Applications
In theroy,
any mold will run faster as a Tachythermtm mold, and we encourage
you to consider a Tachythermtm mold
to lower your costs by reducing molding cycle time. In Practice, however, certain applications are particularly well suited
to benefit from the Tachythermtm advantages. These include:
· Cycled temperature molding
Cycled temperature molding is known by many names, including variothermTM,
RTC, ATT, and RHCM. It involves alternately heating the mold (during
injection), and then cooling the mold (during the cooling phase). This technique
is particularly useful in micro-molding
and molding of extremely thin-walled
parts. If can also be used for parts with long flow paths, as a simpler alternative to multi-gated or
sequential valve gated molds. Fine surface finish and detail is attainable,
even with filled resins. This technique
is also very useful for molding heat and shear sensitive materials (e.g. bioresins, acrylonitrile), as filling
and packing the mold cavity at low melt temperature and mold temperature may be
difficult, without shear-producing high injection pressure and speed. The
cavity surface stays hot until it is filled and packed, but it rapidly cools
once packing is complete. With a Tachythermtm
mold, the entire mold need not be heated and cooled, but only the high thermal
conductivity envelope surrounding the cavity. This enables faster cycle times.
· Medical device molding
Medical devices often have unusually
stringent dimensional and form requirements, despite their sometimes complex
geometries. The uniformity of cooling in a Tachythermtm
mold helps eliminate distortion, which is usually a result of uneven cooling,
enabling very tight dimensional control.
· Micro-embossing
Most embossing machines for micro-embossing applications (e.g. microfluidics),
have heating and cooling means incorporated into the platen. This requires the
entire platen and tool to be heated and cooled during the embossing cycle,
which costs valuable manufacturing time. With a Tachythermtm
mold, only the embossing tool is directly heated. This shortens cycle
times and saves energy.
· Micro-molding and thin-walled molding
When cycled temperature control is not used for micro-molding and thin-walled
molding, the mold is typically run very hot, to allow the narrow mold cavity to
fill before the melted polymer freezes off. In such cases, it’s particularly
helpful to have as efficient an exchange of heat between the mold cavity wall
and the cooling medium as possible, because a large ΔT is not available to
drive the movement of heat from the cavity wall. The high thermal conductivity
envelope, which surrounds the cavities of a Tachythermtm
mold, facilitates the movement of heat out of the cavities, practically
as fast as is thermodynamically possible.
· Molding in electroformed cavities
Since Tachythermtm
molds have electroformed cavities, they are ideally suited for
applications in which electroformed cavities are traditionally used. Though
this is not practical for applications where shim electroforms are used (e.g.
optical discs), it is true for leather and
wood-textured molds, optical component molds, automotive lighting molds, road marker molds, etc. If your mold is
already electroformed, why wouldn’t you take advantage of the unparalleled
thermodynamic efficiencies of a Tachythermtm
mold?
· Molding of complex shapes in three
dimensions
Because
complex three dimensional shapes
defy uniform cooling with gun-drilled cooling channels, these molds invariably
have hot spots, which limit how fast the molding cycle can be run. The
conformal cooling channels and high thermal conductivity envelope of Tachythermtm molds are designed to eliminate
such hot spots and to virtually suck heat from the cavity walls, efficiently
and evenly.