OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
5. Methods for preventing wrinkling in deep drawn parts
5.1. Using a Blank Holder
In most deep drawing processes, a constant blank holder pressure is applied throughout the entire drawing action.
Variable blank holder pressure, however, has been employed with some success. A pneumatic or hydraulic blank
holder cushion can vary the blank holder pressure linearly over the stroke of the machine. A numerically
controlled (NC) die cushion can be used to provide a variable blank holder pressure over the course of drawing
action. An NC die cushion can dramatically increase the allowable die cavity depth while preventing both
wrinkling and cracking.
5.2. Die Cavity Design
Choosing a flange radius that is just large enough to prevent cracking or can minimize the potential for wrinkles.
Additionally, considering minimizing the part complexity and any asymmetry can also help. Incorporating a
multi-step drawing process offers a variety of advantages in preventing wrinkling in deep-drawn parts. Designing
the blank geometry to minimize excess material can reduce the potential for wrinkling. Adjusting the sheet metal
grain in an asymmetrical design to minimize the compound of grain stresses and the general stresses of the deep
draw process is something to take into consideration [24].
5.3. Other Factors
Lubricants reduce the friction between the blank and the punch and die cavity and can be liquid (wet) or films
(dry). Generally, they are applied to the blank before drawing. While lubricants can facilitate the metal flow into
the die cavity, consider increasing the blank holding force to account for the reduced friction. Today, computer
aided design and finite element modelling are used to create part and die designs and to simulate the deep
drawing process, significantly reducing the costs of tooling and labour in the design process.
6. Conclusion
The present work investigate and analyses facts like in spite of all precautionary measures there are macro and
micro level chances of denting, cracking, and wrinkling which needs to be diminished using probabilistic
approach. Component & deep drawn die have been modeled. The IGES data exported easily to the Fast Form
software. The component namely Silencer Protector is modeled in CATIA & the Fast Blank software has been
utilized for the blank development. Accordingly die and punch system has been modeled and developed too. It
was also observed that the wrinkles generated on the deep drawn parts are found in the thin sheet component and
that wrinkles are generated when die and punch parts not matched and aligned suitably. For enhancing the
quality of wrinkle free oriented drawn component hard chrome
plating on die and punch was preferred. It was observed that wrinkle is strong when analysis is performed
without blank holder. Based on the observations some methods for preventing wrinkling in deep drawn parts like
using a blank holder, die cavity design, lubricants, finite element modelling suggested.
References
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Distributions for Deep- Drawing Processes with LS-Dyna and optiSLang, Weimarer Optimierungs- und
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[2] Matthias Mihm, Department of Mechanical Engineering Northwestern University, Evanston, IL 60208,
USA January 1999.
[3] Die Design Handbook, 1955, ASTME McGraw Hill Book company Inc., New York.
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[6] Cao J, Wang X. An analytical model for plate wrinkling under tri-axial loading and its application.
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