spierings (2012) - orthotec presentation final.ppt ... · 3 who is inspire? inspire inspire is a...

Research Collection

Other Conference Item

Opportunities for designing material properties by SelectiveLaser MeltingOrthoTec 2012, 12-13 September 2012

Author(s): Spierings, Adriaan B.

Publication Date: 2012

Permanent Link: https://doi.org/10.3929/ethz-a-010335524

Rights / License: In Copyright - Non-Commercial Use Permitted

This page was generated automatically upon download from the ETH Zurich Research Collection. For moreinformation please consult the Terms of use.

ETH Library

https://doi.org/10.3929/ethz-a-010335524

http://rightsstatements.org/page/InC-NC/1.0/

https://www.research-collection.ethz.ch

https://www.research-collection.ethz.ch/terms-of-use

Opportunities for designing material properties

by Selective Laser Melting

A.B. Spierings

Manager R&D SLM

Inspire – institute for rapid product development irpd

St. Gallen, Switzerland

OrthoTec 2012

-

12-13 September 2012

1

Agenda

� Introduction

– Who’s inspire?

– R&D focus of irpd in the field SLM

� Why Additive Manufacturing?

� Background and motivation

� Materials and methods

� Results

– Material density

– E-modulus

– Hardness

� Example

� Conclusions

Spierings, Adriaan © 01/2012 inspire AG2

3

Who is inspire?

INSPIRE

inspire is a competence center with a closerelationship to university and is a commoninitiative of Swissmem, the Swiss FederalInstitute of Technology (ETH), and the Swissgovernment.

Its goal is to support the Swiss machine buildingIndustry by researching for industry and solvingproblems in various areas of research such asmethods, processes and technologies.

www.inspire.ch

researchindustry

Strategic Partner

of ETHZ

Spierings, Adriaan © 01/2012 inspire AG

4

Filds of activity (inspire)

www.inspire.ch


5

Who’s inspire?– irpd?


Organisation irpd

R&D

- Material & process development

for SLS / SLM

- Medical manufacturing &

engineering

- Projects (EU, CTI, B2B, =)

- Education: PhD, student projects

Services / production

- Services in production (RP, AM) using

SLS, SLM, 3DP

- Reverse Engineering / Construction & Design

- Consulting

6Spierings, Adriaan © 01/2012 inspire AG

SLM-research focus @ inspire-irpd

� Materials� Process parameters for SLM materials / powders

� Properties of SLM materials (static, dynamic, =)

� Development of “new” materials� MMC / hybrid materials, new alloys

� Process� Reduction of the tendency for cracking /

internal stresses

� Optimization of materials properties

� Simulation of the SLM welding process

� Optimization of process productivity

� Applications� Lightweight structures

� Functionally optimized parts & applications

� Equipment� Investigation into a future SLM machine setup for special applications

� Optimization of the overall-productivity

Materials

Process

MachineEquipment

Applica-tions

7Spierings, Adriaan © 01/2012 inspire AG

Why Additive Manufacturing (AM)?

� AM technologies allow the production of highly complex structured

parts

Production «layer by layer»

� Only the selective consolidation of a raw material (powder, fluid, =)

in a 2D area

� No undercuts � complexity plays almost no role


- Raw powder materials

- Plastics (SLS)

- Metals (SLM)

-=

- Typ. layer thicknesses:

- SLS: 0.05 - 0.1 mm

- SLM: 0.02 – 0.07 mm

- Tool (Laser):

- SLS: CO2

- SLM: ND-YAG

“Scanning”

mirrorOptik

LASER

beam

LASER

sintered

Part fixed in

powderPowder

container

LASER

Part

Zylinder

Roller

for new powder


� No undercuts � complexity plays no role

«Complexity for free»



� Highly complex structured parts=

= some examples


Inspire-irpd: Cancellous bone model Inspire-irpd: Grid-structure

Inspire-irpd: Medical instruments / tools Inspire-irpd: Medical instrument, div. Parts.



= some examples: Thalus bone

Thalus bone replacement


Inspire-irpd: Patient-specific

thalus bone

AM manufactured- Freedom of design

- Patient-specific

- Fully dense

But- High thermal inertia

- Heavy

- No elastic deformation

� No shock absorption

Thalus bone scanning and during

implant



= some examples: Implants / Implant design

Implant design


Inspire-irpd: Trochanter Implant

design

AM manufactured- Freedom of design

- Patient-specific possible

Requirements- Optimized mechanical

behaviour

- ev. Bone ingrowth

Inspire-irpd: Implant



= some examples


Source: SLM solutions GmbH

Hip implant

(*) L.E. Mur et.al, Microstructure and mechanical properties of open-cellular biomaterials prototypes

for total knee replacement implants fabricated by electron beam melting,

Journal of the Mechanical Behavior of Biomedical Materials, Volume 4, Issue 7 (2011), 1396–1411

In medical applications, especially for implants

� An implant should ideally offer the same

mechanical stiffness as the (original / connecting)

bone.

AM offeres structural optimization:

� Design with optimized

mechanical behaviour,

in order to fulfill the mech.

requirements coming from

the structural behaviour of

the orignal bone.Knee implant with structural

optimization (*)



«An implant should offer the same mechanical behaviour / stiffness as the

(original / connecting) bone.”

� This is already

beeing done –

«State of the art»

� Porous structures:

Ingrow of bone cells

into the outer layers

of an implant.

However, the mechanical behaviour of such structures is difficult to characterize=


Fraunhofer IWU: Implant with mechanically optimized structure

� Are there other options for not only to designing the structure,

but also the mechanical behaviour of the material?

Background & Motivation

� =highly improved functional & structural parts


Additive Technologies (e.g. SLM)

Master forming technology

� Selection and optimization of

Processing parameters

� «Generation» / influencing

material properties:

- porosity

- mechanical properties

Structural & mechanical part optimization

� Functionally and mechanically optimized

Additive: «Freedom of design»

� Extremly complex parts

� Structural optimization

Materials & methods

� Aim:

� Machines

Machine: ConceptLaser – M2

• Laser power

up to 200W

• Suitable for

- Stainless steels

- Titanium

- CoCr

- =


SLM machine Concept M2 @ Inspire-irpd

Freedom ofdesign


Material microstructure

Mechanicalproperties

Mechanicallyoptimized parts

AM: √√√√ AM: !

Materials & methods

� Aim:

� Materials

Material: SS 17-4PH / AISI 630

• Well known & widely used

• Hardenable

• Tyically used for instruments etc.

• Powder: D50 ≈ 18 µm


Freedom ofdesign




Mechanicallyoptimized parts

AM: √√√√ AM: !

Fine powder, used for SLM

Materials & methods

� DOE setup: Full factorial design

Processing parameters: 5 factors with 2 levels each

1. PLaser 105 W & 190 W

2. vscan 800 mm/s &1300 mm/s

3. Layer thickness: 30 µm & 50 µm

4. Build direction: Vertical (90°) & horizontal (0°)

5. Heat teatment: without / with

Fix value:

• Hatch distance: 0.0975 mm (35% overlap)





3 samples for each

combination

� 96 tensile bars

Materials & methods

� Samples

– Turned to the final geometry according to DIN 50’125 – B4x20

� Analysis

– Density measurement

– Archimedes method, applied

on separate test cubes

– Micrographs

– On separate test samples

– Mechanical testing

– ZWICK type 1484

– Pre-load: 20 MPa

– Speed: 10-3 s-1

– E-Modulus, Rp0.2, Rm, A


left: ZWICK 1484 right: blank, pre-formed and

drilled tensile specimen

Results

� Microstructure / porosity

– Achieved porosity range

– Lowest: 99.9%

– Highest: 73.9%

Measured on separate test cubes

– The processing parameters

significantly affect porosity

– Pore size & shape

– For low energy input (low

laser power / high scan speed)

– Pores begin to be interconnected


Cross-sections showing porosity

upper: PLaser = 190W, vScan = 1300mm/s, tLayer = 50µm,

lower: PLaser = 190W, vScan = 800mm/s, tLayer = 30µm.

Results

� Material density & Energy densiy

– The material density is highly

influenced by the applied

Energy-density:

- Plaser= Laserpower (W)

- vscan= Scan speed (mm/s)

- hs= Hatch distance (mm)

- tLayer= Layer thickness (mm)


Dependency of material density on applied energy density.

Layersscan

Laser

thv

PdensityE

⋅⋅=−

� Material density is predictable!

It allows the selection of a suitable set of processing parameters for a

required material density.

Results

� Hardness

– Hardness (HB2.5 / 62.5)

– For fully dense material:

- 0°orientation: 400

- 90° orientation: 389

– For higher porosity values:

� Hardness is also depends

on the stiffness of the

(remaining) material.

� Stiffness and deformation behaviour of the remaining material is dependent on

- E-modulus

- Yield strength (� plastic deformation of material)


Dependency of hardness on material density

Results

� E-Modulus

– E-modulus depends

in the heat-treated condition

on the material density.

– Differences between

horizonal and vertical

build orientation is

9.9 ± 2.9 GPa (5.7%) for

all material densities.

� It is possible to calculate E-Modulus from part density using formula from

Boccaccini1:


Dependency of E-modulus on material density, for heat treated material

1 Boccaccini, A.R. and Z. Fan, A new approach for the Young's modulus-porosity correlation of ceramic materials.

Ceramics International, 1997. 23(3): p. 239-245.

RPP

RPEE MP

⋅−+

⋅−⋅=

)1(

)1( 2

- EM = Pore-free modulus. 194.5 Gpa

= mean value for horizontal and vertical build orientation

- P = porosity

- R = 0.21 fitting parameter, correlated with pore size & distribution

Results

� Designing space for E-Modulus – Hardness – Yield strength


Correlation between hardness, Yield strength and

E-modulus

� Cantilever

– Dimensions: L x W x H = 85 mm x 4 mm x 2.5 mm � Iz = 5 mm3

– Material: 17-4PH - hardened

– Load 9.8N (1 kg)

� Elastic deflection:

No deflection without load E = 199 GPa

Elastic deflection

- calculated: 1.9 mm

- Measured: ≈ 1.8 mm

E = 99.2 GPa

Elastic deflection

- calculated: 3.9 mm

- Measured: ≈ 4.3 mm

Example


Z

3

IE3

LP

⋅⋅

⋅=d

cantilever

Conclusions

� Options offered by SLM


Conventional:- 1 processing parameter set

� Typically dense and rigid

Designing material properties locally:- n processing parameter sets

� local material optimization

Designing material properties globally:- 2 processing parameter sets

� Core-shell design

Freedom of design:- 1 processing parameter set

� structural optimization

Conclusions

� Selective Laser Melting

– Allows geometrically complex structured part

– Designing elastic material properties within a

wide range.

� This allows locally optimization of part structure and

material behaviour by optimizing processing parameters.

� Application-adapted global mechanical behaviour


Inspire-irpd: Medical parts

Thank you for your attention


Building of Empa St.Gallen SLM lab, inspire-irpd

Alex

SLM

Operator

Pirmin G. LevyK. Wegener

Thanks toD

spierings (2012) - orthotec presentation final.ppt ... · 3 who is inspire? inspire inspire is a...

Documents