Ultrasonic Plastic Welder

Thanks Eng,

I was planning to try out this machine to melt some fabric or thin plastics do you feel that that can be done, with this machine at 20 KHZ?

What would the horn need to look like? The fabric will be man made materials.

***Do you have an answer as to the connection to the RF port, as per my previous questions? I am uncertain if I have a complete machine here.***Is there a wire connection made to the base tooling, or is that fully stationary? I will contact Branson, and have heard that their units are very reliable. I understand that the horns are often made from titanium, is this a requirement, or are there other materials that can be used as horns? (tuned of course).

Is there a simple way to assure the amplifyer is OK without switching the machine on?

Thanks,

MG.

The unit cannot be tested unles there is a proper welding horn and fixture attacted. The Amphenol connector contains an interlock wiring connection so the amplifier cannot be energized without a connection...for safety reasons....

Contacting Branson is the best advise. They also can advise you for the proper design of a welding head.

Are you certain that I can not test at least components of this US unit? I would like to test the amplifier. It is easily removable, can it not be checked with an Ohm meter or scope? I am sure when they manufacture it they test it some-how. There likely is also a way to check to see if there is a frequency at the amplifyer connection side.

Any knowledge in this area?

MG

Branson designs each horn specifically for the job, so it is best to have them make the horn for you.

Branson is a good source of information. I have used many of these welders and never had a problem with touching the horn. Yes, it can damage bones, but fortunately, flesh attenuates the vibration, so not much acoustic energy reaches your bone. I also never developed any kind of hearing problem. The frequency is out of the range of most humans, and the acoustic output is very small. You can test the machine without a horn attached, but you will need something like a small accelerometer to mount in place of the horn in order to measure the output. Horns can be made out of stainless steel on a lathe. Horns are almost always 1/2 wavelength long, but you can make them multiples of 1/2 wavelength for more reach. Horns are always smaller on the output end than the input end because you are looking for amplitude gain. The gain is generally the ratio of input area to output area. Linear taper is the simplest type of horn. Exponential taper gives the most gain. There are also many other horn designs, such as bi-cylindrical, etc. Each has specific advantages and limitations. If you have other specific questions, fire away.

Hi Welderman, thanks for the great reply. I have contacted the Canadian Branson branch and will see if they can help me, so far their hourly fees are out of this world, and they did not have a lot of time for me. I should be able to get the welder going on my own. I can easily turn something like a stainless horn on the lathe. I noticed that most rectangular horns have cut outs (slots of certain length) how are those calculated, or what is the software that is used? I am still unclear as to the "RF" labelled three prong connector on the back of the unit, likely 2 of the wires need to be bridged in order to start the frequency and vibrations of the unit - does that seem correct? If I bridge two of the three can I damage something in the unit? I am currently looking to get a set up going to see if I can melt some man made fabric to itself, or to other materials such as sheet metal steel - any thoughts on that? Surely there must be some method to minimize physical noise when the horn touches a piece of metal.

Please elaborate a little more on the frequency as well as what you mean by exponential taper. The unit frequency is 20 khz I believe. I am looking to use something like a roller, I saw something like that on the Branson web site.

What do you know about Fabric slitting with ultrasound?

I really appreciate your help. Do you know where on the internet I can get some more documentation on my unit AES 901?

MG.

I can answer general questions, but never having used the Branson machine you describe, I can't answer questions on this specific device. If you can't get a manual from Branson, try some of the used equipment dealers. A linear taper horn is analagous to a megaphone in the acoustic range. An exponential horn is analagous to the bell of a brass instrument. Horns are a method of impedance matching the driver to the load, for more efficient energy transfer. Linear horns are simple to design and construct, but not as efficient as exponential tapers for very high amplitude gain. Picture a horn as a resonant extension spring with both ends moving 180 degrees out of phase. The center of the spring will not be moving. However, the center is where the strain is the highest (that's where the horn will get warm and where it will fail). Acually, the point of 0 motion is the 1/4 wavelenth point and is not in the center, if the horn has gain. A stainless steel linear taper horn at 20 khz will be about 3.8 inches long. I generally make them longer than 1/2 wave length and then tune them on a lathe for maximum gain. I also suggest you obtain a book on ultrasonics. I used Heuter and Bolt, but I'm sure more modern texts are available. The rf connector on your unit is a mystery to me. It may be that you are missing the power supply, oscillator, and amplifier which might be housed in a different container. I suggest you open your unit and try to locate these components. Another clue would be whether your unit has a power cord and controls on a panel somewhere.

The controls seem to be in the unit I am not sure about the RF generator.

As mentioned before, the unit powers up, the air cylinder can be actuated by applying air manually and moves, I assume that at that time something triggers the RF, and I can`t find the switch that does this. There is a linear electronic scale encoder attached which presumably gives a signal to the control unit. Any more thoughts?

Thanks,

MG

The RF you mentioned is actually a 20khz oscillator and power amplifier. You should be able to locate a control panel with an off/on switch and a power knob. Inside, you should find a DC supply as well as an oscillator and power amplifier. Most ultrasonic devices are about 1.0 Kw, so you should find some high power semiconductors on a heat sink. Another clue would be to trace the wires that go to the connector you spoke of. If those wires go directly from the connector to the ultrasonic transducer, it's an indication that you are missing the control unit.

Try contacting http://www.usedultrasonicwelders.com/sonitekindex.htm. They carry used and rebuilt welders like yours. From their web site, you can learn that the 901 is a fully integrated unit with all controls built in.

Hi welderman,

I went to their website, and contacted them. On their website they show the machine I have 901 AES, however with a sub unit (control box?) next to it. I found that the RF frequency generator is very expensive, and I am still unsure if that box shown on the website is the RF generator or not. I do not have this control box. Sonitek was fairly short and I did not get to inquire about the box in detail. As mentioned before, it is likely that all controls are build into my unit. Any ideas what to look for on an RF circuit board? I am sincerely hoping that the RF module is not missing. Any more thoughts before I will have the unit inspected? This will likely cost a fortune.

Just another thought -

talk to folks who operate ultrasonic welding machinery and many will tell you that they have a radio going in the shop nearby. During the 'weld' cycle, the cycles given off actually disturb the radio signal - the operators can hear this and know that a welding cycle has indeed occured -

Jim