innovative manufacture - the manchester association of ... manufacture.pdf · hollow shell having a...

Innovative Manufacture

Dr Jim MethvenSchool of MACEThe University of Manchester

[email protected]

Manchester Engineering Association, March 15, 2011

What is Innovation?

o Something Newo Something Differento Something Clevero Something Original

Implies Creativity

Many responses to a single stimulus


Why Innovate? Drivers?

o Modern industrial practice – empowerment, leano Kaisan – Continuous improvemento Competitivenesso Cost, quality, speed, environmental impact


Who cares?

o Not Customerso Not the Bank Managero Not the MDo Not … Anyone?

o (compare with TV chefs)


The Design Map

Market

Manufacturing Route

Artefact

Material

OpticalElectricalPhysicalThermal

Mechanical“Special”

Functions

Note the direction of this arrow!!!

There’s no connection here

Cost, Number

Shape, Size, Complexity

Packaging,Distribution


The Design Path –Train Journey

Never arrives but enjoys the journey: should be put down

Start

Finish

Steps are milestones such as decisions, investment, prototypes, tooling, pilot manufacture, etc. Some have to be re-traced


Market Information - ONS

Household Items %

Microwave 83

Washing Machine 92

Dishwasher 25

Fridge/Freezer 93

Tumble Drier 53

Video Recorder 88

CD Player 76

Satellite Receiver 37

Mobile Phone 52

Population UK %

Under 16 19

16-34 25

35-65 40

Over 65 16

Total population of the UK is 60.9 million

Total working population is 29.5 million

o Market information is essential in the design process. Market data are available (free) from the Office for National Statistics (www.statistics.gov.uk/)

o Use this information to get a rough estimate of the market size for an artefact


Design for Stiffness (Flexural Rigidity)

D=EI

Increase E by creating a composite material that incorporates reinforcing fibres

Increase I by creating a sandwich structure that incorporates a lightweight core

Increase I by increasing the thickness, t.

D depends on t3

BUT Cooling time depends on t2

t

Typical thermoplastic

Increase I by creating ribs on the “back” surface. Wall thickness is reduced so cycle time is reduced AND stiffness is increased


Which plastics are used to make … ?

bottle cap seals LDPEbottle caps HDPE LDPE PSbottles (general) LDPE PP PS

bottles (medical) PP

bottles (carbonated drinks) PET

bottles (lubricating oil) LDPE

bottles (shampoo, cleaning fluids, milk and fruit juice) HDPE

bowling balls HDPEbowls PS HIPS PMMA

boxes (general) PS PMMA

boxes (stacking) HDPE LLDPE

boxes (fish, meat and eggs) PS

bra clips PA

brackets and structural components in office products PPE PCManchester Engineering Association, March 15, 2011

Materials Properties

o BPFn www.bpf.co.uk/

o BPRn www.britishplastics.co.uk/

o Tangram Technology … n http://www.tangram.co.uk/

o Polyinnovation … n www.manchesterpolymergroup.com/

o Matwebn www.matweb.com/

o Engineering Tips Forumn http://www.eng-tips.com/


Processes

o Thermoplasticso Reversibleo Heating, melting,

metering, cooling

o Thermosetso Irreversible o Heating, metering,

reaction, cooling

o Injection Mouldingo Blow Moulding o Thermoformingo Vacuum Formingo Rotational Mouldingo Extrusion

o Castingo Encapsulation o Reaction Injection

Moulding


Thermoset Composite Processes

o Irreversibleo Heating, metering, fibre impregnation, reaction, cooling

o Contact Mouldingo Spray Moulding o Resin Transfer Mouldingo Resin Infusiono Tape Layingo Fibre Placement

o Compression Mouldingo Transfer Mouldingo Wet Mouldingo Filament Windingo Pultrusiono Autoclave Moulding


Which Process? – Breakeven Analysis

o Breakeven analysis used to quantify a typical “run length” for different manufacturing routes according to the amortisation of the tooling cost

o The approach is less useful than it was 20-30 years ago particularly as a result of “cheap” tooling and increasing levels of imports

o Even injection moulding is “viable” over a run length of a few hundred mouldings

Start-up Cost B

Start-up Cost A

These costs must be amortised over the number of mouldings made


Shape Classification


SHAPE DESCRIPTION

Panel/Plate Solid section of predominantly constant thickness and which is predominantly flat or only slightly curved

Hollow Shell having a solid skin which bounds a cavity such as a bottle, bucket, bin, etc.

Half-Shell Shape that comprises a predominantly open, plane base and a more or less complex bounding wall. Two make a clam-shell

3D Solid section of some complexity, typically incorporating features such as ribs, bosses, changes in thickness, etc.

Film Thin (less than say 200µm). Membrane-like (cannot support a bending stress)

Sheet Solid material, constant thickness (200µm-10mm)

Profile Solid (constant thickness) material bounding a number of open or closed channels

Preferred Process (Thermoplastics)


SHAPE DESCRIPTION

Panel/Plate Compression moulding, Injection Moulding

Hollow Rotational Moulding, Blow Moulding

Half-Shell Injection Moulding, Vacuum Forming, Thermoforming

3D Injection Moulding

Film Blown Film Extrusion

Sheet Sheet Extrusion

Profile Extrusion

Note that all these shapes, apart from film, can be made in glass-filled or mineral-filled thermoplastics. For these materials the only viable processes are compression moulding, injection moulding and extrusion

Preferred Process (Composite Materials)


SHAPE DESCRIPTION

Panel/Plate Compression Moulding, Pultrusion, Contact Moulding, Spray-Up, Resin Transfer Moulding, Resin Infusion, Autoclave Moulding

Hollow Compression Moulding, Pultrusion, Filament Winding

Half-Shell Compression Moulding, Injection Moulding, Resin Transfer Moulding, Resin Infusion, Reaction Injection Moulding

3D Compression Moulding, Resin Transfer Moulding, Injection Moulding, Resin Infusion, Reaction Injection Moulding, Autoclave Moulding

Profile Pultrusion

Rough Cycle Times


Method Cycle Time, s (unless stated) Method Cycle Time, s (unless stated)

Injection Moulding 30-60 Tape Laying Depends on part geometry and complexity. Anticipate typical cycle times in the order of tens of minutesBlow Moulding 20-60 Fibre Placement

Thermoforming 40-80 Compression Moulding 60-180

Vacuum Forming 40-100 Wet Moulding 60-180

Rotational Moulding 1500-2400 Filament Winding 10kg/h

Extrusion (Line Speed) 15m/min Pultrusion (Line Speed) 1m/min

Casting 300-1200 Autoclave Moulding 30min -24h

Encapsulation 60-300

Reaction Injection Moulding 60-180

Contact Moulding 60s per ply per m2

Spray Moulding 10s per ply per m2

Resin Transfer 10-60s per m2

Resin Infusion 20-120s per m2

Some Examples

o Thermoformingo Microwave Pultrusion

o Re-Barso Hinged Profileso Microwave Effecto Sintering

o SAFIRE and Bra-Wireso Composite Springso Foam Filled Boardo Pultrusion on a Spaceshipo Solid State Lighting


NERCOR

o DTI/Industry Fast-Track Award Reference J350B

Partners

o The University of Manchester o Haywood Rotomoulding, Rochdale o Tecni-Form, Stone


Rotational Moulding

o Hollow aluminium or steel mould charged with plastics powder and rotated at between 2 and 10rpm in 2 orthogonal directions in a gas-fired oven

o Typical oven has volume in the range 5m3 to 50m3 and a gas burner delivering energy in the range 200,000BTU/h to over 3x106 BTU/h (106BTU/h=~293kW). The oven temperature is set in the range 220oC-350oC.

o Powder fuses to a consolidated skin on the inner surface of the mould over roughly 25 minutes. Once the powder is consolidated, the mould is indexed to a cooling station and after another 20minutes or so the material is sufficiently cool to be de-moulded.

o Heat transfer is extremely energy inefficient since it depends on low velocity air flow and, as a result, the process has a Specific Energy Consumption (SEC) of about 6.5 kWh/kg of product. This compares with less than 2kWh/kg for injection moulding.

o Project Target is to reduce the SEC of the process


Outcomes

o Intensification of heat transfer was effected by making a number of modifications includingn incorporation of heat transfer pinsn heat pipesn oven modification (baffles)n process modification (Temperature cycle)

o All resulted in minor improvements of around 5% saving in energy

Sump mould with Al heat transfer pins attached. The inclusion of the pins

roughly doubles the surface are a of the mould


Radical Change to the Process

o Redesign the process around the use of a mould which is heated directly through slip-rings

Box Mould 175mm x 175mm x 75mm – Manufactured by CNC machining of Aluminium with heaters attached by means of strangle bands

Mould in place in the lab moulder made as part of the project

One of the slip-rings through which the heaters are supplied with power and the data are collected from thermocouples in and on the mould


Uniformity of Heating

For direct heating, the uniformity of the temperature of the aluminium mould is important. Here this is measured and modelled using an aluminium plate. Note the witness to the heater locations


Successful Outcome

o The SEC for the new process is in the order of 1.2kWh/kg, that is to say a nominal energy saving of more than 80%

o A second (larger) lab machine is under construction

o Partner companies are considering full-scale implementation

0

50

100

150

200

250

300

0 500 1000 1500 2000 2500 3000

Time (s)

Mouldings produced by the lab moulder

Time –temperature curves for the new process (The temperature label from the ordinate has been omitted in error)


Electroheat – Overview

Microwave Radio-Frequency (RF) Induction

General

Typical Frequency 915MHz, 2450Mhz 13MHz, 27.1MHz, 40MHz 50Hz-200kHz

Source Magnetron ‘C’-Class oscillator Inverter

Applicator Conductive box Electrodes Helical or spiral (pancake) conducting coil

Equipment

Power (CfM Labs) 1.5kW, 2450MHz 12kW, 27.1MHz 7.5kW, Self-Tuning (200kHz max)

Manufacturer Sairem, France Relco, UK Inducto-Heat Banyard (Lepel, USA)

Load

Material Dielectric Dielectric Conductor

Heating Effect Polarisation Polarisation Eddy current. Magnetic hysteresis

Heating Characteristics

Volumetric Yes Yes Heating depth increases with decreasing frequency

Instantaneous Yes Yes Yes

Non-Contacting Yes Selectable Selectable

Selective Yes Yes No?


Characteristics of Electromagnetic Heating

o Instantaneouso Volumetric or Surfaceo Non-Contactingo Selective

These unique characteristics are key to the implementation of a commercially viable electromagnetic heating system

One source of the “microwave effect”?


MAP Line : TM010 Cavity

Pyrex Die

Brass Cylinder, 5mm wall

ID=83mm

138mm

ResinSpeed m/min

PowerW

Epoxy 0.7 340

Polyester 2.0 590

Modar 4-5 700

Vinyl Ester 7 10005mm Diameterφf = 0.62

Precursor


Summary (Modar 865 Composites)Area,mm2

Speed.m/min

Power.W

Efficiency

19.6 4.5 700 1

60 1 755 0.63

78.5 0.8 1.5 0.33(95 0.7 1.2 0.44)

proprietary resin system


Re-Bars: Corrosion of RC

Migration of De-Icing Fluid(Chloride ions)

Rust Formation on Steel Rebar

Expansion and Cracking

Spalling – Accelerated Corrosion

STEELGRP

EUROCRETE DATAo Rebars subjected to a saturated solution of

Calcium Hydroxide (pH=13) at 80oC for 28 days

o Equivalent to 50 years "service"o 25% reduction in tensile strengtho 4% reduction in modulus of elasticity


Rebar - Form

o Since the form of a rebar is that of a long, thin profile, the immediately obvious (continuous) process for manufacture of a fibre-reinforced rebar is pultrusion

o The surface of a rebar must incorporate undercuts transverse to its axis so that it is mechanically keyed into the concrete matrix.

o Provision of undercuts precludes conventional pultrusion since they will lock the profile into a rigid pultrusion die.


Peel-Ply Process

Textured Fabric

Textured FabricFabric “peeled off” thecrosslinked profile

SmoothPrecursor

TexturedProfile

Pultrusion Die

o Reduced heat transfero Reduced Line Speedo Cost of the material

o Loss of resino Cost is estimated to be about 4x that of an

equivalent “smooth” profile


Overwinding

o Provision of mechanical keying is accomplished by overwinding the rebar profile before crosslinking so that the composite rebar incorporates a helical undercut along its entire length.

o By exploiting the non-contacting nature of microwave heating there is no need for a rigid pultrusion die. This is an example of “die-less” pultrusion


Overwinder

Safety cage

Winding arm with glass bobbin


Travelling Wave Applicator (TWA)

96,000 tex E-glass core9mm φ

Pitch is determined by the line (pulling) speed and the speed of rotation of the overwinder

1m length of WR340 waveguide

Microwave Power in(2450MHz)

Pulling Direction

Core from Overwinder

Dummy Water Load

WaterExcess Power Out

up to 3 ends of 2400 tex

CrosslinkedProfile(to Haul-Off)


TWA - Electrical

4gXY

λ=

o5.22=φ

E-Bend

X

Y

E-Field Decay

TE-Mode

ChokeChoke

E H

Microwave Power in(2450MHz)Water

Load

Excess Power Out


Re-Bar Line: Applicator End

B

C

A

Microwave Generator

Overwinder

Overwound Core

Applicator

C

A

B

D

D



Re-Bar Line: Haul-Off

Microwave Generator

Overwinder

Applicator

Haul-Off

Re-Bar

D

A

B

E

AB

D

E

F

F


Overwinding Control

Flow of resin generatedby overwinding

Should be matched to theline speed and permeability

Acceptable profileLinear Density 135g/m

“Corkscrew” profile produced as a result of excessive overwinding tension

Consolidation


Beam Testing

o Three 9mm rebars incorporated into the tensile face of a rectangular beam 125mm (H) x 75mm (W) x 1000mm (L) at a centreline depth of 100mm

o Beam subjected to 4-Point bending with a minor span of 250mm and a major span of 900mm

250mm

900mm

P

NmPM2

325.0×=


ACI 440 Design

Composite rebar Elastic to failure and exhibits no yielding. Design is based on failure by concrete crushing (ACI-440). The level of composite required is GREATER than the balance ratio and the beam is said to be OVER-REINFORCED

Balance Failure SIMULTANEOUS failure of the rebar in tension and the concrete matrix in compression

Mild steel rebar Failure by yielding of the steel rebar (ACI-318). The level of steel required for yielding is LESS than the balance ratio and the beam is said to be UNDER-REINFORCED.

cf ′

bafc′85.0

cf ′

ff

c

f Afff

b

d

cu

AfNA

a = 1c

ffu

c

fu

Afffu

b

d

cu

AfNA

a = 1c

Balance Failure

Over-Reinforcement

bafc′85.0


Rebar Properties

Parameter Value Concrete Strength,MPa 41 Concrete Factor 1 Concrete Design Strength, MPa 41 FRP Modulus, GPa 41 FRP Strength, MPa 1056 FRP Factor 1 FRP Design Strength 1056 ρ fb 0.00292 1.4ρ fb 0.0041 Bars Required for 1.4ρ fb 0.64 Bars Used 3 ρ Used 0.0192 K = ρ /ρ fb 6.57 Predicted Ultimate Moment, Nm 4884 Predicted Failure Load, KN 30

2'59.01 bdff

fMc

ffffn

−=

ρρ

cufcuff

ccuff EE

fEf εε

ρβε

5.085.0

4)( '

12

−+=

Maximum stress in rebar

Nominal Moment Capacity


Design Data

0

1000

2000

3000

4000

5000

6000

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 0.022

Reinforcement Ratio

Ben

ding

Mom

ent,

kNm

0

200

400

600

800

1000

1200

1400

1600

1800

2000

GR

P S

tres

s, M

Pa

BalanceRatio

1.4* Ratio at Balance

Ratio Used 0.0192


Test Data

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14Deflection, mm

Instrument Noise

Onset of Cracking


Testing to Failure

Testing Rig

Ultimate Failure

Failure Load, kN

Measured 32Calculated 30

GOOD AGREEMENT!

But …


Economics and Market

o This bar weighs 150g/mo Realises about £20/houro Must be made faster or multi-streamed

THERE IS POTENTIALn 946,000 tonnes of rebar used in the UK (1999)n 4% is Corrosion Resistant (Stainless, Epoxy Coated) n Say half could be GRP – Equivalent to 5000tn Equivalent to 10% of the Total EU Pultrusion Market


Conclusions

o Process is technically viable o Consolidation may be enhanced by overwinding with a

shrinkable fibreo Improved coupling and hence faster line speeds by

incorporating a susceptor in the core resino Multi-streaming by using 915MHz or Radio Frequency (27MHz)o Magnetron Lifetime?


Selectivity of Microwave Heating

Moisture levelling (drying of paper or carpets)

Substrate (low loss)

Water (high loss)

Bonding of Ceramics

Alumina phase(low loss)

Grain Boundary phase(high loss)

Mince Pies


In General ...

o All industrial processes involve mixtures of materials

o The components in the mixture will have different loss factors

o The component with the greatest loss factor will heat preferentially in a microwave cavity

o The temperature of the mixture is non-equilibrated


Now ...

o If the “hot” species is engaged in a chemical reaction ANDo If the rate of this reaction is of the same order as the rate of

temperature re-equilibrationTHEN o The non equilibrated temperature WILL influence the reaction kinetics,

the reaction path (yield) and the morphology of the material

THIS IS POSSIBLE ONLY WITH MICROWAVE HEATING

o Examplesn Lewis (Imidization)n MAP (High Loss factor of peroxide – High rate of initiationn Difficult to “prove” – Gedeye, Mingoes and othersn BUT – Hamelin – “inverse microwave effect”


Potential

o In systems in which temperature re-equilibration is relatively slow. Perhaps where interfaces are encountered - such as

o Heterogeneous Catalysiso Interfacial Bondingo Emulsionso Sinteringo Foamso Rubber Toughening

OR

o Add a susceptor to achieve selectivity as in sintering of UHMWPE

Coat the surfaceWith a susceptor

… and preserve the morphology of the bulk

Heat this and, by conduction, a shallow depth of the granule


Sintering of PE using Susceptors

0 20 40 60 80 100

Trigonox C

Trigonox 21

Ethylene Glycol

Diethylene Glycol

Propylene Glycol

DiPropylene Glycol

Polyalkylene Glycol

Sunflower Oil

20g samples, 10 minutes at 900W, 6% by weight


DASS Cable

Distribution Plate

To cylindrical TM010 Cavity

Borosilicate Die

Rovings from Impregnation Bath

Core from Storage Reel

Product

2.5mm GRPannulus

Interstitial Jelly

Optical Fibre

PET Tape

PET Tube

Core6mm OD

Linear Density 122g/m

Transients


Power ON

Modar 865, 3m/minute 50mm is equivalent to 1s

DieEntrance

DieExit

89.25

114.25

50.2

71.8

Power OFFcrosslinkednot crosslinked

Transients offer Hinged Pultrusions

o Turning the power on an off in a prescribed sequence results in cured straight regions and partly (or uncured) regions which can be shaped and cured after pultrusion

o This offers the prospect of making artefact such ads space-frames

o The curvature of the uncured regions invariably results in local buckling which can be mitigated by hoop winding the entire profile


Power Off


Induction Heating: Materials

Property Mix 1 Mix 2

Thermal Conductivity, W/m/K 0.77 2.5

Specific Heat Capacity, kJ/kg/K 0.94 0.81

Density, kg/m3 2220 2650

Weight of sample, g 120 140

Proprietary Rubber/Resin compositions incorporating metal fibres and metal fillers


Typical Oven Cycle

0

50

100

150

200

250

0 30 60 90 120 150 180 210 240 270 300 330 360

Time, minutes

Tem

pera

ture

, C

Transfer toCooler 216 mins

Oven Off211 mins

3-hour hold at 200C

3.3 [degrees/min]

2.1 [degrees/min]} Linear Region only


Pancake Coil – Unconstrained

Pancake coil above specimen

Infra-Redpyrometer

Data logger

Coil

123.4

s


Mixes 1-3: Backface Temperatures 60s Exposure

0

50

100

150

200

250

0 50 100 150 200 250 300 350 400

Time, s

Tem

pera

ture

, oC

Mix 1

Mix 2

Mix 3

60s Exposure

Manufacture of Bra Wires

o Marks and Spencer – replacement policy of electrical goodso “Loose” steel bra wires ruin washing machineso Thicker and hence stiffer regions of fabric to replace wires made by

computer aided embroidery and other methods slow and expensiveo Desire for a “plastic” replacement but cannot contain glass fibres …

and by the way the steel ones cost 2p

o The function of a bra wire is a mystery – a quasi-encastré fixing of the bra to the chest wall so that the bosom becomes a supported cantilever

o Simple enough to “replace” the steel with a composite material in principle but how to mould it bearing in mind the large number of sizes required – dedicated tooling would be prohibitively expensive


The Solution

o Use two reinforcing fibres: one thermally stable and the other having a controllable thermal shrinkage

o Use a cross-head extruder to impregnate a combination of the fibres with a simple thermoplastic such as polypropylene and produce a “straight wire”

o Cut the wire into appropriate lengthso Heat the wires in a simple jig which represents the target profile

o It worked – Field testing was extremely popular o Too expensive in the long run (10p) and not quite stiff enough for the

larger sizes


Temperature Response


Cross-section A-A

Profile bends to give a

U-shaped curve in the horizontal

plane

1-7 minutes at 160oC

A A

Polyester (PET) fibres Cotton Fibres

SAFIRE (Self Assembling Fibre Reinforcement)

o Reinforcement of thermoplastic polymer products by long glass fibres ( 5–10 mm) at low fibre volume fraction (3%-5%)

o Assembly is created during processing by means of a proprietary fibre separating device followed by a fibre lacing device

o Key is the creation of a robust “mat”


0

10

20

30

40

50

60

70

0 2 4 6 8 10

Tensile strength (MPa)

Percentage of glass fibre v/v

20 deg C

60 deg C

85 deg C

120 deg

Composite Springs

o Leaf-Spring by pull-forming – Pultrusion followed by Compression Moulding (1970s). Ford Econoline Van

o Sulcated Spring by layup or compression moulding (1970s) RAE/TBAo Post-buckled pultruded spring (MACE 2010)


Post-Buckled Springs


Section Rigidity (EI)

Stiffer Springs – Lost Wax

o Curved hollow tubeso Lost Wax Method


R

Section Rigidity (EI)

R3

Stiffness

Stiffer Springs - Braiding

o Bladder Moulding using a braided sock


o Solar Panels up to 18m longo Supporting struts are simple profiles – readily identified with

manufacture by pultrusiono In a spacecraft, power and space are at a premium

o Re-examine the process in the light of these constraintso No power available to heat a rigid steel die (No rigid steel

die)o No prospect of using an impregnation bath

Manufacture in Outer Space


Space-Ship Pultrusion

o Transport only the raw materials and, maybe a pump

o Pull the fibre through a heat-shrinkable sleeve (a) before leaving

o Pump resin in the tube and move it by hand, peristalsis-style along the length of the tube (b)

o Attach the far end of the tube to something and stretch taut

o Run a heater along the stretched tube – to crosslink the resin and at the same time to consolidate the profile as a result of the shrinking of the sleeve (c)


(a) (b)

(c)

o Target is to fill an 8 foot by 4 foot corrugated board with low density PU foam

o Consortium plan is to sell the filled boards a pre-packed furniture

Foam-Filled Boards (CRAFT G5ST-CT-2002-50374)


o A typical board consists of paper skins between which are glued layers of flutes created by a crenulated roller. The whole thing is held together by an adhesive

o Free expansion from a “crushable” mould was unsatisfactory (3 foot rise, 2 foot width)

o A bespoke “porcupine” of needles to inject into each flute was too expensive

Foam Filled Boards – Finally


o Create a pillar box slot in an oversized board and insert a sacrificial runner

o Close the faces of the slot with PE film and support the board in a large clamp

o Inject the PU mixture through the runner

o Success. The first full board

Acknowledgements

o Professor Stephen Busho Dr David Blackburno Dr Reza Ghaffariyano Dr Zainal Abidino Dr James Myerso Dr Madhu Athinarayanan o Annette Neuendorffo Karl Jamiesono David Rigby


o It is predicated on the high efficacy of a typical high brighness LED (HBLED) of around 100 lumens per Watt (lm/W) compared with that of a CFL (80lm/W) and that of a tungsten (GLS) lamp (12lm/W)

o The project is concerned with the efficiency of the power driver and the management of heat transfer within the HBLEDs. In practice, this has required the group to consider the design of complete lighting units (luminaires)

Luminaires


Measurements and Analysis

Clockwise : • Photo-goniometer, Sackville A18,6• Finite Element Heat Transfer Analysis

of torus luminaire• LightTools® illuminance simulation of

“Open” LED array • Open LED array


Desk Lamp


o A smaller desk version of this design is based on a hexagonal plate that houses 1, 1W LED on each edge

o This generates around 2500 lux for an input power of 10W, compared with around 1600 lux for a pearl 40W GLS bulb

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