LM138 138°C Lead-Free Low-Melt Metal Moulding Alloy

LM138 is a highly pure eutectic of the bismuth-tin alloy. It has a precise melting/solidification point of 138°C and exhibits very low liquid to solid volume change (+0.7%). These properties make it highly suitable as a castable, melt-out core for hollow composites moulding processes, most commonly alongside prepreg laminates. Being cadmium and lead-free, LM138 requires no special considerations in a regulated production environment.

When used in a typical lost-core process, LM138 can be reused indefinitely, making it both economical and environmentally friendly in repeated production.

Typical Uses

The most typical application for LM138 is in casting solid cores or mandrels for a ‘lost core’ moulding process. In this process, resin and reinforcement, usually in the form of prepreg, is laminated around the outside of the core before being consolidated using shrink tape or a vacuum bag. The component is then heated to a temperature sufficient to cure the resin in the prepreg but not high enough to melt the core. Once the prepreg is cured the bag or tape is removed and the temperature is increased to above the melting point of the alloy, at which point the core can be easily poured out and re-used.

Although most often to make fusible cores or inserts for use with prepregs, LM138 can also be used in other composites moulding processes including hand-layup and resin infusion, providing that the resin systems used in the process will not be damaged by being heated to the 138°C melting point of the alloy.

Due to its low melting point, very low liquid-to-solid volume change and good mechanical properties, LM138 also finds uses in thermal protection devices, as anchoring or support material and in radiation shielding.

• Fusible core / lost core / melt-out core in composites or injection moulding
• Work holding / anchoring and support
• Press tools

Where a slightly lower melt-out temperature is required, we also have our LM95 low melt-alloy which has a melting point of 95°C, making it suitable for use with prepregs or processes which would not tolerate the 138°C required to melt out the core.

Composition

Physical Properties

The recommended casting temperature for LM138 is 165°C - 190°C. LM138 has a density of 8.6g/cm³ so the volume of your casting in litres should be multiplied by 8.6 to find the number of kilos of LM138 required to fill it.

LM138 has excellent ductility and good fluidity. In common with all bismuth alloys, it undergoes gradual equilibrium following solidification, exhibiting slow dimensions changes, the rate of which is dependent on post solidification treatment.

Safety Considerations

Unlike other low-melting point alloys such as 'Woods metal', LM138 does not contain harmful cadmium or lead, which offers health and regulatory advantage over other alloys. Suitable protective gloves and equipment should always be used when handling hot liquid metal.

How to Buy

LM138 is supplied in 1kg ingots. Please enter a 'Qty' for the number of kilos required. Volume discounts will be automatically applied.