Improving Infrastructure on the Tracks

Keeping railways safe and running efficiently has always been vital. What’s new are the welding and refurbishment methods by which this is being achieved.

Passenger and cargo trains rely on switches to ensure there isn’t overlap with other trains sharing the tracks. Switches have several components, and one vital component is called a frog. Why frog? When railroads were new, horses and buggies were still around, and the angular switch looked similar to the part of a horse’s hoof called the frog.

The shape of railway switches looks like the frog of a horse’s hoof.

Railway frogs must withstand a lot of force switching fast-moving trains between tracks. Derailments can result from damaged or worn-out frogs. Therefore, switches must be durable. Railway frogs and other switch components, such as diamonds, are made of a cast austenitic, high-manganese steel known for its work-hardening characteristics and high toughness. The points and wings of the frog need to remain on spec to ensure trains change tracks without issue. As the parts wear, they need to be replaced or refurbished.

In the past, when fewer trains were running, it was easier to make repairs on the line.  Nowadays, it’s more common to remove the frog and replace it with a new or refurbished part. Damaged switches go to the rail yard and get placed in water-filled steel tubs; the water is used to quench the frogs during repair welding so the heat input doesn’t bow or flex the metal. Rows of tubs allow multiple welders to work at a time. These areas are known as frog ponds. This process is still in place in many areas. Because frogs are more universal and can be manufactured in large quantities, rail companies can keep replacements on hand. However, diamonds are unique to their location and can have lead times of a year or more to restock. Supply chain issues make refurbishment more necessary, and the need for welders also makes that increased demand more difficult to fill.Specialized wheels allow the HAMR trucks to access remote areas for trackside welding.

Going Another Route

Holland L.P., Crete, Ill., a provider of progressive solutions for the rail industry, is changing the process by easing the need for new replacement parts and minimizing the need for repairs to be done by welders who could be working on other projects.

Louis Flenner, product manager of the Holland Automated Manganese Refurbishment (HAMR) program, detailed the process they have developed to refurbish frogs and diamonds using specialized trucks mounted with generators, robotic arms, and welding systems to address frog repair both on the track and in a frog pond.

Before the refurbishment can happen, the HAMR teams use plasma cutting and grinding to cut away the damaged manganese steel. They then set the points to specify for the robot the damaged areas to build back. This process allows the operator to be farther from the fumes and also move to a safe distance for trains passing on adjacent tracks without stopping the work.

Productivity is another factor. The robot is two to three times faster than manual application. Its speed allows for complete refurbishment in-track or trackside instead of patch repairs, replacement, or scrapping the part.

Weld quality consistency is another reason to go robotic. Due to availability shortages and staff turnovers, the person who repairs the part this year isn’t likely to be the same next year, meaning the quality of the weld can change. Weld quality isn’t as variable with robotic welding. Some of the parts the HAMR team refurbished are still in service three years later when previously they might have lasted three months before repairs.

“You have a lot of expertise and experience that has left the market over the last 10–15 years,” Flenner said.

When weld quality can mean the difference between trains arriving on time or a derailment, those welds must be of consistently high quality.

Refurbishing switches, diamonds, and frogs can take place with robotic welding.

Laser Welding and More

Manganese steel has specific requirements for welding. Heat above 500°F will damage the base material and potentially warp and bend the frog, making low heat input a must for any kind of welding.

Few options met the HAMR team’s quality requirements. They began with laser welding, which uses a directed energy to melt the base material and filler metal to create the weld. The laser uses a system of mirrors and lenses to direct heat to the weld and requires a specific alignment and calibration. This process performed well and stayed within the necessary specs, but the team wanted additional options.

Any new process would have to hold up to the strict guidelines, low heat input, and high standards achieved with laser welding. One possible option was the cold metal transfer (CMT) process from Fronius. This gas metal arc welding process uses a reciprocating wire and precisely controlled arc to keep heat input to a minimum.

Flenner said HAMR has tested laser welding side by side with CMT. “We’ve had phenomenal results with both,” he said.

The program has done so well for rail companies that Holland is expanding the number of trucks and areas served. Currently, it offers services to all of North America and is expanding into Australia and Europe. The company also plans to continue with the dual technology options of the laser and CMT processes. Its fleet of three trucks will soon double. When asked about future challenges, Flenner brought up the low availability of the specialized truck platforms and the challenges of hiring skilled staff and training new employees.

The truck teams consist of one operator and one laborer. Ideally, both should be trained in several areas of welding, cutting, grinding, electrical work, and general maintenance. Ensuring these mobile teams can deliver a quality product is key to improving rail infrastructure.

This article was written by Justin Smith (segment specialist) and Rhonda Zatezalo (content specialist), both of Fronius USA, Portage, Ind., for the American Welding Society.