Boron-Doped Diamond Thermistor for Thermal Sensing of Diamond Coated

“If it's a complicated profile with varying features, like a chamfer, undercut, taper, or curves, all of these features on a workpiece typically suggested that you will need multiple axes of motions,” said Sarang Garud, product manager, turning/drilling/boring, Walter Tools, Waukesha, Wis. “This is where reverse profiling makes sense. It’s also very common for ID boring to have internal profiles, so we see reverse profiling in those applications too.”

In traditional turning operations, the cuttings tool moves towards the chuck and spindle rather than away from it. This is because, typically, the cut should always travel in the strongest direction. A typical setup will feature a chuck, which is where the workpiece is held tightly, which is the strongest part of the machine tool. All of the cutting forces are absorbed in the axial direction into the chuck and spindle of the machine.

Recent internal testing with the new Harvi Ultra helical milling platform achieved over 100 minutes of tool life running at 47m/min with a 0.12mm/tooth chip load. The radial depth of cut was 25mm and the axial depth of cut was 76mm.

In many cases, the part itself will determine if reverse profiling makes sense. If it’s a simple cylindrical workpiece that requires the removal of 0.05 in. of material, then it doesn’t make sense to profile.

“There is tooling designed to both profile and reverse profile,” he said. “This is known as multidirectional profiling. If this method is employed, cutting cycle times can be reduced.”

The challenge with using reverse profiling is ensuring that the workpiece doesn’t get pulled out of the chuck from the axial forces. Part geometry and setup play significant roles in determining if reverse profiling makes sense.

Says “At higher radial engagements, the insert is cutting the material for longer time which creates more heat at the cutting zone. The heat will not go into the titanium chips, like when milling steels, so controlling the heat is critical. Lower cutter speeds at higher radial engagements is a good practice. At lower radial engagements, higher cutting speeds can be achieved,” said Scott Etling, director of global product management for Indexable Milling at Kennametal.

“If coolant is used, it should always be applied to direct chips away from the cutting area,” said King. “Cutting geometry is on the trailing side of the cutting edge, which also is the side of the toolholder body. Cutting depth and chip clearance all need to be verified.”

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“When profiling, you are using the 35-degree angle going towards the spindle, using one cutting edge,” said Garud. “When reverse profiling and moving away from the spindle, you are using the other cutting edge. That’s a significant tool life advantage. Secondly, it can save a lot of time because you are not rapiding out then coming back in.”

Kennametal has responded to requests for a new carbide grade to machine titanium 6Al4V at higher cutting speeds, rather than increasing feed rates or increasing depth of cuts that result in increased cutting forces on the workpiece, fixtures and machine spindles.

Lindsay Luminoso, sr. editor/digital editor, contributes to both Canadian Metalworking and Canadian Fabricating & Welding. She worked as an associate editor/web editor, at Canadian Metalworking from 2014-2016 and was most recently an associate editor at Design Engineering.

The grade has an advance cobalt binder that provides exceptional thermal fatigue resistance, without sacrificing the toughness customers have experienced with KC725M or X500. In addition, Kennametal’s proprietary AlTiN/TiN coating enhances the wear resistance at the cutting edge.

“The edge condition on the KCSM40 grade still looked great. And we are getting many other fantastic results. In one face-milling operation on a hardened steel wear plate, the number of passes was reduced from 234 to just 22,” said Etling.

The depth of cut with any type of profiling tends to be much smaller than roughing, medium, or finishing depth of cuts. However, the depth of cut should be more than the corner radius of the insert.

“Turning (OD) and boring (ID) are terms used to change the diameter of a plain cylinder (OD) or hole (ID),” said Ken King, chief operating officer, THINBIT, Fort Wayne, Ind. “In profiling operations, the cutting tool is used to create shapes and complex grooves in a workpiece. Profiling and turning/boring operations are similar operations. Generally, we define reverse profiling as moving the cutting tool away from the chuck or collet while cutting.”

This is why setup is one of the biggest factors determining success for reverse profiling. Without a strong and proper setup, both the tool and workpiece face forces that can make this operation impossible to complete.

For example, many components requiring complex profiling, including contours, chamfers, and undercuts, tend to be produced at high volumes where there is a high demand for reduced cutting time.

“This tilts the cutting edge quite a bit, which means that chips become very thin using that same feed rate,” said Garud. “To make up for that chip thinning, the feed rate needs to be increased, almost sometimes 50 to 60 per cent higher than traditional profiling. This can be an advantage because you are taking out material that much faster and potentially expanding the tool life using both sides of the insert.”

Luminoso has a bachelor of arts from Carleton University, a bachelor of education from Ottawa University, and a graduate certificate in book, magazine, and digital publishing from Centennial College.

While both types of profiling are equal in cutting parameters, the biggest drivers for choosing reverse profiling are chip evacuation and finished part geometry. THINBIT

The target cutting speed for KCSM40 in Ti6Al4V was 53m/min at 327cm3/min 327 metal removal rate for 60 minutes. Not only does KCSM40 achieve this, but has also offered milling titanium at speeds up to 85m/min at a lower radial depth of cut.

Called KCSM40, the company has taken the toughness of its most popular milling grades KC725M and X500, and increased the thermal crack resistance and wear resistance that will enable customers to machine at higher cutting speeds, without sacrificing that original toughness.

“Reverse profiling is very good for avoiding chip packing in blind bores,” said King. “It also makes chip evacuation easier as it naturally directs chips out of the bore.”

“It’s really an opposite thought process for programmers and operators,” said King. “Pull from chuck versus push toward the chuck changes axial forces, and chips flow differently. Reverse profiling pulls on the part and pulls on tools, which could result in pulling the cutting tool out of its holder or pulling the stock out of the chuck.”

For more information contact Kennametal South Africa on TEL: 011 748 9300 or visit www.kennametal.com

Lead angle plays an important role in chip development. For applications using a V-style insert with a conventional profiling lead angle is 107.5 degrees, that lead angle suddenly becomes 35 degrees with reverse profiling.

There are many advantages of reverse profiling. For example, in many cases, a V-style insert is used for profiling. These diamond-shaped inserts are very sharp and have a very narrow 35-degree included angle.

“There are a few things to watch out for,” said Garud. “It’s important to be careful when going up to a shoulder when moving away from the spindle. You also have to manage the exit of the tool so that you are not crimping chips between the shoulder and the insert. Depending on the condition, you can back off from the cut in a 45-degree angle when you are rapiding out. Then you can come back and do a finishing pass later, especially if you have multiple passes going toward the shoulder.”

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If your workpiece has a complicated profile with varying features, like a chamfer, undercut, taper, or curves, you will need multiple axes of motion. Walter Tools

“Machine tool capabilities are important to understand,” said Garud. “On the hardware side, a rigid setup is important. You don’t want long overhangs. The rest of it can be managed through depth of cut, corner radii, and basic process parameters. A CAM program also will likely be necessary. If it is a simple undercut, this can most often be done manually. But typically with profiles, the complexity requires a good CAM system.”

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The experts agree that reverse profiling is often associated with ID work. Part of the reason for this is because chip evacuation can be challenging in a bore. Birdnesting that occurs on the OD is manageable. However, with birdnesting that occurs with ID work, chips don’t easily come out and you risk damaging the insert because it will recut the chips.

King added that while both types of profiling have equal cutting parameters, the biggest drivers for choosing reverse profiling are chip evacuation and finished part geometry.