Hi Joe:
There are a few pieces of information missing from your quest. I don't know Aloris well enough to know what size square shank tools to recommend. Also, Titanium is a pure metal element, but you are probably working with a titanium alloy. Most common alloy is 6Al4V and is used to the greatest extent in the aircraft industry and medical industry. It is typically heat treated and commonly ranges from 34 to 44 Rc. 6Al4V can also catch fire when machining without coolant and with a worn tool. So, be careful not to allow chips to accumulate on and around your machine. Safe speeds are 125 SFM for roughing with Carbide, 150 SFM for semi-finishing and finishing. On an enclosed CNC machine with huge coolant volume and pressure, 150 to 250 SFM are common with the proper carbide grade, topography, coating and edge prep. On a manual machine we just cannot be that aggressive. Start with feed rates of .003-.006 IPR, but chip control is very difficult. You won't see nice little 6 and C shaped chips. So be careful and cautious. If your material is 99.9% pure Ti, it cuts like butter but only go after it with a sharp tool without a hone. The .003 feed mentioned above wouldn't be very successful with a tool that has a .002 hone at its edge. The hone would deflect the part, cause major heat, and probably strain harden the part surface. If you wish to use coated inserts, do not use a CVD coated insert. CVD coatings, unless it is extremely thin, MUST be applied to a honed edge because of its tendency to build up on the cutting edge where the Flank and Rake Face meet, further enlarging the hone. PVD coatings are best suited for their oxidation resisting properties. AlTiN and TiAlN PVD coatings are predominant in the this field of application and excellent for Austenitic stainless steel as well. 300 series stainless steels such as 303, 304, 316, 316L (great for welding, "L" does not mean Lead, it means Low Carbon), 321, 347, etc). These PVD coatings can be applied directly to a dead sharp edge and have little effect on edge sharpness. Most of the major carbide cutting tool companies have adopted the ANSI/ISO conventions and use common grade naming and target material groups as part of their material and application targets. Most major manufacturers have quality products that you can apply to Ti and SS. If you stick with the major carbide manufacturers (Kennametal, Widia, Sandvik, Mitsubishi, Sumitomo, Iscar Walter, Seco) they create grade designations to target specific materials. The letter "P" in the application range suggests that the grade is for Steel. "M" = Stainless Steel, "K" = Cast Iron, "N" = Non-Ferrous, "S" = Super Alloys (Inconel, Titanium, Hastelloy, etc) H = Hardened materials. Also, a number between 1 and 50 applies to a grades bulk toughness. The higher the number the greater the toughness. A grade used for heavily interrupted cutting would have a big number in the grade name. Likewise, a finishing grade would have a low number to indicate that its primary use is for light un-interrupted cutting and fine finishing, indicating that it lacks toughness but, has excellent wear resistance. For tough steel applications, look for a P-40 grade, a steel finishing grade look for a P-05 or P-10 grade. Kennametal has simple grade designations. Their Steel roughing grades are KCP05, KCP10, KCP25. K-Kennametal, C-Coated, P-steel, 05 Finishing and so on. Widia, WP15CT... Widia, P-Steel, 15-general un-interrupted turning, CVD coated, T-turning. Look at some manufacturers literature and it should start to make sense.
The Inserts from Kennametal that will work superbly for your application is a CNGP431 or 432 Best grades for Ti and SS are K68 (un-coated), K313 (un-coated), KC5025 (PVD TiAlN) (best for manual machine) or KC5010 (PVD TiAlN). The "G" in the third position indicates that the insert is ground and has a sharp edge. The "P" in the 4th position means tat the insert has a 10 deg. positive edge. Put it in an MCLNR124B tool holder and it will be a 3/4x 3/4 square shank tool with an OAL of 4-1/2". This is a negative rake insert, which means that the side of the insert is neutral or 90 degrees. The holder will tip the insert 5 degrees negative for radial clearance, but since the top of the insert is molded 10 degrees positive the result is a 5 deg. positive top topography. This will be quite free cutting and will deliver excellent tool life, finish and significantly reduce burrs. Widia has a similar grade in the same geometry with a slightly different coating. CNGP431 or 432 grade TN10U (PVD TiAlN/TiN) and TN15U uncoated at a very attractive price. Widia is sold through local distribution and Fastenal.
I don't know what boring bar size you are after, but for small bores from 5/8" on up, a CPGT3251 or CCGT3251will do nicely. These are different pocket geometries for either insert. You will find the largest selection of bars using the CCMT/CCGT style insert. These inserts are the same: the CCMT is simply Molded to size (+/-.002) and will have a honed edge, weather it is coated or not. The CCGT is Ground and has a size tolerance of +/-.001 but needs to be ground to achieve that tolerance. These inserts will have some geometry on the top of the insert that will typically be identified at the end of the insert geometry numbers such as "LF" = Light Feed, or "FP" which indicates Finishing Positive but these are not part of the ANSI/ISO description.
I know this is a lot of information but its a start. Titanium is not difficult to machine, OK sometimes if you have to peal the beta layer off the OD of a large forging, but if you are working with bar stock, pay attention to speeds and feeds and use a sharp edge and you will have success. Remember to clear chips. If you are going to tap this material, be sure to find a titanium specific tap. Ti has a tendency to spring back on the clearance of a standard tap and want to lock it up. Ti specific taps have additional clearance built in to reduce this tendency.
Good Luck!
Best Regards, Gary
