Compression Molding

Question 1

What’s the role of the mold release agent?

Answer 1

The mold release prevents the materials from bonding with the mold surface.

Question 2

. Describe the Compression Molding Process?

Answer 2

Materials (fiber/resin) that are pre-weighed to a specific size charge, placed in a
(closed) mold, and heat and pressure applied in a press till part is cured

Question 3

What are the processing variables to consider in compression molding?

Answer 3

Mold temperature, charge pattern/placement, molding pressures, press closing
speed, cure time.

Question 4

Which parameter above is the most important? (Mold temperature, charge pattern/placement, molding pressures, press closing
speed, cure time)

Answer 4

Temperature- variations can result in premature gelation or not full cure.

Question 5

How do we estimate amount of material needed to fill a mold? in the case of
Frisbee?

Answer 5

Volume of the cavity should be determined and correct amount of material
calculated to match that with minimal waste. In the Frisbee, the mass of
Polypropylene was determined which was in relation to its material density and
volume.

Question 6

How does one calculate the press force as it is on the tooling?

Answer 6

Depending on the hydraulic pump, can produce a constant pressure of 2000-5000
psi. This pressure is placed on the lower end of the hydraulic ram and push on the
platen and thus on the mold. The max force a press can develop is based on
cross-sectional area of the hydraulic ram and the geometric area of molded part.

Hydraulic Pressure (PSI) * CS area of ram (in^2) / Geometric area of part (in^2) = Pressure on mold

Question 7

Where can you find information on the materials being used in this process?

Answer 7

Material Safety Data Sheets (MSDS)