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Tools/metallathe/induction: Difference between revisions
→Level 2 Induction
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Expands the range of objects that can be worked
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|The 3 tool types
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* HSS/Tungsten-Steel tools are robust, easy to use and can be reground indefinitely but are limited by temperature and best used with copious coolant/lubricant if making heavy cuts.
* Brazed carbides can be sharpened to a razor edge and take fine cuts but are the most brittle and although they can be resharpened we can't do it at the lab, they have to be sent away.
* Cemented carbide insert tools are hard, wear-resistant, usually have a anti-friction coatings, they're less brittle than brazed carbide but still chip easily but paradoxically hate being used too gently, because of their coatings they're not as sharp as the others.
* Carbides must never EVER be stopped inside work, and cooling should be flood or not at all, never intermittent.
* Using the wall chart to select the proper spindle speed for each tool/material combination
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Need to know the proper tool for each job
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|Using taps and Dies
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* Taps
** Semi-profile and full profile, taper-second-plug types, correct drill sizes.
** Holding in the wrench, using the dead-centre to steady and align
** Proper lubricant using the gelled or liquid CT-90
** Chip-breaking pattern on use (1 in, 1/2 out)
** Care to avoid cross-threading
** Feeling for proper depth on blind holes
** Caution about brittleness - your workpeice is lost if you break a tap
** Cleaning off when done.
* Dies
** The flush and taper sides, using closed and split dies and the advantages of each, correct rod sizes.
** Holding in the wrench and adjusting split dies.
** Being even more careful about proper alignment, hard to start sometimes.
** Holding in the tailstock holder, proper lubrication, chip breaking, cleaning
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Tapping and threading are pretty common operations but with the brittleness of the tools there's quite a few gotchas people need to be warned about, so it's neither
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|Tool Inspection
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* Checking the tools with magnifying glass and the inspection microscope upstairs, what good and bad looks like on each of the 3 tool types.
* Recognising wear and polishing on HSS tools and when it's OK and when the edge had been lost.
* Looking for wear or more likely chipping on brazed carbide, the procedure for getting them re-ground if they need it.
* Inspecting inserts, recognising the colour change where the coating has been worn off, looking for chips on the edge and working out if they're going to affect your work and if the insert needs changing, looking if the chip-breaker is still OK or is clogged/worn.
* Letting people know that breakages are inevitable and although we should try to avoid them, but they're not THAT expensive when they happen.
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Bad tools will give bad results!
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|Changing carbide inserts
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* Where the torx keys and new inserts are kept, releasing the old insert and disposal/Recycling.
* Thorough cleaning of the insert seat including a solvent wash if needed and cleaning the screw-thread.
* Examining the holder for condition and damage.
* Using the supplied bolt, substitutes are NOT allowed.
* Handling the inserts carefully and avoiding being cut by them, inserting in proper orientation, screwing down with a suitable level of force.
* Checking using the microscope that it's seated properly and ready for use, checking for insert snugness.
* If you just broke an insert, checking the workpeice for carbide fragments.
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At this level we can expect people to change an insert, but not to grind their own tooling
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|Tool shapes for various operations
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* The different tools we have focusing on the carbide insert ones, covering Roughing, Finishing, Shoulder, Beveling, Parting, and Boring.
* Do not including grooving, knurling, threading, or custom profile tools.
* Describe how they are used and for what operations, cover the effects that support or lack of and size and angle of tip have on strength and depth of cut that can be done.
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At this level people should be shown how to do a wider range of operations and the tools they require.
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|Differences between roughing and finishing
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* Roughing removes bulk material rapidly, for getting parts down to approximate size and shape.
** Cuts can be large and fast within the capacities of the lathe and tooling.
** Is usually done with copious coolant and care must be taken not to cause excessive distortion of workpeice or tool
** No consideration is given to surface finish
*Finishing brings the part to final size and gives a higher surface finish
** Are done at higher speeds
** Cuts are smaller although you need to be aware of minimum cut sizes using the carbide insert tools
** Coolant may or may not be used but cutting fluid should be.
** Finishing cuts are also used on small workpeices or when the tools are far-extended to reduce cutting forces.
* Using the wall chart to pick the proper spindle speed, note that flood coolant increases allowed speed 20%.
* Reiterate the signs of rubbing and what to do about them.
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Covering the 2 basic types of cut and when to use them▼
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| Using the slide locks
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* Locating each of the slide locks, how you use them when parallel turning and facing to get smoother and more accurate cuts.
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Accurate surfacing
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▲Tapping and threading are pretty common operations but with the brittleness of the tools there's quite a few gotchas people need to be warned about, so it's neither induction nor intermediate
▲Using the wall chart to pick the proper spindle speed, note that flood coolant increases allowed speed 20%. How chip type changes with speed and DOC, mention how the different types of swarf are formed and how to change from one to another. Reiterate the signs of rubbing and what to do about them.
▲Covering the 2 basic types of cut and when to use them
▲Using the slide locks Locating each of the slide locks, how you use them when parallel turning and facing to get smoother and more accurate cuts. Using them to avoid accidental moves when working but caution that leaving them on will cause instant damage to lathe if the power-feed on that slide is engaged. Accurate surfacing
Selecting Feeds and Depth-of-Cut Chip loading and how it affects chip form, Normal depths of cut for HSS/Carbide tooling and typical feed rates that should be used. The values listed here are deliberately conservative and faster material removal rates may well be possible depending on circumstances, as always, listen to the lathe, watch the chips and adjust speeds and feed accordingly.
For the carbide insert tooling
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