Ways to get more life out of a tap. Most ways to increase the life of a tap relate to changes in usage of the tap.
Use the Right Cutting Fluid
A good cutting fluid, sulphurised or chlorinated, for use on steel and cast iron components, and a lighter fluid or neat cutting oil for use on aluminium and non-ferrous components. Make sure the cutting fluid is applied before the start of tapping, and reapplied on long material. The HSE’s guidance on the safe use of cutting fluids provides useful information on both the tap life and operator safety aspects of their use.
Drill the Pilot Hole to the Correct Size
If the pilot hole is too small then the tap will have to remove too much material from the work piece, which can cause rapid wear to the cutting edges. Use a tap drill chart to establish the correct diameter of the pilot hole to use for the type of thread being cut. A hole that is even 0.1 mm under the nominal diameter can place excessive load on the flutes of the tap.
Match Speed and Torque to the Material For Electric Tapping Machines, see https://www.cotswold-machinery-sales.co.uk/roscamat-tapping-machines/electric-tapping-machines/roscamat-tiger-electric-tapping-machine/.
Tap speed increases with the ease of the material being machined. Hard materials require slower speeds, e.g. stainless and other very hard alloys will blunt or break the tap within a few holes of mild steel. Set the torque clutch low so that the machine disengages from the tap before the tap binds.
Clear the Flutes During the Run
Swarf can soon pack into the flutes of the tap, causing excessive friction and heat to be generated. Clearing out the flutes during the running in of the tap to the full hole depth, will help to prevent the swarf packing into the flutes, and in particular in blind holes where all the swarf can pile up.
Store Taps Properly Between Jobs
Rolling taps in a drawer can easily be chipped by being knocked against other taps. Keep your taps in a rack, on a roll, in a tap case, or even in the original plastic case. A single chipped edge can, within a short space of time, bring about a severe deterioration in thread quality, on an electric tapping machine that is capable of going through a number of taps very quickly.
Keeping all of this in mind will extend the life of your taps as well as guaranteeing quality threads.
