Page 33 - MetalForming November 2009

simulations should be employed. Perhaps the most significant state- ment made by your customer was that sandblasting the die components seems to solve the problem, if only temporarily. Sandblasting the die components effec- tively retards the flow of material by increasing the friction between the die surface and the sheetmetal. Unfortu- nately, as the material is drawn across the pressure pad hundreds and thou- sands of times it is smoothing the sand- blasted surface, which in turn decreas- es the friction (requiring the tool to be
sand blasted again).
An alternative to sandblasting would
be to minimize or eliminate the lubri- cation between the die and sheetmetal surfaces in the area of the tool being sandblasted. This may require that lubrication be applied only to one side of the sheet. Altering the amount and location of the lubricant will change the friction coefficient in the affected areas of the die, which the sandblasting also accomplishes.
Finally, I am assuming the die was designed correctly to begin with. This means the draw reduction ratios (per- cent reduction), die radius, punch-nose radius, pressure-pad calculations and die-polishing techniques were correct and are being maintained throughout production.
Q: In 1977 I enrolled in a tool and die apprenticeship. Since then I have worked as a tool and die maker, die designer and estimator. For the past 10 years I have freelanced until a lot of my customers went out of business. My question is pretty straightforward: Is there still any future left in this industry?
A: Yes. Without question there is a very exciting future for our industry. The question that really needs to be asked is, “What will our industry look like in the future?” It is important for us as an industry to answer this ques- tion appropriately because it changes how we train our apprentices.
For example, 10 years ago the
beginning of a die design involved unfolding the product geometry into a blank, determining the best blank orientation for feeding and optimal material utilization, and then creating a strip layout with all of the process steps. Today, the beginning of a die design involves acquiring material properties, converting product geom- etry into finite element models, defin- ing frictional conditions, applying restraining forces and establishing boundary conditions.
ditions. Many of the technologies for this approach already are available; but, who do we have that is qualified to implement it?
Further out into the future, per- formance requirements for stamping die will be directly linked to the per- formance requirements of the stamp- ing. Advanced computer programs will concurrently design the metal stamp- ing and its corresponding die, based on an “optimization target.” Possible tar- gets might include minimum part weight, maximum performance, least cost for the die based on the number of stampings to be produced, or the adaptability of the die to make multi- ple stampings with very different fea- tures and/or dimensions.
In the future, dies will be designed
and built using what I call, Perform-
ance-Based Die Engineering Strategies.
The premise is that we design and build
dies in a manner similar to that of prod-
uct designs. Design criteria will be based
on performance requirements such as
loading conditions, deflections, veloci-
ties, wear, vibration and thermal con- foundations for such a system. MF
SUCCESS
Not convinced? MIT and other uni- versities already are beginning the
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