LM6 – Aluminium Casting Alloy (A1-Si12) Colour Code – Yellow
This alloy conforms to BS 1490 : 1988 LM6.
This alloy, having high resistance to corrosion and excellent castability, is most suitable for marine ‘on deck’ castings, watercooled manifolds and jackets, motor car and road transport fittings, thin section and intricate castings such as motor housings, meter cases and switch boxes. For very large castings, e.g. cast doors and panels where ease of casting is essential, for chemical and dye industry castings, e.g. pump parts, for paint industry and food and domestic castings. It is especially suitable for castings that are to be welded.
The ductility of LM6 alloy enables castings to be rectified easily or even modified in shape, e.g. simple components may be cast straight and later bent to the required contour.
It is equally adaptable for sand and permanent mould castings and for die castings.
LM27 – Aluminium Casting Alloy (A1-Si7Cu2 Mn 0.5) Colour Code – Green/Blue
This alloy conforms to BS 1490 : 1988 LM27.
LM27 is a very versatile alloy and, with its excellent castability, it is suitable for most general purpose castings where moderate mechanical properties are desirable, such as general engineering components, domestic and office equipment, household fittings, electrical tools and switch gear, automobile engine and transmission components.
It is equally suitable for sand and permanent mould castings of thick or thin sections, and for castings required to be pressure tight. In short, it can be used with the advantage of slightly superior castability for all kinds of applications for which LM4 is used and may be expected, in time, to supersede the older alloy.
LM25 – Aluminium Casting Alloy (A1-Si7 Mg 0.5) Colour Code – Yellow/Blue
This alloy conforms to BS 1490 : 1988 LM25.
Castings are standardised in the as cast (M) condition, the precipitation treated (TE) condition, the solution treated and stabilised (TB7) condition and the fully heat treated (TF) condition.
LM25 alloy is mainly used where good mechanical properties are required in castings of a shape or dimensions requiring an alloy of excellent castability in order to achieve the desired standard of soundness. The alloy is also used where resistance to corrosion is an important consideration, particularly where high strength is also required. It has good weldability.
Consequently, LM25 finds application in the food, chemical, marine, electrical and many other industries and, above all, in road transport vehicles where it is used for wheels, cylinder blocks and heads, and other engine and body castings. Its potential uses are increased by its availability in four conditions of heat-treatment in both sand and chill castings. It is, in practice, the general purpose high strength casting alloy, whose range of uses is increased by its availability in the as-cast and partially heat-treated condition as well. When fully heat treated to (TF) conditions the tensile strength increases to 230-280N/mm2 from 130-150 N/mm2.
LM0 – Aluminium Casting Alloy (99.50+% Aluminium) Colour Code – White
This alloy conforms to BS 1490 : 1988 LM0.
The main fields are electrical applications, food and chemical plant, including slush cast spouts, and to a lesser degree, jewellery and light trim. The greatest use is undoubtedly electrical, where the high conductivity of the unalloyed metal offers obvious advantages; in addition, ductility enables it to be readily deformed under pressure and use is made of this, for example, in cable clamps. It is widely used for cast rotors for electric motors but a composition having a higher iron content than is allowed in LM0, would have better castability and is generally preferred. Barron-Clark Castings are able to produce aluminium castings from a wide variety of alloys and specifications. Listed below are some typical properties for alloys in regular use at Barron-Clark Castings.
Typical Mechanical Properties
|Sand Cast||Chill Cast|
|Alloy||EN: Spec||Type||Comments||0.2% Proof Stress||Tensile Stress||Elongation||HB||0.2% Proof Stres||Tensile Stress||Elongation||HB|
|LM 6M||44100||AI-Si12||Excellent corrosion resistance||60-70||160-190||5%||50-55||70-80||190-230||7%||55-60|
|LM 25M||42000||AI-Si77 Mg 0.5||General purpose alloy||80-100||130-150||2%||55-65||80-110||60-200||3%||55-65|
|LM 25TE||42000||AI-Si77 Mg 0.5||Single stage precipitation treatment||120-150||150-180||1%||70-75||130-200||190-250||2%||5-95|
|LM 25TF||42000||AI-Si7 Mg 0.5||Fully heat treated variant for good strength and machinability||200-250||230-280||0-2%||90-110||220-260||280-320||2%||90-110|
|LM 27M||46600||AI-Si7 Cu2 Mn 0.5||General purpose alloy||80-90||140||1%||70-85||90-110||160||2%||75-90|
|LMO||N/A||99.5+% AL||Electrical, Food and Chemical Applications||30||80||30%||25||30||80||40%||25|