November 2021 Volume 3

AUTOMATION

Flood Welding in the Forging Industry By David Lee

No other single process or control system introduced to forging has had the same economic impact potential since closed die forging began. Flood welding, or progressive manual cast welding as it is also known, is the process of streaming molten metal with electric arc into a steel alloy cavity, resulting in an impression that performs better than new. The first recorded flood weld repair of forging dies occurred in 1952 for Chryslers Detroit Forge Plant byWeldMold Company in a small suburban Detroit shop. Founded in 1945 with the goal of reducing the tooling costs in the forging industry, the first challenge was the development of alloys that would be appropriate for the high impact energies, abrasion and temperatures that are found in hot forging applications. A second goal was to develop a method to deposit these alloys and complete the process as quickly and efficiently as possible. In the Beginning Modern closed die forging began in 1862 at Samuel Colt’s Patent Firearms Company. Dies had a life cycle measured in re-sinks. As the impression became increasingly worn, the blocks were pulled from the hammer for re-sink. Each impression renewal brought the block closer to the scrap heap. One hundred sixty years later, some forge operators keep this practice alive. Welding in the Forge No one seems to know when welding as a means to repair a forging die was originally introduced to the industry or how that introduction was made. It is known from Weld Mold Company history that the weld repair of forging dies in the 1940’s was done most commonly with stainless steel grades of electrodes, described as “the best we had at the time”. Some tool and die electrodes existed at the time but were not suited to forging dies. Stopgap measures at best, these repairs permitted the dies to complete production by building up worn flashlands, covering impression cracks, or engineering changes. Doing a full face resink was still the accepted practice for complete cavity renewal, every forge had a die room that was constantly manufacturing new dies to replace blocks that were scrapped after three or four production cycles. The purchase of new die steel was a large part of the production budget and product cost. At one time, every forge shop had vast piles of worn, broken and obsolete forging dies and forging equipment. By 1947, the first innovation addressing both alloy development and high deposition welding was called the “Pack Rod”. Weld Mold Company’s patented Pack Rod provided deposition rates of 5-10 lb. /hour, compared to 2-4 lb. /hour of the electrodes then

currently available. Produced by welding the bare end of the small diameter tool and die electrodes to a larger diameter (1/2”) core wire, leaving enough of the core exposed to be gripped in a custom electrode holder, weld deposit chemistries and characteristics could be controlled by combining different tool steels together on the Pack Rod. The time and cost of fabricating them and being limited to 14” in length was a disadvantage that needed a solution. In 1948, development began on an electrode with a single core wire with alloying contained in the flux coating. These would be easier to use, less expensive to make and had a longer length than the pack rod. Working with forging customers, the formulations and procedures were perfected by trial and error. Because these electrodes were hand dipped well into the 1950’s, production was sufficient only to supply Weld Mold Co.’s needs. However, the effectiveness of the flood welding process and products led to an increase in the number of forging companies using welded dies. The automation of the electrode manufacturing process in 1955 by extrusion meant that for the first time, the electrodes could be made in sufficient volume to supply the forge companies that wanted to weld for themselves. By the late 1950’s, a decade after development began, true forging die welding alloys were commercially available. Because anything larger than 1/2” diameter by 24” long was hard to handle, even with custom made long handled holders, something else needed to be done. The Weld Mold ARM was developed in the mid 1950’s to permit the use of electrodes up to 5/8” in diameter and 30” in length and weld deposition rates had improved to 45 lb. /hr. This permitted a complete rethink of what may or may not be repairable in the forge. Patented in 1959, the ARM is used around the world. What would have been a scrapped hammer base or ram in 1950, is now routinely repaired. As the years progress, replacement forging components have longer lead times and higher costs. In 1965, the 3/4” electrode would be added to the available offerings, providing a solid 60lb. /hr. deposition rate. Beginning with the high deposition rate of the Pack Rod in the ‘40’s and large diameter electrodes in the ‘50’s, a process was needed that would take full advantage of these industry changing advances. That process, originally known as “The Weld Mold Process” is now commonly called “Flood Welding”. When properly applied, flood welding can provide; indefinite life to a forging die, improved productivity of a cavity, allow previously un-repairable forging components to be repaired, reduce the need to maintain vast inventories of die steel and spawned an industry that even 60 years ago, didn’t exist anywhere in the world, except in a small shop outside of Detroit.

FIA MAGAZINE | NOVEMBER 2021 28