introduction to micromoulding dr ben whiteside irc in polymer engineering, dept. mechanical &...
TRANSCRIPT
Introduction to MicromouldingIntroduction to Micromoulding
Dr Ben WhitesideDr Ben Whiteside
IRC in Polymer Engineering, IRC in Polymer Engineering,
Dept. Mechanical & Medical Engineering, Dept. Mechanical & Medical Engineering,
University of Bradford, Bradford UKUniversity of Bradford, Bradford UK
Dr Ben WhitesideDr Ben Whiteside
IRC in Polymer Engineering, IRC in Polymer Engineering,
Dept. Mechanical & Medical Engineering, Dept. Mechanical & Medical Engineering,
University of Bradford, Bradford UKUniversity of Bradford, Bradford UK
ContentsContents
• Micro/nanotechnology• Micromoulding
• Challenges• Process Technology• Mould Manufacture• Product Assessment
• Micro/nanotechnology• Micromoulding
• Challenges• Process Technology• Mould Manufacture• Product Assessment
Capsule EndoscopyCapsule Endoscopy
Capsule contains: Camera Transmitter Optics Battery
Capsule contains: Camera Transmitter Optics Battery
Capsule EndoscopyCapsule Endoscopy
Full colour images for diagnosis of bowel problemsFull colour images for diagnosis of bowel problems
Digital Micro mirror Device (DMD)Digital Micro mirror Device (DMD)Texas Instruments
16 m x 16 m pixel geometry
Micro-assembly: Laser-fibre alignment- packaging?
Micro-assembly: Laser-fibre alignment- packaging?
Lab-on-a-Chip devicesLab-on-a-Chip devices
Circuits similar to conventional silicon circuits but using fluids rather than electricityCircuits similar to conventional silicon circuits but using fluids rather than electricity
Allows rapid chemical and biological screening of samples
Each chamber in the illustation contains 1/1 000 000 000th of a litre!
Allows rapid chemical and biological screening of samples
Each chamber in the illustation contains 1/1 000 000 000th of a litre!
Current Manufacturing TechniquesCurrent Manufacturing Techniques
Silicon wafer techniques requiring:Clean-room fabricationExpensive Illumination Processes
Silicon wafer techniques requiring:Clean-room fabricationExpensive Illumination Processes
Micro-Injection MouldingMicro-Injection Moulding
• Can the injection moulding process be adapted to offer a cheap, high output process for the production of micro-scale components?
• Can the injection moulding process be adapted to offer a cheap, high output process for the production of micro-scale components?
ChallengesChallenges
• Controlling the moulding machine• Melting the polymer• Measuring the required amount of material• Injecting the material rapidly
• Making the moulds• Contain very fine details• Need to be durable
• Checking/Packaging the product• Quality control• Handling very small products
• Controlling the moulding machine• Melting the polymer• Measuring the required amount of material• Injecting the material rapidly
• Making the moulds• Contain very fine details• Need to be durable
• Checking/Packaging the product• Quality control• Handling very small products
Standard IM – material wasteStandard IM – material waste
Conventional MouldingConventional Moulding
4-cav. Mould4-cav. Mould
• Part weight:Part weight: 4 mg4 mg• Sprue weight:Sprue weight: 2530 mg2530 mg• Shot weight:Shot weight: 2546 mg2546 mg• Material efficiency:Material efficiency: 0,16 %0,16 %• Cycle time:Cycle time: 17 sec.17 sec.
courtesy: Battenfeldcourtesy: Battenfeld
Standard IM – Material DegradationStandard IM – Material Degradation
• Screw/barrel typically contains 500g polymer• Assuming a 0.5g product running every 20
seconds – material would be at melt temperature for 5½ hours
• Material can degrade
• Screw/barrel typically contains 500g polymer• Assuming a 0.5g product running every 20
seconds – material would be at melt temperature for 5½ hours
• Material can degrade
Picture of injection barrel here
• Purpose built micro injection process
• Servo-electric injection
• Optimum screw size – 14mm
• Automatic parts handling
• Clean room filtration
• Modular
• Purpose built micro injection process
• Servo-electric injection
• Optimum screw size – 14mm
• Automatic parts handling
• Clean room filtration
• Modular
Battenfeld Microsystem 50Battenfeld Microsystem 50
Battenfeld Microsystem 50Battenfeld Microsystem 50
Part weight 0,0008 gPart weight 0,0008 g courtesy: Battenfeldcourtesy: Battenfeld
POM Micro-gearPOM Micro-gear
Weight 2,2 mgWeight 2,2 mg courtesy: Battenfeldcourtesy: Battenfeld
Polycarbonate hearing aid sensor housing
Polycarbonate hearing aid sensor housing
Micromoulding – the truth?Micromoulding – the truth?
Making the mouldsMaking the moulds
• Moulds need to have:• Very accurate dimensions• Good surface finish• Good durability
• Moulds need to have:• Very accurate dimensions• Good surface finish• Good durability
Making the moulds - MicromillingMaking the moulds - Micromilling
Cutters as small as 0.1mm rotating at speeds up to 120 000 rpm
All held in special housing to minimise vibration and changes in temperature
Cutters as small as 0.1mm rotating at speeds up to 120 000 rpm
All held in special housing to minimise vibration and changes in temperature
Making the moulds – Micro Electro Discharge Machining
Making the moulds – Micro Electro Discharge Machining
The electrode and woprkpiece are connected to a DC power supply and are brought close together, but never touch
Sparks jump across the small gap which heats up the workpiece metal to about 1200ºC, causing it to evaporate
The electrode and woprkpiece are connected to a DC power supply and are brought close together, but never touch
Sparks jump across the small gap which heats up the workpiece metal to about 1200ºC, causing it to evaporate
Making the moulds – Laser MachiningMaking the moulds – Laser Machining
High frequency pulsed lasers focussed on the steel causing it to evaporate.
The laser is aimed using a computer to cut out a cavity in the steel
Problems can occur when the steel ‘spatters’ or is recast in the local area
High frequency pulsed lasers focussed on the steel causing it to evaporate.
The laser is aimed using a computer to cut out a cavity in the steel
Problems can occur when the steel ‘spatters’ or is recast in the local area
Making the moulds – Micro-StereolithoraphyMaking the moulds – Micro-Stereolithoraphy
Object is built up of slices created by illuminating the top surface of a bath of special polymer with a laser
When a slice is complete, the stage holding the part drops down a fraction of a millimeter so the next slice can be made
Object is built up of slices created by illuminating the top surface of a bath of special polymer with a laser
When a slice is complete, the stage holding the part drops down a fraction of a millimeter so the next slice can be made
T-Shaped cavity made for us by Rutherford Appleton Labs
Electroplating required to create mould
Cylinders will form holes for pins to eject the moulded part
T-Shaped cavity made for us by Rutherford Appleton Labs
Electroplating required to create mould
Cylinders will form holes for pins to eject the moulded part
Making the moulds – Micro-StereolithoraphyMaking the moulds – Micro-Stereolithoraphy
Making the moulds – LIGA ProcessMaking the moulds – LIGA Process
• Able to form a number of cavities simultaneously
• Excellent surface finish
• Only 2.5D structures
• Requires expensive hardware
• Able to form a number of cavities simultaneously
• Excellent surface finish
• Only 2.5D structures
• Requires expensive hardware
Product AssessmentProduct Assessment
• How is quality control implemented for such small components?• Optical systems
• How do we find out how rigid and hard the product is?• Need to use Atomic Force Microscopy techniques
• How is quality control implemented for such small components?• Optical systems
• How do we find out how rigid and hard the product is?• Need to use Atomic Force Microscopy techniques
Machine Vision SystemsMachine Vision Systems
CCDCameraCCDCamera
RobotRobot
ProductProduct
• Fully Automatic – no user intervention required
• Able to measure dimensions/areas/geometric features
• Can be performed during the process
• Fully Automatic – no user intervention required
• Able to measure dimensions/areas/geometric features
• Can be performed during the process
Machine Vision SystemsMachine Vision Systems
Smallest product moulded at the UniversityLargest diameter 1mmMass 0.34mg
Smallest product moulded at the UniversityLargest diameter 1mmMass 0.34mg
Atomic force microscopyAtomic force microscopy
Can be used to study very small areas of a component to measure:-
Surface finish
Internal structure
Mechanical properties – hardness etc
Can be used to study very small areas of a component to measure:-
Surface finish
Internal structure
Mechanical properties – hardness etc
Surface detailsSurface details
‘Ridges’ caused by the tools used to make the cavity‘Ridges’ caused by the tools used to make the cavity
Structures inside the productStructures inside the product
Rose patterns tell us about the structure of the polymer and how strong we can expect the product to beIndent shape also indicates how hard the product is
Rose patterns tell us about the structure of the polymer and how strong we can expect the product to beIndent shape also indicates how hard the product is
Indent
ConclusionsConclusions
• Standard injection moulding machines are not well suited for producing microscale components
• Micromoulding offers a cheap and productive means for the manufacture of small components
• A number of techniques are being explored to find the best method for cavity production
• Testing of the moulded parts is currently only possible using expensive, high-tech apparatus.
• Standard injection moulding machines are not well suited for producing microscale components
• Micromoulding offers a cheap and productive means for the manufacture of small components
• A number of techniques are being explored to find the best method for cavity production
• Testing of the moulded parts is currently only possible using expensive, high-tech apparatus.