Esco Tool introduces a family of right-angle, welding-end prep tools designed for highly alloyed, small-diameter tubes that require precision beveling CCMT Insert prior to welding.

The Esco Ground MillHog Beveler is a right-angle-drive inner diameter (ID) clamping tool that features a push-pull clamp and release mechanism that engages and disengages easily. Ideal for beveling tubes and small pipes with a high percentage of chrome, this tool is said to produce precision welding-end BTA deep hole drilling inserts preps without cutting oils and comes in pneumatic, electric and battery powered models.

Enabling users to achieve X-ray certifiable welds without hand grinding, the Esco Ground MillHog Beveler is suited for tube and pipe from 0.5" ID to 2.25" outer diameter with 0.5" thick walls and only needs a 1.5" radial clearance. It has totally sealed construction and can be used in any orientation.

タグ ：

#Carbide

#Turning

#Insert

It seems that in many corners of the metalworking world one sees trends away from the specialized and toward the more generalized. In automotive manufacturing, for example, the big, dedicated, transfer-lines are giving way in many applications to flexible, modular units that can be effectively used for families of similar parts and then re-used for a whole new family of components.

Then there's the idea of machines that turn/mill or, depending on your perspective, mill/turn, which is helping general metalworking job shops and production shops to complete in one setup what took many operations across different tools to machine. And of course there'Cutting Inserts s the machining center, which combines several independent machining operations such as milling, drilling and tapping into a single, one-stop processing center.

Likewise in the cut itself, where the work of metalcutting actually gets done, there have been advances in multiple operation capability from cutting tool builders as well. An example of this is the grooving cutter for turning.

In this article we'll look at how the application scope for these cutters has expanded beyond just grooving and cut-off. We'll also look at the milling cutter equivalent—slotting tools—and discuss how these tools are being applied in new and different ways.

To find out what these tools can and cannot do, we talked to Horn, USA (Franklin, Tennessee) about how to use grooving and slotting tools in turning inserts for aluminum applications that fall outside of what has been their traditional niches.

The advent of the indexable insert grooving-tool has delivered huge benefits to shops that use them. Advances in carbide pressing technology allow chip breakers and various geometric configurations to be imparted onto even very small width cutters.

The payoff for shops has been better quality both in size and surface finish, not to mention significant increases in cutting speeds resulting in faster cycle times.

During virtually any plunge feed grooving operation, tremendous cutting forces in the form of heat and stress are generated at the tip of the insert. Insert design goals are directed to overcoming these factors. Increased tool life, accurate dimensional repeatability and better surface quality are the results.

The relative contact area between the grooving tool and the workpiece is very narrow. Grooves down to 0.010 inch can be cut with indexable insert tools. Grooves can also be large. In some applications, groove widths of 1.75 inches are plunge cut using an insert with the same width.

Regardless of the groove width, all plunge-grooving operations basically operate in the same way. A Z-axis feed creates axial forces that are directed into the insert edge. The edge is supported (Horn's holder supports 80 percent of the insert's length) by the tool holder body which, in turn, is held in the turning center tool turret. Ultimately, the forces, which on plunge cuts are pretty much straight-line, get channeled into the machine tool base.

There are many standard and special insert sizes, shapes, coatings and substrate combinations available for grooving. Cutting toolmakers have covered plunge grooving well.

However, many shops are extending the use of grooving cutters by performing some turning operations, which is side cutting, with the grooving insert. Moving from a single axis plunge feed to an X-Z axis combination is where shops really see some production gains by extending the versatility of grooving inserts. But there are some process considerations to examine before ripping a contour or turning a face with a grooving tool.

Unlike plunge grooving, which works to the mechanical strength of the insert and holder, turning along the workpiece axis has the opposite affect. Turning exerts radial or side forces on the insert and holder that are trying to bend or deflect the tool. The relatively thin cross section of the grooving tool provides little mass to offset this tendency toward deflection.

Horn and other grooving toolmakers have designed inserts and holders that allow for the deflection from turning without a loss of precision or performance. This is done in several ways.

On combination grooving and turning inserts, geometry is designed and then pressed into the blank creating free cutting in both axial and radial directions. Relief angles on the side of the insert allow chip clearance during side cutting operations. Free cutting geometry reduces cutting forces. Reduced cutting forces reduce deflection.

In most applications where these inserts are applied, the job requires cutting between shoulders. Usually when the distance between shoulders is too large for a single grooving insert to be plunged, turning passes between the shoulders are necessary. Side turning also produces better surface finishes on the sides and bottom of the cut than plunge cutting.

In these cases, Horn recommends a minimum grooving insert width between 0.098 and 0.400 inches. Wider is better for side cutting with a grooving insert. And even with a stiff tool setup, there are some programming considerations for side cutting as well (see box).

By its nature, the grooving insert is a tricky shape to grab. This is especially true in smaller widths. It's long and narrow because the cutter is used to plunge deep between relatively narrow shoulders. This shape, unlike a triangle, square or round insert, doesn't provide a large surface area on which to clamp.

Even in plunge cuts, forces are trying to twist the insert out of its seat in the tool holder. Side cutting puts even more demand on the tool holder's ability to hang on to the insert.

To help overcome the side cutting forces, Horn presses a prism shape in the top and bottom longitudinal axes of the insert. This prism fits a corresponding slot in the toolholder clamp. An insert, without some sort interlock shape between it and the holder, will tend to shift or possibly loosen under cutting conditions.

Under clamp pressure, the prism and its receiver on the tool holder secure the insert top and bottom over the full length. This clamping system helps the insert resist deflection from side cutting forces while at the same time maintaining a rigid connection between the insert, holder and machine turret. A rigid connection between the tool holder and insert is a critical consideration for shops that want to side cut with grooving inserts.

Milling operations too can take advantage of multiple operations using one cutter. An example is the slot-milling cutter. Usually its specialty includes cutting keyways and T-slots. Generally cutting a slot or key involves feeding the X or Y axis while the Z axis is fixed at the programmed depth.

With the advent of circular and helical interpolation on machining centers, the versatility of these typically dedicated cutters has been expanded. Horn and other cutter makers produce indexable insert cutters that can face mill, clean up a bore, scribe a thread, groove, or step inside the bore, all with a single tool. But without interpolation, these operations would require dedicated cutters to perform them.

An impetus for shops to get more operations from a given cutting tool is the relatively small tool capacity of most turning center turrets. The ability to load a sufficient number of tools for more than a couple of jobs is often restricted by turret capacity. This extends setup time from job to job.

If a shop can use a grooving tool for two or more operations that would traditionally take individual cutters, it saves those valuable tool pockets for other tools or redundant tools. This extends to the tool room as well, with less insert and cutting tool inventory to stock and maintain.

Using grooving tools for side turning is not suggested as a replacement for general purpose turning tools. Likewise, slot-milling cutters cannot perform face milling and boring as well as tools specifically designed for these functions.

However, in an application where turning between shoulders and facing operations or, ID boring with internal grooves are called for, using one tool for several is a good option. In a milling application, the ability to face a surface then interpolate a bore and cut a spiral groove or O-ring slot with one cutter saves cycle time.

The idea behind using one tool for more than one operation is to help shops save cycle time and reduce complexity in some of their processes. Advances in insert pressing and grinding technology along with better substrates and coatings allow inserts to be used in innovative ways. And, when combined with the versatility of the modern CNC machine tool, the cutting tool and machine applied together can help get the job done better, cheaper and faster.

タグ ：

#Cutting

#Inserts

Nearly every aircraft is prone to tiny cracks that begin at holes used to insert fasteners and that, if not addressed, can eventually migrate from one hole to the next and cause structural failures.

Split sleeve cold expansion, from Fatigue Technology (Seattle, Washington) is a process for surface milling cutters increasing the fatigue life of holes in metal structures. The process radically expands a hole, creates a zone of residual compressive stresses around the hole and protects it from the effects of cyclic stresses. This is done using a tapered mandrel fitted with a lubricated sleeve and drawing the mandrel/sleeve combination through the hole using a hydraulic puller.

Most of the Fatigue Technology's production consists of cylindrical parts, so the company has focused on obtaining the latest turning technology from around the world. It has five nine-axis Index G3000 mill-turn centers with dual spindles, dual turrets, a milling head and a rotary axis on each spindle that precisely locates a milled workpiece. The company also has two Star six- and seven-axis lathes with a sliding headstock that feeds the work through the DNMG Insert machine to produce very long parts. It has many other conventional four-axis and two-axis turning centers.

This advanced complement of metalworking machinery provides the potential for high levels of productivity and accuracy, but it also creates programming challenges. Controlling all of those axes is a major task, but optimizing the complex capabilities of these machines and simplifying the process of accessing their capabilities is even more difficult.

The company also faces extremely tight time constraints. For example, Fatigue Technology's contract with Boeing specifies that 80 percent of jobs must be completed within 24 hours of the time the order is received.

To meet these challenges, Bob Renfrow, manufacturing manager at Fatigue Technology, selected Esprit CAM from DP Technology (Camarillo, California) as the company's CNC programming software.

The programming process begins when the design engineer sends an approved solid model in the Parasolid format. The CNC programmer defines the boundaries of the finished part and selects which operations will be performed while the part is held in the front and back spindles, making it possible to perform all machining operations in a single setup. The program is then automatically transferred from one spindle to the other. Operations are also divided between turrets, so that if 1 inch of metal needs to be removed, the two turrets are placed close to each other. They split the cut up so it can be performed in half the time that would be required by a single turret machine. The CAM system can control spindle speed in either constant rpm or constant sfm mode.

"Esprit will automatically determine the best way to perform the individual operations based on the characteristics of the tool," Mr. Renfrow says. "Then it will calculate the cycle times for each operation and display them in a bar chart. The programmer can then add ‘Sync' and ‘Wait' codes to synchronize the machining operations, and the bar chart immediately displays the updated cycle times. The programmer can also drag and drop operations from one turret or spindle to another and click on the appropriate place in the chart to view the actual G-codes for a specific operation and make edits on the fly.

"When the programmer feels that the program is ready, he produces a part on the computer and watches as the CAM software simulates every machine movement including tailstock operations, bar feeds and part exchanges. Finally, he zooms in on a computer image of the actual geometry that will be produced by the program in order to be sure it will meet the customer's requirements. The programmer can see exactly where he has missed undercuts and dimensions and can go back to make the necessary corrections."

Fatigue Technology programmers also take advantage of Esprit's tooling system, which uses ANSI/ISO standard coding to simplify the process of defining cutting tools. These standard tools, along with custom tools created by the company's programmers, can be selected and inserted into a program. The correct inserts, holders and turrets are shown during the machining simulation and appear on a setup sheet that is automatically produced with each program. The program, along with the setup sheet, is released to the shop floor electronically.

Mr. Renfrow has gone one step further to speed programming of families of parts that are produced on a regular basis. He writes a macro that defines the basic operations used to produce the part and that accepts the variables that define the final dimensions of the part from a SQL database. The macro is carefully optimized and tuned to minimize cycle times and ensure that everything runs correctly. Programmers need only enter the actual dimensions of the part into a spreadsheet in order to generate a new program in a matter of a minute or two.

"Using these methods, we can produce very complicated CNC programs in a very short period of time, then verify them on the computer to make sure they are correct," Mr. Renfrow says. "Everything is then delivered electronically to the operator on the shop floor so that in a matter of a few hours, we can go from design drawings to cutting chips.

"When you have a Boeing 747 sitting idle on a runway somewhere, waiting for one of our tools, every second counts."

タグ ：

#Cnc

#Turning

#China