June 13, 2006
To compete in a global market, all stampers need adapt their manufacturing processes. By mixing automation with electronic controls, job shops can increase output and exceed past manufacturing goals.
|Photos courtesy of Jackie Dorris.|
To compete in a global market, all stampers need to adapt their manufacturing processes.
Electronic automation of tonnage monitoring, die protection, feed control, job programming, and counterbalance or slide adjust can be the easiest to implement.
Automation hardware includes quick-change tooling, transfers, die carts, and robots (see Figure 1). Current equipment has evolved from its primitive past. For example, tool clamping has improved, as well as tool handling for quick changes. Low-profile clamps and locking systems can reduce downtime, as well as hydraulic clamps, positioning pins, rolling bolsters, die lifters, and other mechanical tooling transfer units.
Software. Electronics can help stampers evaluate processes and pinpoint weaknesses. The software available can show the percentage of press utilization and give stampers real-time information, in both numerical and pie chart formats, about when bottlenecks are occurring. A stamper can use networking software to show the amount of lost production during tooling changeover. By reviewing this time, a stamper can see that the time lost might be decreased by using rolling bolsters, die carts, or quick-die-change clamping.
Software also can assist with manufacturing scheduling, showing production rates in parts per minute and strokes per minute. Job storage and retrieval software can help make job changeover easier for the novice operator. Maintenance can track and schedule their preventive maintenance using software that handles both downtime codes and scheduling. Plant managers can use their time better by being able to review and allocate resources where needed by tracking all of their pressroom operations.
Automation hardware includes quick-change tooling, transfers, die carts, and robots
Safety. Reducing part handling keeps an operator outside of the press die area and the risks associated with it. Transfers and progressive tooling can reduce opportunities for injuries and manual operation fatigues like carpal tunnel.
From a manufacturing standpoint, there is no value added when an operator handles a part. This is simply a required process, sometimes the result of poor planning or lack of advanced equipment.
Advanced Dies and Tooling. New dies are engineered to tighter tolerances with better materials and are now designed with maintenance and built-in process monitoring.
Die manufacturers also are working with press manufacturers and controls manufacturers to help stampers receive tooling that can be better integrated into a manufacturing system. As a result, stampers have less downtime and can produce better parts quickly and efficiently. Integration is another important aspect when it comes to controlling automation in a pressroom.
Press controls have changed quite a bit in the past 40 years. In the beginning, press controls could only start the motor. Today electronic controls can safely monitor and operate ancillary equipment, ensuring that the press is in a safe location in the stroke before unclamping the die (see Figure 2). They also can control press speed, transfer direction, die shut height, and feed length and adjust for programmable die protection. In most cases, this can be done by programming in a specific job number. As a result, stampers can have quicker, more accurate changeovers, which frees the operator to handle other tasks.
Electronic controls also can monitor job status, advance feed lengths, check progressive dies, vary press speeds, and guarantee all press functions are operating properly. Parts counts and advance external transfers have improved the manufacturing process by reducing downtime, engineering changes, and plant maintenance.
In one programming change, slide adjustment for the correct die height, air counterbalance, transfer programming of multiple axes, motor speed, and cushion air settings can be modified. By automatically making adjustments to each ancillary device, changeover times can be dramatically reduced.
Electronic controls can safely monitor and operate ancillary equipment, ensuring that the press is in a safe location in the stroke before unclamping the die.
Setup errors are reduced because all of the controls can be networked together, providing real-time press data, programming feedback, downtime codes, and time studies—keys to Six Sigma and lean manufacturing. Based on Six Sigma and lean manufacturing principles, these systems use light to indicate press status and sound for alerting operators.
Time is money. If you've ever had to troubleshoot a transfer line, you know how much money is lost when multiple presses go down. Great improvements have been made in electronics to assist in troubleshooting. From better onscreen integration with press functions to feedback from peripherals, reporting software can reduce downtime in the long run.
A tonnage monitor reports only tonnage. It won't report if a lubricator isn't pumping correctly unless all press functions are tied together. Tying multiple functions with a job entry number reduces the opportunity for inaccuracy.
For example, when an operator enters a specific job number, a servo feed automatically adjusts to the proper feed length; the slide adjusts the shut height and counterbalance. Tonnage and die protection units are programmed for the maximum allowable tonnage measurements, and die protection sensors are set as well as scrap parameters. Programmable limit switches are set to actuate blow- offs and other ancillary devices
Tying press functions reduces set up time and allows an operator to prepare material, make necessary bin preparations, and complete paperwork.
Electrolux, a manufacturer of 30-inch, freestanding electric and gas ranges, faces some of the same challenges all job shops face. One is to adjust quickly to customers' new requirements and the need for short part runs while maintaining a high level of quality.
By implementing automation with electronic controls, Electrolux improved its total productivity more than 10 percent and reduced downtime by 12 percent. With the automation, the appliance-maker also exceeded its goal of producing 2.45 million units at its Springfield, Tenn., plant than previously produced.
To start, Electrolux used production monitoring software to identify hardware changes needed in its part handling operation. As a result, the appliance-maker modified its processes by adding conveyors, mechanical transfers, and progressive dies.
To increase productivity, the appliance-maker fitted all mechanical presses with transfer mechanisms, die transfers, and machine mount transfers. Electrolux also refined its progressive dies to perform more operations with Linknet software to monitor, control, and respond to multiple die changes per shift, which require material, feed pitch, and die sensing changes. To go from one part to the next with little to no downtime, Electrolux incorporated real-time access to its pressroom to arrange its manufacturing schedule to coordinate with press availability.
The software also showed which jobs were high-volume. These parts were placed on dedicated presses and transfer press lines so they could run longer without interruption. Lower-volume parts were produced on secondary lines. Tooling changeovers and quick die change were studied to improve these processes. The information gathered helped establish benchmarks for each press and die and was helpful for creating a preventive maintenance schedule.
Because of real-time press networking, an operations manager knows when a malfunction occurs and can dispatch service personnel. Electronic controls have diagnostic screens, which direct personnel to the cause of failure. Now, when a press line stops, it doesn't take more than a half-hour to troubleshoot the problem. The cure can now be found in a few minutes.
Visual alerts pinpoint press malfunctions or die problems. A problem that previously took 45 minutes to troubleshoot could now be solved in 10 minutes. Now operators can solve basic problems that used to require considerable downtime.
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