TIG micropulse welding -
the ideal alternative to laser welding
Laser welding is a very well-known welding process, but it still places high safety demands on the operator and requires high investments for the systems, equipment and protective devices required for welding. What is less well known, however, is that there is also a cost-effective alternative to laser welding that achieves comparable results – at significantly lower costs.
What is laser welding?
Similar to other welding processes, laser welding is used to weld workpieces or metallic alloys together. The difference to other processes is that a laser is used as the energy source for the welding, the laser beam of which is focused on the area to be joined. Due to the high energy density of a laser, the metal heats up quickly and precisely and melts at the point hit by the laser beam. After cooling, a permanent welded joint is created. The metallurgical welding process itself therefore hardly differs from alternatives to laser welding, such as micro-pulse arc welding, except that the energy used comes from a different energy source. CO2 lasers, diode lasers and fiber lasers are all used as energy sources.
Types of laser welding
Depending on the energy applied, there are two fundamentally different laser welding processes:
Deep penetration welding (keyhole welding):
Deep penetration welding is carried out with high laser intensity so that the metal surface is heated to the point of vaporization. The laser beam penetrates deep into the workpiece, creating a cavity with a plasma-like consistency in the form of a keyhole. Deep penetration welding is by far the most common variant of laser welding.
Heat conduction welding
In heat conduction welding, the laser heats the surface of the workpiece at a low intensity above the melting point of the alloy. This does not achieve a deep penetration effect, as the materials are only joined with a comparatively flat weld seam.
Whether deep penetration welding or heat conduction welding is the better alternative cannot be determined across the board. In any case, deep penetration welding is required for high penetration depths, but this in turn has the disadvantage of a visually visible, usually rather deep weld seam due to the higher energy input. If only low material thicknesses are welded, heat conduction welding may well be the method of choice, especially because this process is known for its tendency to produce smooth and visually appealing weld seams in addition to even smaller structural changes.
When welding very thin materials, the previously mentioned micro-pulse arc welding can also be at least an equivalent alternative to laser welding.
What is laser welding used for?
Laser welding is used in many different areas, including, among others:
- Automotive: Welding of body parts, cooling and heating components, drive batteries for electric cars, electronics, etc
- Aerospace: welding of lightweight components and complex structures as well as joining and repairing heat protection components
- Electronics: Electrical contacts that have to withstand increased operating temperatures
- Medical technology: manufacture and repair of surgical instruments and implants
- Jewelry industry: production and repair of jewelry made of precious metal alloys
- Dental technology: manufacture of dental and orthodontic structures and products
- Repair welding of surfaces, especially in tool and mold making
- Classical mechanical engineering and joining of metallic materials
As a rule, all weldable metals and alloys can be welded with a laser welding machine, e.g. steel, aluminum, stainless steel, copper, brass and many more. With special laser welding sources, it is also possible to permanently join workpieces made of plastics and polymers by applying energy and melting.
In most of the areas of application mentioned, apart from plastic joining, it is also possible to work with alternatives to laser welding. Depending on the application, it is often possible to achieve similar results at significantly lower cost using a micropulse TIG welding machine, for example.
Safety during laser welding
In addition to the protective measures generally required for welding, such as wearing protective clothing and appropriate ventilation, e.g. by extracting the fumes and vapors produced during welding, further protective measures are required for laser welding due to the specific danger posed by the laser beam. These include, among others:
- Shielding of the workplace through complete enclosure (laser protective housing) to prevent unwanted propagation of laser radiation
- Welders must wear protective goggles to protect their eyes from laser radiation
- Regular check and inspection of the laser welding machine for correct function and safety
In addition to these direct measures, organizational measures must also be taken. These include
- Installation of warning signs at all access points to the laser workstation and access controls to prevent unauthorized handling and commissioning
- Regular training of all employees who use the laser welding machine
- Emergency plan that defines immediate measures in the event of an accident or technical malfunction
In Germany, companies that use laser welding equipment must appoint a laser safety officer in accordance with the relevant occupational health and safety regulations, who is responsible for the development and implementation of these measures and must also prepare a risk assessment. Laser safety officers must complete appropriate training courses prior to their appointment and demonstrate their professional qualifications through regular further training and continuous renewal.
Comparison of laser welding vs micropulse TIG welding
Due to its high level of awareness, its versatility and the relative novelty of the technology compared to other welding processes, laser welding is now widely used and enjoys a high level of awareness. However, the acquisition of a laser welding machine is often hindered by the still relatively high costs.
The micro-pulse TIG welding process developed by Lampert is the perfect alternative to laser welding, achieving comparable results at significantly lower costs. Both welding processes also have individual properties that can prove to be both advantageous and disadvantageous depending on the desired application. The following table shows a comparison of the two processes, which can be used as a decision-making aid between a laser and a micropulse TIG welding machine. The individual properties must be evaluated individually for each specific application.
| Laser welding | Micro-pulse TIG welding | Note | |
| Precision and accuracy | Very high | Very high | In practice, both methods lead to comparable results |
| Reproducibility | Very high | Very high | With devices of comparable quality classes, both methods demonstrate excellent repeatability |
| End ring depth | – 0.1 to 1 mm (heat conduction welding) – Up to 10 mm and more (deep welding) | <0.1 to approx. 1.2 mm | The greater the penetration depth, the greater the necessary heat input and thus the risk of distortion. In the precision range, penetration depths of over 1 mm are rarely required |
| Heat input | > 3500°K (heat conduction welding) > 10,000°K (deep penetration welding) | approx. 3000 to 3500°K | |
| Welding speed | Very high (up to 10m per minute or 50 points per second) | Up to 5 points per second | Laser welding is much better suited to the automated welding of large quantities |
| Versatility | – Welding of all weldable alloys possible – Manual and automated welding – Stationary application | – Welding of all weldable alloys possible – Manual and automated welding – Mobile and stationary application | |
| Special features of challenging materials | – Risk of reflections on highly reflective surfaces – Risk of damage to directly adjacent materials (e.g. precious stones) | – No restrictions on highly reflective surfaces – No damage to adjacent materials | Due to the energy source, the laser beam acts directly where it hits the workpiece. Micro-pulse TIG welding also ensures that the weld is always made on the metal alloy (current flow only through metal) |
| Usability | – Setting the parameters is simple to moderately complicated depending on the manufacturer and product – Generally prior technical knowledge helpful or required | – Setting the parameters in a single-screen menu – Previous technical knowledge helpful, but not required | |
| Protective equipment | Complete enclosure and shielding from scattered radiation required. In many countries, the training and appointment of a laser safety officer is also required by law or due to standard specifications | Eye protection system stationary (microscope) or mobile (welding helmet). Use of protective gloves recommended, otherwise no separate protective equipment required | With the micropulse TIG welding system, the eye protection system is usually already part of the welding system set. |
| Acquisition costs | High: >EUR 30,000 for welding systems of comparable quality (without protective equipment) | Low: Approx. 4,500 to 10,000 EUR incl. protective equipment | Cheaper laser welding devices are also often available, but the results do not match the quality of micro-pulse TIG welding devices |
| Maintenance costs | Regular maintenance of the laser source in accordance with the manufacturer’s specifications and, if necessary, cost-intensive replacement of the laser diode | Maintenance-free device. Regular regrinding of the tungsten electrodes required | In micropulse TIG welding, the electrodes must be replaced if the minimum length is not reached. The replacement costs for this are low. |
| Shielding gas consumption | Average to high (usually greater distance between shielding gas supply and workpiece) | Low (shielding gas supply directly at the electrode) | For optimum shielding gas supply, a small distance to the workpiece with a medium flow velocity is important, especially for alloys that tend to become brittle (e.g. titanium or nitinol) |
