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grinder to make perfectly round balls

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  • grinder to make perfectly round balls

    On the FAG bearing website, it says:
    "In 1883, Friedrich Fischer who was the founder of FAG bearing invented a spherical grinder in Schweinfurt, which can create exactly round ball. The invention of FAG Bearing was recognized as the basis of the rolling bearing industry."

    Wikipedia says: "Friedrich Fischer (1849–1899) from Schweinfurt, Germany, is considered the father of the modern ball bearing, having invented the process for milling standard bearings in 1883." "His machine allows steel balls to be ground to an absolutely round state for the first time – and in large volumes. Thanks to this innovation, he lays the foundation for the entire rolling bearing industry. Thus, the worldwide success story of the ball bearing begins in Schweinfurt." " ... 1896 Friedrich Fischer applies for permission to build a new plant near the train station in Schweinfurt – a step towards a new industrial dimension. The new plant produces 10 million balls per week. The company is incorporated one year later.

    What kind of machine was this - was it really a grinder? - or was it more of a sphere lapping machine, the kind used in making mirrors?
    Last edited by Elninio; 06-08-2013, 02:30 AM.

  • #2
    The pictures I've seen are of two counter-rotating plates with the balls between and a grinding/lapping media added depending on the stage of finishing.

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    • #3
      If you rub a bunch of similar sized sort of round balls between two parallel coaxial disks together with an appropriate abrasive it will automatically produce perfectly round balls all the same size. It's like making surface plates by rubbing three together in sequential pairs, The only thing they all have in common is a flat, or in this case spherical balls, and same size surface.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Close to spherical, but not exactly. To obtain "perfect" spheres they would need to be manufactured in orbit exactly where the earth's & moon's gravity cancel out each other.

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        • #5
          There has to be a bit more to it than rubbing balls between two flat plates. The balls start out imperfect, they would tend to find the easiest way to roll. Some balls at least would roll on their least diameter and wear into a shape having a narrow cylindrical tread with roughly spherical ends.

          Or am I missing something?

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          • #6
            Chipmaker has it right. The balls were machined to as close as conventional machining methods could get them, then they were clamped between two oscillating plates with a lapping compound. My understanding was that this lapping was not a quick process---It took two or three days.---Brian
            Brian Rupnow

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            • #7
              I don't really understand how gravity would affect the roundness as the balls are revolving randomly. This page shows the basic steps:
              http://www.steelballindia.com/manufacturing.html
              There's a cartoon here as well at 2:00
              http://youtu.be/eGyoMuE4gDQ



              Igor
              Coincidentally just back from Schweinfurt
              Last edited by ikdor; 06-08-2013, 11:13 AM.

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              • #8
                Originally posted by ikdor View Post
                I don't really understand how gravity would affect the roundness as the balls are revolving randomly. This page shows the basic steps:
                http://www.steelballindia.com/manufacturing.html
                There's a cartoon here as well at 2:00
                http://youtu.be/eGyoMuE4gDQ

                Igor
                Coincidentally just back from Schweinfurt
                While minute, it causes enough out of roundness that it can be measured. You may want to read this: http://articles.latimes.com/1991-05-...g-manufacturer

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                • #9
                  I bet the Allies in World War II dropped tons and tons of bombs on that plant.

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                  • #10
                    Originally posted by Dr Stan View Post
                    While minute, it causes enough out of roundness that it can be measured. You may want to read this: http://articles.latimes.com/1991-05-...g-manufacturer
                    That's a fun experiment. It's not of any use for bearings though as a hollow sphere will be full of tensile stress....

                    Igor

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                    • #11
                      I don't remember where I saw it, but they have discovered ball making machines that work on the same principle from at least as early as the Roman period. They were making stone balls.

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                      • #12
                        Or am I missing something?
                        The presence of other balls (more than two).
                        Free software for calculating bolt circles and similar: Click Here

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                        • #13
                          Originally posted by Bill in Ky View Post
                          I bet the Allies in World War II dropped tons and tons of bombs on that plant.
                          Once they got woke up!

                          The story I heard was that a lost German bomber in fog randomly dropped his bomb load in trying to get back home. It seems he unknowingly hit a British ball bearing factory causing chaos and panic. The British distributed their ball bearing manufacturing to various remote places and concentrated on locating and bombing German ball bearing plants.

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                          • #14
                            Sorry, but as far as I remember, it took the USA quite some time to 'wake up' to the German threat to world peace.
                            Richard - SW London, UK, EU.

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                            • #15
                              Originally posted by ikdor View Post
                              That's a fun experiment. It's not of any use for bearings though as a hollow sphere will be full of tensile stress....

                              Igor
                              I'm confused. Are you referring to residual thermal stress resulting from the melting/solidification process?

                              Perhaps large hollow ball bearings could be 3D-printed, then finish ground. But what applications would require them?
                              Allan Ostling

                              Phoenix, Arizona

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