Page 31 - Plastics News August 2018

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some larger-tonnage, thin-wall packaging applications. These materials may contain special additives like PTFE
For both electric and hydraulic equipment, however, D ÁXRURSRO\PHU RU VLOLFRQH IRU D ORZ FRHIÀFLHQW RI
medical molding machines must be closed-loop systems friction and low-glide-force performance. Compared
with precision injection and clamp movement. Today, with commodity materials, engineering materials are
many medical devices incorporate small, intricate harder to process and have narrower processing windows.
parts with complex, multi-functional geometries. This Validation requires documenting the material melt-
requires injection molds with complex actions or mold ÁRZ LQGH[ 0), DQG HQVXULQJ WKDW WKLV YDOXH LV ZLWKLQ
movements.Medical molders need controls to avoid cross- D VSHFLÀHG UDQJH 1\SUR UHTXLUHV PDWHULDO FHUWLÀFDWHV
contamination between jobs, with rigorous line-clearance of analysis (COA) or conformance (COC) with each
procedures and frequent process audits. ORW RI PDWHULDO WR LQGLFDWH ERWK PHOW ÁRZ LQGH[ DQG

Molds used in medical molding can have as many as 128 ÀOOHU FRQWHQW &HUWLÀFDWLRQV IRU HDFK ORW DUH UHYLHZHG
cavities. They include hot- or cold-runner, single- or at incoming inspection and before use. Lot numbers
two-shot mold designs. Because mold validation is time- become part of the DHF and provide traceability
consuming and expensive, molds must be built to high for the material used in molded parts. Traceability
quality standards that will achieve millions of cycles. For resolution is available to the box level. In engineering
best results, they are made of high-quality steels such as PDWHULDOV DGGLWLYHV VXFK DV RLOV DQG ÀOOHUV DUH FRQWUROOHG
420 stainless steels, H13 or S7. Some medical applications by percentage. To ensure consistent processing and
preclude the use of nickel-plated components. Other molded part performance, a medical molder must
applications don’t allow beryllium copper components specify and document non-substitution agreements.
that make direct contact with plastic parts. Microtiter Engineering materials must also comply with restrictions
plates used in blood diagnostics are a good example, or regulations such as USP Class VI (U.S. Pharmacopeia
as beryllium copper may interfere with the binding of biocompatibility), ISO 10993 biocompatibility, and BSE/
antigens inside the plastic wells and affect diagnostic TSE (bovine-free compliance).
results. Another example is a molded surface that contacts :KHQ KLJK YROXPH FRORUHG PDWHULDOV DUH XVHG PHGLFDO
EORRG ÁRZ RU D GUXJ IRUPHG E\ D PROG FRPSRQHQW WKDW molders like Nypro buy precolored or color-compounded
could transfer small particles of beryllium copper. Material materials. Low-volume colored materials are mixed at
handling also poses extremely important considerations 1\SUR IURP FRORU FRQFHQWUDWHV 0DWHULDOV ZLWK ÀOOHUV DUH
for medical molders. Contamination from using the wrong always precompounded at the material supplier.
material is costly. It’s an even bigger problem if the Employees
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controls to avoid cross contamination between jobs, with Last but certainly not least, highly skilled employees
rigorous line-clearance procedures and frequent process are one of the “Four E’s” that medical molders must
audits. Typically, material handling is performed outside have in order to succeed. Managers, engineers,
of the cleanroom. Material is vacuum transferred from technicians, inspectors and operators must know and
the gaylord into a dryer, if required, and then vacuum understand current Good Manufacturing Practices (cGMP)
transferred into the molding machine hopper. for both medical molding and assembly, and work with
care and diligence to ensure high levels of quality
Proper material handling also helps to prevent black-
speck contamination. Often, black-speck allowance and compliance.The complexity of medical molds and
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investing in the proper environment, equipment,
WKH FXVWRPHU·V TXDOLW\ VSHFLÀFDWLRQV 0RVW EXW QRW DOO engineering-material processing knowledge, and highly
medical products require 100% virgin material. Regrind is
not allowed when there is risk of contamination or the skilled employees, device manufacturers may find a
loss of mechanical properties. Avoiding regrind can also particular molder ill equipped to meet their needs.
minimize the presence of black specks. These key fundamental elements of medical molding
can make the difference between success and failure in
Engineering materials medical-device manufacturing and being awarded new
opportunities.
Many medical molding applications use highly engineered
materials to improve performance in medical devices. Courtesy: Plastics Technology

31 August 2018 Plastics News