Branson Guide: Joint Design and Material Compatibility for Spin Welding Manuals & Guides

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Spin Welding

Rib on Plastic Port

Stationary Fixture

Driving (Spinning) Tool

Slot/Recess in Plastic Part

Figure 1.

Drive Details

Drive (Spinning) Tool

Spinning (Upper) Part

Figure 2.

Self-Aligning

Drive Details for

Automation

Joint Design and Material
Compatibility for Spin Welding

General Description: Spin welding is a tech­nique for welding thermoplastic parts that
utilizes a circular spinning motion, in con­junction with applied pressure, to weld two
parts together. The part-to-part interface
must be circular. One part is held stationary
in a holding fixture as another part is rotated
against it using applied pressure. Heat gen­erated by the friction between the two parts
causes the plastic interfaces to melt and fuse
together producing a strong hermetic seal.

This bulletin should be used as a guideline to
aid the designer during the initial concept
stage of designing a product for spin weld­ing. Any dimensions given in the designs
should be used as guidelines only, since the
specifics of your application may require a
variation to the basic design.

If you have questions or need assistance in
designing your parts, contact your local
Branson representative, your regional tech­nical center, Branson in Honeoye Falls, NY, or
the applications lab at Branson headquarters
in Danbury, CT.

Key Design Considerations

There are several factors necessary for
successful spin welding, including a determi­nation of the speed for part rotation, and
appropriate pressure of the driver as the
parts are spun together. Also, a good spin

welding joint should have a weld area
greater than a typical wall section of
the part and must also provide sufficient
part-to-part alignment.

It is necessary that parts to be spin welded
have a circular axis (such as a sphere,
cylinder, disc, or ring) and a drive feature
to enable spinning of the upper section
(see Figures 1 and 2).

Primary Factors Influencing Joint Design

All of the following questions should be
answered prior to the design stage to gain
a total understanding of the weld joint
requirements:

• What type of material(s) is to be welded?

• What is the overall part size and

configuration?

• What are the final requirements of the

part?

• Is a structural bond desired and, if so,

what load forces does it need to resist?

• Is a hermetic seal required? If so, to

what pressure?

• Does the assembly require a visually

attractive appearance?

• Is flash or particulate objectionable

inside and/or outside?

• Any other requirements?

Typical Spin Welding Joint Designs

Note: Dimensions given in the
designs should be used as GUIDELINES
ONLY, since the specifics of your
application may require a variation
to the basic design.

T = Wall Thickness
B = 1.5 x T
C = Clearance 0.005 - 0.010"
R = Radius ~0.050"
L = Lead-in 0.020 to 0.040" at a minimum
i = Interference 0.010 to 0.020"

depending on part size,
requirements and tolerances

T = Wall Thickness
F = 30° min
A = Depth of weld

~0.5 x T to 0.8 x T

C + D = Weld surface,

~2.5 x T

E = A + 0.010"

B+0.010"

Figure 3. Shear

Joint Design

B+0.010"

Figure 4. Flanged Shear

Joint Design

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B+0.010"

B+0.010"

Figure 5. Shear Joint Design for Nylon

Figure 6. Tongue

and Groove Joint
with External Skirt

Table 1. Material
Weldability

The codes in this table
indicate relative ease of
welding for the more
common thermoplastics.

Note: The ratings do
not relate to the
strength of the weld
obtainable. Use these
tables as a guide only,
since variations in
resins, fillers, and part
geometry may produce
slightly different
results.

Branson Ultrasonics Corporation
41 Eagle Road, Danbury, CT 06813-1961
[phone] • Fax: [phone]
www.bransonultrasonics.com

e-mail: [e-mail]

475 Quaker Meeting House Rd.,

Honeoye Falls, NY 14472
[phone] • Fax: [phone]

Figure 7. Tongue
and Groove Joint

MATERIAL WELDABILITY

Amorphous Polymers
ABS 1-2
ABS/polycarbonate alloy 2
Acrylic 2
Acrylic multipolymer 2
Butadiene-styrene 1-2
Phenylene-oxide based resins 2
Polyamide-imide 2-3
Polyarylate 2
Polycarbonate 1-2
Polyetherimide 2
Polyethersulfone 1-2
Polystyrene (general purpose) 1-2
Polystyrene (rubber modified) 2
Polysulfone 2
PVC (rigid) 1-2
SAN-NAS-ASA 1-2
PBT/polycarbonate alloy 2

SW-1 © Branson Ultrasonics Corporation 2011

The Emerson logo is a trademark and service mark of Emerson

Electric Co.
Revised and printed in the U.S.A. 8/2011

Figure 8. Tongue and Groove Joint
with External Flash Trap

MATERIAL WELDABILITY

Semi-Crystalline Polymers

Acetal 2-3
Cellulosicas 2
Fluoropolymers 3-4
Liquid crystal polymers 2-3
Nylon 1-2
Polyester, thermoplastic

Polyethylene terephthalate/PET 2-3

Polybutylene terephthalate/PBT 2
Polyetheretherketone - PEEK 3
Polyethylene 3
Polyphenylene sulfide 2
Polypropylene 2

Code: 1 = Easiest, 5 = Most difficult.