Lower commodity prices (i.e., less money to spend for new equipment) and an industry-wide move to faster field speeds with ground-engaging tools may reignite farm interest in the mining industry’s long-standing practice of hard-facing tool surfaces to renew their shape and protect them from additional wear.
Chris Monroe, training specialist at Hobart Brothers Co., longtime welder and welding supply manufacturer, says on older equipment, hard-surfacing generally returns worn parts to nearly new condition for about 25-75% less than the cost of replacement parts.
“The process also lengthens the life of surfaced parts by 30-300% more than non-surfaced parts,” she explains. “In some cases, specialized hard-surfacing alloys provide even greater wear resistance than original parts.”
Abrasion accounts for 55-60% of farm equipment wear. The bulk of that comes from low-stress scratching — where metal wears away from ground-engaging tools by the scouring action of sand, soil and rock across the equipment as it moves through the soil.
As planting and tillage field speeds increase to boost productivity and profits, so does tool wear, but wear increases faster than field speed. Engineers say doubling field speed quadruples wear on parts running in the soil, explaining why many growers complain that “wear steel” isn’t as good as it once was.
Build-Up & Overlay
- Hard-facing offers off-season shop business as growers maintain existing equipment.
- New weld-on, wear-resistant tiles could cut inventory while boosting service opportunities.
- Faster field speeds mean more equipment wear and need for service.
The two main hard-surfacing techniques used in farm and dealer shops are build-up and overlay, says Monroe.
“The build-up method involves layers of welds placed on the equipment to return the metal parts to their original dimensions. This provides excellent protection against impact but offers low abrasion resistance,” she explains.
“Overlay, which involves additional protective layers of welds added to the part, provides excellent wear resistance and is often used to protect new equipment.
“Combinations of build-up and overlay techniques can be used to restore older parts to size and then protect them from wear.”
Hard-surfacing weld beads for overlay are applied in one of three patterns: waffle (a diamond or square pattern), stringer lines and dots. Monroe says the location of the wear, the type of wear and the type of material causing the wear all determine which pattern should be used.
“Regardless of the hard-surfacing pattern used to protect a particular type of equipment, there are many types of hard-surfacing alloys or filler materials for the job,” she adds, noting the different materials are designed to protect against different types of wear.
Also, the base metal, generally carbon, low alloy or highly wear-resistant austenitic manganese steel, determines which alloy or filler material is used and whether pre- and/or post-heating is necessary in the process.
Miller Electric training material explains carbon or low alloy steel is probably the most commonly hard-faced material. Higher carbon or alloy content materials are more brittle and, therefore, require pre-and post-heating in some applications.
Also, Miller officials say austenitic manganese steels need to be held under 500 F during the hard-facing process to avoid increased brittleness — a tough proposition when affixing the hard-facing materials by brazing.
Monroe says, ultimately, doing the best job of hard-facing requires the knowledge or guidance of a trusted welding distributor or filler metal manufacturer as well as someone who is very familiar with heat control in welding.
“In the end, however, it doesn’t matter whether the equipment is old or new, the result from the hard-facing process is the same: greater impact and abrasion resistance, longer equipment life, and less downtime for repairs,” she says.
Something New: Weldable Tungsten Carbide
While the major welding supply companies in the U.S. have a host of hard-facing consumables in both stick rods and flux-core welding wire, it’s been several years since any new materials have been introduced.
Across the Atlantic, however, Tenmat Ltd., in Manchester, England, has introduced a new weldable tungsten carbide material called Ferobide and offers it in four tile sizes from 40 x 40 mm to 25 x 60 mm for overlay hard-facing. Currently, the material is in use across Europe and officials plan to unveil it for North America in February at the National Farm Machinery Show in Louisville, Ky.
“Hard-surfacing generally returns worn parts to nearly new condition for about 25-75% less than the cost of replacement parts…”
— Chris Monroe, Hobart Welding Products
Rupert Coggon, Tenmat’s business development director for Fire Protection and High Temperature Products, says Ferobide uses a steel matrix to bond tungsten particles together for a material that resolves some of the limitation of traditional wear protection materials.
“The patented forming process, developed over the past 8 years, provides wear resistance similar to tungsten carbide in a form that can be easily cut with an angle grinder and welded in place with commonly-used stick or MIG welders equipped with regular electrodes,” he explains.
“In the past, tungsten carbide overlay tiles had to be brazed onto the tool at temperatures around 1,300 F. That process often softened the parent material causing additional wear-prone areas on the tool and usually involved having specialists do the brazing. Also, brazing is pretty much a metallic ‘glue,’ and if not done properly, the tiles can come off before they are worn out,” Coggon says.
With this new material, Coggon says farmers can place the tiles where they know they need them and install them with the equipment they currently have in their shops.
“The heat of the welding process is very localized so a farmer installing Ferobide is not likely to affect the hardness of the parent material — which also leads to longer equipment life,” he adds. In addition, the material resists chipping better than traditional tungsten carbide materials.
For dealers, Coggon says these tiles offer an easy-to-handle premium product that can be sold to upgrade standard parts. “The same easily-stored tiles can be used on almost any design of wear part, so inventory can be minimized,” he adds.
“If dealers in North America are similar to those in Europe, they will stock standard steel (low cost), a hard-faced (medium cost) and a tungsten plated (high cost) option for their major customers,” he says. “So, potentially they just need to hold the low cost steel parts and then add Ferobide tiles as the upgrade. In doing so, they reduce inventory to one part plus tiles instead of three different parts of the same component.”
Another advantage of the new technology is the low-cost of shipping small tiles instead of heavier complete plow, harrow and planter components.