Design Considerations

Metal Specifications

Tooling

What is Investment Casting?

Investment Casting, also known as Lost Wax Casting is a metal-forming technique. What makes this technique unique is its use of wax moulds to create complex metal structures.

Investment casting is a technique that has been in use for thousands of years. Its earliest recorded use dates back to 2500 BC, to create idols, ornaments and jewellery. In its earliest uses, natural beeswax made the patterns and clay created the moulds. Today, 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 and left to dry and solidify to create the mould. It is then placed in a furnace to melt and remove the wax leaving only the mould. We then pour the liquid metal into the cast, where it is then cooled down and the cast removed. The cast must still be hot so that the metal can flow into the small grooves and corners.

Examples of Sylatech Lost Wax Castings

casting of a model aicraft engine
Model Aircraft Engine
casting of an automotive air vent fascia
Automotive Air Vent Fascia
casting of an automotive light housing
Automotive Light Housing
casting of a railway catenary component
Railway Catenary Component
casting of a breating apparatus component
Breathing Apparatus
castings of waveguide bends
Cast Waveguide Bends

Our Unique Lost-Wax Casting

We use a unique block moulding version of the Lost-Wax Casting method. This affords customers a process capable of producing thin walls and lightweight components. For this process, we work only in the casting of non-ferrous metals. This specialist process delivers small castings with a ceramic shell wall as fine as 0.2mm. Our rapid prototyping capability allows us to test metal prototypes within days.

Our in-house tooling capability is integral for the production of tools. We use these tools in the creation of wax patterns. We incorporate the gating system within the tool’s design to ease the casting process.
 
The plaster-based refractory materials we use are unable to sustain a high temperature. This limits the process to the casting of non-ferrous metals only. This is unlike ceramic mould materials when creating stainless steel castings.
 
We are able to ensure all casting has exacting dimensional accuracy. This is all due to our in-house CNC Machining capabilities. Our unique manufacturing method affords greater benefits compared with other techniques. They cannot compete with the surface finishes, lightweight and fine tolerances achieved.

Sylatech is certified to AS9100D and to Nadcap for Welding.

Lost Wax Casting Process

Sylatech’s foundry casting process achieves excellence in the production of copper and aluminium alloy lost wax investment castings.

  • Certified to AS9100.
  • Rapid prototyping in metal through 3D printing.
  • Specialists in thin-wall and lightweight parts.
  • The process delivers high-quality surface details and finishes.
  • Ideal for small or micro components.
  • Materials: Aluminium Casting (AB2), Silicon Brass Casting (MB1) and Manganese Bronze Casting (HTB1 & HTB3).

The Lost Wax Casting Process is a fast and cost-effective metal casting method. It is perfect for both small batches and large quantities of up to 150,000 per year. It is able to produce parts with complex details, superior finishes and thin wall capabilities, without the need for machining.

The Sylatech Lost Wax Investment Casting Process
The Sylatech Lost Wax Investment Casting Process

We are able to produce non-ferrous foundry castings with a wall thickness as fine as 0.2 mm, more likely 1-3 mm. Our rapid prototyping capability affords engineers a fast route to test their prototype designs in metal within a few days.

Our unique casting process allows for rapid production in a 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.

Metals Cast Tolerance
Aluminium Alloys +/- 0.1 per 20mm
Copper Alloys +/- 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.

Global Sourcing

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:

mm inch
Section Tolerance Section Tolerance
0 - 15 ±0.08 0.0 - 0.6 ±0.003
15 - 25 ±0.13 0.6 - 1.0 ±0.003
25 - 50 ±0.25 1.0 - 2.0 ±0.010
50 - 75 ±0.37 2.0 - 3.0 ±0.015
75 - 100 ±0.50 3.0 - 4.0 ±0.020
100 - 125 ±0.60 4.0 - 5.0 ±0.025
125 - 250 ±1.00 5.0 - 10.0 ±0.040

Flatness

Generally held to ±0.13mm (0.005") per 25mm (1.00") square.

Straightness

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.

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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.

Wall Sections

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.

Size (cubed) Suggested Wall Thickness
up to 10mm (0.4") 0.2mm - 1.0mm (0.008" - 0.04")
25mm (1.0") 0.5mm - 1.5mm (0.02" - 0.06")
75mm (3.0") 1.0mm - 3.0mm (0.04" - 0.12")
100mm (4.0") 1.5mm - 3.0mm (0.06" - 0.12")
above 100mm (4.0") 2.0mm (0.08") upwards
Macaque in the trees
Cast example of 1mm (0.040") wall thickness throughout
Macaque in the trees
Cast example of thick and thin wall sections
Macaque in the trees
Cast example incorporating ribs to improve flatness and rigidity
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Wall thickness and flatness over large surfaces are better controlled if through-holes and ribs are incorporated in the design.

Wall Section Tolerances

mm inch
Section Tolerance Section Tolerance
up to 0.5 ±0.10 up to 0.020 ±0.004
0.5 - 1.0 ±0.15 0.020 - 0.040 ±0.006
1.0 - 2.0 ±0.20 0.040 - 0.080 ±0.008
2.0 - 4.0 ±0.25 0.080 - 0.160 ±0.010
4.0 - 8.0 ±0.30 0.160 - 0.320 ±0.012
Macaque in the trees
Cast example incorporating holes to improve flatness and reduce weight

Special Features

Soluble Cores

Complex internal features such as swept bends can be formed by the use of soluble cores (orange wax). Tolerances however may require relaxing.

Wax Assembly

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.

Integrated Labelling

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
Logos
Names
Numbers
Lettering
Direction
Instructions
Product ID
Part No.
Issue No.
ID for version traceability
Date code
Graduations
Raised pad for engraved serial no.
Label recess
metal casting widget showing raised lettering
Raised lettering/instructions
metal casting widget with recessed label
Label recess
metal casting widget showing sunken issue number
Drg. no. and issue on sunken pad
metal casting widget with graduation markings
Graduation markings
metal casting widget with sunken lettering
Sunken lettering
metal casting widget showing sunken pad lettering
Logo, no., date raised on sunken pad

Surface Finishes

As Cast

“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.

Chip Rumbling

Removes any sharp edges left after finishing, leaving a surface suitable for most subsequent “finishing” processes.

Shot Blasting

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.

metal casting widget
An example of highlighting a drawing to show important cosmetic surfaces
Examples of support using a side hole

Applied Surface Treatments

We can apply the following treatments:

Alocrom1200/1000 / Chromate Conversion

Surtec 650 Roche complaint processes provide corrosion resistance to aluminium parts whilst providing an electrically conductive surface.

Anodising

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.

Plating

Can be applied to most alloys.

Hipping (Hot Isostatic Pressing)

Is used to improve the mechanical properties of aluminium castings by sealing internal voids.

Impregnation

Can be carried out on “as cast” or machined parts where pressure tightness is essential.

Paint/Powder Coating

For protection or visual purposes.

Heat Treatment

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:

TreatmentsUKUSAEN
As cast/manufacturedMFF
Solution heat treated and artificially age hardenedTB7T4T4
Artificially age hardenedTET5T5
Solution heat treated and artificially age hardenedTFT6T6

Sylatech Design Guide

Download the Design Guide

Get in touch!

Call us on: +44 (0) 1751 432 355 to discuss your investment casting project with our foundry engineers and benefit from their professional expert advice.
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Sylatech Process Guide

Download the Process Guide

Sylatech Aluminium and Copper Specifications

Aluminium and Copper Specifications