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Low melting point alloys & their uses

Posted February 15th 2017

William Rowland Limited is able to produce a wide range of low melting point alloys at our foundry in Birmingham. We can produce to known industry specifications or alloys that are tailored to meet our customers’ specific requirements.

Fusible alloys

A fusible alloy is essentially a type of metal alloy which can be fused with ease. These metal alloys can be melted at temperatures that are relatively low. They are typically eutectic alloys, meaning they have a sharp melting point.

Fusible alloys are often used as the term to describe alloys that have a melting point which is below 183 degrees Celsius.

What are fusible alloys used for?

Fusible alloys are irreplaceable in a range of applications where their low melting point is fundamental:

  • Tube and profile bending
  • Work holding of delicate or irregular pieces
  • Fusible cores for plastic or composite moulding techniques
  • Fusible plugs for boilers and pressure vessels
  • Fusible safety devices for fire prevention such as sprinklers
  • Lens blocking
  • Rapid prototyping of press tools

 

Most low melting point alloys are bismuth based and William Rowland can produce a range of quality bismuth-based alloys to exacting specifications, including:

WR 47                   Lens alloy – used for Lens blocking

WR 58                   Lens alloy – used for Lens blocking

WR 70                   Bend alloy – used for Tube and profile bending

WR 137                 Press alloy – used for Work holding, fusible cores

Bend alloy – WR 70

One type of low melting point alloy William Rowland produces is bend alloy (WR 70).

Bend alloy is one of the most extensively used alloys in industry due to its primary characteristic of expansion on solidification from the molten state. This makes bend alloy an ideal material to support metal tubing with thin walls during bending operations.

The alloy has a sharp melting point of 70 degrees Celsius and can consequently be melted with hot water.

Lens alloy – WR 47 & WR 58

Lens alloys are part of the group of bismuth-based ‘fusible’ alloys. Indium is added to the alloy in order to give it a considerably lower melting point. Lens alloys are eutectic alloys, characteristically possessing a sharp melting point at 58 or 47 degrees Celsius. This low temperature is ideal for acting as a ‘button’ or holding medium in the grinding of lenses.

Possessing stable characteristics, and being easy to melt, lens alloy can be reused repeatedly if required.

Primary use of lens alloy

The primary use of lens alloy is in grinding operations when it proves invaluable in holding glass or plastic lenses. WR 47 is best suited for plastic or composite lenses, whilst WR 58 is used primarily for glass. Due to its low melting properties, lens alloy is also a suitable component in the fuses of safety equipment. Lens alloy can also be effective in proof casting.

Press alloy – WR 137

Press alloy is considered close to eutectic having a relatively sharp melting point at 138°C. It has greater hardness and tensile strength than other fusible alloys and lends itself to anchoring, work-holding and low volume presswork. WR 137 exhibits minimal expansion upon solidification from the molten state, this is useful for holding machined parts where shrinkage or expansion may deform the finished part.

Casting alloy

Casting alloys are a range of low temperature alloys based on tin, lead or bismuth that are suitable for production of jewellery, models, figures, artwork, collectibles, ornaments and memorabilia.

William Rowland produces many different grades of casting alloy to suit the customer’s process and production requirements, however we will also produce to a customer’s individual specification. Our casting alloys are suitable for the professional or hobbyist and we produce many grades that are safe and easy to work with using only the minimum of basic equipment.

Lead-free pewter alloys are popular for jewellery, artwork and collectibles where reproduction of fine detail and cast finish are important, as well as being safe for human contact . These alloys are commonly high in tin and alloyed with copper and antimony. As-cast finish is very good and cast objects polish very well to a silver lustre.

For applications in which lead can be tolerated, the range of alloys is extensive, generally providing cheaper alloys but ones which can be tailor-made for specific purposes such as thin or bulky items, reproducing fine detail, malleability or achieving a particular surface finish. These alloys commonly contain tin, lead and bismuth but may also contain antimony and zinc.

William Rowland casting alloys are suitable for a range of casting techniques such as centrifugal and gravity casting into rubber or silicon moulds.

Contact us today for any requirements of low melting point alloys.

LMPA

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