1. Near Net Shape technologies
Thixomoulding – Rheocastingg g
Thibault Boulanger (SIRRIS)
21/10/2010
le centre collectif de l’industrie technologique belge
TableTable
1 Introduction : thixo platform1. Introduction : thixo platform
2. Principle of semi-solid technologies
• Thixomolding of magnesiumg g
• Rheocasting of aluminum
3. From principles to industrial applications
Thi ldi• Thixomolding
• Rheocasting
4. Future developmentsp
2

2. 1 Thixo platform1. Thixo platform
Located at the Pôle d’Ingénierie des Matériaux de Wallonie:Located at the Pôle d’Ingénierie des Matériaux de Wallonie:
• University of Liege (ULg): metallurgy, induction heating,
i l i l i d l i l isimulation, aluminum and steel processing analysis
• Center for the Research in the Metallurgy (CRM): metallurgical
expertise, steel processing, analysisp , p g, y
• SIRRIS: design, process, moulds, prototypes, magnesium
processing
www.sirris.be | info@sirris.be | 3
2 Principle of semi- solid technologies2. Principle of semi- solid technologies
650
700
Mg - Al alloy phase diagram
rheocastingthixomolding
e(°C)
500
600
650
liquidus
solidus
Į + liquid
Temperature
300
400
Į + ȕ
% Al (i i h )
10 20 30 40
200
0
AZ91D % Al (in weight)AZ91D
thixoforging
4

3. Interest of these technologies
l lMaterial
preparation
Process
specificities
Material
properties
5
Comparison with conventional technologies
re
Rheocasting
rere
Rheocasting
re
Thixomolding
re
Thixomolding
re
Conventional
casting processes
re
Conventional
casting processes
re
Conventional
casting processes
Temperatur
Liquidus
Temperatur
Liquidus
Temperatur
Liquidus
Temperatur
Liquidus
Temperatur
Liquidus
Temperatu
Liquidus
Temperatu
Liquidus
Temperatu
Liquidus
T
Cooling and
holding
TT
Cooling and
holding
T
Reheating
Semi-solid
T
Reheating
Semi-solidSemi-solid
T
Semi-solid
TT
SolidusSolidusSolidus Solidus
Reheating
Solidus
Reheating
Sand
casting
Solidus
Squeeze
Low
pressure
casting Sand
casting
Solidus
Squeeze
Low
pressure
casting
Solidus
Squeeze
Low
pressure
casting
Time
Casting
TimeTime
Casting
Time
pellet at RT Casting
Time
pellet at RT Casting
Time
Die casting
Squeeze
casting
Time
Die casting
Squeeze
casting
Time
Die casting
Squeeze
casting
6

4. Relationship between tensile strength slurryRelationship between tensile strength, slurry
temperature and porosity
Eutectic phase
Primary alpha phase
porosity
400
a)
ı = k1 fs + k2 fm exp - (bPeff)
250
300
350
ilestrength(MPa
100
150
200
0 0 0 5 1 0 1 5 2 0 2 6 3 1
ultimatetensi
Solid fraction (%)
0,0 0,5 1,0 1,5 2,0 2,6 3,1
porosity (%)
source: Scharrer (2008)
2 1 Thixomolding of magnesium2.1 Thixomolding of magnesium
e
Thixomolding
e
Thixomolding
Temperature
Liquidus
Semi-solid
Temperature
Liquidus
Semi-solid
Solidus
Reheating
Solidus
Reheating
Time
pellet at RT Casting
Time
pellet at RT Casting
8

5. Advantages of thixomolded magnesium parts
• Lightness : density of 1 82 (versus 2 7 for aluminium and 7 8 for steel)• Lightness : density of 1.82 (versus 2.7 for aluminium and 7.8 for steel)
• High thermal conductivity
• Better heat resistance than plastics
• No creep at room temperature and limited up to 150 C for specific alloysNo creep at room temperature and limited up to 150 C for specific alloys
• Good electrical conductivity
• Limited porosity (below 1%) because of laminar filling and limited air-
entrapment
• Good surface quality (low roughness can be achieved)
• Excellent damping properties
• Electromagnetic interference EMI and radio frequency interference RFI
shieldingshielding
• Dimensional precision net-shape or near net-shape:
• -tight tolerances
• excellent dimensional repeatability
• Flatness
• High specific stiffness and ultimate tensile strength as compared with other
materials
Tolerances of thixomolded parts
Linear tolerances
Global size THIXO HPDC Mg HPDC Al
Up to 25.4 mm +/- 0,020 +/- 0,075 +/- 0,100 mm
b 2 dd 2 2 /Above 25,4 mm, add + 2 + 1.5 + 2 —m/mm

6. Example of tolerances on industrial component
LP
Linear dimension shown is 63.5 mm.
The Thixo-Tolerance allowance for that
dimension is:
LINEAR DIMENSION
First 25.4mm of dimension + - 0.025mm
38.1mm at 1—m per mm + - 0.038mm
Total tolerance for 63.5mm + - 0.063 mm
ACTUAL RANGE 48
CUSTOMER
TOLERANCE RANGE
ACTUAL RANGE 48
PCS.
-0,1 -0,05 0 0,05 0,1
CONVENTIONAL
PRECISION
TOLERANCE RANGE
mm
source: Thixomat
2 2 Rheocasting of aluminum (RHEOMETAL)2.2 Rheocasting of aluminum (RHEOMETAL)
RheocastingRheocasting
Temperature
Liquidus
Temperature
Liquidus
Temperature
Liquidus
T
Solidus
Cooling and
holding
T
Solidus
T
Solidus
Cooling and
holding
Time
Solidus
Casting
Time
Solidus
Time
Solidus
Casting
12
RSF_A356_slurry_forming.wmv

7. Rheometal machine principle
13
Basic differences with conventional HPDC
1. Slow filling of die – laminar flow
2. Lower temperature – semi-solid state
3. Primary crystals small, equiaxed, non-dendritic

8. 1 Laminar filling
• Less erosion on tooling
d
1. Laminar filling
• Minimised air entrapment – no air porosity
2 Lower temperature
• Shorter solidification time
L h i li (l h l f i )
2. Lower temperature
• Lower heat impact on tooling (less thermal fatigue)
• Less interaction with tooling (erosion and soldering =
l l b i ti / li )less lubrication / cooling)
• Less shrinkage = limited deformation during cooling /
better dimensional tolerancesbetter dimensional tolerances

9. 3 Equiaxed primary crystals
• Homogenous microstructure regardless of thickness
Feeding possible with the proper gating and
3. Equiaxed primary crystals
• Feeding possible – with the proper gating and
component design even solidification shrinkage can
be avoidedbe avoided
3 From principles to industrial applications3. From principles to industrial applications
Thi ldi h l• Thixomolding: mature technology
• Rheocasting: pre-industrial stage technology
18

10. Thixomolding: mature technologyThixomolding: mature technology
DeburringDegatingInjection
www.sirris.be | info@sirris.be | 19
BARCO Security Systems
R j ti t• Rear projection systems
• Replacement of 2 parts by one
I j i i 2 i ld• Injection in 2 cavity mold
• Tight tolerances
h h h d• No machining apart the threads
• AZ91D

11. VERHAERT
JAVAD
DIGITAL THEODOLITE
VERHAERT
• DIGITAL THEODOLITE
• Injection from 3 parts in one mould
(b h dl f l k)• (base + handle + safety lock)
• Less machining
9• AZ91D
BARCO – Vision BMS
• SENSOR FOR TEXTILE MACHINES
• Injection FROM 2 x 3 PARTS IN 1 shot• Injection FROM 2 x 3 PARTS IN 1 shot
• Very tight tolerances
• Visual aspect• Visual aspect

12. CE+ T
Vid h• Videophone
• Injection of 6 different parts in 1 shot
Ti h l• Tight tolerances
• Surface treatment
9• AZ91D
Mould
E d
Thixo network makersEnd-users
1. Platform of expertise
2 Pre-industrial line
Machining
shops2. Pre-industrial line
3. Process control
4. Good design practices
S f
shops
SIRRIS
5. Industrial surface treatments
6. Safety issues during machining
7. Industrial network to produce finished parts
Surface
Treatment
suppliersp p
8. Network for supply of magnesium chips and recycling of scraps
9. Simulation software to support the mould design
10 B i f ld d i10. Basis of mould design
11. Marketing of the actual advantages of thixomoulded parts
24

13. Rheocasting of aluminum: pre- industrial
stage technology
25AlSi7Mg0,6Y40 or A357
Productivity gains, examples
Factor HPDC RheoMetal Remark
Cycle time 60 shoots/ h 90 shoots/h -40% average
ki dLocking force 840 ton 320 ton End pressure: 160
Bar
Waste 5% 0,1% Due to porosity
Porosity Middle None Porosity free
The data is collected via trial castings from:The data is collected via trial castings from:
• Automotive
• Telecom
G l i d t• General industry
26

14. Rheocasted parts, examples
Radio filter Medical eq Heat sinkRadio filter Medical eq. Heat sink
Radio filterLoad wheel Car box
27
Radio filterLoad wheel Car box
4 Future developments4. Future developments
Thixomolding: alloys and toolsg y
Thixoforging: process and tools
Rheocasting: process and case studiesRheocasting: process and case studies
28

15. Near Net Shape technologies
Thixomoulding – Rheocasting
Thank you for your
tt tiattention
29