If the CNC machine's operation is critical to the functioning of the company, bring it up with with management at higher and higher levels until the CEO says (usually more diplomatically than my exact wording here)
The IT policy that's in your way is so important that no exceptions are allowed - damn your CNC machine
or, alternatively, tells the VP responsible for IT
Karen, fix this ASAP!!! Efficient and cost effective operation of these CNC machines is critical to our success and your job is to help, not hinder, the company. Henceforth and at the CNC team's discretion, materials and time wasted by reboots of a CNC machine because IT insists it be connected to the intranet will be charged to your department - get back to me by EOB today informing me that the problem is now solved and how it was solved. Remember, the CNC team is your customer, not the other way around.
On the occasions where I have had the misfortune of working at a large corporation with annoying and disruptive IT rules, I've had success with similar strategies. Yes, it's a pain, but I've always gotten the problem solved.
For example, we told customers of our product (a relatively small portion of the corporate revenue but perceived as being a fairly outsized "future" for the company) to disable virus scanning on the directory we cached temporary files in. Yet our IT prevented us from doing so on machines we were using for performance testing/characterization. I never had to go above the IT director level to get that resolved (albeit, I had to rinse and repeat every six months or so as some audit caught the "non conforming" machines).
Or, for another example that's happened at more than one company I was at, is the edict that comes down from IT that
All software not on the IT approved list must be uninstalled from all machines.
At which point I do a quick audit of my dev machines and my group's dev machines and find various open source software (such as emacs, gnuplot, etc) that developers are using that are not on the "approved list" (mostly because IT can't find someone to pay for the product and 'support' - and the deniability that comes with that). I then send the list to IT (ccing the level above the drone whose issuing the edict) asking them to
Please verify that we must uninstall these products immediately. Be aware that, due to the resulting unanticipated decrease in productivity, we will have to extend existing schedule commitments (including those that external contracts are contingent on) so I will need to raise this up to the executive level.
They invariably respond with something like
Okay, for now you can keep these programs installed while we research these products.
I then follow up with
When is the review scheduled for completion?
to which the answer is usually something like (which they just make up having no idea what to do)
I then put an item in my calendar for one month in the future and when that's hit and no update has been received (and it never has been), send off a note along the lines of
I'm checking up on the status of the developer installed product list I sent one month ago - is the review completed and when can I expect to see the results as I need to know so I can adjust schedules we have made, and are continuing to make, based on productivity levels with all of these programs being available.
and usually get a response from someone in IT who dearly wants to stay out of the hornets' nest along the lines of
The review is ongoing, your group may continue using the programs on your list until it's completed.
It's never gone beyond that and no developer in my group has ever had to delete a single such program. Sure, I sometimes have to repeat this process once every year or two, but I've got it down to a science.
Similar techniques have worked in the past to get IT to stop nagging me (and eventually my boss) about me exceeding email quotas (which IT didn't dare enforce by just rejecting email to my inbox so was stuck with "soft edicts"). My boss eventually came to me and asks why he's being bugged about my email quota and I told him "I've x emails in my inbox from the several years I've worked here. From time to time I search through them looking for something from the past. It's true that probably on 10% of the emails in my inbox are likely to be needed, but I estimate it will take me 3 work days to identify and delete the other 90%. When would you like me to schedule that?" and I never again heard from anyone about my email quota and never spent any time purging "unneeded" emails.
Make it an economic argument with evidence (details on the latter is rarely needed - the drones making these rules don't understand how, you, the customer actually uses their "services"). That usually works. Once you've stood up and roared and embarrassed IT a couple times, things get much easier -- but make sure you're standing on firm ground, not just complaining because you "don't need no stinking badges". It is sometimes much more effective to be feared than loved (you can outsource those issues requiring "love" from IT to others when necessary).