Investment Casting, also known as Lost Wax Casting, is an industrial metal-forming technique that uses wax moulds to create complex metal structures.
Investment casting is a technique that has been used for thousands of years, with its earliest recorded use dating back to 2500 BC used to create idols, ornaments and jewellery. In its earliest uses, natural beeswax was used for the patterns and clay was used for the moulds. These days, we use master die wax to create an infinite range of designs.
That wax is then coated in a thick layer of ceramic shell castings to create the mould. Once the precision casting has dried and solidified the wax-casting is placed in a furnace where the wax melts out of the cast leaving just the mould. Whilst the mould is still hot liquid metal is poured into the cast, allowing it to go into the small grooves and corners., where it is then cooled down and the cast is removed.
Examples of Sylatech Lost Wax Castings
Lost Wax Casting
At Sylatech, our unique block moulding version of the lost-wax investment casting method affords customers a process capable of producing thin walls and lightweight components. Working exclusively in the casting of non-ferrous metals, our specialist process delivers small castings with a ceramic shell wall thickness as fine as 0.2 mm, and more typically 1-3 mm. Our rapid prototyping capability affords engineers a fast route to test their prototype designs in metal, within a few days.
Sylatech’s in-house tooling capability is integral for the production of tools, which are used in the creation of wax patterns. To facilitate the casting process, the gating system is incorporated within the design of the tool.
The plaster-based refractory materials used within Sylatech’s lost-wax casting manufacturing processes cannot sustain a high temperature when the molten metal is poured. This limits the process to the casting of non-ferrous metals only. This is unlike ceramic mould materials formed from a ceramic slurry which are used when creating stainless steel castings.
Whilst metal casting is commonly known as a process for producing near-net-shape components, through Sylatech’s additional in-house CNC machining capability, we can ensure that all castings have exacting dimensional accuracy. Sylatech’s manufacturing method affords greater benefits to other investment casting processes, particularly pressure die casting and sand casting, which cannot compete with the surface finishes, lightweight and fine tolerances achieved by our plaster-based process.
The lost wax casting process provides a fast and cost-effective method for both small batches and large quantities of up to 150,000 per year. Parts with complex internal and external detail, superior finishes and thin wall capabilities can be produced, without the need for machining from solid.
Our process is capable of producing non-ferrous foundry castings with a wall thickness as fine as 0.2 mm, and more typically 1-3 mm. Our rapid prototyping capability affords engineers a fast route to test their prototype designs in metal within a few days.
Our specialist lost wax investment casting process affords us the ability to take a customer’s concept and achieve reality in a fast and cost-effective manner. By combining our non-ferrous investment casting technology with best practice CNC machining, Sylatech can overcome many of the constraints placed on engineering design whilst delivering the highest quality.
+/- 0.1 per 20mm
+/- 0.1 per 20mm
Metal Casting Company
Sylatech is one of the largest Metal Casting Companies in the UK, manufacturing a wide range of bespoke metal components for a broad range of companies across the globe. We are supported by a heritage of 57 years of delivering precision custom metal castings.
We are trusted by our partners to produce high-quality systems and components matching their exact designs.
In response to customer demands to supply alternative alloys, Sylatech has developed relationships with a number of other suppliers globally.
Where projects require components from other suppliers, we are able to manage this process for you and aim to be a single source for all of our customer’s precision components.
We take full responsibility for ensuring the product is to the correct specification and the correct quality. We also actively manage all customs and shipping on behalf of our customers.
Examples of global sourcing projects that we have undertaken for our customers include:
Lock industry components are sourced overseas and machined at Sylatech.
Steel cast links for the rail sector.
Brass components are used in the food industry.
Electronics connecting couplings are used in mining.
Door and retail furniture components.
Sizes and Tolerances
Sizing and Tolerances depend on the geometry of each part, but the following tolerances are suggested as a guide to designers.
Lengths including hole diameters held to:
0 - 15
0.0 - 0.6
15 - 25
0.6 - 1.0
25 - 50
1.0 - 2.0
50 - 75
2.0 - 3.0
75 - 100
3.0 - 4.0
100 - 125
4.0 - 5.0
125 - 250
5.0 - 10.0
Generally held to ±0.13mm (0.005") per 25mm (1.00") square.
Generally held to ±0.1mm (0.004") max per linear 25mm (1.00").
Squareness and Angularity
±0.5 degree Note: Angular tolerances are affected by irregular geometries.
When tolerancing, use of a central feature as a datum may allow detail to be cast that would otherwise carry too large a tolerance. Where a mechanical
interface feature is required on a surface, it helps to use the centre of the feature as a datum.
Constant section thin walls are preferred but large changes in the section can be accommodated through critical analysis of the component design and special tooling design features.
Suggested Wall Thickness
up to 10mm (0.4")
0.2mm - 1.0mm (0.008" - 0.04")
0.5mm - 1.5mm (0.02" - 0.06")
1.0mm - 3.0mm (0.04" - 0.12")
1.5mm - 3.0mm (0.06" - 0.12")
above 100mm (4.0")
2.0mm (0.08") upwards
Wall thickness and flatness over large surfaces are better controlled if through-holes and ribs are incorporated in the design.
Wall Section Tolerances
up to 0.5
up to 0.020
0.5 - 1.0
0.020 - 0.040
1.0 - 2.0
0.040 - 0.080
2.0 - 4.0
0.080 - 0.160
4.0 - 8.0
0.160 - 0.320
Complex internal features such as swept bends can be formed by the use of soluble cores (orange wax). Tolerances however may require relaxing.
Tooling for a complex component can sometimes be simplified by joining two or more patterns together at the wax stage. This enables the requirement for brazing after casting to be eliminated.
Cast Gears and Teeth
Components requiring teeth for gripping or gear applications may be impossible to produce by machining. The definition achieved by the Sylatech process is ideal for these applications.
Integrally cast rivets can be peened over to give an economic, strong and permanent joint.
It is possible to include many types of permanent product identification which can eliminate the further need for labelling. Logos and text may be produced with the minimum cost if the design ensures that detail is in the line of the draw of the wax from its die.
Ideally, cast labels should use raised lettering on the casting face (engraved into the wax tool). Where such information must be below a functional surface, it can be sited on a pad sunk into the cast face.
Preferred depth of engraving: 0.25mm - 0.5mm (0.010" - 0.020")
Types of Labels
ID for version traceability
Raised pad for engraved serial no.
“As cast” – parts removed directly from the mould have a surface finish equal to or better than 0.8 micrometres (32 micro inches); this finish may show variable colour.
Removes any sharp edges left after finishing, leaving a surface suitable for most subsequent “finishing” processes.
Using stainless steel shot is generally suitable for brass components and gives a slightly polished surface.
Glass Bead Blasting
Produces a more highly polished surface finish and is most suitable for aluminium parts.
Special Surface Effects
Such as textures and knurling can be incorporated within the Sylatech casting process.
Automatic Grit Blasting
Gives a uniform matt finish, suitable for most subsequent finishing operations.
Applied Surface Treatments
The following treatments can be applied:
Alocrom1200/1000 / Chromate Conversion
Surtec 650 Roche complaint processes provide corrosion resistance to aluminium parts whilst providing an electrically conductive surface.
Protective purposes can be carried out on aluminium alloy castings but cast alloys do not readily accept decorative anodised finishes due to the silicon content.
Can be applied to most alloys.
Hipping (Hot Isostatic Pressing)
Is used to improve the mechanical properties of aluminium castings by sealing internal voids.
Can be carried out on “as cast” or machined parts where pressure tightness is essential.
For protection or visual purposes.
Various heat treatments can be applied to harden components. This is carried out generally to aid subsequent machining and enhance component stability. Suffixes to the material grade are used to denote the heat treatment carried out: UK and equivalent USA and EN suffixes are shown below:
TreatmentsUKUSAENAs cast/manufacturedMFFSolution heat-treated and artificially age hardenedTB7T4T4Artificially age hardenedTET5T5Solution heat-treated and artificially age hardenedTFT6T6
Solution heat treated and artificially age hardened
Artificially age hardened
Solution heat treated and artificially age hardened