How are piston rings made?

The type 98 oil ring invented by the Teetors was a really interesting ring. It was a Cast Iron spacer, 2 steel rails and the expander spring behind. The trick was cutting the slots, my wife usually did packaging or inspections but one time when work was slow in the 70's she had to do that job (they called it groove). It was basicly an indexing lathe with a set of milling cutters that were plunged in to the rings at several locations. The rings were "potted" on an arbor with spacers, compressed and clamped down. If you screwed up and cut a slot where the gaps were it was all scrap. Sometimes it would kick a pot out if you didn't get it seated correctly, that was pretty exciting. The Teetor brothers as Perfect Circle are also responsable for teflon valve guide seals, the speed control(Speed-o-stat,before electronics were a real factor), perfecting the chrome plating process for rings and also perfecting centrifigal casting for cylinder liners.

They used to use a lot of local vehicles for testing various piston ring and cylinder liner setups, I had a 4010 JD with test rings in it. That set ran 2600 hours and only burned a total of 7 quarts of oil (they changed it for me every 150 hours, weighing what went in and came out every time).

By the way the marks that indicated which side went up were very important. Most of the oil control rings had a slight taper grind on the face and it needed to be cone side up so on the down stroke it would scrape the oil off the cylinder wall insted of riding over it and letting it get into the combustion chamber.

Also most PC rings that were one piece were ran through "face lap", a machine that ran the rings for a number of cycles through a cylinder sleeve like machine with a fine grit compound. This is where you worked if you had low seniority. I don't know if they pioneered this process but it was responsible for eliminating the extensive break in period for new engines.

Sorry for running on, but thanks for the memories you brought back.

As I recall the rings were made of gray cast iron in the shape of a flat continuous ring. These rings were then run through a Blanchard grinder to grind the sides of the ring flat, parallel, and smooth. The ring was then put in a "Cam Turn" jig and outside of the ring was machined into the shape of a piston ring in its unassembled state, or in other words cam shaped not round. The rings were then placed in a fixture and a slot was cut opposite the high point of the cam to form the ring opening.

The rings were then compressed and placed in yet a fixture which was the size of the finished bore for which the rings were being made. The rings were clamped between its top and bottom surfaces and the inside diameter was then bored to its finished size.

Cast iron oil rings were compressed, clamp on a spindle and that spindle was placed on an indexing head. The head would index the stacked oil rings and a set of milling cutters would cut the oil grooves in the ring indexing between cuts to the next oil groove location.

All Ford rings had to be subjected to an addition step called "Pot Lapping" where the ring was placed in a pot the diameter of the cylinder for which it was being built. The assembly was bathed in lapping compound and the ring was cycled up and down in the bore the to make it perfectly fit the correct bore size.

Cast iron rings with locking ends were finished in the same manner as ther other rings however the final step was to have female machine operators run each end of each ring through a milling operation to cut first one locking tab on one end and then flip the ring over to cut the mating tab on the opposite ring end.

This is an over view of something I did 43 years ago so much has changed in that amount of time. I don't believe Muskegon Piston Ring is still in business.

After going through the Cam Turn and Inside Bore, the next stop was my station - the Finish Mill which had a traveling table with an arbor of rings which run under a spindle carrying a small saw blade which trimmed the slot. It looked much like a radial arm saw with a tiny blade. The slot width was controlled to about 2 or 3 thousandths of an inch with shims behind the precision jig that held the rings. Production averaged about 48,000 rings a night on my station. I still remember how sharp the rings were - always had some cuts.

The next stop for the rings was the most boring operation in the factory - the Pip Marker. That put a dot on one side of each ring so you could tell which side was up. Apparently that was important for the final operations and for installing the rings.

I forget what we called the final operation that machined the rings to ten-thousandths of in inch precision, but the machines generated a lot of heat - not a good job for the middle of the summer.

There was also a chrome plating operation for some rings, a heat treating oven that I occasionally ran, degreasing tanks, and other operations.

It was a mind-numbing job - enough to convince me to go off to college, and a career in computer technical support.

I had a chance to visit Oldsmobile's engine plant near Lansing in 1985, and what a difference! Most machines were computer controlled, automatic conveyors moved all parts, and it was operated by a fraction of the workers that would have been required in earlier years.

The St Johns factory is still open, but is owned by Dana, now. I'm not sure how much longer it will be there, I've heard rumors that another outfit is trying to buy Dana. I think the Muskegon plant is closed.