Production and properties of sustainable wood-

welded panels from North American species

Benoît Belleville, UlavalTatjana Stevanovic, Ulaval

Antonio Pizzi, ENSTIBAlain Cloutier, Ulaval

June 19 2011

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Plan of presentation

• Introduction and problematic

•Bibliographical review

•Objectives of research

•Results and discussion

•Conclusions and perspectives

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Introduction

•Rotational wood-dowel welding has been

shown to rapidly produce wood joints of

considerable strength without any adhesive.

•Mechanical properties similar to PVA

adhesive.

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Wood-dowel welding: How ?

•Mechanical friction at the interface;

•Temperature-induced softening and

degradation of polymer material;

•Composite formation: fibers/molten wood

material matrix.

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Wood-dowel welding mechanism

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Wood-dowel welding: The interest ?

• Interesting and sustainable alternative for

paneling applications

•Green technology (only wood)

•Opportunity to increase productivity and

reduce costs in the furniture industry

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Problematic

•Evaluate the suitability of two North American

hardwood species, sugar maple (Acer

saccharum) and yellow birch (Betula

alleghaniensis) for the design of panels using

wood-dowel welding technology.

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Specific objectives

•Produce wood welded panels

•Evaluate mechanical properties under

constant and varying hygrometric conditions

•Compare with its PVA-glued counterpart

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Material and Methods: Paneling

•Wood-dowel welding performed with a

machine designed for paneling purposes.

•12 panels produced for each species

•6 PVA-glued panels produced for each

species in parallel for comparative purposes

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Material and Methods: Paneling

•25x30x225 mm wood slats (12 per panel)

• Insertion along the edge and through

neighbouring slat (~50 mm)

•Dowels configuration

•2.5 cm spacing between dowels and from edges

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Material and Methods: Welding parameters

•Commercial smooth wood dowels (Ф 9.67 mm)

in pre-drilled hole (Φ 7,67 mm)

•Optimized wood-dowel welding parameters for

individually studied species

•Sugar maple : 1000 RPM, 25.0 mm s-1

•Yellow birch : 1000 RPM, 16.7 mm s-1

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Material and Methods

•Panels tested following a typical protocol for

wood composite panels

•Three-point bending test

•Delamination following multiple cycles at

different hygrometric conditions

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Material and Methods: Three-point bending test

MTS QT 5 KN universal testing machine

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Material and Methods: Three-point bending test

•Load concentrated at center

•Dowels not continuous

throughout the panel (50 mm)

[1]

•Estimated load at break (σmax)

Yellow birch: 1502 N

Sugar maple: 1630 N

3

maxmax 2

D

LF

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Material and Methods: Delamination

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Results and discussion: Bending

•2 types of failure: Centre of

the panel or next to it.

•Fracture always in the dowels

•No slippage along weldline

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Results and discussion: Bending

Table 1. Average bending strength results

1Standard error

Species Type of

laminated joint

Fmax ±SE1

N

Estimated Fmax

(eq.1)

N

Sugar maple

Welded 1696.4 (136.2) 1630

Glued 5746.1 (764.9) -

Yellow birch

Welded 1790.2 (38.4) 1502

Glued 5212.7 (521.9) -

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Results and discussion: Delamination

•No deformation observed in panels submitted

to conditioning cycles.

•Delamination observed in both types only

under dry conditions although not affecting

bending properties.

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100% sugar maple

No adhesive

66 cm wide (26’’)

46 cm high (18’’)

36 cm deep (14¼’’)

228 wood dowels

Small-scale crib

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Conclusions and perspectives

•Welded bond joint is not the weakest link

affecting panel mechanical properties.

•Wood-dowel welding is suitable for paneling

of North American species.

•Additional work required to improve the

automated assembling technique and panel

stability.

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Acknowledgements and partners

Thank you for your attention!