Finishing, Adhesion, and Assembly

1
Finishing, Adhesion, and Assembly

• MFG 355

2
Material removal

• Traditional
• Cutting, Drilling, Milling
• Surface finishing
• Issues
• Heat transfer
• Peck drilling
• Skip-tooth saws
• Increased cutting speed
• Slower cutting advance
• Hole size (shrinkage)
• Cutting fluids
• Brittle/soft
• Composites

3
Traditional Machining

• Used to make minor shaping corrections
• Used to trim excess material
• Used often in thermoforming and blowmolding
• Sometimes parts are molded oversized so that they
  can be machined to exacting tolerances

4
Material removal water jet

• Typically used with the more difficult materials
  (composites, very hard plastics)
• Water-jet can cut most materials, even composites
  effectively

5
Material removal lasers

• Laser cutting burns the material away
• In clear materials, holes can be cut between
  surfaces without affecting the surface
• Focus adjustment can reduce kerf, heat distortion
  and depth of cut

6
Material removal hot wire

• Traditionally used for foams
• Can cut any thermoplastic
• Material may flow back together

7
Joining

• Adhesive joining Definitions
• Adherends/substrates pieces to be joined
• Adhesive glues
• Applicator the device used to put on the
  adhesive

8
Adhesive Joining (Adherends)

• Surface preparation
• Cleaning
• Chemical etching
• Flame treatment
• Corona treatment
• Plasma treatment
• Coupling agents
• Mechanical abrasion
• Especially important for some materials (PE)

9
Adhesive Joining (Adhesives)

• Liquids, pastes or solid films
• In all cases the adhesive goes through a liquid
  phase
• Chemical change
• Structural
• Hot melt
• Pressure sensitive
• Water based
• Radiation cured

10
Non-Traditional Joining

• Fusion
• Heat materials and force them together
• Ultrasonic
• Vibrate the materials to soften them and force
  them together
• RF (radio frequency)
• Similar to Ultrasonic at a different frequency
• Spin/Friction stir
• Material is not raised in temp to the Tm
• Some of the strongest joints

11
Non-Traditional Joining

• Induction
• Electromagnetic heating
• Requires some metallic filling in the plastic to
  be joined

12
Mechanical Joining and Assembly
13
Finishing

• Runner and Sprue Removal
• By hand with wire cutters
• Done by operator between part cycles
• Proper gate design can reduce problems with waste
  removal
• Flash Removal
• Colder is better
• Cryogenic flash removal
• Traditional cutting methods

14
Coating and Decorating

• Painting (liquid or powder)
• Sometimes requires surface treatments
• Environmental and safety issues
• Powder coating replacing liquids (solvents)

15
Coating and Decorating

• Electrostatic coating of any material
• Metallizing
• Can be done as a barrier coat

16
Coating and Decorating

• Printing
• Similar to painting except that it is usually not
  the entire surface
• Screen printing (UV ink cure)

17
Coating and Decorating

• Hot stamping
• Appliqués
• In-mold decorating
• Decals

18
Coating and Decorating

• Laminating
• Joining layers together by pressing

19
Coating and Decorating

• Embossing/Texturizing
• Giving shape to a layer using an embossing roll
  or stamp

20
Thank You
21
Joining

• Adhesive Bonding
• Materials
• Processes
• Designs
• Non-adhesive Bonding
• Fusion
• Ultrasonic
• RF
• Spin
• Induction
• Friction stir
• Mechanical Joining and Assembly

22
Finishing

• Runner System Trimming and Flash Removal
• Coating and Decorating
• Painting
• Printing
• Metallizing
• Laminating
• Texturing
• Post Mold Forming