When you're faced with a decision between solid or indexable drills, the answer isn't whether you need one or the other: It's when each type becomes appropriate and on which types of jobs. Many shops miss out on improved drilling performance because they're unsure of these choices. Think through your materials, operations, hole size and drill performance when you make your selections, and you'll find the right choice for each situation.
Beyond material specifics, keep these considerations in mind during your tool selection process. First, solid drills typically run faster than indexable drills because they provide two effective flutes instead of one, and their split point offers good positioning because it centers and locates well. By contrast, the center insert on indexable drills saves time because it eliminates the need for a pilot hole.
An individual solid drill creates only one type of hole and tolerates a limited number of re-sharpening operations. An indexable drill handles a wide range of complex drilling situations with versatility. For example, to drill into solid stock; step over and punch holes; and create half holes, holes in corners, inner interruptions and cross holes, you need an indexable drill.
Size forms another criterion that helps you choose between solid and indexable drills. Solid drills rise in price as their sizes increase, whereas indexable drills put one insert's four edges to work creating large-diameter holes with minimized costs per cutting edge. Conversely, at small sizes, indexable drills become impractical because their screws and inserts shrink to sizes that become difficult to handle. When it comes to roughing and finishing, solid drills typically are used to produce finished holes, while indexable ones tend to excel in hole roughing operations.
Surface finish also plays a role in choosing drills. Although you may need to follow up both solid and indexable drills with a secondary operation to obtain very high-quality surface finishes, indexable drills typically work for roughing operations, requiring the use of a boring head and a reamer to obtain tighter tolerances. Solid drills typically achieve around 40 micron Ra in a single pass.
For fast productive holemaking, special optimized geometries on solid carbide drills are well suited for specific material groups. The FEEDMAX™ -P solid-carbide drill from Seco Tools, for instance, is designed for iron and steel, and capable of running at extreme speeds and feeds.
In the case of indexable drills, you change inserts and chip breakers, instantly turning them into sharp, ready tools that can target a range of materials. Seco’s recently re-engineered Perfomax® indexable drills deliver higher drilling parameters and longer tool life along with exceptional chip control and evacuation.
