ROTARY BROACHING IN HARD MATERIALS UP TO 55Hrc
Last week I was reading through the latest edition of Cutting Tool Engineering Magazine. What caught my attention was the article “Broaching Revolution”. Link to this article. This was a great article on the many ways rotary broaching can be used in manufacturing today. The industry leading companies featured in the article, talk of the tech advances made over the last few years, including, tool coatings, HSS material upgrades, cryogenic processing, etc. These advances have helped improve broach tool life. However in this article, these industry leading broach manufacturers admit, their broach tools fail in materials approaching a hardness of 42 Hrc, yielding only 1-2 pcs per part. This makes their broach tools a very uneconomical option for creating the desired form in a part this hard. In the Medical, Aerospace, and Oil & Gas industries, many of their materials are above 40 Hrc in hardness.
Our broach customers however, are broaching in materials up to 50 Hrc and some instances, up to 55 Hrc. Depending on the size of the hex form, 50-1000pcs can be achieved per broach in materials in 40-50 Hrc hardness range. These are very economical numbers, and way more cost effective over a sinker edm process. Our Rayco HSS broach tools are made from the most common tool steels, and require no coatings or cryogenic processing. We use a 74 year old proprietary heat treat process on our HSS broaches. This heat treat process is very different from conventional HSS heat treat processes, and is still a company secret.
The Rayco Process of heat treating HSS starts with mill annealed steel and hardens uniformly through the steel. An unusually fine, tough grain structure is obtained at high hardness. The transformation of retained austenite to finely tempered martinsite, is accomplished much more easily and at a higher percentage than conventional heat treated HSS. This also yields a much finer grained structure, where grain growth is not a issue at high hardness R/C 66-69. This fine grain structure can be approached in conventional heat treating only by holding the hardness very low (around 62 Hrc in most HSS) which naturally lowers wear resistant properties. Rayco Processing brings out the most superior wear resistance and toughness in any HSS.
In softer materials where conventionally heat treated HSS broach tools perform well, Rayco Processed HSS broach tools usually out perform with 2-7 times the tool life. The answer is in the heat treat, and not as much the material. Whatever HSS steel our competitors use and a give a fancy name to, at the end of the day, that HSS material would have much greater tool life, if it was heat treated with the Rayco Process. We guarantee our broach tools will out perform our competitors, or your money back.