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Tools/metallathe/induction: Difference between revisions
Some info on titanium
imported>Stever |
imported>Stever (Some info on titanium) |
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* discontinuous turning
* Altering the change-gears and speed limits (540)
*
* Using the dial indicator to maintain position on complex cuts
* Calculating feeds&speeds for other materials not on the standard table
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(Some stuff we lack parts for yet)
* Advanced materials - Titanium/Magnesium alloys/HSS (We don't
** Titanium
*** Grades of titanium available, unless otherwise specified Ti6Al4V is the most common
*** Properties of titanium and how they affect turning
**** Poor thermal conductivity - Rapid heat buildup and critical need for coolant
**** Heat goes into material, NOT chips - Even worse heat build up
**** Thermal hardening, if you let heat build it'll harden and become un-turnable
**** High toughness, Steel tooling is possible if razor sharp but carbide is preferred, brazed carbide can be very effective
**** Flammability, swarf is a serious danger
*** High toughness and tendency to hardening means low tool speeds are required, 15m/min is a common choice
*** Excellent set-up rigidity is vital, use centers or steadies wherever possible, be very aware of work and tool stick-out and tool position relative to the slides
*** Normal cutting depths, 0.5mm for roughing, 0.3mm for finishing, DON'T try to take skim cuts if you can help it
**** Spring passes are to be avoided unless vital, and if they are vital be aware you'll only get to make one spring pass before the work is too hardened to turn any further
*** Feed rates, 0.1mm/rev is a good starting point, but experiment and watch your chips closely
**** Chips probably won't break no matter what you do, aim for tight curls, beware of birds-nesting as it's a serious fire risk
*** Avoid discontinuous cuts if you possibly can, they're very damaging to tools
*** Cuts must be decisive, you must not dwell with tool in contact with work, rubbing causes rapid hardening
**** Cuts should be done using power feed whenever possible as it's hard to achieve proper evenness manually
**** Cuts should enter at full speed, no gentle lead-ins
**** Once cut completes then the tool must be backed away from the work immediately, it cannot rest at the end position, not even for a second
*** After every cut, remove the swarf to a safe location where it can't be ignited from the work, and inspect the tool
*** Drilling Titanium
**** Uncoated HSS are often ineffective
**** TiN/TiAN coated drills are OK
**** Cobalt or Carbide drills are best
**** Peck drilling is essential as it's impossible to cool the drill tip effectively
**** Pecks must be small (2.5mm or 0.5 x drill diameter, whichever is less)
**** Drill must be fully withdrawn between pecks to be cooled by the flood coolant
**** Check for work heating every peck
**** Watch your chips carefully and re-sharpen the drill the moment there's any sign of degradation.
*** Parting off is possible with carbide tools, but only if the center is drilled, full-depth parting is difficult
**** If the part-off is deep it may be necessary to change spindle speed during the operation.
** Magnesium
** HSS/Hardened materials
* Advanced tooling that exists but we don't have, Cubic Boron Nitride, Diamond (We don't carry this tooling)
* Workholding using all chuck types and recovering concentricity (Need lathe-dogs to demonstrate the catchplate)
* Using reamers
▲* using fixed and travelling steadies (Don't have a fixed steady yet)
* turning between centres (Need lathe-dogs to demonstrate the catchplate)
<div id="level4"></div>
== Level 4 induction ==
We welcome suggestions for what should be covered in an advanced course if we're able to run one
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