Page 41 - MetalForming September 2010

a wave due to a change in its speed. This is most commonly observed when a wave passes from one medium to another at an angle. We have all experi- enced this when we are at the edge of a body of water. When you dip a fishing rod into the lake, the rod seems to have broken within the water. The speed of light in water differs from what it is in air. This difference accounts for the perceived distortion of the immersed fishing rod as the light waves are bent due to the differences between the speed of light in air and water. The same holds for a straw immersed in a glass of water. The straw appears to be broken due to the refraction of the light.
So who cares? What could the above possibly have to do with in-die sensing? Everything! Oil and/or coolants, even in minute amounts of it, may cause make- or-break optical sensor applications as the light is refracted unexpectedly. Dust, shavings, galling, etc. can cause light to improperly reflect off the target’s sur- face. Vibrations of tooling and/or parts may cause unexpected blurry reflec- tions, leading to nuisance stops as the target goes in and out of focus.
It is paramount that one be sensitive to the effects of focus, reflection and refraction when working with photo- electric sensors of all types. As we saw in the previous installment of this series, color is nothing more than the vibra- tions of photons. This too can be quite challenging in some applications as the photoelectric sensor may be sensitive to variations of target colors. Coupled with focus, reflection and refraction, it then is understandable why I have advo- cated for decades the need to properly simulate the sensor application, first and foremost, on a test bench. To forego the bench test and simply mount the photoelectric sensor directly from its box and into a die, may be, at the very least, a most frustrating exercise in futil- ity. Always bench test first. MF
The Tooling Challenge
As an automotive parts supplier, Cowles experienced punch breakage causing 6 to 7 stops per 20,000 parts,
run on a 250-ton press at 35 strokes/min. Severe galling on the sides caused the punch ends to actually rip off as they would
weld themselves into the material strip on the upstroke of the press. One week of downtime for 20,000 parts.
“We can actually re-sharpen the punches for continued life whereas previously they broke and were a total loss”
Whyn Pelkey, Engineering Manager of C. Cowles & Company New Haven, CT
The Phygen Solution
FortiPhyTM UltraEnduranceTM Coating has given C. Cowles & Company:
• Up to 7x longer punch life with high abrasive-wear resistance
• Spectacular lubricity – no more problems with the material catching & breaking the punches
• Saves downtime – parts are now completed without shutting down the press, removing the complicated tooling and replacing the broken punches – now an inventory of coated punches is on the shelf
• Punch edge stays sharp during the production run and allows re-sharpening as required
• Visit www.phygen.com/Success_Cowles.html for the full story
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METALFORMING / SEPTEMBER 2010 37
Phygen Coatings, Inc. / Toll Free 888.749.4361 / phygen.com / email: tech@phygen.com