Capacitor-Discharge (CD) Projection Welding is the fastest form of resistance projection welding. It is an economical alternative to various traditional resistance weldings. As the name suggests, it uses capacitors to deliver power to the weld parts. The transmission of energy takes place within milliseconds. In the process, a bank of capacitors is charged to a preset voltage. It is then discharged through a pulse transformer. The machine required power just to charge the capacitors bank; the power requirement is very less as compared to other resistance welding processes. The weld time is very short (mostly 3 to 12 milliseconds). Short weld times forms negligible blackening, heating of welded components.
The features such as low distortion welds, high production speed, ability to weld dissimilar metals, and high carbon material make this form of welding a wise choice, used across a wide range of industry vertices.
What is a capacitor discharge projection welding machine?
Capacitor discharge projection welding machine is the fastest form of resistance projecting welding which uses capacitors to deliver power to parts. As capacitors are charged with substantial amounts of energy, the energy is released into the parts rapidly within milliseconds.
Capacitor discharge projection welding machines are essentially a resistance welding process. During this process, the capacitors are charged with preset voltage, and then discharged via a pulse transformer. This enables very high current to pass through in a very short time which leads to exceptional projection welding quality.
The power requirement is often negligible compared with other resistance welding process since the capacitor discharge projection welding machine requires power only for discharging the bank of capacitors. This results in the saving of power usage as well as the connected loads. Since the weld time is very short (typically 3 to 12 milliseconds), water cool for the electrodes is not required and the heating or blackening of welded components are negligible.
The resistance projecting welding technology is ideal for projections welding, thin sheet spot welding and dissimilar metal welding. For those who place high regard in aesthetics, power saving and consistency in projecting welding should employ this technology.
The rise of capacitor discharge projection welding machine
As a matter of fact, capacitor discharge technology has been around for a while, and with safety concerns and technological advancement being taken into consideration, it not hard to see why conventional resistance welding is being improved significantly. Here are two of three core reasons that led the capacitor discharge projecting welding system to take off:
● Heat-affected zones are virtually eliminated: Capacitor discharge projection welding machines deliver a laser, welded-like joint, which means that the metallurgy characteristics of steel remain virtually the same as it did prior to the capacitor discharge welding process. Similar to the laser weld, capacitor discharge weld conveys a joint that largely limited surface spatter and deformation, but is also less expensive than a laser weld.
● Robust power supply is not required: In most cases, you do not need a large draw on a power distribution network when using a capacitor discharge projection welding machine. But this can be a problem in some areas (e.g., rural community). In some respects, a capacitor discharging projecting weld can be run under the same electrical power as a residential electric dryer, and this can be cost-effective for manufacturers who have to rearrange the electrical configuration and the floor layout of the workshop. Moreover, some manufacturers find themselves having to interlock their resistance welders because of the lack of adequate AC power at their location. This can in turn limits the strain on the power distribution network, and a capacitor discharge projecting welding can eliminate this kind of electrical coordination.
● Long-lasting Electrodes: Because the energy (even at high level) delivered in the capacitor discharge projecting welding is concentrated for such a short time, the wear on the electrode is less compared with the conventional resistance welding process. As a result, electrodes can last for 10 times as long depending on the applications, meaning parts can be machined quickly afterwards. And because the electrical discharge is so rapid, the part does not overheat upon completing the welding. The user wearing proper gloves should have no issue handling the part comfortably. He should be able to hand it as if he was handling sheet metal. Nevertheless, keep in mind that certain materials like stainless steel can retain heat due to the higher resistance compared to other metals like mild steel.
Why do automobile industries use CD projection welding?
Capacitor-Discharge (CD) projection welding is widely used in automobile industries. If we talk about the benefits of using CD Projection Welding in automobile manufacturing, a few advantages such as welds without distortion, discoloration, surface deformation are worth taking into consideration. This welding form also maintains mechanical part tolerances. Using CD welding, the welded automobile parts don’t need cleanup or finish, it can be directly assembled and thus saves lots of time and effort. If we talk about welding costs and efficiency, this form of welding is still a winner. It has a low operation cost and requires less power to function. Let’s have a look at more reasons why it is widely used in the automobile industry.
Key Benefits & Applications Of CD Projection Welding
· CD Projection Welding can be used for a variety of automobile components.
· It provides consistency in the delivery of the current. This feature makes it a more reliable form of welding.
· It provides high current delivery in a short time. This feature makes it the fastest form of projection welding.
· It can be used for welding automobile nuts, bolts, washers etc.
· It is used for welding on hot stamped parts, hence fulfils specific parts welding requirements.
· It is used for welding shock absorber components, fuel tanks, leak-proof welds.
· Welding near heat-sensitive parts is possible with this welding form.
· As we mentioned earlier, it is best when your goal is power saving.
· It does not require a water cooling system due to short weld times.
Beyond welding. Technology that improves your product.
Capacitor Discharge Welding. Current up to 200,000 A. Weld time of less than 10 milliseconds. 70% lesser power requirement, compared to conventional projection welding, remains the most important advantage of Capacitor Discharge welding.
Capacitor discharge (CD) projection welding
In CD Projection Welding the weld area and location is predefined by giving a small projection (1 to 4 mm) on one of the weld components. During welding, the projection collapses under the electrode pressure and very high current passing through the electrodes fuses, the metal fuses to create the join. With weld time of less than 10 milliseconds and focused discharge of weld energy,
the heat does not conduct beyond welding area leaving the welded parts clean and distortion free.
The CD Projection welding can be performed on a multiple projections, simultaneously. The work-pieces are pressed at the projection using pneumatic/hydraulic or servo motor drives.
Advantages
1. The best in aesthetics: No black marks, spots or distortions. Just clean and beautiful welds.
2. Significantly lower Kva: Up to 70% savings in power, for every weld that you do.
3. Totally leak proof welds: Trusted for leak-proof for most critical applications.
4. Freedom from post weld processes & costs: Save time and costs with no need for post weld processes, whatsoever.
5. Requires no water cooling: With no heating of electrodes, the need for water cooling is eliminated reducing costs of electrode and fixture maintenance.
6. Run it on genset: Lesser demand for input power means machine can run on 3-phase power supply.
7. Weld heat sensitive parts: Minimal heating and lowest welding time enables welding of heat sensitive parts with ease.
8. Weld dissimilar surfaces: Strong, clean joins even for all surfaces similar or dissimilar.
9. Lower day-to-day running cost: Lowest operating costs with minimal maintenance and significantly lower power consumption.
Technical Specialties
-Consistent current delivery
-Heating and fusion only at the actual welding area
-Delivers current up to 200,000 A
-No effect on welding quality due to normal voltage fluctuations
How capacitor discharge welding works
The CD Resistance Welding process is ideal for quick and repeatable mass production processes that require tight dimensional tolerances. Capacitor discharge resistance welding is ideal for projection, press-fit and annular ring projections up to 4.5″ in diameter. Low marking welds can be better achieved due to the small heat affected zone and dissimilar metals that can often not be welded using conventional resistance welding can be successfully welded using capacitive discharge resistance welding.
Applications of capacitor discharge projection welding machine
As mentioned previously, resistance projection welding has been improved so much over the years that their use has been extended across industries in many applications. Some of the common applications include: shock absorber components, oil filters, oil port to cylinder tube welding, projection nut welding, projection bolt welding, window regulators, automobile components, leak proof welds, switch gear, fabricated stainless steel impellers, auto electrical, diamond tools, hydraulics, batteries, heavy duty transformers, name plate welding, silver contact welding, sheet metal parts, brake shoes, sheet metal furniture parts, dissimilar metal parts, relays, ball to rod welding, etc.
