Pressure Forming:
Pressure
Forming is the method used to produce injection mold quality, high
definition plastic component parts, housings and containers without the
huge expense of tooling. It involves positive pressure to force the
heated plastic into the mold cavity. This is called pressure
thermoforming or blow forming
Pressure Forming Working Operation:
The
highly versatile pressure forming process utilizes air pressure, from
20 to 150 psi, to force the heated sheet into a temperature controlled
mold cavity. Vent holes are provided in the mold to exhaust the trapped
air. The final part features sharp definition of intricate contours and
tight radii. Textures and accurate details are built right into the
tooling. Low-cost, highly aesthetic plastic parts of varying sizes are
possible due to the application of air pressure, as well as more
sophisticated process controls that better monitor tool and sheet
temperatures while controlling material shrinkage during forming.
Types Of Molding operation:
- Positive Mold
- Negative Mold
Negative molds have concave cavities. A positive mold has a convex shape.
The
basic advantage of Pressure Forming over Thermo forming is the cost
advantage for small production items. The mould cost for thermo forming
is considerably higher in comparison to pressure forming thus for a
lower quantity precision job the best suitable method used is pressure
forming.
Application:
Pressure
forming is used to create in a wide array of plastic products used for
packaging of food trays, blisters, covers, internal parts, housings
equipment, bezels, bases, and spare parts for use in business machines,
electronics, computers and peripherals, bio-medical applications, and
instruments.
Features:
Pressure
forming achieves features beyond the capabilities of vacuum forming
including louvers, ribs, recessed areas, crisp details and logos.
Pressure
forming is ideal for small to medium sized production runs that do not
justify the high cost of injection molding dies. Additionally, because
the aluminum tooling used in pressure forming has an unlimited
lifecycle, due to the non-abrasive process versus injection, it saves a
great deal of money over many years of continued use. Pressure form
tooling usually costs less than 10% the cost of an injection tool. There
is also a significant time savings (sometimes 25%) in tooling lead
time. Sheet gauges .020" – .500" are capable of being pressure formed.
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