Active Disassembly

Self Disassembly Electronics

Labour for disassembly represents a large fraction of recycling electronics

Products that can non-destructively take themselves apart??

Active Disassembly with single generic trigger

Not necessary to have records or plans on how to disassemble

Active Disassembly

Active Disassembly

Active Disassembly

Active Disassembly

Smart Materials

Two basic families of smart materials– Shape Memory Alloys– Shape Memory Polymers

Below a certain “transformation temperature” (Tx) they behave as standard engineering materials & can be used in the normal way

Above this critical temp they undergo a shape change that can be reversible if the temperature is lowered again

Tx can be controlled within a wide range of temperatures Proper use of different activation temperatures can enable a

designer to create a product that could take itself apart sequentially

Shape Memory Alloys

A group of metals made up of two or more metallic elements with particularly remarkable shape-changing and force provision properties

As the temperature crosses or changes across a critical value (Tx), known as Austenite Finishing Temperature they undergo a large and predictable shape change the so called Shape Memory Effect (SME)

Corrosion resistant and biocompatible Mechanical strength to form fasteners Tx can be placed between -190 C to 190 C

Shape Memory Alloys

Shape Memory Polymers (SMPs)

Small group of plastics that can be formed using the normal processes

SME in SMP is different from SMA and is not well understood

Above their transformation temperature or glass transition temperature (Tg) SMPs loose their mechanical strength and return to their original formed shape after external forces are removed

SMP has a very narrow Tg range ~1C. Unlike SMA plastics provide no significant force

Shape Memory Polymers (SMPs)

Shape Memory Effect

One way– Material recovers to the original form one or more times but

must be forcibly reshaped

Two way– Material can recover many times to original shape and

deform again to a secondary form after exposure to second stimulus

Multi-way– Same response as two way but with multiple shapes

reacting to multiple stimulus

SMA Actuators

Released socketed IC’s from PCB’s Disassembly of product housings Nested Disassembly Keyboards CD Players Video games Telephones

SMA Actuators

Characterisation– Non-destruction– Cost effectiveness– Range of permissible temperatures– Triggering temperatures

Heat Sources– Air– Steam– Infrared– Water Baths

SMA Actuators

SMA Actuators

SMP Releasable Fasteners

SMP screws placed inside the candidate product so that at Tg the device exhibits considerable mechanical property loss

Effect of “letting go” Returned to their original shape after active

disassembly

SMP Releasable Fasteners

SMP Releasable Fasteners

SMP Releasable Fasteners

Looking Forward

Materials expensive Single Suppliers, Multinationals very slow to

get involved Developed SME in conventional materials Need to get recyclers to adapt

Nanotechnology

The science and technology of building devices, such as electronic circuits, from single atoms and molecules.

IBM Xenon Atoms on Nickel Using Atomic Force Microscopy

Carbon Nanotubes

Extraordinary Strength Conductor and

Semiconductor Properties, Electrical Conductivity 1000 times greater than copper

Can be configured to be almost frictionless

Can be configured to be excellent thermal conductors or insulators

Nanotechnology

Ultimate aim is to manufacture and assemble objects one molecule at a time (bottom up manufacturing).– Reduced resource consumption through

dematerialisation– Reduced chemical pollution through material

substitution– Conversion of current waste into new resources– Enabling recycling at consumer household level

Nanotechnology

Near zero tolerances Stronger, lighter and purer than current

materials– Much greater efficiency in moving parts

Further Reading

Chapter 23 Goldberghttp://www.activefasteners.co.ukwww.wikipedia.comwww.howstuffworks.com