Tool Holder and Collet Maintenance

How often should you clean or replace CNC tools and collets? December 27, 2007

We've been running a Komo Mach II for about two years now. We've been very good about keeping up on the hourly/daily/annual maintenance, but I will admit have not been following along with tooling maintenance.

We've been using the same tool holders (HSK 63) for two years now. I've seen recommendations to replace these on a yearly basis. That would be quite expensive for us, as we have over 30 of them. I do chuck them into a lathe every 3 months or so and clean the rust off of them. Is it really necessary to replace them? They still seem to perform fine.

As for collets, I only replace them when edge quality becomes unacceptable. As with the tool holders, is it necessary to replace them on a set schedule, or do most of you go by feeling?

Along the same lines, would you ever consider calling up an empty tool holder and spinning at a very low rpm, as opposed to chucking it into a lathe, to clean it? As with a lathe, this can be dangerous, but would this be an alternative using good, common sense safety?

I guess to sum it all up in a nutshell, who follows the recommendations religiously and who just goes more by observation in terms of replacement?

Forum Responses
(CNC Forum)
From contributor J:
I have no hands on experience with routers, but I have been researching what the costs to own one of these will be. Last week I attended a Biesse One-2-One and they had an interesting seminar on tooling. You probably do not have rust on those tool holders. They said that brown coating that looks like rust is a buildup caused by small imperfections in the fit of the taper or tools out of balance that in turn cause vibration and leave the brown buildup. We had this with an ISO taper spindle on our shaper. I also thought it was rust and used emery cloth to clean it off. They said using an abrasive to clean it is the worst thing and will ruin the holder or spindle. They recommend a solvent to clean it.

Another thing they talked about was the importance of not using range fitting collets. If you do use them, only use one size shank in them. They recommend always using a torque wrench. There was a lot of discussion about tool balance and how it relates to the spindle life of the machine. They said it is best to balance the holder and tool as a unit. I didnít realize the cost to replace a spindle cartage is about 20K. They said slightly unbalanced tools can shorten the life by 75%.

From contributor G:

As mentioned, use a cleaner to take off the so-called "rust" ("fretting" is the term). To replace these every year is expensive and really not required. If the toolholder is sticking and the solvent does not take off the fretting, you will need to replace.

Collets, on the other hand, should be replaced after 600+ hours, again depending on the type of cuts you do. Panel processing, 600-800 hours. Heavy machining would be sooner, 400-500 hours. Tools are usually more expensive than a collet.

From contributor C:
The collet is more important than the tool. They should be replaced 2-3 times a year depending on how much and how fast they are run. Holders, once a year is fine if they are kept up. The nut is very important as well.