Group Members: Technical Training Officer (TTO) : Sir Azlan

1.Firdhaus

2.Elizabeth

3.Sharkir

4.Safwan

5.Shaffiq

• Introduction

• Material of The Processs

• Tooling/Machine

• Process

• Product

• Advantage and Disadvantage of Process

• Comparison With Other Process

• Conclusion

• The process of molding a material in a confined shape by applying pressure and usually heat.

• Compression molding process is followed by two step first one preheating and pressurizing.

• Compression molding is generally used for thermosetting plastic.

• 1909 when Leo Hendrik Baekeland found thermosetting compound phenol-formaldehyde resins

• Patents on a automatic compression machine date back to 1930

• Its inventor, Alfred Critchlow, founded the Pro Corporation, Florence MA in 1847.

• Pro is said to be the first plastics molding company.

• Development of compression molding was hindered by reaction knowledge.

Hand made mold for hand held mirror

(1870) .

Large scale compression molding

press (1935).

Trimming flash from Ekco radio cabinets

(1934).

• Thermosetting polymers

• Fiber reinforced plastic

• Thermoplastic

Heat compression causes an irreversible chemical charge in the plastic which solidifies the part .

The plastic won’t soften, so the mold doesn’t need to be cooled.

After short interval, the press is opened and the molded part is removed.

Any plastic remaining in the mold is removed by compressed air. The operator breaks the flash.

• Preheated in a dielectric heater.

• The mold is cooled to a point where the plastic retains enough integrity to be removed from the mold without partial distortion.

• The same steps used for thermosets are repeated here as well

• Fibre-reinforced plastic (FRP) (also fibre-reinforced polymer) is a composite material made of a polymer matrix reinforced with fibres.

• The fibres are usually glass, carbon, basalt or aramid, although other fibres such as paper or wood or asbestos have been sometimes used.

• The polymer is usually an epoxy, vinyl ester or polyester thermosetting plastic, and phenol formaldehyde resins are still in use.

• Density

• Strength

• Anisotropic property(fiber orientation)

• Shrinkage and wrapage

Fiber orientation induced by the material flow in the mold.

• Compression mold presses are manufactured in a wide variety of sizes.

• Most presses utilize a hydraulic ram in order to produce sufficient force during the molding operation.

• The tools consist of a male mold plunger and a female mold.

Press Mold

• Sheet molding compound (SMC) 1. As with other thermosets, SMC is a mixture of polymer resin, inert fillers,

fiber reinforcement, catalysts, pigments, stabilizers, release agents, and thickeners.

2. Manufacturing of SMC is a continuous in-line process.

• Bulk molding compound (BMC)1. BMC is available in bulk bags as well as slug form. T

2. he mixing operation can be done in a number of ways.

3. Premix employs three methods for combining glass with paste: a continuous screw mixer, a sigma blade mixer and a plough blade mixer.

• The compression molding starts, with an allotted amount of plastic or gelatin placed over or inserted into a mold.

• Afterward the material is heated to a pliable state in and by the mold.

• Shortly thereafter the hydraulic press compresses the pliable plastic against the mold, resulting in a perfectly molded piece, retaining the shape of the inside surface of the mold.

• After the hydraulic press releases, an ejector pin in the bottom of the mold quickly ejects the finish piece out of the mold and then the process is finished.

• (1) loading a precise amount of molding compound, called the charge, into the bottom half of a heated mold.

• (2) bringing the mold halves together to compress the charge, forcing it to flow and conform to the shape of the cavity.

• (3) heating the charge by means of the hot mold to polymerize and cure the material into a solidified part.

• (4) opening the mold halves and removing the part from the cavity.

1.The quantity of molding material

2.Pressure of the molding process

• Range of pressure 2000-3000 psi(13.8-20.7 MPa)

3.Mold temperature

• Temperature range 300ºF to 375ºF (149⁰C- 191⁰C)

4.Cure time variables.

• The period required to harden thermosetting material to partial and complete polymerization is called cure time

• Flash type compression moulding is used for shallow parts but results in higher material losses.

• Semi-positive compression is used for closer tolerance work or when the design involves marked changes in thickness and Positive compression is used for high density parts of composite sheet moulding components, bulk moulding compounds or impact thermosetting materials.

• This process is commonly used for manufacturing electrical parts, dinnerware, and gears.

• This process is also used to produce buttons, buckles, knobs, handles, appliance housing, radio cases, and large containers.

• Automotive parts• Hoods, bumpers, fenders, spoilers, etc.

• Medical equipment• Caps and plugs to blood separation machines and ultrasound equipment

• Aerospace• Electrical connectors to guided missiles

• The process is now a very widely used manufacturing technique because it is:

• Cost efficient

• Suitable for high volume production

• Capable of producing large components

• Efficient in material usage – wastage is minimal

• Physically quick and efficient with a low number of process steps

• Capable of producing detail features such as holes – which with

• Other molding techniques would need additional machining to deliver.

• Curing time large

• Uneven parting lines present

• Scrap cannot be reprocessed.

• No delicate pieces

• Uneven parting lines

• High initial investment

• secondary operations (e.g. trimming)

• Mold depth is limited

• Product consistency

• Efficiently deliver high volumes of components economically.

• With the drive towards more fuel-efficient, hybrid power technology and lower production costs, then we are likely to see some significant new ways of using the technique.

• Add to that the almost daily development of exotic materials –both the base resins or plastics and the reinforcement materials –and the increased refinement of the press machinery and processes, then the future is surely one of continued growth.