Increase Uptime, Decrease Occurrence Of Sharpening With Shearing Tool

Shearing steel sheets into panels is high volume business at Advanced Distributor Products (ADP) (Grenada, Mississippi). With nine high speed turret punching machines that run around the clock 6 days a week, the company calculates that it fabricates 90 tons of steel a week, most of which is sheared and formed into panels for evaporator coils, air handlers and gas heating products.

ADP is a division of Heatcraft and the Lennox family of companies. Heatcraft is a major supplier to the heating and air conditioning industry and has extensive sheet metal fabricating operations located in three plant locations in Grenada, Mississippi.

˜According to Pat McMurphy, ADP manufacturing technician, demand for the company's products has soared, necessitating a three-shift, six-day operation of its punch press department. To help keep up with demand, Mr. McMurphy, working with the company's press operators, constantly seeks ways to improve productivity. When analyzing tool performance, one particular tool stood out-a shearing tool installed in each machine's turret required sharpening on average once per 24-hour work cycle.

"The time required to replace a shearing tool was only 10 minutes, but we wanted to improve on that," says Mr. McMurphy. "Even though we have backup tools sharpened and ready to be installed, 10 minutes downtime a day (three shifts) per machine is a lot when factored across all nine machines. We looked at that 90 minute total of lost press time in a three-shift, 24-hour workday as a real challenge."

Mr. McMurphy called in Terry Stewart, sales representative for Mate Precision Tooling (Anoka, Minnesota), for his recommendations. Mr. Stewart suggested a test of Mate's 114 style G-9 fully guided 0.125-inch by 2.5-inch rectangular shearing punch, capable of shearing mild steel up to 0.315 inch thick. The tool was installed in the company's Murata Wiedemann Centrum 3000 with surprising results. "We got nicely squared panels with good clean edges and didn't have to sharpen the tool for nearly 4 weeks," says Mr. McMurphy.

The tool's design promotes long tool life. The assembly is fully guided so that it overcomes side-load and twisting pressures. Guiding features squarely and tightly control the punch point where it contacts the sheet, so the punch accurately pierces a hole even when punching partial hits. The tool assembly also provides accurate and close tolerances among guide, punch and stripper, controlling against both sheet and edge distortion and saw toothing.

The tool has a stripper opening of 0.0015 inch (total clearance to punch point), which supports and guides the punch point. This increases hole accuracy, improves stripping and prevents scrap from rising into the assembly.

"We were pleased with the test results," says Mr. McMurphy, "both because of greatly increased tool life, and the sheared components had nicely finished edges without any noticeable sheet distortion. We ran nearly 4 weeks without sharpening, so we brought in Mr. Stewart again to plan our next step in the upgrade process."

ADP operates three Amada, three Finn-Power and three Murata Wiedemann turret presses. Like most companies with rapidly expanding fabricating operations, ADP adds machines as needed, the newest being the Amada Vipros 368 acquired last year. The other machines range in age from a few years to 10 years old. All utilize shearing tools that required sharpening every day. The question posed to Mr. Stewart was how to get improved run time in all of ADP's nine turret presses, which were different models, ages and tooling styles.

The solution for the Murata Wiedemann presses was relatively simple since the first machine tested, the Centrum 3000, performed well with the 114 G-9 tooling. The two other Murata Wiedemanns, when equipped with the Mate 114 G-9 tooling, performed equally well. With its Finn-Power presses, ADP tooled up with Mate Nova G-9 fully guided 0.200-inch by 3.250-inch rectangular shearing tools. With its three Amada machines, ADP tooled up with Mate's Ultra fully guided 0.250-inch by 4.250-inch shearing tools.

"Mr. Stewart also taught us an important maintenance step that adds to tool performance," Mr. McMurphy points out. "We need to be certain the turret station is aligned correctly when installing the new shearing tools, especially in the machines with the auto index stations."

Mr. McMurphy said that with the new shearing tools punching 0.024-inch to 0.030-inch mild steel for most panel components, his operators were able to produce square parts even when running the presses at near 100" percent speed, which ranged up to 300 hits per minute in the newer machines. Part squareness is an important issue because most of ADP's panels require shearing on all four sides, after which they are bent to shape with the corners "clinched" together. With the new Mate shearing tools, Mr. McMurphy reported that even at the highest press speeds, parts were sheared consistently square with smooth edges so part fitup was never a problem.

At the urging of Mr. McMurphy's supervisor, Jerry Warren, a computer model of new tool cost, toolchange cost, and tool sharpening cost was calculated for both old and new punches for its three Murata Wiedemann Machines. This was done after the first test was completed with the new Mate tools to justify making the switch to the other two Murata Wiedemann machines and eventually to all nine turret presses.

The annual projected savings for new tool costs, sharpening and labor versus old tool costs for three Murata Wiedemann turret machines was $14,454.

After submitting the tool justification analysis to ADP management, the decision was made to switch to Mate tools in all nine turret punching machines. The results for the nine machines proved equal to the original testu. Mr. McMurphy reports, "With Mate tooling, we're able to maximize each machine's run time, regardless of brand or model, and get the fastest setups and longest tool life possible. By maximizing our punch press run time, we are able to produce and ship more product with the same labor and capital dollars invested."