Joining Techniques

Question 1

Joining techniques
Adhesives (for joining like and unlike materials)
Contact adhesive
Applications

Answer 1

Metals and polymers; unlike materials, e.g. Plastic to wood; general purpose: fabric to most materials

Question 2

Joining techniques
Adhesives (for joining like and unlike materials)
Contact adhesive
Advantages

Answer 2

• able to bond unlike materials.
• bond forms very quickly. so less need for clamping, etc.
• ideal for gluing large sheet materials.
• sold in metal tubes for easy application.

Question 3

Joining techniques
Adhesives (for joining like and unlike materials)
Contact adhesive
Disadvantages

Answer 3

• must be applied to both surfaces and some time must be allowed before they can be pushed together.
• relatively expensive.
• solvent-based so contains harmful volatile organic compounds (VOCS).

Question 4

Joining techniques
Adhesives (for joining like and unlike materials)
Acrylic cement
Applications

Answer 4

Acrylic

Question 5

Joining techniques
Adhesives (for joining like and unlike materials)
Acrylic cement
Advantages

Answer 5

• rapid bonding of acrylics.

Question 6

Joining techniques
Adhesives (for joining like and unlike materials)
Acrylic cement
Disadvantages

Answer 6

• can be difficult to apply and give a neat joint.
• relatively expensive.
• solvent-based so donations harmful volatile organic compounds (VOCS).

Question 7

Joining techniques
Adhesives (for joining like and unlike materials)
Polystyrene cement
Applications

Answer 7

High impact polystyrene (not expanded polystyrene)

Question 8

Joining techniques
Adhesives (for joining like and unlike materials)
Polystyrene cement
Advantages

Answer 8

• strong bond - melts surface of pieces to be joined and causes them to weld together.
• able to use a brush to apply (water- like consistency) and absorbed into joint by capillary action.

Question 9

Joining techniques
Adhesives (for joining like and unlike materials)
Polystyrene cement
Disadvantages

Answer 9

• relatively expensive.

* solvent-based so contains harmful Volatile organic compounds (VOCS).

Question 10

Joining techniques
Adhesives (for joining like and unlike materials)
Epoxy resin
Applications

Answer 10

Most materials including expanded polystyrene

Question 11

Joining techniques
Adhesives (for joining like and unlike materials)
Epoxy resin
Advantages

Answer 11

• high-performance adhesive giving high-strength bonds.
• chemical reaction hardens immediately.
• versatile - can be made flexible or rigid, transparent or opaque/coloured, rapid or slow setting.
• excellent heat and chemical resistance.

Question 12

Joining techniques
Adhesives (for joining like and unlike materials)
Epoxy resin
Disadvantages

Answer 12

• reaches full strength only after a few days.
• expensive
• often requires manual mixing of resin and hardener, which can be messy.

Question 13

Joining techniques
Adhesives (for joining like and unlike materials)
Polyvinyl acetate (PVA)
Applications

Answer 13

Woods (and porous materials)

Question 14

Joining techniques
Adhesives (for joining like and unlike materials)
Polyvinyl acetate (PVA)
Advantages

Answer 14

• gives a strong joint.

* real inexpensive.

Question 15

Joining techniques
Adhesives (for joining like and unlike materials)
Polyvinyl acetate (PVA)
Disadvantages

Answer 15

• surfaces need to be securely clamped together for long periods in order for PVA to harden.
• generally not waterproof (although some brands are)

Question 16

Joining techniques

Preparation

Answer 16

Adhesives require clean and thoroughly prepared surfaces in order for the joint to fully bond. As polymers often have a smooth and shiny surface finish, they should firstly be cleaned and roughened with an abrasive paper before bonding. Metal surfaces should also be degreased and roughened with an abrasive paper. Woods are porous so the adhesive will ‘soak’ into its surface. Once the adhesive has been applied to the cleaned and prepared surface it then has to cure (harden). It is important that the two surfaces are held in place securely so that they do not slip as this process can take several minutes, or hours.