JEC COMPOSITES MAGAZINE - Issue #61 - November/December 2010 - 12

ith its Pressurex® pressureindicating sensor film, Sensor Products Inc. provides a solution for determining weld area pressure distribution. According to the company, this film can be used to ensure uniform pressure economically and precisely.
Fig. 1: Using Pressurex® for setup in ultrasonic welding

Precise mapping

EQUIPMENT
Welding

Increasing bond strength and reducing defects in ultrasonic welding
Pressure adjustment

The ultrasonic welding technique, which uses high-frequency ultrasonic acoustic vibrations to create solid-state welds, is becoming more popular for composite materials such as carbon fibre. To optimize the weld and prevent defects, the horn and anvil must be precisely aligned during set-up so that the horn exerts uniform pressure across the entire weld area. Here is one solution.
bonder, the film instantaneously and permanently changes colour in direct proportion to the actual pressure applied. The precise pressure magnitude (PSI or kg/cm²) is then easily determined by comparing colour variation results to a colour correlation chart (conceptually similar to interpreting Litmus paper, Fig.2). If desired, the film can be further analyzed. Pressurex® is extremely thin (0.10 to 0.20 mm) and flexible, which enables it to conform to curved surfaces. These pressure maps show that there are pressure variations across the weld zone that can result in less than optimal weld strength.

The routine use of Pressurex® during ultrasonic welding set-up helps ensure proper contact pressure and alignment between the horn and anvil (Figure 1).

This results in welds of greater bond strength, and also helps to reduce the incidence of rejected products, thereby lowering base factory costs.

Pressurex® is an easy-to-use tool that reveals the distribution and magnitude of pressure between any two contacting surfaces. When placed between the horn and the anvil of the ultrasonic

jec composites magazine / No61 November - December 2010

Such variations are generally caused by a lack of alignment between the horn and anvil, or by dirt or residue on the horn. To fix these conditions during set-up, the operator has to proceed as follows: 1) turn on the ultrasonic welder and set the supply air pressure; 2) place a flat gauge on the contact

Headquartered in New Jersey and established in 1990, Sensor Products Inc. is a manufacturer and distributor of tactile pressure sensing solutions. Their customized and off-the-shelf products are installed within all of the Fortune 500 industrial companies as well as thousands of smaller manufacturing firms. Their sensors are used in applications as diverse as tyre testing or semiconductor manufacturing, and from R&D labs to space missions. Additionally, Sensor Products provides in-house and on-site stress and pressure mapping analysis, as well as a variety of regional technical seminars.

About Sensor Products

Fig. 2: Pressurex® pressure profile after image analysis

point of the anvil to simulate the thickness of the parts to be welded; 3) lower the horn onto the flat gauge to calibrate the height setting; 4) align the horn tip and the anvil; 5) place Pressurex® on top of the flat gauge and lower the horn to exert light pressure on the film as shown; and 6) adjust the horn tip as needed through repeated set-ups with the sensor film. The set-up is correct when the pressure density on the film is uniform in colour. More information: www.sensorprod.com

http://www.sensorprod.com

JEC COMPOSITES MAGAZINE - Issue #61 - November/December 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #61 - November/December 2010