Christa Kettlewell
Allied Machine & Engineering

From industry publications to social media to talk on the shop floor, the conversation currently surrounding the manufacturing industry is rising carbide costs. This conversation is forcing shops to take a closer look at their holemaking operations and find ways to navigate these rising costs without sacrificing productivity or quality. However, even as alternatives to solid carbide tooling are evaluated, the focus should not just be on tooling cost but, rather, where carbide adds the most value and where it might be overused. While looking at the initial cost of a drill is often the first inclination, there are many different factors to consider amidst current market conditions: diameter of the tool in terms of cost per hole and material, tool life, changeover time, machine uptime, and inventory burden. So, the question ultimately becomes when do replaceable insert drills make more sense than solid carbide?

Answering this question requires close examination of productivity. Sure, solid carbide drills can often run at higher penetration rates, particularly for smaller diameters, and penetration rates are what typically correlate to productivity. However, productivity means more than just running the tool faster. Replaceable insert drills exceed the productivity of solid carbide in terms of the replaceable nature of the cutting edge—simply unscrew the insert, put in a new one, and the machine is back up and running. Solid carbide tools on the other hand must be taken out, put back in, and often reset in the collet to retouch off depths—not to mention regrinds when the tool wears out. In connection with this is the excess inventory of solid carbide versus replaceable insert tooling. There is less money tied up in tooling crib inventory of a small carbide insert than a solid carbide drill. Therefore, the decision between solid carbide and replaceable tip is bigger than cutting speed, and reframing the mindset of what productivity means can aid in shop-floor efficiency.

Aside from productivity, there are other key areas where replaceable insert drills create the most value. One of the strongest arguments for replaceable insert drills is for longer length applications because the body is steel with carbide only at the cutting edge. Ultimately, as length increases, replaceable insert drills become more attractive. This is also true for certain diameters. Holes that are a half inch and up are where replaceable insert solutions start to make more practical sense. While solid carbide can still excel here, the economics begin to shift. Lastly, larger, deeper applications heavily favor replaceable insert drills. In applications over one inch and 7xD and up, replaceable tip systems are highly competitive on both cost per hole and penetration rate; the tool can be run close if not at the same penetration rates as solid carbide. Nevertheless, the attractiveness of replaceable insert drills really depends on the end user’s priorities. For smaller runs, shops may focus more heavily on initial purchase price while larger production environments shift the focus to cost per hole.

The question of performance may still be a concern when comparing drill types, but the advances in replaceable tip technology have helped close the performance gap. Not only are there custom body diameters that better support the tool and create less insert overhang, which more closely replicates what a solid carbide drill does, but there are also options for body specific holders where the insert is fully supported all the way through the cut. The steel holder design also provides more flexibility due to the myriad number of inserts you can use from ISO-specific geometries to super cobalt inserts to custom insert geometries. That same flexibility carries over to custom tooling where replaceable insert drills can also compete in step drill applications. Whether the operation calls for chamfering or counterboring, special replaceable insert bodies can be designed to produce a variety of forms while reducing reliance on solid carbide tooling.

Still though, there are applications where solid carbide has the edge. At smaller diameters, shops may prioritize speed and simplicity, making the economics of a replaceable tip system less compelling. Additionally, if rigidity is of extreme importance or penetration rates can’t be compromised, then solid carbide might still be the better option. Ultimately, there are advantages and disadvantages to both solid carbide and replaceable insert drills, but as the price of carbide continues to rise on a frequent basis, the question remains: how can shops get ahead and justify their carbide usage?

There’s no one-size-fits-all solution to what the manufacturing industry is currently facing, but carbide strategy matters now more than ever. Rising carbide costs are not simply a purchasing problem; they are a manufacturing cost issue. Shops that respond effectively will evaluate holemaking based on total cost, productivity, and smart carbide allocation. And while replaceable tip drills are not a universal replacement for solid carbide, there’s no question that they become compelling when carbide prices rise.