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MCP low melting point alloys solve problems of bending thin wall
sections and tubes easily and inexpensively because they: melt at
70° centigrade - easily handled expand on solidification -give
maximum support are completely re-usable - economic in use - easy
and safe to handle.
View the
Bend Data Sheet Here in PDF Format
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| Eight
steps to successful Tube Bending
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 1.
Preparation The bore of the tube must be cleaned free from dirt, rust,
scale and grease. Any form of dry cleaning can be used but pickling
or wet treatments should be avoided as they may affect the performance
of the oil film (see step 2). NOTE: It is important that the tube
is capable of taking the bend required. No supporting medium will
help a tube which has not been properly annealed. If in doubt, check
with the tube supplier. |
 2.
Oiling To prevent alloy adhering to the bore of the tube after the
melting-out operation, a continuous thin film of oil should be deposited
on to the bore wall. This is best obtained by plugging one end of
the tube filling with a straight mineral oil such as Shell Vitrea
27 and then drained to leave just a thin film. Motor oils are not
suitable for this purpose, but soluble soaps can be used as an alternative. |
 3.
Pre-heating Tubes must be warmed in order to prevent premature chilling
of the alloy before the tube is completely filled. Water is a good
medium for this operation but care must be taken to prevent water
entering the tube. |
 4.
Loading Molten MCP 70 alloy should be poured smoothly and steadily
into the tube to fill completely in one operation. An alloy temperature
of 85°C to 90°C is ideal for most sizes of tube but this may
be increased for the smaller bore sizes 1/4" (6mm) and below. |
 5.
Quenching This is a most important step as quenching ensures that
the alloy is in its most suitable condition for bending. It must be
carried out immediately after the alloy has been poured, and before
it has solidified. The operation should ideally be carried out in
a tank of circulating cold water and the tubes lowered in carefully
to prevent movement of the alloy whilst molten. Tubes should not be
removed until the alloy is completely solid and this could take approximately
15 minutes for a 1” (25 mm ) tube. |
 6.
Bending Allow the tube to reach ambient shop temperature after quenching.
Slight warming (to 30°C maximum) may be necessary in very cold
conditions. Bending should be carried out slowly and smoothly avoiding
shock loading, using any of the conventional bending techniques. |
 7.
Unloading The bent tubes should be immersed in near boiling water
and tilted to allow the alloy to escape. Violent movements should
be avoided.
When all the alloy has drained from the tube, quench in cold water.
CAUTION. Do not apply direct flames to a loaded tube. If the middle
is heated and the ends of the tube remain filled with solid alloy,
the tube may burst. |
 8.
Cleaning The unloaded tube should be left in the quenching tank for
at least two minutes. This is necessary to ensure that no liquid droplets
of alloy remain in the tube. A tight fitting pull-through passed 2
or 3 times from each end of the tube should leave the bore completely
clean. |
Low Melting Point Bismuth Alloys
Imagination plus METSPEC low melting point alloys help make ...
• Turbine Blades
• Plastic Spoons
• Danish Modern Furniture
• Rifle Barrels
• Eyeglass Lenses
• Electronic Assemblies
• Chemicals
• Ceramic Pottery ... and more . . . perfectly and profitably.
Click Here for
a Detailed Spec Sheet of types of Bend Alloys Available
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| Low melting point, or fusible, alloys
melt in the unusually low range of 117°F to 300°F. Containing
bismuth, which expands on solidification, the alloys retain this distinct
property. By adjusting composition, it is therefore possible to produce
a series of alloys which have dimensional stability on casting, or
have a significant degree of growth . . . as much as 0.005 inches
per inch. Similarly, an infinite variety of melting points can be
produced. Normally METSPEC alloys are used by simple gravity casting,
but they are also pressure cast or sprayed. And, being stable metals,
can be remelted and used again and again. |
Positioning/Locating
When two parts have to be mated together in an exact relationship,
there is NO BETTER METHOD than the use of METSPEC expanding fusible
alloy. When any of the expanding METSPEC alloys is cast into a cavity
it will exert outward pressure on the walls. Such close fitting between
one part and another cannot be surpassed by the finest toolmakers.
The necessity for expensive jigs or handwork, where very precise location
is required, can be avoided by setting up the operative part in an
oversize hole in the other, and by filling the gap quickly and precisely
with a METSPEC alloy. The location of parts with a complicated section
(e.g. blanking punches) is simplified greatly.
Holding
If an irregular part must be worked, a symmetrical block of METSPEC
alloy cast around the piece will hold it rigidly while it is being
machined. When the work is done, the alloy can be melted away in hot
water. As another example, prescription optical lenses must be supported
over their entire surface when they are ground and polished. The holding
device must conform accurately to each individual lens. The high fluidity,
low melting point and dimensional stability of METSPEC fusible alloys
makes them ideal.
Supporting
Hollow parts and thin sections can be difficult to work because they
are not strong enough to withstand the load imposed by machining.
This problem is overcome by filling the workpiece with METSPEC alloy,
forming a solid block. Another useful © advantage is that burrs
are avoided because of perfect support by the alloy. Easy recovery
of the alloy from the swarf makes the process inexpensive. In the
same way, tubes and open sections can be loaded with a METSPEC fusible
alloy before forming. They then behave as though solid and can be
bent without rippling or flattening.
Joining
METSPEC alloys which contain tin and indium will wet other metals,
and can be used like conventional solders with flux. Indium has the
property of wetting glass, quartz, glazed ceramics and mica ... and
when alloyed with tin, it makes an excellent joint between these materials
and ANY solderable metal.
Forming
When conventional toolmaking techniques are too costly or slow, use
METSPEC fusible alloys. Sheet metal forming tools are a good example,
along with jigs and fixtures, dies for wax and plastic injection molding,
blow molding, vacuum forming tools and molds for resin or plaster.
Dimensional stability and low melting points which are essential for
fusible cores are available in METSPEC alloys, and they are widely
used for high precision electroforming mandrels or coring cast resins
and reinforced plastics.
Duplicating/Imaging
The difficulty of visualizing cavities as solid forms or reverse engravings
in their true perspective is usually overcome by proof casting. Inspection
of a diesinker's work is best done by casting a METSPEC alloy into
the die, obtaining an exact reverse reproduction. They are used widely
in dieshops and toolrooms where accuracy is a must.
Annealing
METSPEC alloys maybe used as furnace seals, heat treating baths or
as heat transfer media.
Fusible Core
Fusible alloys provide a wonderful alternative to the lost wax process
for reproducing intricate internal details, for example the inlet
manifold for an internal combustion engine. The alloy is cast or formed
into the shape required which is then over molded with plastic. The
alloy is easily removed by melting at low temperatures. |
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