DRAGON INNOVATION, INC. !

DESIGN  FOR  MANUFACTURING  !

COURSE 7: PART 2 - COMPRESSION MOLDING !!!!!!!

SCOTT N. MILLER | CEO | @DRAGONINNOVATE | WWW.DRAGONINNOVATION.COM

Compression Molding Overview

Typical Compression Molded Parts

• Gaskets and Seals

• Couples

• Remote Button Pad

• Hoses and Fittings

Compression Molding Advantages

• Can use variable wall thickness • No flow lines or knitting (O-Rings) • Low Cost • Suitable for high volume manufacturing • Flexible Materials / Can use Thermosets • Good surface finish • Low residual stress

Compression Molding Disadvantages

• Slow cycle time requires multiple cavities (configuration issues and cost)

• Cannot regrind excess material • Simpler parts • Requires workers to place resin and remove flash. • Typically planar parts (limited mold depth)

Compression Molding Process

Process

• Thermoset charge placed in open mold cavity • Mold closed with heat and pressure • Crossing linking • Manual extraction and flash trimming

Process

Compression Molding Part Design

Design Guidelines

• Typically planar / flat parts • OK to have non-uniform wall thickness • Flexible component

Materials

Common Materials

Alloy  /  Resin Young’s  (MN/m2)

Yield  (MN/m2)

Spc  Gravity  (g/cm3)

Cost  ($/kg)

Die  Life  (cycles)

Pressure  (psi)

Wall  Thickness  (mm)

Melting  Temp  (C)

Silicone 70,000 250 6.6 1.80 500,000 3,000 1.0  –  1.5 420

Natural  Rubber 80,000 330 5.8 1.90 500,000 5,100 2.0  –  2.3 430

Neoprene 125,000 150 2.7 1.70 100,000 7,000 2.0  –  2.3 660

Melamine  Formaldehyde  

45,000 150 1.8 2.93 180,000 7,000 2.0  –  2.3 650

Phenolic 100,000 215 8.4 6.60 15,000 5,800 2.0  –  3.0 950

28,000 70 1.13 4.00 300,000 16,000 2.0  –  3.0 130

• Silicone • Natural Rubber • Phenolic

Common Materials

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