While on the tour, Dvoracek saw a demonstration of SW Twin Cutter heads, but the KAISER representative made a point to show that this body could facilitate much more than just common boring jobs. He demonstrated face grooving, balanced- and stepped-boring, and even compatibility with insert holders for back boring and chamfering. That got Dvoracek thinking about a challenging feature that A&L is often called on to produce that requires two different types of tools, and makes for long, complex cycles.

“There are companies that require face grooves with major diameters as small as 0.2 mm,” says Duane Drape, national sales manager for Horn USA Inc., in Franklin, TN. “This is mostly aluminium, but I have had customer requirements to get that small with steel at 50 + Rockwell.”

“Exotic materials are not for production jobs—these are low volume applications,” says Tom Ficker, regional sales manager for Cogsdill Tool Products, Inc., with responsibility for Canada. “The problem with precision grooving in high nickel alloys is that you beat down on the grooving insert almost from the get-go.”

Just in time (JIT) manufacturing, by nature, increases setups and shrinks batch sizes. This puts shops in a bind, because more setups and smaller batches are typically less profitable; but saying "no" to work can be even more painful. The burden to search out creative ways to reduce cycle and setup time in order to realize a profit falls to the shops that commonly perform JIT work and on the shops that can’t afford to turn it down when the opportunity arises.

Solid carbide grooving tools are usually L-shaped. Part of the challenge is that even the non-cutting, or “leg” part has to fit into the bore diameter. Given that the bottom of the L, or the “foot” has to be even smaller, strength becomes an issue, as does the fact that groove depth is limited. As a result, with bores of less than 2 mm in diameter the best tools are now constrained to a groove depth of around 0.2 mm.

How best to approach grooving a small part has a lot to do with the materials involved: repeat, high volume applications tend to be with softer metals, with specialty one-offs applying to higher value applications, often with tougher alloys.

“The cutting process produces pressure on the work piece and on the tool. Controlling the pressure during machining dictates how successful we will be [in producing an effective cutting tool]. We can control cutting pressures by controlling the width of the grooving insert; the wider the insert, the more pressure it will produce. We also grind positive rakes on the inserts to control the pressure and to act as a chip former to control the chip shape and size.”

When grooving small pieces, cutting pressure tends to be relatively high. Aside from slowing feed rates, it can also help to use high lubricity coolants that work well in tight spaces.

Hydraulics, given their need to control pressure, create demand for inside diameter (ID) and outside diameter (OD) grooving seals and threads, as well as relief grooves. In the automotive sector, miniature grooving applications include fittings for air bags and fuel injection components.

When he returned home, Dvoracek reached out to BIG KAISER, the exclusive dealer of KAISER tooling, and explained what he saw on his trip. When Gerard Vacio, BIG KAISER’s regional sales and support engineer, visited A&L, Dvoracek showed him how they were using the combination of a small-diameter, long-projection end mill and a grooving tool for the job. The end mill machined an OD boss and the inside wall of a face groove at the bottom of the boss. The grooving tool then cut the remaining face groove geometry. Dvoracek explained to Vacio that in addition to the time involved with resetting depth offsets to blend the end mill and grooving tool, the end mill was prone to breakage.

“You need the chips to be able to freely get out of the bore and away from the cutting action so they do not interfere with the machining process.”

Vacio agreed with Dvoracek’s initial instinct, that the SW Twin Cutter could improve the process. He also explained that the head’s versatility, whether running as a dedicated tool or only as needed for one of its varying capabilities, fit right in with the JIT work typical at A&L.

As a result, Cogsdill’s tools are better suited to high production lines, an area that has seen some big changes of late. Only a few years ago, small bores were typically 4 mm, but now leading vendors are delivering off-the-shelf bore grooves to 2 mm, with specialty applications going much smaller. This has resulted in new abilities—and challenges—when it comes to grooving very small parts, as well as increased demand.

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So confident it was a match, Vacio offered a no-risk trial of the boring head and Dvoracek agreed. He took the print specifications to the BIG KAISER engineering team and was able to quickly turnaround a ready-to-run solution. The head was configured with two insert holders. The inside grooving tool would machine the boss. Once the face of the part was reached, the outside grooving tool finished the outside of the groove.

“The challenge with grooving is that below 1.5 mm it is difficult to make a tool that is strong enough,” says John Stewart, VP of engineering at Bokum Tool in Madison Heights, MI. “The overall determining factor is: What does a groove look like in a hole that size? If it is proportionally very similar to a larger hole then it is theoretically possible to get very small, but it really comes down to the strength of the tool itself.”

But replaceable inserts, single edge, can still get to some small diameters. More cost effective than a solid carbide tool, they can also deliver better axial depth. That said, solid carbide tools are usually more expensive, toolholders aren’t, and there is a risk the holder might break after a dozen or so uses.

Machining grooves and shallow channels. Example: grooving ball-bearing raceways. Typically performed by tools that are capable of light cuts at high feed rates. Imparts high-quality finish.

“This is a double-sided insert that works well with slow cutting forces,” says Kaufmann. “The GUP insert geometry is advanced and versatile, with excellent metal removing rates.”

One such trip took Dvoracek to Europe to visit a machine tool builder. But, it was a side trip to Switzerland that proved most fruitful. Dvoracek swung through Rǖmlang, Switzerland, and KAISER Precision Tooling’s headquarters in search of insight into how Swiss toolmakers are addressing high-cost JIT production.

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A&L Machine, a shop that serves primarily the energy sector and its often on-demand needs, is always on the lookout for ways to expedite critical processes. For Allen Dvoracek, A&L Machine president, this occasionally means travelling to suppliers for a firsthand look at how their products work.

“This tooling has proven much more durable and efficient than the original end mill setup,” Dvoracek added. “We’ve run more than 10,000 parts and have never had to change an insert. And we’ve only changed the offset once, and that was only because we originally set it on the high side of the limit and decided to put it on the low side.”

“It would be preferable to take an indexable insert into small grooves, because it would be more economical. But you often have to go with a one piece design, using a brace tool with a carbide or carbon steel cutter brazed to it.”

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ID grooving in particular can be an issue with small parts, says Steve Geisel, senior product manager for Iscar Tools Inc., Oakville, ON.

“The grades Iscar uses for our inserts depend on how fast the machine spindle can spin,” says Iscar Tool’s Geisel. “10,000 rpm sounds high but remember you are working with very small parts, around .100 in. in diameter. So that 10,000 rpm with a .100 in. diameter works out to be about 260 sfm…we need to design and produce the insert out of carbide grades with coatings that can run at such speeds.”

A frequent issue is whether or not to go with inserts or solid carbide tools. Inserts can be indexable or have only one edge for single use. Inserts tend to be less expensive, but usually can’t get into the smallest bores, and are not as strong as solid-carbide tools.

Single- or multiple-point precision tool used to bring an existing hole within dimensional tolerance. The head attaches to a standard toolholder and a mechanism permits fine adjustments to be made to the head within a diameter range.

If the chip created by the grooving tooth is wider than the finished groove, then you can minimize the possibility that the chip will stay in the groove. But when it comes to harder metals the challenge isn’t chip control so much as creating the chip in the first place. “At 1.5 mm you need to have a tool that is strong enough to create the chip,” says Stewart. “But from there, with a strong alloy like Inconel, it is relatively easy to control the chip. In the case of aluminium and softer materials, where the chip is continuous, it creates greater headaches because the material balls up.”

Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless band; the two basic types are cutoff and contour band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).

As Vacio had forecasted to Dvoracek, when subsequent batches of the part arrived for finishing, the print didn’t call for face grooving. It wasn’t a problem. The outside grooving insert was simply re-positioned to face the OD boss and reset to the boss diameter for rotationally symmetric rouging (RSS). Two inserts performing the same cut doubled the feed rate, reducing production costs in additional ways.

Geisel concurs with John Stewart that the challenge for tooling suppliers is to make a strong, rigid cutting tool or insert.

Philosophy based on identifying, then removing, impediments to productivity. Applies to machining processes, inventory control, rejects, changeover time and other elements affecting production.

Managing chip generation in tight spaces has always been a challenge, because the smaller the hole the harder it is to get the chip out. One approach is to plum or port the tool to get coolant out. There are also advanced tools, like Kennametal’s AF-GUP insert geometry for grooving and turning, that are specially designed for these challenges.

“Slow feeds can be a good idea, depending on the material,” says Bokum Tool’s Stewart. “With smaller sizes a weaker tool neck will want to deflect, especially with carbide, and with increased distance to the groove, feed speeds need to be adjusted downward.”

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

“The results were immediate and undeniable, settling in at application metrics of 590sf and .002ipr,” Dvoracek said. “We’re getting better parts off the machine sooner, allowing us to get to the next job ahead of schedule. Reducing the cycle time by 22 seconds per part will save approximately 40 machine hours a year on this job alone. That’s 40 extra hours of machine utilization that we didn’t [previously] have because of a fairly simple tooling solution.”

“It is important to keep speeds as low as possible when you have small-sized parts,” says Igor Kaufmann, a member of Kennametal Inc.’s global team for turning tools. When grooving miniature parts, Kaufmann emphasizes that the tools still need to fit axially and apply radial force to the bore. As a result, it is hard to ensure that the tool is strong enough, which then leads not only to chatter issues but also challenges with breakage and chip evacuation.

“As a tooling manufacturer, we are being pushed to produce tooling able to groove in smaller, and smaller diameters. Our PICCO line can produce grooves in diameters from as small as 2 mm (.08 in.) and we can go smaller by special request.”

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“The geometries are not standardized, but there are ways to create space at the head of the tool to promote chip flow,” says Stewart. “Sometimes the actual grooving tooth on the cutting tool will have a chip breaker on it—this will help the chip move out and get flushed with coolant.”

The problem with carbide is that reducing deflection increases the risk a tool will break, so it’s important to preserve the strength of the neck of the tool. Tool monitoring is also recommended, because with small cutting edges it can be hard to see or hear when a tool breaks.

Another approach is to compress chip width, thus ensuring it doesn’t lodge in the groove and result in tool failure. Either way, when it comes to grooving small parts, the combination of slow feed rates, proper tool selection, and a strategy for chip evacuation is the best way to ensure success.

Matt Tegelman is the Kaiser product manager for BIG Kaiser Precision Tooling Inc., Hoffman Estates, Ill. For more information about the company’s boring tools and other products, call (888) TOOL-PRO or visit www.bigkaiser.com.

“If you are cutting to small major diameters on the face, where the grooves generally aren’t that deep, the chips are not an issue,” says Drape. “But in ID grooving applications where the groove is deep into a bore, then we need to get coolant in, and also need to break down the chip so it can evacuate.”