I'm a total newbie living in Manchester with a sudden need to get up to scratch on CNC machining. Basically, I'm working on a research project (UAV/drone) which requires components to be cut from 1.5 x 400 x 500 mm and 2 x 400 x 500 mm carbon fibre composite boards using a CNC router. Unfortunately, I've recently found out that a couple of our workshop guys are off on long term sick leave (hopefully not carbon fiber dust! ), meaning that there is a several month backlog on jobs on our CNC equipment (this basically kills my project deadline). I do have access to alternative facilities (ShopBot PRS standardCNC), but will only be able to get limited training on the equipment. I realize that CF is not a straight forward material to machine in terms of quality of finish, tool life and health and safety, so I thought I best come to the experts for advice.
The setup does have an extractor and is in a well ventilated area, and I intend to use a respirator with Hepa filters and disposable clothing during operation. The CNC does not have any intrinsic cooling for the end mill as far as I know (i.e. air/water jet) so this may be a concern given the abrasive nature of the material. However my main concern lies in the choice of end mill needed to cut the CF. I know that the pros use diamond coated tooling, but I cannot really justify the expense (I will probably need 1 mm and 2 mm (and possibly 3mm) cutting diameter to cut the different levels of detail in the design [see attached]). Also, given that this is a one off, I don't want to pay £50+ for bits when they could still snap anyway. The cutting run will probably be a few meters max (nb: cutting sheets in the diagram are 400 x 500 mm).
I was thinking of using a carbide two flute end mill (see below) running at 15000 RPM with a feed rate of ~ 500 mm per minute.
Carbide End Mills 2 Flute - Arc Euro Trade
I have read that people have had some success using diamond cut router bits and diamond burrs in CF, but have not seen any results close up. I do not mind ruining a few carbide bits, as long as I have enough to complete the production run of two sheets. I do, however, require the edge to be decent (no chips, splinters), and want to avoid clouding the CF with overheated tools.
So in summary, I'm wondering....
· What is the best low cost tool to achieve the job in hand and how many will I need to complete it (specific products would be very helpful).
· What is the best feed rate-RPM combo to use
· Are there any DIY methods to keep the bit cool
To be honest, I would be happier having a third party do the cuts, but I just haven't budgeted for this eventuality (I'm on a doctoral grant which is pretty lean and not being able to use in-house facilities is really killing me).
Apologies for the length of this post, but I would greatly appreciate any advice that members would be able to offer me
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