[GreenKeys] [External] FANUC PPR Paper Tape Punch - oil vs. grease

[Jones, Douglas W]

From: Eric Moore [mooreericnyc at gmail.com] -- Tuesday, July 7, 2020 10:45 AM

> Hello, you may remember I was seeking a paper tape punch recently.
> https://www.dnc-electronics.co.uk/wp-content/uploads/2017/03/a13b-0117-b001.jpg

A nice clean looking brick of a machine!

> I see that it has grease on the metal joints, but it seems like light machine oil like starrett oil is recommended for machines like this.

It's new enough that I think you can assume that the grease is factory original and not accumulated from preventative maintenance in years since.

If you have photos to show you which joints were greased, re-grease those joints.  Use fine oil on everything else that looks like lubrication would help.  As a general rule, any lubricant is better than none on joints where there is any sliding contact.  The wrong lubricant will do less damage than none.

Grease where light oil is recommended may slow things down, springs that would normally return things to idle positions may not operate quickly enough, causing, for example, mispunches caused by pawls not being pulled back quickly enough.  Extended running like this can do damage because a partially engaged pawl means that the pressure on the engaged portion of the pawl is higher and may lead to breakage (if only a narrow edge of the pawl engages, that edge can end up chipping off).

My manuals for Teletypes and Flexowriters have detailed lubrication instructions.  Typically, there's set of lubricants -- light oil, a grease, and an oil-grease mixture, for example, and then diagrams showing for each contact point in the system, which lubricant to apply to each point.

Lacking such manuals, there are some simple guidelines:  You want grease on high-pressure bearings where light oil would not provide a thick enough film to prevent wear.  You want light oil on sintered bronze bearings where capillary action keeps the bearing lubricated.  You want grease where motion will fling the oil out of the way, you want light oil where viscous grease will slow the return action of light springs.

           Doug Jones
           jones at cs.uiowa.edu