Design for Disassembly

Transcription

1 Design for Disassembly David Harrison Brian Griffiths Brunel University Thanks to: Dr J.Chiodo, for early design and prototyping work Mr. Habib Hussein, for later design and manufacturing work.

2 Introduction New British Standard in Design for Disassembly Brunel work on active disassembly

3 Specification BS8888 Manufacture BS8887 Verification BS8889

4 Demanufacturing Processes (from Design Output for Manufacture. assembly, disassembly and end of life processing (MADE) BS8887-1:2006 (draft) a) Materials, piece parts and components Minimize non-biodegradable materials. Use compatible materials (in for example chemical, electrolytic, polymer migration terms). Avoid mixing of component and piece part materials which reduce the efficiency of recycling, e.g. metal inserts in plastic parts. Maximize standardization of component variations. Select materials with similar component life to match design life of assembly. Avoid composite materials employing adhesives.

5 Demanufacturing Processes (from Design Output for Manufacture. assembly, disassembly and end of life processing (MADE) BS8887-1:2006 (draft) Group harmful materials in separate, accessible modules. Avoid combining ageing and corrosive materials. Minimize number of piece parts b) Joining Minimize number of fixings and fasteners and standardize types and sizes. Use joining technologies and methods which enable easy separation of components and materials. c) Coatings/finishing Avoid secondary finishing such as painting, coating or plating. Choose durable materials in preference to protective coatings.

6 Demanufacturing Processes (from Design Output for Manufacture. assembly, disassembly and end of life processing (MADE) BS8887-1:2006 (draft) d) Recycling Provide convenient access to valuable and reusable parts. Provide clear identification of replacement/repair modules. Protect sub-assemblies against soiling, corrosion and erosion. Code or otherwise identify parts to facilitate recycling and audit trails to production data. For plastic parts above 50 g, mark in accordance with BS EN ISO 1043 and BS EN ISO Code or otherwise identify materials, including surface coatings and alloys, to facilitate recycling and audit trails to production data. Provide all information to assist recycling in documentation.

7 Sustainable Design REDUCE -design for minimal energy and materials use, and to remove toxics - more effective than concentrating on the recycling of a product after use. RE-USE -design for multiple lifecycles: - better than recycling RECYCLE -design for disassembly: improving separation and sorting of the product materials after use. Currently, disassembly is slow and is often manual.

8 One Possible Solution Automatic or Active Disassembly using Active Self Disassembling Products: (the work of Habib Hussein) Fasteners Smart actuators or releasable fasteners in products produce disassembly when triggered at the end of product life Allows production of high purity, pre-defined fractions, ready for recycling. 18 active fasteners allowed all the components of this Sony Playstation to automatically disassemble.

9 Actuators Using Shape Memory The two materials used were alloys of Nickel Titanium, and Copper Zinc Aluminium. Early trials by J.Chiodo used NiTi rods and discs Later trials used 2 way CuZnAl helical coil actuators Alloys

10 Using smart materials to separate product enclosures. This would potentially allow the circuit boards to removed automatically, and be processed separately from the largely plastic enclosure materials.

11 Shape Memory Polymers Polymers developed by Mitshibushi to have enhanced shape memory characteristics.

12 Mechanism of Shape Recovery in Shape Memory Polymers

13 Shape Memory Polymer Screws Pioneering work by Chiodo used shape memory polymers to create active fasteners applied to the disassembly of electronic products This was the world s first shape memory polymer screw. When heated above the glass transistion temperature, the thread withdraws into the shank

14 LCD removal This shows a bracket for holding an LCD in a mobile phone, which has been moulded in shape memory polymer. Heating the bracket above the glass transition temperature releases the LCD screen.

15 Active Disassembly and the Work was carried out by Jones et al applying these smart materials to disassembly in the automotive sector Issues addressed were Glass removal Instrument panel removal Airbag removal Electrically triggered smart fasteners automotive sector

16 Active Disassembly Fifth Framework Project Blue sky EPSRC funding, followed by EU project with Sony and Nokia. Active screws and nuts Triggered at the end of a product s life to permit automatic disassembly for recycling

17 Problems with the Use of Smart Cost Materials Limited range of Suppliers (sometimes single source) Limited range of operating temperatures for materials Limited range of engineering properties for shape memory polymer (PU based blends) Poor toughness and heat stability for polymers

18 Shape Recovery in Standard Engineering Polymers Some Engineering Polymers exhibit significant degrees of shape recovery Although the strain is recovered less rapidly than with commercial shape memory polymers, there are advantages in terms of cost, availability, range of operating temperatures, and mechanical properties. A number of materials were evaluated for their suitability Selection of most appropriate material was based on the speed with which the material recovers its original form.

19 Comparison of Recovery Times was carried out for various polymer blends T est 2:Recovery against time (for material 1) with relation to bending stress recovery (degrees) time (minutes)

20 Design of Active Snap Fasteners A number of prototype designs of fasteners were produced using ABS/PC blend materials Triple Clip Cantilever Clip Wing Clip

21 Cantilever Clip Snap fits were designed to operate by releasing embedded strain energy On heating the clips straighten, releasing the chassis from the top cover.

22 On heating the clips straighten, releasing the chassis from the top cover. Cantilever Clip

23 Wing Clip

24 Wing Clip Shape Recovery and Disassembly Mechanism

25 Active Disassembly Pilot Plant Hot Air System - 24 kw oven Temperature range degrees C Hot Water Plant Temperature range degrees C (heating media water/glycerin)

26 Results from Active Disassembly Pilot Plant Disassembly Solution Hot Air Activation Temp C Hot Liquid Activation Temp C Cantilever Clip ~ C ~1 117 C ~ C Triple Clip ~ C ~ C Wing Clip No 140 C ~5 120 C ~ C

27 Results The shape recovery in the selected ABS/Polycarbonate blend material may be used successfully to achieve product disassembly. Hot liquid was found to be the most effective approach to triggering shape recovery in the hand held size products tested.

28 Key benefits and Issues with Reverse Logistics One key benefit of active disassembly would be the creation of large volumes of clean, separated polymer for recycling. However, a significant barrier to implementation is the way in which products are collected and processed In the UK there is little short term motivation for manufacturers to be an early adopter of radical technology, as product collection will be of mixed products and the processing techniques adopted will be those appropriate to the majority of products.

29 Automated disassembly used smart materials (ADSM) for a battery charger (Sharp). Source:GLOBAL WATCH MISSION REPORT Waste electrical and electronic equipment (WEEE): innovating novel recovery and recycling technologies in Japan

30 Bold Streamlined LCA Streamlined LCA you can do before breakfast, going to do this by focusing on energy Assumptions: Energy is a good surrogate for environmental impact. Combine extraction and manufacture, as a single number

31 Assume SAME energy input to create 1 kg of any manufactured product 50 MJ / kg (compare with MJ per kg for steel, 56 MJ per kg for a typical polymer, 180 MJ for aluminium, 9 MJ for recycled aluminium) Different manufacturing processes have a small impact, adding in perhaps 2 or 3 MJ Exception! 2000 MJ per kg for electronics!

32 Streamlined LCA 1) Extraction of Material and Manufacture Take product and weigh it then use 50 MJ per kg 2) Use phase plug in kettle and time until boils Energy going in at 2.4 kw Find out how many secs till boil, multiply this by 2.4 kw to give number of Joules used. 3 mins 30 sec = 210 secs 2400 x 210 = number of Joules approx = 0.5 MJ for 1 use of kettle X 15,000 uses over life = 7500 MJ over life

33 If use phase is electrical: Either Use label on product, and time it or Use kwh meter under the stairs or Measure volts x amps x estimated time (not for mains powered products) or Use 1 MJ per 1 worth of batteries

34 DISPOSAL Negligible (typically 1-2 MJ) TRANSPORT Ship Typically MJ per product Lorry Typically 1 3 MJ per product Van Typically 10 MJ per product Car 25 MJ per item