Drop ball testing

[Kurt]

I suppose this will illustrate what a huge dork I've become, but some friends and I were discussing the FDA testing requirements for drop ball testing and came up with a question.

FDA Regulations require that drop ball testing be done using a 5/8 inch, 0.56 ounce steel ball dropped from 50 inches using an apparatus weighing not less than 27 lbs.

My question is this: How much force is actually hitting the lens at the moment of impact? Also, what unit of measurement are we using here? :hammer:

[Darryl Meister]

The force isn't really as important as the kinetic energy the impact creates, which is roughly 0.20 joules.

Best regards,
Darryl

[Kurt]

Thanks! Now I can sleep. I'm so pathetic.

[nawsman]

I inquiring as to where may find a 5/8 inch, 0.56 ounce steel ball, I have just taken over responsibility of all lab equipment and the steel ball for our tester was missing. can you maybe give me some sources. I have tried to call the manufactor (OMI) but I have been told they're out of business or the phone number no longer works. Please help

[Jacqui]

Contact BPI they may have one.

[nawsman]

Is there a differents in size of Steel ball

Safety Vs non safety glasses

[Jacqui]

Yes, safty Rx's require a 1 inch ball.

[AdmiralKnight]

F=ma? :D

[Judy Canty]

Try JA Optronics. Not only are they a great family business, but they're OB members as well.

Member search = JA OPTRONIC

[chip anderson]

Try a manufacturer or supplier of ball bearings. You might even try an automobile repair shop, most have quite a few deceased (often with several balls in the race that are quite virginal) bearings in various diameters laying around.
Same is true for machine shops.

Chip

[Chris Ryser]

Place of origin:United StatesModel No:00087-158Fob Price:US$ 349~495 CHARLOTTEPort:CHARLOTTEPayment Terms:CREDIT CARD OR PREPAIDMinimum Order Quantity:1 Piece/PiecesSupply Ability:20 Piece/Pieces per MonthPackage:PACKAGE: INDIVIDUALLY BOXEDDelivery Time:1-10 DAYSBrand Name:SOS

Sentilles Optical Services A Division of Senasco Inc http://www.alibaba.com/member/jbshst.html

[Barry Santini]

I may still have an army ballistics study that evaluated the (residual)impact resistance of glass, ophthalmic lenses *after* they had been drop-ball tested.

It was done both for heat temnpered and Chem-tempered lenses, if I remember correctly.

Results: In no case was the impact resistance not decreased as the result of drop ball testing. It is a destructive test.

Barry

[obxeyeguy]

It is a destructive test.

Barry

Especially when it doesn't pass.:hammer:

[Chris Ryser]

It is a destructive test.

Especially when it doesn't pass.:hammer:

In 1991 the AR coating community was in fear and uproar because the FDA wanted every AR coated lens to pass through th the test and they were fully aware that many lenses wouldnot pass it.

..........then somehow the matter got dropped and all forgotten and today nobody even mentions it or talks about it.

[HarryChiling]

Wouldn't the standard be easier described as 20 grams for a height of 1 meter?

[chip anderson]

If the ball is passing down a tube as pictured and the tube is not a great deal larger than the tube, you could not clean the tube and soon everything would pass. Don't think Federal Regulations state anything about free fall being required. One could even cheat with some stratigicly placed magnets and "be in compliance."

Chip

[HarryChiling]

If the ball is passing down a tube as pictured and the tube is not a great deal larger than the tube, you could not clean the tube and soon everything would pass. Don't think Federal Regulations state anything about free fall being required. One could even cheat with some stratigicly placed magnets and "be in compliance."

Chip

A little maple syrup down the tube, I get you. ;)

[RT]

No, actually the regulation is fairly precise.

The regulation at 21 CFR 801.410(d)(2) describes the exact procedure for the impact test. The regulation states, "In the impact test, a 5/8-inch steel ball weighing approximately 0.56 ounce is dropped from a height of 50 inches upon the horizontal upper surface of the lens. The ball shall strike within a 5/8 inch diameter circle located at the geometric center of the lens. The ball may be guided but not

restricted in its fall by being dropped through a tube extending to within approximately 4 inches of the lens..."

[Jbird]

Try COLTS Laboratories, I believe they have a listing on there website.

[Chris Ryser]

Try COLTS Laboratories, I believe they have a listing

No, actually the regulation is fairly precise.

No need for more consultation.........RT has given the exact FDA rules that even a testing lab has to follow.

[LKahn]

If your plastic lens has the proper coating, it will pass without difficult.

[Leo Hadley Jr]

I agree with the above post that it is a destructive test.

Look at a treated glass lens through a polariscope and then drop a steel ball on it. Look at it again and guess what, it looks a lot different. Drop another steel ball on it and guess what....Its either shattered or about to shatter. Now mount that lens and put it over your eye.

Would you feel safe?

:hammer:

[Metronome]

Delete.

[Chris Ryser]

Baush & Lomb


Kirk Optical

These units can only be found on the used equipment market.