With engine bays getting smaller, transmissions adding more gears, and every part on modern vehicles getting more complex, designers have been putting more holes onto every component. Those features can be tough to machine economically when dealing with short cycle times and access problems, but modern drill body designs and inserts can address some of those challenges.

Iscar’s Sumocham drill line.
1) Is a pre-hole necessary when drilling greater than 5xD?

Traditionally, when drilling more than 5xD, you’re required to make a pre-hole with the same size drill and matching point geometry and at least half the depth of the diameter – 1xD is better. Iscar’s HCP insert point geometry is self-centering and self-starting, eliminating the pre-hole and drill 8xD to 12xD, going straight into the full depth of the hole, penetrating the material at 100% feed rate and rpm.

Iscar HCP drilling inserts can eliminate pre-hole drilling and allow users to drill at a steeper angle without pre-treating surfaces.
2)  Can you drill on angled surfaces without a pre-hole or spot face?

Standard thinking is if you don’t have a good, flat surface, you need to make a pre-hole, leaving your surface footage and rpm at 100%, but decreasing your feed rate. If the angle is mild, you can use our standard drilling heads – ICP for P-class materials, ICM for M-class materials, or ICK for cast iron – but you’re limited to a maximum of 6° before you must make a spot face or pre-hole. Our new HCP and QCP inserts allow you to drill on an angle up to 12° before requiring pre-treatment. Most angle applications are less than 12°, so the new inserts can eliminate pre-treatment steps.

3) You mentioned High Feed tooling. What is a High Feed tool and how does it differ from the typical milling tool?

High Feed tooling uses an extremely shallow depth of cut when compared to conventional milling techniques/tooling. The main idea is to achieve high material removal rates at, you guessed it, high feed rates. This is made possible by the extreme lead-angle design, which creates a much thinner chip; we must compensate for this by increasing the feed rate. High Feed tooling functions at feed rates 10x to 12x higher than typical milling tools running at conventional cutting parameters.

4) How can machinists increase drill penetration rates?

The limiting factor is how quickly you can evacuate chips. We have twisted coolant throughout the tool, allowing us to have a strong center core while maintaining a deep chip gullet.

With minimum quantity lubrication (MQL), which we’re seeing a lot more of in automotive, especially in Europe, you’re often using air pressure. It does affect your drilling parameters. You’re going to have to drill at a lower penetration rate because you’ve got to get those chips out. If you change the speeds and feeds, you can evacuate the chips if you have as much air pressure as possible.

Twisted coolant flow in Iscar Sumocham DCN drills supports high-volume chip removal.
5) Can replaceable tip drills increase productivity?

In most cases, a customer can live with 0.001" difference in lengths. By having an indexed tip, you’re replacing the cutting tool on the machine instantly without going to pre-setting. Any time you can keep a change at the machine, you reduce the time it takes to change a tool and you save money.