Diamond Systems Tritan Guia de Resolução de Problemas descarregar pdf (Página 35)

Ultrasonic welding

Ultrasonic welding can be performed successfully using shear-

type joints. Shear joints produce strong, hermetic bonds. Shear

joints for Eastman

™

polymers should closely follow the design

suggested in Figure 32. In some limited situations, energy directors

may work satisfactorily; but in most situations, the bond will

not retain enough toughness for the application.

Figure 32 Ultrasonic welding Eastman

™

polymers

Ultrasonic welding advantages, shear joint vs. energy director

• Improved joint strength (2×)

• Improved joint toughness

• Reduced crack propagation behavior

• Improved distribution of loads (shear vs. leverage loading)

• Excellent sealing performance

• Improved interface melt fusion (less sensitive to additives)

• Improved control of joint ﬂash

Typical ultrasonic welding setup conditions

(for copolyesters other than Eastman Tritan

™

copolyester)

• Horn type Aluminum or titanium

• Booster type Green (1:1)

• Welder power 1,000 watts (typical)

• Frequency 20 KHz

• Fixture/nest Rigid or semirigid

• Options Collapse control, constant weld-

energy, computer control

Typical ultrasonic welding conditions

(for copolyesters other than Eastman Tritan

™

copolyester)

• Welding time 0.5–1.0 s

• Hold time 1.0 s (min.)

• Welding pressure 0.207–0.345 MPa

(30–50 psig)

• Trigger pressure Minimize

• Downspeed Minimize

10° (min.)

Flash relief

B (depth of weld) = 1.25  W

After weld

1° Draft angle (typical)

1.5 mm (0.060 in.)

R (typical)

0.5 mm (0.020 in.) min.

0.6W

Slip-fit

Radius

Before weld

A = 0.2 to 0.3 mm  0.025 mm

(0.008 to 0.012 in.  0.001 in.)

Interference per side

0.025-mm

(0.010-in.)

gap (min.)

Support nest

Support

nest

= 30°–45°



20°–30°