Annular cutters are relatively simple tools and are a standard consumable for many users, but like all consumables, the rate of consumption can be significantly improved by treating them well for a better return on your money, so here’s our list of top tips and tricks to help you get more holes from every dollar. Click each title below to read more in-depth!
The first tip should come as no surprise to most, but we’re still surprised by how many operators don’t ensure their drilling machine is firmly located and completely stable. Any movement will risk damaging the cutter and reduce the quality of the hole. With mag drills, check that the surfaces of both the steel you’re clamping to and the bottom of the magnet are clean and free from debris, rust and other contaminants. The steel should also be a minimum of 10mm thick to ensure good magnetic adhesion, thinner steel is unlikely to create a powerful enough clamping force.
If it’s difficult to ensure that the mag drill is completely stable and tightly clamped, a machine with automatic cut-out will help, taking the load off the cutter as soon as a reduced clamping force or magnet movement is detected. It may not completely eliminate damage all the time, but it will greatly reduce the chance of cutters breaking and also avoids overloading the drill motor.
It pays to always ensure that the arbor and mounting system is equally rigid and clean, as just like with the magnet, any interference between the contact surfaces will potentially introduce vibrations & movement, resulting in wear and damage to the cutters (and possibly the holders as well).
Feed rate is an important factor in drilling, if it’s too slow the cutter will effectively just be rubbing on the material and that’s going to build up a lot of heat that will dull and damage the cutting tool (and possibly harden the material too). Of course, too fast a feed rate is also going to damage the cutters, so you need to maintain a steady, firm rate that keeps the cutters penetrating without pushing too hard.
Feed rate is only half the story, of course, as it goes hand in hand with speed. The chart shown below is a good guide for selecting the right speeds for your jobs – try to get as close as you can to these recommended speeds but always keep in mind that these are generalisations, the specifics of your job may mean that you need to use different figures to get the best results.
Clear chips and debris from the cutter after every cut to avoid packing the flutes. The heat and pressure that can build up by flutes not effectively evacuating removed chips is guaranteed to put unnecessary stress on your cutters and may lead to chip binding and premature cutter breakage.
Always use coolant! Use your machine’s through-coolant system if available, it’s designed to help you get the best from your tools. If you aren’t sure how much coolant you should be using, err on the side of caution by going for more, never less. If you’re using soluble coolants, run them rich and if it gets awkward to deliver the coolant to the cutting zone, try neat coolants or wax-based product .
If you’re going to be drilling holes in more than one stage, i.e taking the cutter out of the hole and re-inserting it, always apply coolant to BOTH hole and cutter to minimise the chance of thermal shock when the cutter goes back into the hole
Always use the ejector pin and when the pin starts to get less effective (i.e. when you notice poor slug ejection starting to happen), change the cutter – it’s a sure sign the tool is worn.
Sharp cutters perform better than dull or damaged ones, which will be more likely to overheat or snag, leading to breakage – get them sharpened as soon as you notice their performance dropping off.
Always run-in new or freshly sharpened cutters – use a slightly reduced feed rate for the first few holes. They will last significantly longer if they have chance to ‘wear in’ rather than going hard with them when they are brand new.
Cutters are available in either HSS or carbide-tipped form, so how do you know which is the best choice for your job?
High Speed Steel is a hard material (typically 60+ Rockwell C) and our Reisen cutters generally have a higher cobalt content, making them hard enough for the steel they’re typically drilling into. Because HSS cutters consist of a singe material they are hard throughout, making them more prone to shattering under incurred stress (which is why stability is so important).
On the other hand, a carbide-tipped cutter can use steel that is not so hard, meaning it is more forgiving of any stress it is subjected to. The trade off is that the tips, being very hard, take the forces and in situations where vibration or shock are applied, the teeth will chip, break or even shatter off the cutter body. Both HSS and TCT cutters can be resharpened if they are dull or slightly damaged, but both become uneconomical to repair if the damage is heavy.
