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Quick-Die-Change Strategy--Q&A with an Expert

By: Brad Kuvin

Thursday, September 1, 2016
 

Here’s a sign you’ll likely not find in a press shop: FOUND—EXTRA PRESS TIME

Instead, at the end of a shift you’re more likely to wonder why actual production failed to match what was scheduled. And while the causes of this dilemma can be many, a likely one is overly time-consuming die changes. They can occur for any number of reasons—lack of forklift availability, manpower shortages and missing/hiding tools, for example.

This QDC installation at Racine Metal-Fab, Ltd., Sturtevant, WI, features eight hydraulic ledge clamps (four upper and four lower), two swing-away bolster extensions (40 in. long, 6000 lb./pair load capacity), spring-loaded ball cartridges in the bolster, and a hydraulic power and control module. The company employs a standard clamping plate on all of the dies that run in this press, helping the changeover team to complete die changes in 1 min. (roll a new die into the press, position and clamp).
Making quick, efficient transitions from stamping the last part of one run to first-part approval of the next run continues to take on a growing level of importance, as stampers strive to squeeze every vestige of productivity from their equipment. This in the face of more frequent changeovers due to the need to run smaller lot sizes and minimize work in process. As a result, the industry has made a tremendous push in recent years to wring out every last bit of die-change waste from the process. This has stampers making unprecedented investments in quick-die-change (QDC) equipment, according to Chris Klimowicz, sales manager for PFA Inc. Here, Klimowicz shares his perspectives on QDC strategies with MetalForming.

MF: Where should metalformers begin their quick-die-change journeys?

Klimowicz: Start by setting goals for die-changeover times, and identifying specific pain points. I always ask, “Where are you slow; where do you need to improve? Does it take a long time to find and retrieve dies, for example? Or do workers waste time looking for the tools they need to complete a changeover?”

We recommend that shops start by evaluating their biggest problem area and conduct a detailed case study. Time several changeovers to determine an average baseline time. And, video-record the changeovers to obtain an accurate record.

MF: Are there common steps metalformers should take to ensure they optimize their return on investment in QDC equipment?

Klimowicz: Without a doubt standardization is the most important factor in optimizing ROI. Before investing time and expense in QDC, we recommend that metalformers standardize on clamping height. In fact, they should consider mounting all of their dies on subplates standardized for clamping height, as well as for left-to-right and front-to-back dimensions.

There are basic practices that can be used to ensure quick and accurate die setting, such as use of locating pins or die guides on the press bolster. Whatever a metalformer does to its dies to optimize changeovers, make it the same on all dies. This might seem time-consuming and costly up-front, but it pays off in the end; the benefits from investments made in QDC equipment will compound.

MF: What can metalformers expect to spend to outfit a press with QDC apparatus, and what type of return can they expect from their investments?

Klimowicz: Spend per press depends on press size and the weight of the dies. To equip a bigger machine with heavy dies (10,000 to 35,000 lb.) can cost in the neighborhood of $40,000 for clamps, bolster extensions and die lifters. For a standard 500-ton press, we see an average spend of $10,000 to $20,000 on QDC equipment. ROI, meanwhile, often is measured in months, based on the number of times a press is changed over during a typical shift. And, as noted above, shops that do not take the time to standardize on their equipment will only optimize their changeovers on some of their dies, not on all of them. That can extend the ROI from months to years.

MF: What steps can metalformers take to ensure they’re prepared to work with a vendor of QDC equipment?

Klimowicz: Whether looking to invest in die clamps, bolster extensions or die lifters/rollers, we recommend that metalformers closely survey the equipment they’re using in their pressrooms. Die weight and die density (ratio of weight to footprint) are critical, so that we can calculate the amount of lifting capacity needed per foot and ensure that the metalformer has sufficient lifting capacity for its applications.

Also, take the time to accurately and precisely measure T-slot dimensions—this is critical and may rule out some of the equipment that commonly is available. Without this information, finding the optimum QDC solution is difficult. A key point: Measure T-slot dimensions to three decimal places, understanding that a “standard” 3⁄4-in. slot is anything but standard. And, when you’re dealing with die lifters, we’re typically only elevating the die 0.070 to 0.080 in. above the bolster surface. So, we need to know the precise depth of the slots. Slot width also is critical—we don’t want more than 0.030 in. of gap between the slot and the lifter.

MF: You note a significant increase in the use of QDC equipment in recent years—do you have any recommendations for first-timers?

Klimowicz: For sure we’ve seen a significant pickup in new business since 2013, as well as returning customers. As the market demands more productivity, metalformers must focus on streamlining their changeovers. This segues into the importance of training —don’t skimp on training. When investing in QDC equipment, take the time to educate employees on how and why it’s used. I’ve seen operators remove some of the equipment because they don’t know how to use it.

Maintenance and care of the QDC equipment also is critical. One all-too-common and poor practice that I’ve witnessed is technicians, during a changeover, removing the clamps from their T-slots and hanging them by their hydraulic lines. Don’t do this—the hose can wear and break within a month or two. Purchase and use clamp holders designed specifically for this purpose. Also, when using bolster extensions, plan accordingly and designate a convenient place to place the extensions so that they don’t get hit by a lift truck or otherwise become damaged. Lastly, a clamp’s hydraulic seals do not last forever. Keep a few spares on hand. A few hundred dollars’ worth of maintenance-and-repair equipment can save thousands of dollars in press downtime. MF

 

See also: PFA, Inc.

Related Enterprise Zones: Automation, Tool & Die


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