26 April 2012

Fast Track Laser Welding From Rofin

From Application Development to Full Production within Four Weeks - Imes GmbH, specialists in advanced high-temperature measuring cells, integrate ROFIN‘s laser welding solution at record speed.

The laser has, for many years, been recognised as a productive and reliable tool for industrial material processing. However there are still those, albeit the minority, who have the perception that implementing a new laser process is somewhat cumbersome and a task for larger companies or well-versed laser specialists.

A closer look at how a medium-sized company established a new laser welding process, including application development, system implementation and training within just a few weeks certainly dispels this myth.

Record Sales Require a Doubling of Production
Imes GmbH manufactures high-temperature resistant pressure sensors that are in the main supplied to manufacturers of engines for large ships and static engines, generally with power ratings from 250 kW to 18 MW. In 2011 sales of Imes‘ measuring cells for large gas and diesel engines increased beyond all expectations, breaking every record in the company‘s 15-year history and presenting the company with the challenge of doubling production by the turn of the year.

These record sales were the result of Imes taking advantage of two global trends: climate protection and energy production from renewable raw materials. Climate protection forces the shipping industry to gradually substitute diesel fuel with liquefied natural gas (LNG). As LNG produces lower CO2 emissions compared to oil-based fuels and zero SOX emissions, dual-fuel engines are becoming the industrial standard. Efficient and reliable combustion of varying fuel types requires considerable improvements in the engine management, based on additional measuring sensors in the cylinder block.

Energy production from biogas, however, poses a different challenge. The level of methane, the energy carrier, varies as much as does the composition and quality of raw materials and conditions of microbial degradation. Biogas engines have to maintain efficient combustion with varying fuel qualities while attaining high running times. This again requires intelligent motor management - with sensor-technology supplied by Imes.

Laser Welding Stainless Steel Sensor Housings
The company‘s key product, the HTT-04 cylindrical pressure sensor, measures pressures up to 300 bar, whilst withstanding temperatures of up to 300 °C. A tube made of stainless steel, which houses a thin-fllm technology measuring sensor, has to be screwed into the cylinder block. Another tube contains signal processing electronics and industry-standard connectors to connect to the engine management system. Multiple manufacturing steps require the hermetic sealing of these stainless steel tubes containing sensitive electronics.

Adhesive technology, which Imes had initially used as the joining method, suffered from the extreme vibrations encountered during the long operation times, which average 10.000 hours. Subsequently, an external sub-contract manufacturer was used to hermetically seal the tubes using a laser welding system. Laser welding is ideally suited for precise and robust stainless steel joints. In addition, as parts are processed without any application of force and the heat input is both low and highly localized, the laser is the perfect solution for welding sub-assemblies which contain delicate, heat-sensitive electronics.

Application Development at ROFIN
Early in 2011 Imes Managing Director Stefan Neumann made the decision to introduce the laser welding to his in-house production in order to shorten lead-times and streamline logistics. With no prior experience of laser technology, Imes made initial contact with ROFIN for advice. Stefan Neumann was invited to send samples to ROFIN’s application lab in Starnberg as a first step in the application development process.

ROFIN-BAASEL runs one of the worlds largest applications labs for the evaluation of new laser processes for industrial material processing. A variety of some 30 laser systems, including the newest femtosecond lasers, are permanently available for tests.

ROFIN‘s application engineers quickly developed the optimum laser setup for Stefan Neumann‘s samples. The Select laser workstation, equipped with an additional rotary axis was a perfect fit for this application. The Select is both a manual welding laser and a high-precision CNC system with easy teach-in via a multi-functional joystick. It also offers enough space to cope with the bulky steel-reinforced hoses that are already attached to one component. The CNC-driven rotary axis allows for a fully-automated process, ensuring that each and every part is welded with the optimum parameters, e.g/. laser power, pulse frequency, pulse shaping and feed rate. Guaranteeing process stability is a key issue for Imes, because if a sensor malfunctions in a ship‘s engine it is no trivial matter.

Customer-tailored Laser System
Within a few days of receiving the sample parts, ROFIN demonstrated the solution in its application lab. Neumann was convinced and moreover investment costs met his expectations. ROFIN Sales Manager, Andreas Schöllhorn, suggested adding some optional modules to the laser workstation to extend its application range. Experience has shown that additional laser applications often follow sooner than expected. Neumann, who appreciated ROFIN‘s fast and accurate work, relied on this advice and purchased the system together with the recommended options.

Installation, Training and Production
System installation and setup is always carried out by a ROFIN specialist with extensive customer training experience. Over a two day period, the engineers at Imes learned everything they needed to know about daily operation of the system together with set up procedures for new applications.

Operating the fully-automated, CNC-driven system in production is straightforward. This enhances flexibility within the workplace, as different employees are capable of operating the laser welding system. Full production of the HTT-04 sensor with the new in-house laser welding system commenced very quickly following the brief training programme.

Production Increased by 20%

Today, the in-house laser welding system helps Imes to organize production in a much more flexible and responsive manner. All of this adds up to a production increase of 20 percent. The quality of Imes‘ own weld seams is considerably better than the parts welded by the external contractor. Managing Director Stefan Neumann is very happy with his decision. Looking back he says: “We wanted to introduce a new production technology in a very short time. Therefore we needed a reliable partner who offers fast and un-bureaucratic support. At ROFIN we got the right advice, fast delivery and perfect training. I never would have thought that operating a laser welding system is that easy“.

The additional options selected at the time of purchase have also paid off “We are already welding an additional joint with the laser“ notes Stefan Neumann „and our new product, which we will launch in 2012, features several laser welds“.

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