2. Contents
• What is transfer molding
• Variety of transfer molding processes
• Materials used for transfer molding
• Process of transfer molding
• Applications
• Advantages and Disadvantages
3. What is transfer molding?
• Transfer molding is a manufacturing process
where casting material is force into a mold and
make the casting
4. AboutTransfer Molding
• This is similar to compression molding and injection molding
• But the different from compression molding in that the mold is enclosed
rather than open to the fill plunger
• In injection molding we use heat to melt the material and then press to
make the casting. But in transfer molding we use only pressure to make the
casting.
5. Variety of processes within theTransfer
Molding
• ResinTransfer molding(RTM)
• Uses a liquid thermoset resin to saturate a fiber preform placed in a closed mold
• The process is versatile and can fabricate products with embedded objects such as foam
cores or other components to the fiber preform
• Vacuum assisted resinTransfer molding(VARTM)
• Uses a partial vacuum on one side of a fiber mat to pull the resin in for complete saturation
• Uses a lower plunger forces which allows molding to be carried out with a cheaper
equipment
• This can produce parts with less pourosity than regular transfer molding
6. • MicroTransfer molding
• This is a process that uses a mold to form thin transfer structures as small as 30nm
• Unlike normal scale transfer molding, the micro form can and is used with metals as
well as non metals
7. Transfer Molding Materials
• Thermoset polymer
• This type of polymer is easy to mold and manipulate. But cannot reuse.
• Polyurethane
• Epoxy resins
• Fibers
• Kevlar fibers
• Organic fibers
8. Process ofTransfer molding
• The pre-heated, uncured molding compound is
placed in the transfer pot
• The mold is closed up and under hydraulic pressure, the molding compound is forced through a small hole
into the cavity.
• The mold is held closed while the molding compound cured(thermosets) or cooled(thermoplastics).
9. • The mold is split to free the product, with the help of the ejector pins.
• Any flash and the sprue material is trimmed off.
10. Transfer Molding Applications
• Natural gas industry
• Electrical industry
• Hydraulic industry
• Wind turbine blades
• Medical composites
• Aerospace and automobile parts
• Bathroom fixtures, car body, helmets, etc…
11. Advantages OfTransfer Molding
• Simple production cycle
• Maintain closer dimensional tolerance than compression molding
• Provides uniformity to products than in compression molding
• Fast mold setup
• No heat required to melt the material.This reduces the equipment cost
12. Disadvantages OfTransfer Molding
• Waste more material than compression molding (scraps of thermosets are
not re-usable).
• Production rate is slower than injection molding
• Use higher pressures to uniformly fill the mold cavity
