Which process to choose: Lost-wax, Sand casting or
Die casting?
Below are brief descriptions of the capabilities of metal casting processes with Novosk. Hopefully these
will help you choose the casting method that’s right for your project.
Lost-wax investment casting
Novosk Precision Cast Parts uses this process exclusively. Wax is
injected into an aluminum die to create a wax “pattern”. These wax
patterns are then assembled onto a “tree” which is repeatedly dipped
in ceramic slurry that, after drying, hardens into a mold. The wax is
melted out, the mold is preheated and the metal is poured in.
Advantages: Excellent surface finish of around Ra 3.2,
Tolerances can be held to +/- 0.2 mm in most cases,
Machining reduced or eliminated,
Design & casting versatility,
Can cast very thin walls and utilize cores,
Economical tooling costs.
Disadvantages: higher Kg-prices.
Sand casting
Sand molding is the most diversified molding method in use today.
Loose sand is mixed with a bonding agent and moisture then
compacted onto a pattern. After both halves of the mold are made
they are positioned together and filled with molten metal.
Advantages: Cheapest Kg-prices for produce very large parts,
Complex shaped casting by utilizing intricate cores
Disadvantages: Rougher surface finish and tolerance than lostwax and die casting.
Secondary machining often required
Low production rate
Die casting
Pressure die casting is a quick, reliable and cost-effective
manufacturing process for high volume production. There are two
types of die casting: High-pressure die casting and low-pressure
die casting. Both processes consist of injecting molten metal alloy
into a permanent mold under pressure.
Advantages: Tight tolerance up to +/-0.05 mm,
Smooth cast surfaces Ra 1–2.5,
Low gas porosity,
Very repeatable process for continuous production
Disadvantages: Higher tooling prices
Unable to utilizing intricate cores
Novosk ApS
Daadyrvej 24, 9200 Aalborg SV
Tel: +45 51509988
Fax: +45 98565751
Email: [email protected]
Web: www.novosk.com
Novosk metal casting processes compare chart:
Tolerances on
Critical Dimensions
Minimum Draft
Up to 25mm
Up to 100mm
On Inside Walls
On Outside Walls
Minimum Wall
On Small Castings
Thickness
On Large Castings
Minimum Size of Cored Hole
Ability to utilize Cores
Surface Finish
Alloys commonly used in this form
Typical Production Quantities per year
Typical Tool Life
Sand Casting
Lost-Wax
investment
Casting
High Pressure
Die Casting
Traditional
machining
± 1mm
± 2mm
3°
2°
3mm
5mm
15mm
Yes
Poor
Ra 6.3
Ductile iron
Gray iron
Carbon Steel
Aluminum
Brass
Bronze
± 0.2mm
± 0.5mm
1°
0°
2mm
3mm
2mm
Yes
Good
Ra 3.2
Carbon steel
Stainless steel
Aluminum
Titanium
Special alloys
± 0.1mm
± 0.2mm
1°
0.5°
1mm
2mm
2mm
No
Very Good
Ra 1.6
Aluminum
Zinc
Brass
Magnesium
± 0.01mm
± 0.03mm
0°
0°
NA
1-500
5,000
500-2,000
1,000,000
2,000-500,000
500,000
1-1,000,000
NA
NA
No
Excellent
Ra 0.8
Almost all metals
General guide when designing parts for metal casting:
Thumb rules:
• Try to make over-all even general wall thickness
• Try to make gradual change in material thickness to
help metal flow
• Remember always radius and draft!
Novosk ApS
Daadyrvej 24, 9200 Aalborg SV
Tel: +45 51509988
Fax: +45 98565751
Email: [email protected]
Web: www.novosk.com