Or
Anyone who has spoken with Danielle Toner, production manager of site drilling equipment manufacturer Archway Engineering, about the company’s use of a drill sharpener would wonder why every factory does not use one. When the savings are understood and, bearing in mind that drilling is the most common machining process, the argument in favour of investment becomes compelling. A US-made Darex XT-3000 for repeatedly re-grinding carbide and high-speed steel (HSS) drill bits to as-new condition was delivered by sole UK sales agent 1st Machine Tool Accessories to Archway Engineering’s Elland factory in July 2023. By November 2023 it had already paid for itself, as Toner had not purchased a single new carbide drill in all that time to replace broken or damaged bits. The saving was between £700 and £1500 per month, according to the work going through the factory. “We didn’t previously send drills out for resharpening, so we discarded worn bits,” she explains. “The cost was significant, especially in the case of solid-carbide drills. One component we regularly machine involves using a 160 mm long, single-flute carbide drill and we previously needed four to complete the part. If we ran out of bits, we couldn’t finish the job until the next drill delivery, which delayed the assembly of our products. She adds: “Now, we simply resharpen a bit four times and we’re certain that the component will be finished on time. New carbide drills cost around £165 each, so the saving is considerable and contributes to lower production costs.” This example is by no means exceptional. Another job requires three new carbide drills to make two parts. In a different process, an HSS taper-shank twist drill must pass through 30mm thick EN19 high-tensile steel. A so-called TC shoe made from S355 hot-finish stainless steel tube is drilled in up to 16 places using a split-point, single-flute carbide drill that requires repeat sharpening before the component comes off complete-machined. Toner explains that some bits can need resharpening a dozen times or more, depending on their length, with no loss of tip quality. It takes about 60 seconds to sharpen the point, or maybe a little longer if it is necessary to grind past a chip on a cutting edge. It happens quite often due to the toughness of workpiece materials, and also because of a frequent need to drill cross-holes at various angles into the wall of tubular components. This task has a tendency to damage the cutting edges of a drill as it breaks through. HSS jobber drills from the assembly department also see regular sharpening, which Toner describes as “a massive saving”. It requires the replacement of the 220-grit diamond wheel used for sharpening carbide drills for a 180-grit CBN grinding wheel. The process takes about five minutes, so batches of around 20 HSS bits are set aside and undergo resharpening at the same time. 1st MTA demonstrated the XT-3000 at the company’s Elland factory before Archway Engineering purchased the unit, together with an attachment to enable the sharpening of bits up to 30 mm diameter. The company can process left- and right-hand drills, while attachments are available for sharpening step drills, countersink and spot drills, and others with a 90° point. Standard sizes of carbide drill used regularly by the company include 8, 10, 12 and 14 mm diameter, and up to 6xD in length, although the Darex machine accommodates bits from 3 to 21 mm diameter in normal use. The Darex resharpens bits in a three-step process. An operative places the drill in a finger chuck and sets the length of protrusion at an alignment station. Carbide fingers enter the flute to fix the rotational orientation before the operator tightens the drill in that position by rotating the chuck clockwise. The grind motor starts and, at a second station, the drill undergoes sharpening on both sides while clamped in the same chuck. In an optional final operation, the chuck holding the sharpened drill is presented to a third station for point splitting to shorten the chisel line and lessen the force required for drilling components. “The savings that the Darex XT-3000 brings makes it an obvious investment, once you realise the benefits – we just wish we had done it much earlier,” says Toner. “Our Darex sharpener paid for itself in less than half a year, after which the ongoing monthly savings are continuing to increase our profit margin on all jobs that require drilling operations, which is most of them.” She concludes: “The sales arguments that 1 st MTA make are difficult to ignore. We also purchase Chick work-holding products from them, which have doubled productivity on one of our machining centres. In addition, 1 st MTA has provided us with a new chuck for one of our lathes.” More information www.1mta.com