Split Wax Mold for Hollow Cast Parts
At ChinaSavvy we focus on quality and know that when using the lost wax casting process for your project, compliance with the set limits as well as the quality control of the process, is vital.
Wax Mold Casting
Wax, being the oldest thermoplastic material, today refers not to the material used when looking back in the history of the investment casting process, but rather material that has wax-like characteristics. Casting wax today are modern blends of complex compound containing various components.
The chemical structure and different components in the wax will affect both its expansion and contraction characteristics, thus affecting the behavior of the pattern.
- Emulsified Pattern Wax (Virgin wax material)
- Filled Pattern Wax (Virgin wax material)
- Straight / Unfilled Pattern Wax (Virgin wax material)
- Specialist Wax
- Runner Wax
Emulsified Pattern Wax
Offering special properties for pattern production, emulsified wax makes use of water as the filler in order to reduce the cavitation or sinkage. Because of this wax's easy die release, it is suitable for use in more complex die geometries.
Emulsified wax is also appropriate for use on a wide range of specialized injection equipment and injection temperatures.
It has a low ash content and provides manufacturers with excellent characteristics concerning injection. Emulsified wax has a wide contraction range and delivers a surface finish that is smooth and glassy. With the water acting partly as a filler, emulsified wax has an excellent dimensional stability and can also be reconstituted (these types of waxes can be used to produce a full range of high quality patterns) or reclaimed (these types of waxes can be used for the production of runners).
Filled Pattern Wax (Virgin wax material)
Filled wax is able to be injected into all types of wax presses and is also one of the most widely used waxes when it comes to producing complex, thin walled patterns of high quality. The range of beneficial properties of this wax can also be customized to meet the requirements of individual customers.
Providing both an excellent surface finish and dimensional accuracy, filled wax has a low ash content, a wide contraction range and displays an array of excellent injection characteristics. Offering greater stability, the filler also provides a reduced contraction as well as cavitation. Filled pattern wax can also be reconstituted or reclaimed.
Straight / Unfilled Pattern Wax
Relatively easy to recycle, straight wax is described more as the type of wax originally used in the lost wax casting process. It is able to be injected successfully across a wide range of wax presses and its excellent range of properties can be customized to meet the requirements of customers. Straight wax is also appropriate for use across a wide range of temperatures.
Beneficial Characteristics:Unfilled or straight wax has a low ash content, provides an excellent surface finish and offers manufacturers excellent characteristics in terms of injection. Like Filled and Emulsified wax, it can be reconstituted or reclaimed.
The types of waxes used in order to help in the production of finished wax patterns. These specialists waxes include:
- Dip Seal
- Hard Repair
- Soft Repair
- Spiral Forming
- Water Soluble
- Fast and Total Dissolving Water Soluble Wax
- Extremely Strong and Tough Water Soluble Wax
Examples of different types of specialist waxes:
A wax used for the sealing of ceramic cores, effectively helping the improve the surface finish delivered as well as alleviating core cracking.
Dip Seal Wax:
This is a very 'runny' wax that is capable of flowing into and closing open seals or undercuts.
These are used to vent or strengthen wax assemblies.
A wax that has a very good flow, high strength and the ability to produce complex detail.
This type of wax is used in rapid prototyping and in the production of proof patterns.
A wax that is used for both soft and hard repairs, as well as for molding.
Runner wax is usually formulated to have a slightly lower melting point than the wax used to produce the pattern and, to allow for easier de-waxing, it also has a lower viscosity. Also made from reclaimed wax, runner wax can be:
- Unfilled / Straight Wax
- A wax with added additives in order to fine-tune the melting point, its elasticity, its toughness and its rheology.
- A wax with a percentage of filler in order to improve injection processes, its strength and provide it with a faster setting / hardening rate.
As with emulsified, straight and filled wax, the properties of runner wax can be customized in order to meet the client's requirements.
When choosing a wax, the following properties are key and taken into consideration:
- Both the cavitation and contraction of the wax
- The melting point of the wax
- The congealing / hardening point of the wax
- Both hardness of the wax as well as its viscosity
- The rate at which the wax sets / hardens
- The content of ash
- Stability of oxidation
- The elasticity of the wax
- Reclaim ability or recyclability of the wax used in the process
ChinaSavvy also ensures that casting wax undergoes the following physical tests:
- The actual melting or drop point of the wax
- Its viscosity / thickness
- The set or congealing point of the wax
- Its ash content
- The wax's penetration
Recycling Casting Wax
Wax used in the casting process can be recycled, giving you the added economical benefits as well as environmental benefits. Recycling is done by returning the autoclave wax from the foundry to the manufacturer of the wax where it will undergo cleaning and filtering. The recycling also requires the addition of additives in order to adjust the properties so that it is up to standard and set specifications.
The resulting product will either be categorized as reclaimed or reconstituted. Reconstituted wax can be used to produce a full range of high quality patterns and is sub-categorized as:
- Reconstituted emulsified wax
- Reconstituted filled wax
- Reconstituted Unfilled / Straight wax
- Reclaim wax be used for the production of runners.
The Lost Wax Casting Process at ChinaSavvy
Split-Mold Hollow-Core Investment casting requires the creation of a wax mold. This will be done by first creating a split line on the drawing in order to separate the product (or the component to be cast) in two halves.
Two molds or a single mold with two halves are built into which the wax is injected. The wax molds are now ejected and the parting lines melted using specialized equipment and techniques. The two halves are pressed together, in essence 'gluing' the two parts together.
A feed tree is added to the wax molds and coated in a ceramic slurry, left to dry and then heated in order to remove the wax. The ceramic mold is now heated to approximately the same temperature as the molten metal.
After heating, the molten metal is poured into the ceramic mold, left to cool to room temperature. The mold is broken and the runners are removed, leaving only the casting behind.
ChinaSavvy offers all of its clients world-class services, ranging from quality controls in wax production, to ISO 9001:2008 certified quality assurance.
Back to Main Page: Investment Casting.
Further Suggested Reading:
- The History of Investment Casting
- How precise is Investment Casting?
- Water Soluble Waxes for Hollow Parts
- What Metals can be Investment Cast?