Manufacturing Miniature Balls

Thomson Precision Balls, a Danaher company, specializes in the manufacture and supply of miniature balls.  Miniature balls are usually considered to be anything below 1/16”.

There is a basic difference in the way miniature balls are made when compared with larger balls.  Larger balls are headed into a ball with a Saturn ring or flash while miniature balls are slugged or chopped.

The first step for Thomson to manufacture a miniature ball is to inspect the wire.   A majority of the miniature balls produced are made from wire in coil form.  The wire is inspected for size and surface finish, and no pits or seams are acceptable.  The wire end is then examined for internal structure.

Once the wire has been approved the actual manufacturing process starts.  The wire is then slugged ( cut) into cylinders, making sure the length is correct and the ends have a square clean perpendicular cut, with no burrs accepted. This is the fastest operation producing about 100,000 pieces per hour .  After slugging, the parts are placed in a machine called a flasher where the parts are flashed between two plates, one stationary, the other rotating  such that  the corners of the cylinders are removed. Stock removal at this stage is approximately .006” per hour,  varying with the size of the ball.  After flashing the balls move to a ball grinding  machine where they are soft ground.  Stock removal here ranges form .008” to .010” per hour.

For all the flashing , grinding and lapping the machines are similar in design, one stationary and one rotating wheel or plate.  The difference is in the material that the plates and wheels are made of, the coolant  used, and any additional compounds that maybe  added for cut rates.

Following soft grind the balls are cleaned and dried and then put thru a roll grade operation. The roll grader consists of two precise rotating rolls set apart such that the balls pass over the roller and  only balls sized within established tolerances fall through the gap, while rejects are dropped out.

Balls are then heat treated to ensure proper hardness and reduce retained austenite, and also to meet a particular customer’s specification.

The next operation after heat treat is  hard grind. Stock removal at hard grind is approximately .006” per hour,  followed by another clean , dry, and roll grade .

Next step is lapping-  a rough lap and a finish lap. Rough lap removes about .0006” and improves the sphericity  to at least  25 millions and in most cases 10 millions. A screening or another roll grade depending on the size of the ball is preformed before moving to  the finish lap.

Finish  lap is a light polishing removing .0002” of stock and improving the sphericity  to 3  to 5 millionths.

Barrel cleaning and passivation, if a  stainless steel ball is being produced, is next before they proceed to a centrifuge dry and them on to final  inspection and final gauging.

Final gauging is preformed in our  A2LA certified lap to be sure all standards and requirements are met  before packing and shipping.