Wednesday, November 17, 2010

Dukane Awarded 2010 Ringier Prize for Innovation for Servo Ultrasonic Welding System.

At the recent Med Tech show in Shanghai China, Dukane was displaying its new Servo Ultrasonic Welding Press which was awarded the Ringier Technology Innovation 2010 award in the auxiliary equipment category for plastic welding.  The winner’s of the Ringier Award in each category are chosen by an independent panel of judges for technical and product excellence, and for making a significant technological contribution to China’s plastics industry.

Russ Witthoff, International Sales Manager
Xu Zhenhua, Shanghai Sales Engineer
  Qian Welin, Assembly Technician 




Wednesday, October 6, 2010

Understanding Ultrasonic Horn, Booster, Transducer Mating Surface Flatness

It is essential that the mating faces between an ultrasonic transducer/booster and a booster/horn be flat and parallel. If any air gaps remain, there will be a resultant loss in power output and efficiency. Coupling may be so poor that it might prevent the starting of an ultrasonic stack.

The condition of excessive crowning, or uneven contact surfaces, is normally evidenced by a burnished appearance only around the bolt area of the contact surfaces. This indicates that contact between the components is occurring only at the burnished area and not around the periphery of the surfaces. The contact areas between components can build up excessive heat due to inefficiency of vibratory transmission between the components.

The following flatness tolerances are typically specified:
  • Transducers: 0.0005 in. for 20 kHz and 0.0005 for 40 kHz
  • Boosters: 0.0010 in. for 20 kHz and 0.0005 for 40 kHz
  • Horns (Sonotrodes): 0.0010 in. for 20 kHz and 0.0010 in. for 40 kHz.

Examples of the ultrasonic horn surface not being flat.
 



 Here is an example where there is only 10% of the surface making cont  act with the booster interface.

 
When any of the contact surfaces look like the examples given, please send your tooling to the original manufacturer for re-surfacing. This will extend the tooling life as well as reduce the probability of permanent damage to the components.

What if you can’t spare the time to return the ultrasonic horn, booster or transducer for re-surfacing? If the surfaces are just dirty and not gouged in any way, you may be able to lap the surfaces smooth.

Reconditioning the ultrasonic stack

It is important to check the ultrasonic stack regularly to make sure the components are in good working order. In addition, there are several steps you can take to recondition the stack:

Disassemble the ultrasonic transducer/booster/horn stack and wipe the mating surfaces with a clean cloth or paper towel.
  • Examine the mating surfaces. If they appear to be in good condition, skip to Step 9. If any surface is corroded or shows a dark, hard deposit, it should be reconditioned (Steps 3 - 8). If the mating surface of any component shows evidence of crowning, cupping, or any other out-of-flatness condition, contact an ultrasonics industry professional for advice. Very small, isolated pits in the mating surfaces are generally not a serious problem.
  • If necessary, remove the mounting studs.
  • Tape a clean sheet of #400 (or finer) emery cloth to a clean, smooth, flat surface. A piece of plate glass is usually suitable.
  • Hold the component at its lower end and carefully stroke it in one direction across the emery cloth. Do not apply pressure as the component's weight alone will suffice. NOTE: Use extreme care to avoid tilting the component. Loss of flatness on interface surfaces may render the welding system inoperative.
  • Perform a second stroke, then rotate the part one-third turn and repeat.
  • Turn the part the final one-third and perform the same two strokes. Be certain to perform the same number of strokes (two) at each location.
  • Re-examine the mating surfaces, and repeat steps 5 through 7 until most of the contaminate has been removed. This should not take more than two or three complete rotations.
  • Before reinserting a stud, examine it to make sure the threads have not been damaged. Clean all foreign material, grease and oil from the threads of the stud and the threaded hole using a clean cloth or towel.
  • Replace worn or damaged studs with those specified by the manufacturer. Ordinary steel set screws are not properly heat treated for use as stack studs.
  • Very lightly coat the flat mating surfaces with high-pressure silicone grease or insert a high-temperature polymer film washer (not both) to promote good transmission of ultrasound and prevent the stack components "cladding" together.
  • Torque studs and mating surfaces properly, as indicated in the accompanying table showing Correct Torque Values for Stack Component Assembly. Loose studs or joints will cause overloads or intermittent operation, while excessive tightening results in material distortion that shortens component life.
  • Install the stack in the welder and test ultrasonic operation.

Tuesday, September 28, 2010

Ultrasonic Boosters

The boosters serve two purposes; second mounting point for the stack assembly and either amplify or reduce the amplitude.  Like the transducer, the boosters have a nodal point.  At the nodal point there is a mounting ring designed to fit into the press system or machine mount applications.   There are two types of mounting ring configurations.  Standard boosters have a split mounting ring that houses two “O” rings in a similar configuration as the transducer.    Resonant style boosters have no “O” rings.  These are designed for applications where solid fixed mounting of the stack assembly is critical for the application.  An example would be an application requiring two stack assemblies to weld a single part, because near horn proximity, motion in the stack may allow them to touch.  Resonant boosters eliminate this problem.


Standard and Resonant Boosters

The boosters are either titanium or aluminum.  Titanium boosters, while costly, are more robust and stud thread holes hold up to many assembly and disassembly cycles.  In continuous applications where heat dissipation is a benefit, aluminum boosters are recommended.

Boosters come in different “Gain” ratios.  The mass of the booster below and above the nodal point determine the amount of gain to the amplitude from the transducer.  This is the mechanical means for adjusting the stack amplitude to match the requirement to melt the particular plastic in each application.  It is best to use the optimum booster size for the application.  Leave the generator amplitude setting close to 100% and only make small generator amplitude adjustments when required.  On most horns, the recommended max gain booster size will be stamped on the horn.

Friday, September 24, 2010

Effect of Black Colorant on Ultrasonic Staking.

Sometimes it is difficult to disperse black pigments on polymers, resulting in agglomerates or clumps of pigment particles. These can make for places where cracking can occur when the plastic is stressed. This could be worse in the area of the ultrasonic staking, since the polymer is likely somewhat weakened by the welding process.

It is probably more likely that the black pigments could be increasing the thermal properties of the plastic, so that the material is heating faster causing more degradation than the other colored parts. It may be necessary to adjust the ultrasonic staking conditions for black parts with slightly lower amplitude, less energy input or shorter duration.

Finally, there can be problems with the way the color is added. Assuming that they are adding a color concentrate at the molding machine, if they are adding too much or maybe adding a concentrate that has an incompatible carrier polymer, like polyethylene or nylon, they may not fully blend in the plastic, creating contaminated layers of material.

Monday, September 13, 2010

The 6 quick steps to a successful ultrasonic assembly

Do you have an application that you think could be ultrasonically assembled? Wondering how to get from a couple of pieces of plastic to an assembled part?

This is how our sales engineers tackle an application. While we don’t expect our customers to perform each of these steps, it’s important they be involved in this process. That way they’ll have a better understanding of their systems and know how to maximize the ultrasonic equipment’s potential.

Step 1 - Determine the feasibility of ultrasonics

First examine the components to be ultrasonically assembled. They must be thermoplastics, and if dissimilar plastics are to be welded, they must be compatible (refer to Thermoplastic Compatibility Guide. The parts must also be designed so ultrasonic energy can be efficiently transmitted to the joint.

Using the Amplitude Reference Chart, determine the amplitude requirements of the thermoplastic you’re using. If possible, process a few parts to verify you have sufficient amplitude. Consider using special ultrasonic horn coatings or horn materials if fillers or additives are used in the plastic components.

The last step is to consider your ultrasonic tooling options. Is it even possible to build an ultrasonic horn that will provide the necessary amplitude to the part? Will you need multiple horns or a composite horn? Can the parts be properly supported in a fixture?

Step 2 – Choose the right ultrasonic welding equipment

Once you determine ultrasonics is a viable assembly method for your application, it’s time to choose your welding equipment. Your application and future project needs will dictate whether you need 15, 20, 30 or 40 kHz equipment. The 20 kHz ultrasonic welding system is more versatile, as it can process a variety of part sizes. It’s also ideal when higher amplitudes are needed to melt the plastic. A 40 kHz ultrasonic welding system is usually used for smaller, more delicate applications. Your application will also determine the wattage of your generator (200 to 5,000 watts). Traditionally, the bigger your part and horn, the more wattage you’ll need to run the horn at full amplitude.

How you’ll apply the ultrasonic energy to your parts is another consideration. Hand-held probes are ideal for applications where it’s more convenient to bring the ultrasonics to the part. When control and repeatability are critical, a press system would be recommended. If production rates require speeds that exceed what could be achieved by a standard press, a rotary index parts handling system should be used. Custom mounting and automation of ultrasonic thrusters are other possibilities.

Your ultrasonic sales engineer can help you design your system to meet other specific application needs such as process control and SPC, cooling requirements, and sound enclosures.

Step 3 – Assemble and Install the ultrasonic tooling

Because transducers alone cannot generate enough amplitude to melt the plastic material, your ultrasonic tooling and applications engineer will determine the gain factor that’s needed from the horn to match the amplitude requirement of the thermoplastic. Based on that gain factor, he or she will select the appropriate booster and horn combination.

You’ll need to assemble the transducer, booster, and horn but first examine all mating surfaces for flatness and cleanliness. Remove any foreign matter from the threaded studs and mating holes. Coat one contact surface of each stack component with a thin layer of high pressure grease – but do not grease the studs. Thread the components together and tighten by applying a torque of no less than 13 foot-lbs (17.63 Newton-meters), but no more than 18 foot-lbs. (24.40 Newton-meters).

Once you’ve assembled the stack, install it into your system by following the easy directions in the operations manual. Make sure it aligns with the fixture; use feeler gauges or carbon paper if this becomes difficult.

Step 4 – Set up the welding equipment

After following the simple setup procedures in the operations manual, you should be ready to set the initial press force, trigger force, weld time, and velocity. If your application requires precise melt velocity during the weld cycle, use hydraulic speed control, like the Kinechek® option, which is available on Dukane ultrasonic welding systems. Set the mechanical stop (so the horn and fixture don’t accidentally contact), then determine whether the ultrasonics need to be activated before contacting the parts. If so, use the pre-trigger feature.

If you’re using a process controller, determine and set the most effective primary process control. Welding by distance, peak power, and absolute distance are the most common controls, although welding can also be controlled by time and energy.

Step 5 – Adjust the setup

After you’ve set up your ultrasonic tooling and welding equipment, don’t go into full production – run a batch or two of sample parts. Examine and test (as needed) the assembled parts. If process adjustment is needed, refer to the application troubleshooting section in the “Guide to Ultrasonic Plastics Assembly” to help diagnose probable causes and solutions.

Step 6 – Maintain proper operating conditions

Ultrasonics is a low maintenance process, and Dukane’s ultrasonic welding equipment comes with a 3-year warranty. However, to maximize your welding equipment’s life and performance, it’s important to do some minor cleaning and inspecting after every 500 hours of operation. This includes: removing dust/dirt from the guide rods; applying light oil to the exterior of the air cylinder rod; inspecting wiring to the thruster head; inspecting the air filter; tightening the thruster and fixture mounting bolts (if needed); checking the setup parameters; and inspecting, cleaning, lapping and re-torquing the stack. Regional training programs are also available from Dukane, as is an extensive series of training workshops at the St. Charles facility.

Tuesday, August 31, 2010

How Tight is Tight Enough?

It is important to assemble and tighten your ultrasonic tooling stack to a proper torque. Just assembling the tooling stack as tight as possible could be detrimental to the tooling stack components. For example: the threads on an aluminum booster or aluminum horn can be stripped out due to over-tightening. Conversely, not using enough torque could also be detrimental. The components could come loose and cause the generator to overload. Allowing this kind of thought process to prevail can cause damage to one or more components of the tooling stack.

On Dukane's website you will find our Guide to Ultrasonic Plastics Assembly. Scrolling down to page 91 will bring you into our maintenance section describing various problems that could be associated by not tightening the tooling stack to the proper torque specifications.

Correct Torque Values for Stack Component Assembly

Studs in horns and boosters:






Transducer/booster/horn assembly:








Replaceable Tips on Horns:








The following website address will link you to the Dukane Store where you will be able to purchase the recommended tools to properly torque the Transducer/Booster/Horn assembly:



Once the proper equipment has arrived, please inform your maintenance workers of the proper torque requirements of the tooling stack.

Friday, August 27, 2010

Vibration Welding and Compatibility of Materials

For most applications you weld the same material to the same material. Example (ABS to ABS) To bond two thermoplastic parts it is necessary that the materials be chemically compatible. Otherwise, even though both materials melt at the same temperature no molecular bond will occur. A good example of this is polypropylene and polyethylene. Both are semi-crystalline materials and have a similar appearance and many common physical properties. However they are not chemically compatible, and therefore are unable to weld to each other.
So we need to look at the chart below for compatible materials. If you notice you see that ABS is compatible to ABS/PC, PMMA, PS, PVC and SAN. If we get these two compatible materials we may be able to weld them together with success. (Click chart for larger view)


Now that you know you have two materials that have similar structure you need to answer two more questions.
  1. What is the melt temperature of each of the materials. These two melt temperatures must be within 40 degrees F (20 degrees C). The reason for this is that we are using a friction based process. If one melt temp is below more than 40 degrees F from the other, the lower melt temperature material will go to a complete melt and not melt the higher melt temperature material. This is true for both Ultrasonic and Vibration welding.
  2. The next question you need to answer is the melt flow of the two materials. This is basically a viscosity rating on the material at its processing temperature. Melt flows in the 0-3 and 20-30 range are extrusion grade materials. Melt flows in the 4-12 range are injection grade materials. For vibration welding these melt flows must be within 3 to 4 of each material. Also know that in ultrasonic welding the melt flows should be within 1 of each other.
So now you are asking where do I find all this information? Well you can contact the material suppliers and they are more than happy to share the data sheets on the materials with you. Also the next best thing is to get some 4” x 6” plaques and weld them together. This way you can see a welded “T” plaque of the two materials. Then you can test these materials as well.

If you have any further question please contact Dukane at (630) 797–4900. Or visit our website at http://www.dukane.com/us

Raymond M. Laflamme
Worldwide Automotive Marketing Manager
47757 West Road, Suite C101
Wixom, MI 48393
(248) 613 - 5722

Wednesday, July 14, 2010

Dukane black and gold helps the world be more "green"

Dukane Ultrasonics is playing a key role in helping companies reduce their carbon foot print and to reduce global warming. It is generally understood that ultrasonics is a far more energy efficient process for welding plastic materials than processes such as heat-staking or hot-air welding. However, in addition to these plastic welding applications, Dukane’s ultrasonic welding equipment is an essential part of the systems being used by leading automotive hybrid battery manufacturing companies to do the ultrasonic metal welding of the internal components in nickel metal hydride batteries and more recently, lithium-ion batteries.

For ultrasonic metal welding applications, Dukane has long partnered with Ultex, a Japanese manufacturer which has led the way in providing ultrasonic metal welding solutions to the automotive industry. Every time you see a Toyota or Honda hybrid vehicle, chances are that the battery providing the electric power was made using a Dukane powered ULTEX ultrasonic metal welding system.

When should I consider using ultrasonics to cut my food product?

Ultrasonic food processing involves a vibrating knife producing a nearly frictionless surface to which food products do not stick nor deform. Here are some things to consider when deciding if ultrasonic cutting is the right process for your application.
  • Is your product sticky and causing excessive downtime for blade cleaning?
  • Does your current cutting process smear multiple layers causing a visually unappealing product?
  • Does your current process cause the product to crumble and decrease your yield?
  • Does your current process crush the product during the cut?
If you answered yes to any of the above, chances are ultrasonics can improve your process, if you answered no to all the questions your current method is acceptable.

Below are some pictures that illustrate the quality of cut with ultrasonics.





Here is an ultrasonic blade horn in action.



See Dukane's Food Processing FAQ page for more information.

Tuesday, June 29, 2010

Ultrasonic Welding Effects on Hearing

In air, sound is usually described as variations of pressure above and below atmospheric pressure. These fluctuations, commonly called sound pressure, develop when a vibrating surface forms areas of high and low pressure, which transmit from the source as sound.

Although noise-induced hearing loss is one of the most common occupational illnesses, it is often ignored because there are no visible side effects, it usually develops over a long period of time, and, except in very rare cases, there is no pain. In its early stages (when hearing loss is above 2,000 Hertz (Hz)) it affects the ability to understand or discriminate speech. As it progresses to the lower frequencies, it begins to affect the ability to hear sounds in general.

The upper frequency of audibility of the human ear is approximately 15-20
kilo-Hertz (kHz).
  • This is not a set limit and some individuals may have higher or lower
    (usually lower) limits.

  • The frequency limit normally declines with age.

Most ultrasonic welders have a fundamental operating frequency of 20 kHz. However, a good deal of noise may be present at 10 kHz, the first sub-harmonic frequency of the 20 kHz operating frequency, and is therefore audible to most persons. Ultrasonic welding uses intermittent energy. Only the noise generated during the few seconds of each cycle when the equipment is energized causes exposure to noise. The individual energy cycles are accumulated to equal the duration of exposure. Most of the audible noise associated with ultrasonic sources, such as ultrasonic welders or ultrasonic cleaners, consists of sub-harmonics of the machine's major ultrasonic frequencies.

In extreme cases, this can be disturbing, causing hearing discomfort, occasionally nausea, and sometimes a temporary shift in the threshold of hearing (sound pressure level, or loudness, that can be heard).

Many countries control the amount of audible noise that a worker can receive. In the United States 90 dBA noise level can be maintained continuously for 8 hours. Higher noise levels are permissible for shorter periods of time, typically:



If there is a line operator or other employees in close proximity to an ultrasonic welding system experiencing discomfort, then hearing protection is recommended. Sound enclosures are also available in most cases that would minimize any discomfort to workers near the welding system. For additional information, please read our White Paper titled “Effects of Ultrasonics on Health”.

Myths and Tricks to Successful Thermal Heat Staking

It is a known fact that applying a specific amount of heat to plastic resin using a heated tool will change the characteristics and shape of it, but did you also know that fine tuning the temperature and dwell time it takes to heat that resin can lead to stronger and more cosmetically appealing welded parts?

There are several myths regarding thermal heat staking and tricks to establishing quicker, stronger, and more cosmetically appealing thermal heat welded parts. Here are a few examples:
Myth 1: Post cooling a thermal tip is required on all resins to reduce or eliminate stringing and over welding of a stake or swage.
The Truth: Post cooling only needs to be introduced in a heat welding process when resins, such as Acrylic, are used that require quick cooling.
The Trick: Fine-tune the temperature below the actual resin processing temperature by making very slight changes of 10°F at a time. Each time a temperature change is made, wait 15 to 20 minutes for the changes to take effect in the heated tip. The dwell or (weld time) will need to be adjusted as well to prevent the resin from stringing or burning.

The use of a dual pressure thermal heat staking machine can also eliminate the need for post cool. This feature allows the post to be heated at a lower temperature with a small amount of pressure for a programmed time. After a small amount of time, a greater amount of pressure is applied during the dwell time, collapsing the resin with minimal amount of heat and no post cooling.

Myth 2: Large percentage glass filled or chrome plated studs lack strength and cosmetic appeal after heat staking.
The Truth: Even resins with fillers and coatings can look esthetically pleasing.
The Trick: Use a Pre-Heat to slowly heat up a stud that is to be staked. The resin starts to melt where the glass or chrome plating will not. After the Pre-Heat times out, an appropriate amount of dwell or (weld time) will fully collapse the stud with the correct amount of force applied. This will melt the remaining resin while the glass or chrome plating act as a shell to hold the resin together without melting.

Jerry Downing
Sr. Project Engineer
Dukane Corp. IAS

Wednesday, June 16, 2010

Tony and Paul pull an all-nighter

While it may not be obvious from the picture, this photo was taken at 3:30AM on a Saturday morning. It was a long day that started at 8:30 AM on Friday and would not end until about 8:30 AM on Saturday. This effort was the culmination of what had already been a week of long days which included working through a holiday weekend. However, our customer needed to have their vibration welding machine completed and on a truck by that Saturday afternoon, and Tony and Paul were among a group of individuals who personally lived our Division’s goal of delivering superior customer service and value.


This commitment not only comes from our factory team, it also occurs regularly in our sales team. In the same week that Tony and Paul pulled this all-nighter, two of our sales engineers, Ray and Keith, drove a large vibration welding tool down to a customer to get it installed and running before the next morning, when our customer had to be able to show his end-customer that the tool was in place and ready for production. Ray and Keith left our factory at about 5 PM, drove 5 hours, and then helped install and qualify the vibration welding tool. We got a text message from them at 3:45 AM informing us that the tool was in, and qualified.

While these examples are the exception, the fact that they happen says a lot about the passion and commitment Dukane has when it comes to providing superior customer service. In both cases, it would have been easy to say, “It’s late, let’s finish this tomorrow”, but in both cases that would have meant that the customer would not have been able to meet their commitments. So, Tony, Paul, Ray and Keith went the extra mile to meet the requirements of our customers. Sometimes that means an all-nighter, but is indicative of the heart and soul of our company.

Tuesday, June 1, 2010

Thermal Heat vs Ultrasonics

Thermal heat can provide solutions to many staking, swaging, inserting, and de-gating applications that ultrasonics cannot.

Thermal heat should be considered when working with inserts or stakes that are of various diameters, and/or located on multiple planes and must be processed in a single cycle.

Thermal heat is primarily used when limitations with ultrasonic horns (size, multiple planes, and consistency) are a factor. Other considerations include cosmetic appearance of completed swages or stakes, as well as higher tolerance for glass content and chrome plated parts.

Using thermal heat staking, swaging, and inserting processes can also eliminate particulate that is detrimental to applications such as medical, fluid filters and consumable packaging.

For many customers, the reduction in noise level from ultrasonic inserting or staking of glass filled parts is a significant advantage to switching to a thermal process.

The use of thermal heat also eliminates any vibration concerns that are associated with staking PCB’s to other components. Heat is applied directly to stakes quickly enough that components surrounding the staking post are not damaged.

Overall, when considering heat vs. ultrasonics, review all of the requirements for your application as you may find thermal heat to be the best process.

Jerry Downing
Sr. Project Engineer
Dukane Corporation IAS Division

Tuesday, May 25, 2010

The Benefit of Resilient Fixtures for Ultrasonic Plastic Welding

When is it a better choice to use a resilient fixture made from a Polyurethane casting in place of using aluminum or stainless steel? This question needs to be answered with a series of other questions. The most important of those are: what is the shape of the part, the material being welded, the process being used and the wall thickness?


Parts that have special shapes or that are not flat on the bottom would be considered contoured parts. The shape of these parts could be machined into aluminum or stainless steel but would require programming a CNC machine to cut the detail. Another added step would be that fixture would also need to have the machine tool marks polished out. Pouring a Polyurethane fixture would eliminate the need for programming time and polishing. Although the Polyurethane would need to cure (harden) overnight, this additional time spent is still less costly than programming, machining and polishing. When cured, the Polyurethane casting just needs minor machining before being mounted to a leveling plate.

Amorphous materials and most semi-crystalline materials are good candidates for Polyurethane fixtures. The exceptions are Polypropylene (PP) and Polyethylene (PE) parts; which are considered “softer” materials. Since PP and PE already absorb much of the ultrasonic vibrations, Polyurethane is normally not recommended. If the parts have a textured surface, the texture could be damaged if using aluminum or stainless steel. Using a Polyurethane fixture instead could significantly reduce the surface damage. The reason is that the Polyurethane is poured directly onto a production part (always preferred) so that the textured surface is somewhat incorporated into the casting.

The process being used is important in that normal ultrasonic welding of two plastic components is usually successful if thought out properly. However, when inserting brass or steel inserts, there are times when this process could be problematic due to excessive heat build-up directly under the inserting area that could cause the Polyurethane material to distort and become damaged. In some cases, Brass “plugs” can be added to the fixture directly under the inserting area to eliminate excessive heat and damage to the Polyurethane material.

Thin wall sections may need extra support that the Polyurethane may not be able to provide. In this case, a combination of Polyurethane and aluminum or stainless steel can be used to stabilize the thin wall areas of the assembly.

These are just some of the basic guidelines. Every application is examined on an individual basis to determine which fixture material will produce the best results.

Tuesday, May 11, 2010

Dynamic Balancing of Linear Vibration Weld Tooling

The balancing of Vibration Weld Tooling is critical to the longevity of any manufacturer’s vibration welding equipment. With proper design of the moving half of the vibration tools used in the Linear Vibration Welder, the manufacturer can expect a much longer life from his welding equipment. Also by running unbalanced tools you can significantly shorten the life of your machine and incur tens of thousands of dollars in repair costs.

First let’s discuss the dynamics of the moving half of the tool in a vibration welding tool set. Usually this is the upper half of the tool. The partial g loading chart below shows that at 1.8 mm amplitude and 240 Hertz we get 208 g’s of dynamic load. Therefore, a 100 pound tool moving at 240 Hertz and 1. 8 mm peak to peak displacement becomes 20,800 pounds of dynamic load on the machine.

The following table is g loading calculations (click table for larger view):


So let us assume that a tool is 20 pounds out of balance, 12 inches from the center line of the tooling. This would mean that we have:

(20 pounds) X (12 inches) X (208g) = 49,920 inch pounds of torque on the machine.

This will cause the Linear Vibration head to move in a non linear fashion. It will damage components in the head and make the frequency drives work harder to keep the tool running the application. This eventually will take critical components in the vibration head to a fatigue failure point, thus causing the expensive repair bills.

If you look at the weld tool representation, you will see lightening holes on the upper tooling plate to the back side of the tool. These are there to counter balance the thick portion of the poured urethane nest, thus bringing the tool into balance.



Extensive use of tool balancing was used on the tool illustrated below. Here, not only was the tool plate lightened but the tooling segments themselves needed to be weight reduced to balance the tooling.


The use of steel counter balances can also be used, just remember the upper tool must fall within the manufacturer’s recommended tool weight specifications. The use of good CAD tools can also aid in the balance analysis of a tool before you even cut the materials.

Finally, the tool being balanced in the direction of welding is not as critical. The tool balance from front to back in most machines or 90 degrees to the direction of vibration or along the direction of the weld axis is what must be considered for all good vibration tooling.

For further information contact:
Ray Laflamme
Worldwide Automotive Marketing Manager
Dukane Corporation

Tuesday, May 4, 2010

Composite Ultrasonic Horns

A composite horn is actually a half-wave “coupler” horn with two or more half-wave, tuned horns attached to it. This technology was patented by Dukane in 1973. Because composite ultrasonic horn designs can often eliminate the need to invest in additional assembly systems, they reduce equipment costs and minimize production time for customers.


Composite ultrasonic horn designs are common on applications that cover a large surface area and on applications where there are multiple insertion, staking, or welding points. Some of automotive customers use composite ultrasonic horns to attach insulator pads to door panels.

Another common application that benefits from composite ultrasonic tooling is clamshell packaging (a vacuum-formed blister package). The composite horn saves manufacturers production time and costs, as it welds the package simultaneously at several different points, instead of using a multiple-head system or having an operator weld each point separately.

Composite ultrasonic horns are also instrumental in applications where it’s difficult to create enough amplitude to weld. The amplitude at the face of a composite horn is higher than what could ever be achieved by a single large horn. The amplitude is designed into each of the individual half-wave horn attachments, not the coupler, a higher amplitude is generated at the weld area; this avoids causing excessive stress to the coupler horn.

Although composite horns can eliminate the need for additional assembly systems, cut production times, and lower labor costs, they are more expensive than standard horns. The added cost is due to the extra metal and machining the composite horns require.

Typical composite horns have aluminum couplers and titanium half-wave attachments. In addition to the expense of titanium, all of the half-wave attachments must be tuned within 50 cycles of each other. And they must be properly mounted onto the coupler horn.

The most common mounting method utilizes a 1/2- or 3/8-inch threaded stud at the top of the half-wave attachment; it’s screwed into a threaded hole at the output face of the coupler. It’s also possible to use a “tuned bolt” to fasten the half-wave attachments. The bolt is mounted through the coupler; then the horn attachments are bolted to the coupler. The “tuned bolt” method is primarily used on composite horns that have two or more blade horn attachments.

In addition to the extra metal and machining that’s required, composite horns have more design considerations than a standard horn. We always have to make sure the horn we’re designing is balanced. But when we deal with composite horns, all of the horn attachments have to be positioned evenly around the coupler, so the weight is evenly distributed. Sometimes the attachments are different lengths and different shapes, but you still have to keep the horn balanced.

But despite the added challenges in the design and manufacture of composite horns, they have provided consistent performance and productivity for Dukane customers. If an application can use a composite horn, the increase in productivity and the cost savings are so great that the initial added cost in tooling is more than justified.

For more information on ultrasonic assembly and other horn designs, you can view our Guide To Ultrasonic Plastic Assembly.

Dukane Participated in 2010 UIA Symposium

The 39th Annual UIA (Ultrasonic Industry Association) Symposium held in Cambridge, MA, included 80 participants from 48 organizations representing 11 countries. The program included one day of industrial presentations on Monday April 12th, two workshops, a poster session on Tuesday April 13th and a day of medical presentations on April 14th.

Dukane was a proud Sponsor, as well as an exhibitor and presenter in a poster session. Our poster presentation was “What is New in iQ Series Ultrasonic Systems?”


Dukane made equipment was used in several presentations, including the keynote presentation of the industrial session by Prof. Avi Benatar of OSU (see below). Other presentation, where Dukane ultrasonic generators and transducers were used included the following: “Determining Bond Quality from VHPUAM Process Parameters” by Matt Short, EWI, The Ohio State University; “UAM Fabrication of Metal-Matrix Smart Material Composites” by R. Hahlen and M. Dapino (presented by Mark Norwood), EWI, The Ohio State University; “Advanced Analysis and Characterization of the UAM, VHP UAM Bonding Process” by D. Schick, R. DeHoff, M. Sriram, M. Dapino and S.S. Babu (presented by Mark Norwood), EWI, The Ohio State University.

Both the Newcomers to Ultrasonics Workshop and the Finite Element Modeling Workshop were highly rated by symposium participants. Keynote presentations by Prof. Avi Benatar, The Ohio State University on “Servo-Driven Ultrasonic Welding of Semi-Crystalline Thermoplastics” and Robin Cleveland, Boston University on “Medical Applications of Shock Waves” provided fascinating information on diverse ultrasonic applications.

“Protease Inactivation in Milk by Thermosonication and Impact on Milk Characteristics” by Sakthi Vijayakumar, David Grewell, Stephanie Jung, and Stephanie Clark, Iowa State University represented an evolving ultrasonic application. “Propagating Ultrasound Energy through a Catheter Around Bends” by David Constantine, James Sheehan and Jeffrey Vaitekunas presented a unique medical ultrasound application.

An electronic copy of the proceedings on a flash-drive pen is available for $95 from UIA by emailing uia@ultrasonics.org

The 40th UIA Symposium will be held in Glasgow, Scotland, UK on 23 – 25 May 2011. Professor Margaret Lucas, University of Glasgow, will serve as the Symposium Chair. For a copy of the Call for Presentations, go to www.ultrasonics.org or contact UIA at +1.937.586.3725.





Tuesday, March 16, 2010

What Happened to Your Ultrasonic Weld Quality?

By Miranda Marcus, Applications Engineer, Dukane IAS

The most important factor in troubleshooting problems in ultrasonic welding is understanding the fundamentals of the process. With this basic knowledge, most problems can be easily diagnosed and resolved. Even so, sometimes your time-tested weld recipe may suddenly fail for no discernible reason.

Perhaps your ultrasonic welder has been running the same application for months, maybe years, with no problems. Abruptly, this cheery continuity is disrupted. Has your weld strength decreased? Are you seeing excessive flash? Does your welder overload as soon as the cycle starts? Here, we will discuss a few unseen factors that can cause sudden changes in your ultrasonic weld quality and how to prevent and correct them.

KNOW THE BASICS
Ultrasonic welding works by applying a vibration at a frequency of 15 to 70 kHz to a plastic part. This vibration is generated through the use of piezoelectric ceramics in the transducer, that convert an electrical signal into mechanical motion. The transducer creates a vertical vibration that is then translated through the booster, and subsequently, the ultrasonic horn. The ultrasonic horn is typically designed to contact the part directly above the weld area so that the vibrations can travel though the upper part to the weld area.



The ultrasonic vibrations create cyclical strain at the weld area, which generates heat that melts the plastic in a restricted area and welds the two parts. Because the ultrasonic vibration acts on the entire weld surface, an energy director is often added to control the melting and reduce the amplitude necessary to achieve a weld.

It is important to prevent metal-to-metal contact on your ultrasonic horn to increase its longevity. Because the horn is a tool with acoustical properties, users should be careful to preserve its structural integrity. Any nicks or gouges in the surface of the horn act as stress concentrators that can rapidly lead to cracks when the horn is in use.

WARNING SIGNS
Many signs can indicate a change in your ultrasonic welding process. Some indications of a problem with your part include decreased weld strength, increased flash, and the appearance of cosmetic damage. Some things that signify a problem with the welder or ultrasonic horn are an increased wattage draw, a change in the sound of your weld (typically apparent on lower-frequency welders), and overloading.

The first step in eliminating unseen problems is to record your welding setup. Make a “Weld Process” sheet that includes information such as your weld parameters (weld time, hold time, trigger mode, amplitude); manual settings (thruster height, pressure); and the critical dimensions of your part (diameter and energy-director/shear-joint size). Also include photos of the welder, showing the alignment and design of the horn and fixture. Refer to this document when problems arise—it may save you a lot of time and trouble.

There are many not-so obvious factors that can negatively impact your ultrasonic weld quality. One of the most frequent causes of problems in a long-running process is wear on the mold that produces the parts to be joined. This is a slow, but sure, event in any molding process. Because most joint designs are relatively small compared with the size of the overall part, changes in their size or shape may go largely unnoticed. For many applications, a change in shear width from 0.016 in. to 0.020 in. can make a huge difference in weld quality. Such changes can be caused by just 0.002 in. of mold wear on each part.

Another important factor is environmental changes such as ambient heat, cold, or humidity. Humidity is a particular concern if you are using a hydrophilic material such as nylon, polycarbonate, or polysulfone. Very cold temperatures can cause polymers to become brittle, which may cause them to crack rather than weld at a normal welding pressure. High heat can lead to longer solidification times, causing problems if you are working with short hold times.
Some materials are less sensitive to process changes. Try switching to an easily welded material, like ABS, to achieve greater consistency in your process.

Probably one of the most overlooked factors contributing to ultrasonic welding problems is changes in the time from molding the part to welding the part. Proper ultrasonic welding setup can be drastically different when welding “cold” parts as opposed to welding “hot” parts. It is generally not a good idea to weld “cold” parts to “hot” parts.

If at all possible, leave plenty of time for the part to cool after molding before welding. “Hot” parts are more difficult to control and can cause inconsistency in your weld process. Also, try to perform the welding operation in a climate-controlled environment to eliminate seasonal effects on your process. This is especially important in humid regions.

MORE FACTORS TO CHECK
Sometimes poor ultrasonic welds can be traced back to the injection molding process. Injection mold wear can lead to a rounded energy director in the part (upper right), which produces a weak weld (lower right). A well-maintained mold produces a sharply pointed energy director (upper left), which produces a stronger weld (lower left) with lower welding amplitude and less flash.

If you know it is not your parts causing the problems, it could be your ultrasonic tooling. Occasionally a horn will develop a crack. While most horns will not run at all after forming a crack, some do. Those will often emit a high-pitched ringing sound or run at a higher wattage than normal. It is very important to discontinue use of a cracked horn because it tends to put excess stress on the transducer and can lead to broken piezoelectric ceramics.

Probably the easiest diagnostic test is to mix-and-match your ultrasonic stack if you have multiple welders of the same frequency. Try the horn with a transducer and booster that have been working well. If all is good after this switch, then you know the horn is not the problem. Likewise, you can put a working stack in a questionable welding machine. This is a quick and easy way to locate the trouble spot in your machine without any special equipment.

If you find that the problem is your horn, check it for cracks. To locate cracks in a horn, spray it with a foaming cleaner. Then use the test feature on your welder to introduce short bursts of ultrasonic energy into the horn. The cleaner will collect in the crack and turn a blackish color. WD-40 oil can be used if a foaming cleaner is not available.

Finally, the welding fixture has a significant effect on the accuracy and precision of your welds. Make sure the fixture is providing support to the entire joint area, and that there is no room for misalignment of parts during loading. When welding softer materials such as polyethylene and polypropylene, be sure that there is support around the joint area in both lateral and vertical directions. Soft materials tend to deform outwards, which will hinder or prevent proper welding.

Thursday, March 11, 2010

How does your Ultrasonic Probe/Stack work?

Ultrasonic Probe
Plastic welding is the most common application of ultrasonic assembly. To perform ultrasonic plastic welding, a vibrating tip is brought into contact with one of the work pieces as shown in Figure 1–1. Pressure is applied and ultrasonic energy travels through the material, increasing the kinetic energy (or heat) at the contact point of the two parts. The heat melts a molded ridge
of plastic on one of the pieces and the molten material flows between the two surfaces. When the vibration stops, the material solidifies forming a permanent bond.



Ultrasonic Probe Configuration
A basic ultrasonic probe consists of:
  1. A housing which contains the transducer which converts electrical energy into mechanical vibrations.
  2. A horn to transfer the mechanical vibrations from the transducer to the parts to be welded. A basic ultrasonic probe is shown in Figure 1–2. As indicated, the horn is secured to the transducer with a threaded stud. The transducer housing also has a connector for attaching the high voltage coaxial cable which delivers the high–frequency electrical signal for exciting the transducer. This signal is supplied by a separate ultrasonic generator.
ultrasonic probe

Transducer
The transducer supplies the ultrasonic vibrations by means of piezoelectric converters which transform electrical energy into mechanical movement. Power applied to the transducer at 20kHz can range from less than 50 Watts up to 3000 Watts.

transducer

The transducer is made from a number of polycrystalline ceramic elements separated by thin metal plates, clamped together under high pressure. When an alternating voltage (dV/dt) is applied to the converters (or ceramics), a corresponding electric field (dE/dt) is produced which results in a variation in thickness (dL/dt) of the ceramic elements. This variation in thickness induces a pressure wave (dP/dt). Because the molecules or atoms of a solid are elastically bound to one another, the pressure wave results in a wave propagating through the material which is reflected by the ends the metal mass of the converter.

See Figure 1–8 for a graphical representation of this. When the length of the assembly is tuned to its frequency of excitation, it resonates and becomes a source of standing waves. A typical transducer without its housing is shown in Figure 1–3. The output amplitude from a 20kHz transducer is only about 20 microns (0.0008 inches), so this amplitude needs to be amplified by the horn (and possibly a booster) to do useful work.

Ultrasonic Horn
The horn acts as an acoustic waveguide or transformer to amplify and focus the ultrasonic vibrations to the work piece. The ultrasonic horn has three primary functions:
  1. It transfers the ultrasonic mechanical vibrational energy (originating at the transducer) to the plastic parts through direct physical contact, and localizes the energy in the area where the melt is to occur.
  2. It amplifies the vibrational amplitude to provide the desired tip amplitude for the thermoplastic and weld process requirements.
  3. It applies the pressure necessary to form the weld once the joint surfaces are melted.



The ultrasonic horn is precision machined and designed to vibrate at either 15kHz, 20kHz, 30kHz, 40kHz, 50kHz or 70kHz. Figure 1–4 shows five aluminum alloy horns ranging from 15kHz to 50kHz. The higher the frequency, the shorter the acoustic wavelength, and consequently the smaller the horn. Notice that the 30Khz horn is only half the length of the 15kHz horn. The tuning of an ultrasonic horn is accomplished using electronic frequency measurement. Inherent variations in material composition prevent tuning by dimensional machining alone. Horns are usually manufactured from high–strength aluminum alloys or titanium. Both metals have excellent acoustical properties to transmit the ultrasonic energy with very little attenuation.

There are many different ultrasonic horn shapes and styles depending upon the process requirements. Factors which influence the horn design are the materials to be welded and the method of assembly. The gain of the ultrasonic horn is determined by its profile. Figure 1–5 shows four different gain profiles. The input vibration amplitude to a horn from a 20kHz transducer is only about 20 microns. This is not enough to generate enough friction achieve a melt temperature for most thermoplastics. Therefore the horn must amplify the mechanical vibration so that the amplitude is sufficient to melt the thermoplastic. The amplitude at the tip of the horn typically ranges from 30 to 125 microns (1.2 to 5.0 thousandths of an inch) at 20kHz.




An optional threaded tip can also be used when the application calls for staking, a swagging profile or a pointed spot weld. In Figure 1–1, one of the plastic parts had a small ridge used to initiate the melt process. Here in Figure 1–6, the tip provides the energy director since there is only one piece to be melted in a staking operation. Replaceable tips are not commonly used in high–volume production environments. For long–term or high–wear production, a horn with a custom machined tip coated with chrome, carbide or titanium nitride will provide excellent wear resistance.



As the frequency increases, vibration amplitude typically decreases. Higher frequencies are used for seaming of thin materials and delicate parts that do not require a lot of amplitude. Since the horns become smaller at higher frequencies, closer spacing can also be achieved. Some factors to consider for high–frequency (e.g. 40kHz) ultrasonic welding versus lower–frequency (e.g. 20kHz) ultrasonic welding are listed here.
  1. For a given amplitude, stress in the horn increases at higher
    frequencies.
  2. Wear on the horn is greater at high frequencies.
  3. Clean and flat mating surfaces between the horn, booster and transducer are more critical as the frequency increases. At 40kHz, surface flatness specifications are between 0.0005" and 0.001" (13 to 25 microns).
Booster
The primary function of a booster is to alter the gain (i.e. output amplitude) of the probe. A booster is amplifying if its gain is greater than one and reducing if its gain is less than one. Gains at 20kHz typically range from less than one–half to about three. A booster designed to be mounted in a fixture between the transducer and horn is shown in Figure 1–7. This is commonly referred to as a probe stack. Since the horn cannot be clamped, only the transducer and booster can be secured. Therefore a secondary function (and sometimes sole purpose) of a booster is to provide an additional mounting location without altering the gain when the probe stack is secured in a press. The neutral (1:1) or coupling booster is added between the transducer and horn and mounted in the press by its mounting ring which is placed at the nodal point (where the standing wave has minimal amplitude). See Figure 1–8 for a graphical representation. Note that the maximum stress occurs at the nodal points.



Wednesday, March 10, 2010

What are the effects of Ultrasonics on your Health?

Introduction
Users of ultrasonic welders and ultrasonic cleaners inquire, from time to time about the effect of ultrasonic energy on the health of the operator. This paper is a brief summary of the nature of ultrasonics and its potential effects on health.

The Nature of Ultrasonic Energy
Ultrasonic energy is mechanical energy as contrasted with other forms of energy such as nuclear particle radiation (x-rays, beta rays), electromagnetic energy (radio frequency waves, diathermy, microwave radiation), or invisible light (infrared, ultraviolet light waves). The source of ultrasonic energy is the ultrasonic transducer: a linear motor that converts
electrical energy to reciprocating mechanical motion similar to a high-speed hammer. The motion occurs at a rate of 20,000 strokes or more per second, and is above the hearing range of the average person.

The ultrasonic mechanical motion, when propagated in air, is severely attenuated since air is an extremely poor sound transmission medium as compared to the metal and plastics in which it is intended to travel. Further, when the energy is propagated into a three dimensional space from a point source, it diminishes at a cubic rate each time the distance is doubled (i.e., every time the distance is doubled, 1/8 of the energy remains). The ultrasonic airborne energy is also absorbed into soft, non-reflecting materials (e.g., worker’s clothing or noise abatement foam materials). The remaining airborne ultrasonic energy is therefore diminished thousands of times as compared to the source. Equipment operating at ultrasonic frequencies may produce noise in the audible frequency range due to the workpiece vibrating at an audible subharmonic of the ultrasonic operating frequency.

Direct Contact with Ultrasonic Energy
As with all high-speed rotating or reciprocating machinery, direct contact with ultrasonic energy must be avoided at all times. All Dukane welding equipment carries appropriate warning signs against contact with components developing high levels of ultrasonic energy.

Exposure to Airborne Ultrasonic Energy
Ultrasonic welding equipment has been in use for more than 40 years. Medical and scientific literature reports no documented health hazard from airborne industrial ultrasonic energy reaching an operator.

Cardiac Pacemakers and Ultrasonic Energy
Pacemakers are not affected by airborne ultrasonic energy, but may be affected by electromagnetic energy. All equipment capable of generating ultrasonic energy also produces electromagnetic energy (usually in the radio frequency range). All Dukane ultrasonic equipment must comply with Federal Communications Commission regulations specifying limits on the conducted and radiated energy which may emanate from the equipment. There are many types and kinds of pacemakers. It is not known to what extent the different types are sensitive to various levels of electromagnetic energy. Until more is known about pacemaker reaction to R.F. emission, it would be prudent not to place workers with pacemakers near ultrasonic equipment. A report discussing R.F. emission is: “The Biological Significance of Radio Frequency Radiation Emission on Cardiac Pacemakers,” Report SAM-TR-76-4; USAF School of Aerospace Medicine, Brooks Air Force Base, Texas 78235.

Ultrasonic Energy & Audible Noise
The human ear cannot respond mechanically to airborne ultrasonic energy; it therefore is inaudible. The associated audible noise and lower frequency subharmonics can in extreme cases, be disturbing, causing hearing discomfort, occasionally nausea, and sometimes a temporary shift in the threshold of hearing (sound pressure level, or loudness, that can be heard). Many countries control the amount of audible noise that a worker can receive. In the United States 90 dBA (“A”= international “A” scale) noise level can be maintained continuously for 8 hours. Higher noise levels are permissible for shorter periods of time, typically:



Ultrasonic welding uses intermittent energy. Only the noise generated during the few seconds of each cycle when the welding equipment is energized causes exposure to noise. The individual energy cycles are accumulated to equal the duration of exposure

Workers subjected over many years to excessive noise (e.g., textile mills, saw mills, coal mines) suffer a permanent hearing loss, such loss being greater than the normal loss associated with aging. It is desirable to limit the audible noise to permissible levels, by constructing sound enclosures, rotating employees at the workstation, or requiring the use of hearing protectors. A list of personal hearing protectors and attenuation data is available in HEW Pub. #76-120, 1975,
NTIS-PB267461, and can be obtained from National Technical Information Service, Port Royal Road, Springfield, VA 22161.

Noise Measurement with Sound Level Meters
Sound level meters are available which measure sound levels at the workplace. The sound must be measured at ear level where the worker stands while working. The noise exposure is measured in “dBA, slow response.” The calibration of such instruments is done at frequencies below 10 kHz, rendering them potentially very inaccurate at higher frequencies.
Standard noise level meters may be used only to accurately determine sound levels within their calibration range, and may provide erroneous readings above 10 kHz. Only instruments designed for use with special high frequency microphones will provide accurate results above 10 kHz. Pub. # S1-4-1971 (R1976) “Specifications For Sound Level
Meters” is available from American National Standards Institute Inc., 1430 Broadway, New York, NY. 10018.

Wednesday, January 27, 2010

New or used equipment? Buy or lease? How do I decide?

When considering a new piece of equipment, it is not all that different from shopping for a new car. Should I buy new, or will used be okay? I don’t want to overspend, but I don’t want to get stuck with a lemon either. The answer starts with an assessment of needs. Is this the family car or a first vehicle for your teenage son? Probably somewhere in between. We look at three primary areas: 1) What is the life of the project? 2) How critical are the part requirements and how demanding is the process? 3) What do you need in terms of dependability or reliability in meeting delivery demands?

We first look at the life of the project because, if the number of parts produced is high, the decision is easy. If you are looking at a three-year run on 2.5 million parts, a $20,000 machine costs less than a penny per part and, with purchase/lease options, this expense can be timed as needed. With a part-cost this low, why take any risk in terms of performance or reliability or even that you might have to replace the machine midway through production. And why not give yourself all the technical support and applications assistance and training that comes with new equipment. But if your need is more short-run, there is more to consider.

We next look at the part requirements and what will be needed from the equipment to product quality parts consistently. First, we consider the part tolerances, the part performance and how critical the assembly process will be. Then we look at the overall manufacturing process, the degree to which parameters and materials may vary, and the severity of the environment and how taxed the equipment will be. Whether you are making the plastic toy in a kid’s meal, or a hermetic seal on a pacemaker, there can be aspects of almost any operation that push equipment to the limit.

Next, we consider the importance of dependability. If you are manufacturing for inventory on a stand-alone machine, a three-day shutdown may be of little consequence. But if you are producing for just-in-time delivery to an automotive assembly line, a one-hour delay can cost thousands. In placing a value on dependability, consider whether you have other similar machines that could cover the load, and to what extent your own people are able to service your equipment. Alternatively, consider the availability of parts and the reliability in being able to get the service or answers you need when you need them.

With a realistic assessment of needs, we then look at the choice between new and used equipment. In this industry, new equipment comes with an entire basket of services at no additional cost, such as technical support, applications assistance, service and training. Here again, the value you place on these services depends to some extent on your in-house-capabilities.

Manufacturers typically charge $1,000 per day, plus expenses, for field calls for service or applications assistance. And with used equipment, most warranties are not transferable because equipment can be exposed to such a wide variety of adverse conditions. For these reasons, Factory Certified used equipment can be an attractive option. Dukane offers all our same service and support, plus a limited warranty, on used Dukane equipment that has been through a complete inspection at our facility. Another alternative is our rental program, which allows you to choose from our entire product line. This can be a cost-effective solution for short-term needs and rental payments can be applied toward purchase. We also offer numerous leasing options with various terms to match the life of a project. Similar to renting, leases can lead to ownership, through a dollar buyout at lease end, and payments can be expensed in the current period without tying up capital.

Today, more than ever, there are a lot of purchase options when considering equipment. And in today’s business climate, the incentive to save a few dollars is real. Yet, at the same time, competition has never been more fiercefiercer and your customers’ demands are not getting easier. We’ve tried to provide as many equipment alternatives as possible and area eager to help you evaluate which is best for you.

Tuesday, January 26, 2010

Trigger by Power Feature Aids Weld Consistency

Introduction
Dukane’s patented Trigger by Power option (now in the iQ Series of ultrasonic generators) can be used to produce more consistent welds by requiring a sufficient and repeatable amount of pressure/force to be applied to the part before the actual weld cycle starts. Trigger by Power is a cost effective alternative to trigger by force. However, unlike Trigger by Force, Trigger by Power does not require additional, expensive components such as a load cell, amplifier board or cabling. In effect, the system uses the ultrasonic stack as a load cell. When the ultrasound is activated, the amplitude is ramped up to the Trigger Amplitude setting and held there until enough force is applied to the part to reach the Trigger Power setting. At that point the weld cycle begins and will continue until the weld control parameter (Time, Energy or Power) is reached. Sufficient force must be applied to the part to trigger the weld cycle. Otherwise, the Trigger Timeout is reached without starting the weld cycle.

Settings for Trigger by Power:
Trigger Amplitude
This is the percentage of amplitude the generator applies to the horn before it reaches the Trigger Power setting. The range of the Trigger Amplitude setting is from 20-100%. Set this value so it is low enough not to scuff the part, but the value should be high enough that the Trigger Power setting is reached when the desired force is applied to the part.
Trigger Power
This is the power level that must be reached at the Trigger Amplitude setting for the weld cycle to start. The range of the Trigger Power setting is based on the power rating of the specific iQ generator used. This setting must be high enough so the iQ generator does not trigger while ramping up to the Trigger Amplitude, but it should be low enough so that it can be reached at the current Trigger Amplitude setting when the desired force is applied.
Trigger Timeout
This is the maximum time the welder remains at the Trigger Amplitude setting before aborting the weld cycle. The range of the Trigger Timeout setting is from 0 to 30.000 seconds. This setting should be long enough so that there is sufficient time to apply the force required to reach the Trigger Power setting. However, the Trigger Timeout setting should not be so long that the weld could be adversely affected by the horn being in contact with the part for too long at less than the Trigger Power setting.
How is Trigger by Power Used?
Ultrasound must always be activated before contact is made with the part. Once the horn comes in contact with the part, the force is increased until the Trigger Power setting is reached. At this point the weld cycle starts and continues until the control parameter (Time, Energy, or Peak Power) is reached. If the Trigger Power setting can’t be reached, either increase the Trigger Amplitude setting, decrease the Trigger Power setting, or increase the amount of force applied to the part.