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issue: July 2004 APPLIANCE Magazine
Plastics & Plastic Parts
Plastic Triplets: High Power Plastic |
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by David Simpson, Contributing Editor
When designing its new Zeus anesthesia workstation, Draeger Medical (Telford, PA, U.S.), a manufacturer of auxiliary medical equipment, chose Victrex Peek polymer for the radial blower on the workstation’s ventilator component. It was chosen because of the material’s high strength and purity. |
| VICTREX PEEK polymer was chosen because of the material’s
high strength and purity. |
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Medical
device maker Draeger Medical found that VICTREX PEEK polymer,
supplied by Victrex USA, suited the high strength and
purity
needed in a blower for
its Zeus anesthesia workstation. |
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The electrically powered radial blower is central to the equipment’s
new E-Vent Plus ventilation technology. Reaching speeds of up to
42,000 r/min in less than 200 msec, the blower checks and constantly
ventilates the patient. To achieve this type of acceleration, the
moment of inertia and the weight of the blower wheel need to be
as low as possible. “The wheel must be strong enough to prevent
its fins from bending due to the enormous centrifugal forces that
occur at these speeds,” explains Andrew Ragan, Victrex global
leader, Industrial. “High seam strength is also essential.” |
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To meet these requirements, Draeger Medical uses
non-reinforced VICTREX PEEK polyaryletherketone from Victrex
USA Inc. (Greenville,
SC, U.S.) to injection mold the 2-in (55-mm) wheel, which has
a wall thickness of just 0.012 in (0.3mm). The wheel has a
tensile strength of approximately 14,500 psi (100 MPa) at a
temperature of 74°F (23°C). It also has the purity
required for clinical use.
From a production point of view, manufacturing the blower
presented a number of challenges. The wheel is made in a tool
with 23 slide bars in an injection molding process. It must
form a homogeneous, partly crystalline structure. Special attention
was given to the parting system and the geometric placement
of the ejectors to maintain the tight tolerances required for
high balancing quality and to minimize warping in the connection
between the shaft and the hub. “Because semi-crystalline
VICTREX PEEK can achieve maximum flow rates of up to 40 gal/min
(150 l/min) with an excellent response dynamic, it does not
require any more working gas,” says Mr. Ragan. “As
a result, operating costs are considerably reduced.”
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