Cement manufacturing can be daunting if not done with the proper tools, especially when it comes to pulverizing stone. A hammer mill, containing over a hundred individual “hammer”-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 if not made of an optimal material equipped to handle the task.
Although a hammer is made of steel, a leading worldwide cement manufacturer learned just how important hammer steel grade and shape are to the fatigue life. For years, this cement manufacturer purchased hammers made from an expensive grade of tool steel which was burned from steel plate. Unfortunately, these “burnouts” from steel plate did not live up to expectations, and the cement manufacturer was unsatisfied with the wear life and frequent teardowns of the hammer mills.
Each teardown resulted in several days of downtime for this plant that was expected to operate 365 days per year. After replacing the hammers approximately every 50 days, the manufacturer realized it could not afford the plant to be shut down seven to eight times per year.
Clifford-Jacobs Forging Co., a producer of impression-die forgings, learned of this potential new customer’s hammer mill problems. As an expert in custom forged products, the Illinois-based forging company identified areas for improvement with the hammers and decided to capitalize on this opportunity by assisting the cement manufacturer in finding an alternate grade of steel for their hammer units. Knowing that excessive wear was due to shape as well as type of steel used, Clifford-Jacobs asked Timken to collaborate with it to produce a hammer unit solution that would allow the customer to get the job done efficiently and with the least amount of downtime. From there, the two companies discussed options that would meet the customer’s needs for this particular application.
Clifford-Jacobs engineers, in consultation with the cement manufacturer’s engineers, developed a design for forged hammers with more material mass in the impact zone that would offer significant longer wear life at a lower cost than burnouts from plate steel. After consulting with the customer, Timken Steel’s metallurgical staff proposed the 4340 grade of high alloy steel and furnished data to support its recommendation. This grade would extend the forged hammers' fatigue life because of its durability and abrasion resistance following a post-forging heat treatment. The cement manufacturer agreed to both Clifford-Jacobs’ and Timken’s proposal and the new process began immediately.
Truly a team effort, Timken produced the alloy steel and shipped it to Clifford-Jacobs, who forged the hammers to the new design. With results much better than expected, the new forged hammers lasted a minimum of 80 days, a 60 percent increase compared to the original hammers burned from plate steel. This improvement reduced the number of hammer mill changeovers from seven to four per year and created more production capacity.
Timken’s modified steel also is more readily available than the expensive tool grade of plate steel previously used, saving time as well as overhead costs. Pleased with both Clifford-Jacobs’ and Timken’s expertise, the customer placed a repeat order for 300 additional forged hammers.
“By working closely with Clifford-Jacobs, we were able to combine our expertise for an improved solution that allowed Clifford-Jacobs 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 importantly to them, they in turn are able to better serve their customers because of our partnership.”
“Timken is where we turn for assistance to help our customers be more successful in their business,” said Justin McCarthy, Vice President of Sales & Marketing of Clifford-Jacobs. “This is just one of several ongoing examples of how Timken Steel assists us in offering total solutions to our customers.”