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Timken Alloy Steel Improves Hammer Mill

Timken Alloy Steel Improves Hammer Mill

The Timken Company produced a longer-lasting grade of steel, 4340, to be forged by Clifford-Jacobs Co. into hammers, for stone-crushing hammer mills used in cement manufacturing.

A hammer mill, containing over a hundred individual hammers — shaped pieces of steel, used to crush stone — is used in cement manufacturing to pulverize limestone for cement, ready-mixed concrete, gypsum wallboard, and other related products. The hammer mills run non-stop for weeks, and over time the individual hammers wear down and fail, unless they're made of a material equipped to handle the task.

Steel is what the hammers are made of, and recently a global cement manufacturer learned exactly how important is the grade of steel used to fabricate the hammers, in terms of the hammers' service life.

For years, this cement manufacturer had selected hammers "burned" from steel plate made from an expensive grade of tool steel. Unfortunately, these "burnouts" from steel plate did not live up to expectations. The low wear l i fe a nd f requent tear-downs resulted in several days of downtime for the hammer mills — not good for a plant that expects to operate year-round. Hammers were being replaced about every 50 days, so the plant would face a shut-down seven to eight times per year.

Clifford-Jacobs Forging Co., Champaign, IL, producers impression-die forgings and experts in custom forged products, identified several areas for improvement with the hammers. Among the changes was a decision to locate an alternate grade of steel.

Knowing that excessive wear was due to shape as well as to the type of steel used, Clifford-Jacobs asked The Timken Co. ( to collaborate on producing a hammer unit that would allow the customer to get the job done efficiently, and with the least amount of downtime.

Clifford-Jacobs engineers developed a design for forged hammers with more material mass in the impact zone, which projected significant longer service life at a lower cost than burnouts from plate steel. Timken's metallurgical staff proposed a high-alloy steel and furnished data to support its recommendation.

The recommended steel grade, 4340, would extend the forged hammers fatigue life because of its durability and abrasion resistance following a post-forging heat treatment recommended by Timken's metallurgists. The cement manufacturer agreed to Clifford-Jacobs' and Timken's proposals, and the new process began immediately.

Timken produced the alloy steel and shipped it to CliffordJacobs, which forged the hammers to the new design. The results exceeded expectation: the new forged hammers last a minimum of 80 days, a 60% increase from the original hammers burned from plate steel, reducing the number of hammer mill changeovers to four times per year.

Timken's modified steel also is more readily available than the expensive tool grade of steel plate previously used, saving time as well as overhead costs. A repeat order for 300 additional forged hammers was placed.

"By working closely with Clifford-Jacobs, we were able to combine our expertise for an improved solution, that allowed CliffordJacobs to ‘forge' a great relationship with its customer," said Mike Szum, sales specialist, steel of Timken. "Not only do we offer guidance and answers to our customers, but more important to them, they are able to serve their customers better because of our partnership."

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