a cost – effective choice for manufacturers in the foundry industry.
 
The combination of paraffin wax and stearic acid in mold materials is ideal for achieving the precise and intricate designs often required in lost wax casting. The excellent wetting properties and improved thermal stability ensure that the mold material can withstand the various stages of the casting process, from molding to the final dewaxing and casting phases. This results in high – quality castings with fine details and minimal defects, meeting the exacting standards of industries that rely on lost wax casting for their metal components.
 
Adjusting the ratio of paraffin wax and stearic acid affects the mold material’s performance. Increasing the paraffin wax content by 10% raises the mold material’s strength. However, exceeding 80% paraffin wax can cause foaming on the mold material’s surface, leading to poor pattern quality and reduced coating ability and flowability. Increasing the stearic acid content by 10% improves the mold material’s coating ability, flowability, and thermal stability. But when stearic acid exceeds 80%, the mold material’s strength and toughness drop significantly.
 
Paraffin wax stearic acid mold materials, commonly used in lost wax casting, possess moderate strength and thermal stability, with a softening point of 31°C. During the casting process, stearic acid can undergo displacement reactions with active metals and neutralization reactions with alkalis or alkaline oxides. These reactions form water – insoluble soaps that can degrade the mold material over time. The sticky soap residue resulting from these reactions may adversely affect the surface quality of the final casting. Since the saponification process consumes stearic acid, it is beneficial to add new stearic acid when reusing the mold material. This helps to stabilize the performance of the mold material and maintain consistent casting quality.
 
The performance of the mold material is influenced not only by the ratio of its ingredients but also by the melting point of the paraffin wax. Research has shown that using paraffin wax with a melting point above 60°C, as opposed to the standard 58°C, can enhance the mold material’s strength and thermal stability while also reducing shrinkage. These improvements in the mold material’s properties can lead to higher – quality castings with better dimensional accuracy and surface finish.
 
Despite the advantages of paraffin wax stearic acid mold materials, such as ease of preparation, molding, demolding, and good reusability, they have certain limitations. Their relatively low thermal stability makes them prone to deformation and saponification degradation during the production process. This necessitates recycling treatment before the mold material can be reused. Additionally, the residual acid solution generated during recycling can pose environmental pollution risks if not properly managed.
 
In response to these challenges, various stearic acid – free wax – based mold materials have emerged in recent years. These alternatives aim to overcome the limitations of traditional paraffin wax stearic acid mold materials while retaining their beneficial properties for lost wax casting applications.
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2.2.2-Paraffin Low Molecular Weight Polyethylene Mold Material in lost wax casting

The paraffin wax low – molecular – weight polyethylene mold material is composed of 95% paraffin and 5% low – molecular – weight polyethylene, with the latter having a molecular weight of around 2000 – 5000. This blend offers good compatibility between the paraffin and low – molecular – weight polyethylene. This mold material has a melting point of 66°C and a softening point of approximately 34°C.
 
Using low – molecular – weight polyethylene instead of stearic acid – based wax material brings several advantages to the lost wax casting process. It achieves high strength and good toughness in the mold material. The mold surface is smooth, and the material has stable chemical properties. After use, there’s no saponification issue, and the material recovery process is more convenient. However, due to its higher viscosity, it’s necessary to appropriately increase the temperature of the paste – like material and the wax injection pressure during molding. These adjustments help ensure the mold material flows well and fills the mold cavity adequately, maintaining the precision and quality expected in lost wax casting.
 
This type of mold material combines the advantages of paraffin wax and low – molecular – weight polyethylene, making it an excellent alternative to traditional stearic – acid – based mold materials. It addresses some of the limitations of previous materials while retaining the essential properties required for effective lost wax casting.
 
Innovations in wax-based acid-free mold materials involve incorporating substances such as polyethylene (PE), EVA, lignite wax, montan wax, and rosin. Among these additives, low-density polyethylene has limited solubility in paraffin, typically not exceeding 10%. However, the solubility of polyethylene in wax materials increases as its molecular weight decreases. Consequently, low molecular weight polyethylene and EVA, with molecular weights ranging from 2000 to 5000, demonstrate better solubility compared to low-density polyethylene. Given the molecular structure similarity between polyethylene and paraffin, adding polyethylene to wax-based mold materials serves as a crystallization nucleus. It refines the paraffin crystals and enhances the mechanical properties of the mold material, which is highly beneficial in lost wax casting processes.
 
Incorporating low molecular weight polyethylene into paraffin-based mold materials can significantly improve the strength and heat resistance of the mold material used in lost wax casting. Nevertheless, excessive addition may lead to increased shrinkage without proportionate performance enhancement. Similar effects can be achieved by adding EVA. Practical applications have revealed that polyethylene exhibits aging characteristics over extended use, which can degrade the performance of the mold material. Adding lignite wax can boost the thermal stability of the mold material but also raises its melting point and injection temperature.
 
Polyethylene and other polymers possess both crystalline and amorphous structures, creating a unique coexistence of these two regions. Within polyethylene spherulites, polymer chains are interconnected, with each chain passing through several crystalline and amorphous regions. The presence of these interconnecting chains contributes to polyethylene’s significantly higher strength compared to wax materials.
 
In addition to polyethylene and ethylene-vinyl acetate copolymer (EVA), polystyrene can also be added to wax materials. Polystyrene features a high melting point, low sensitivity to temperature changes, lower thermal deformation than wax materials, and higher strength, hardness, and transparency.
Introducing polystyrene into the mold material can enhance its strength and softening temperature, which is advantageous in lost wax casting. However, due to its high viscosity and poor demolding properties, the application of polystyrene in lost wax casting is somewhat restricted.
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Frequently Asked Questions About Lost Wax Casting‌

Lost wax casting is a manufacturing process that involves creating a mold, pouring molten metal into the mold, and then removing mold to reveal the finished part. It is different from other casting methods in that it allows for the production of highly complex and intricate parts high precision and accuracy.


A wide range material can be used in lost wax casting, including stainless steel, aluminum, copper, brass, and various alloys-performance materials such as titanium and Inconel can also be used.


Lost wax casting is used in various industries including aerospace, automotive, medical, military, and jewelry.

When choosing a lost wax casting manufacturer, it is important to consider factors such as quality of products, experience and expertise, production capacity, customer service and support, price competitiveness.

To get a quote from a lost wax casting manufacturer, you typically need to provide them with the part design, material requirements and expected production volume.

The typical lead time for lost wax casting varies depending on the part complexity and production volume, but can range from a few weeks to several months.

To ensure the quality of investment cast parts, is important to work with a reputable manufacturer that uses quality control processes and has a track record of producing high-quality.

Common defects in lost wax casting include porosity, shrinkage, cracks, and surface irregularities.

Lost wax casting is generally a more expensive manufacturing method compared to casting methods, but it offers benefits such as the ability to produce complex parts with precision and accuracy.

The minimum order quantity for lost wax casting varies depending on manufacturer and part complexity.

Lost wax casting manufacturers typically offer post-casting services such as machining, surface finishing, and assembly.

The typical tooling cost for lost wax casting depends on the part complexity and production volume, but can range from a few thousand to tens of thousands of dollars.

The maximum wall thickness for lost wax casting depends on the material and part geometry but is typically around 1 inch.

The maximum weight limit for investment also depends on the material and part geometry, but can range from a few ounces to several hundred pounds.

Lost wax casting can be used produce parts with internal cavities using ceramic cores.

The typical surface finish for investment cast parts is around -250 RMS (root mean square) but can be improved additional surface finishing processes.

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    At SipxMach, our goal is to help our customers lower production costs and increase production rates and quality. Interested to see what SipxMach can do for you and your team? Contact us to schedule a tour of our state-of-the-art facility

    • Contact:  Rubio
    • Email:             [email protected]
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    • Office Add:  No.551, Baosheng Avenue, Huixing Street, Yubei District, Chongqing, China
    • Foundry Add:  No. 4 Jindi Avenue, Dongcheng Street, Tongliang District, Chongqing