August 2023 Volume 5

EQUIPMENT & TECHNOLOGY

David’s great grandfather worked with steam-driven machinery, but by the late 1980s and early 1990s, manual machining and EDM processes gave way to digitally programmed NC and CNC machinery. During the 1990s came CAD/CAM technology, a tool that helped program die sinking on CNC machines in three dimensions. In subsequent years multi-axis machine tools added versatility and efficiency to the machining of die blocks. For example, if you add a rotary table to a 3-axis machine you have a 4-axis machine. Add a spindle and you have a 5-axis machine; and a rotary table for a 6-axis system. “One of the major innovations to die making is the change in cutting tools. The transition from high-speed steels to carbide, and adding multiple flute designs and advanced coatings, have improved material removal rates,” said Soltow. “Earlier die block materials were much softer than today’s material. Now we have many different material choices with a large range of hardnesses. Also, through the use of CMMs and laser scanning techniques, we have experienced significant changes in our quality control requirements. In some cases, we have experienced a twenty-fold tightening in dimensional tolerances; where .060” tolerances used to suffice we are now asked to achieve .003” tolerances.” Asked to speculate on what is ahead for tooling in forges, Soltow said, “The future probably means more specialization. Like for many industries, the need by die shops and forge shops for skilled tradespeople is becoming more of an issue. Finally, the need for good die shops and forges to work together is even greater.” As is typical in their industry, S & S Die Co. has evolved through many changes to stay competitive. The tools used today have changed drastically since first-generation Oliver worked with steam driven machines. In 2008 they relocated the operation from the original 30,000 square foot space to an 80,000 square foot facility, purchasing an abandoned manufacturing building and renovating it into a modern productive plant.

Examples of modern machining centers. Courtesy of S & S Die Co,

Modern Die Design and Die Coatings When it comes to tooling design one of the first, and perhaps the most critical, decision to be made is material selection. Steel producers have developed numerous alloys to serve as die materials, though no single alloy specification is suitable to every application. Most forges today use annealed H13 steel or an FX steel (or equivalent). H13 is a chromium-molybdenum hot work steel selected for its resistance to repeated heating and cooling cycles. Annealed H13 steels, with slightly varied alloying formulations are available as a variety of trade names from various suppliers. FX® (a Finkl Steel trade name), is a Ni-Cr-Mo steel offered in a range of heat-treated conditions that balance wear and fracture resistance. Cobalt and tungsten are also important alloying elements for die materials. According to Terrance McInerney, Sales Representative for Gemini Group, a Bad Axe, Michigan, supplier of forging dies, “The time that a heated workpiece is in contact with the die is an important design consideration. Various forging equipment types, such as presses (hydraulic, mechanical, screw), upsetters and hammers, each

A retrospective look at a die shop from S&S Die Co.

FIA MAGAZINE | AUGUST 2023 18