Centrifugal Casting Alloys

Centrifugal casting is a versatile process for reproducing in whitemetal castings

the artistry of the pattern maker.

Introduction

Centrifugal casting in rubber moulds is a versatile process for reproducing in whitemetal castings

the artistry of the pattern maker. Because of their low melting points and high fluidity, tin- based and

tin- lead alloys are ideal for casting items such as models, costume jewellery, buckles, buttons and

figurines by this method.

As well as having lower toxicity, tin- rich alloys are more fluid and are better able to reproduce fine

Detail . Tin- lead alloys are more economical and usually more suited to heavier sections.

Alloy Choice

The alloy chosen should provide sufficient fluidity for the castings being made and have the ability

to feed the casting as it solidifies. As whitemetal freezes, it shrinks, so more metal is needed to

avoid shrinkage cavities or porosity. Metals which freeze gradually over a temperature range have

more opportunity for fresh metal to feed into the casting, to fill the space left by this shrinkage.

Metal Handling

Safety

Always wear a suitable face vizor or safety glasses when handling molten metal. Please refer to the

Safety Data Sheet for safety and handling instructions.

Storage

Whitemetals should be kept clean and dry before use. Different grades should be segregated

carefully to ensure defined characteristics.

Melting

To avoid metal spitting caused by moisture, warm the sticks and ingots before adding them to

molten metal. Add solid metal a little at a time, to avoid large temperature fluctuations. Stir the

molten metal gently and thoroughly, ensuring uniformity throughout the melt without creating

excess dross.

Temperature Control

Good temperature control is essential for high quality castings. Whitemetal should be held at a

temperature where it is completely liquid or completely solid and not in the slushy range in

between.

Casting Temperature

The metal should be cast into a warm mould, using the lowest metal temperature needed to produce

good castings. Excessive temperature shortens the life of the rubber moulds and produces

unnecessary dross. Moulds are warmed by pre- heating in an oven or by discarding the first few

castings made.