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Injection Molds For Molding Of Medical
Components
The injection mold is a key component in the overall process of making
a finished medical product. The process of building injection molds to
produce components for these products is best understood if one knows
the driving factors of why plastics are the material of choice in the
first place. In recent years, medical products are making greater use
of plastics in a broad range of applications. Plastic materials have
overtaken the use of materials such as stainless steel, glass and
woven fabrics in many applications because of several
key-distinguishing attributes. It is through an understanding of what
the medical customers are looking for that we can define what steps
are important in the design and construction of medical injection
molds.
There are five(5) main points that
accelerated the use of plastics in medical products.
Reliable dimensional stability
Parts meet functional requirements
Low cost
Fast turnaround from concept to parts
Clean, particulate free parts
The medical industry has recognized the
advantages of using plastics and have learned to expect them and rely
on these advantages. The medical industry now demands higher levels of
quality and at a lower cost. As a result, the tasks involved to
address these needs have become more complex.
An important starting point is to have one person in charge of the
process for coordinating the transfer of a part design on paper to a
finished part coming out of the mold. This person, for the purpose of
this presentation, is called the Tooling Engineer. The Tooling
Engineer ideally has extensive experience with mold design technology
and mold shop machine processes. This person will coordinate all the
communications that are critical to making the job a synchronous,
harmonious process.
Relationship Between Part Design and Mold Design
The first part in the process is to
initiate open communication, early in the process, between the product
designers and the Tooling Engineer. The objective is to build a solid
foundation for the tooling project to start form. There are many times
when a product is designed in such a way that it becomes extremely
difficult and complex to Construct a tool that can make the part. Once
the mold design and tool construction starts, it is expensive to
change the design or start the process over again.
An example of this would be to change the location of an undercut by
moving it closer to or directly on the ideal parting line for the
mold. Up front planning such as this can eliminate the costly use of
secondary side action slides. Additional mold action steps will
increase the size of the and reduce the number of cavities possible
for a given size mold. More importantly, additional mold action steps
can increase the likelihood for quality problems related to flash and
mold wear issues.
Selection of a Mold Maker
The selection of a mold maker is the next area that deserves
considerable attention. There are many ken factors that should be
considered in this process.
The Tooling Engineer needs to be closely
involved because of the frequent communication required between the
tool designer, the tool shop personnel and himself. An excellent
overview of the process involved is written in an article entitle "How
to Pick a Top Quality Toolmaker", issued in Plastics Technology
Magazine in the January issue of 1993.
Some of the critical factors involved in the process are as follows:
Uniformity between molds (component
interchangeability) |
