The Carbide Inserts Blog: https://ccgtinsert.bloggersdelight.dk
2023年12月
The Carbide Inserts Blog: https://ccgtinsert.bloggersdelight.dk
The performance of diamond cutting tools in particular points to one of the most harmful misconceptions affecting the use of high-performance tooling. That is, the belief that the price of the cutting tool equates to the cost of the process.
Diamond Innovations machining products manager Jim Graham calls this the “sticker shock” fallacy. A shop compares the price of, say, a high-performance CBN tool to the price of a general-purpose carbide insert. Seeing the price difference, the shop assumes the high-performance tool is less economical. Is it?
In truth, the gravity turning inserts high-performance tool may or may not be the right choice—but the price is too small a factor to make that determination.
While the cutting tool’s price does add to the cost of the process, the same cutting tool also subtracts from the cost of the process through savings in various areas.
To make the point even more clearly, consider that a machining facility is not delivering a tool to its customer—it’s delivering a part. Therefore, the cost of the part should be the focus. And the price of the tool is such a tiny portion of the cost of the part that it is actually very easy for a high-performance cutting tool to bring the overall cost down.
The pie chart illustrates this. In a typical machined part, the cutting tool accounts for only 3 percent of a machined part’s cost. By contrast, labor and machine time account for much larger percentages—around 30 percent apiece. By allowing more parts to be machined per hour or per shift, a high-performance cutting tool reduces the impact of both of these big contributors to part cost.
The price of tooling is actually an ineffective place to look for savings. Would you rather have a 30 percent savings on your cutting tools or a 20 percent increase in cutting speed? The analysis on this page shows that the right choice is not even close. Assuming the baseline cost of the part is $10, the reduced tooling cost would save only 9 cents. By comparison, the increased speed would save 16 times that much—even after assuming that the tool that achieves this speed increase is 50 percent more expensive.
Now try that same analysis with a BTA deep hole drilling inserts tool that costs two times or three times as much as the baseline tool. It can easily be shown that even very large increases in tool cost do not affect the savings resulting from even conservative gains in productivity.
In addition, some shops apply high-performance tooling to achieve levels of savings that are truly off the chart—at least off of the chart on this page. Tooling engineered to provide both long life and high reliability can make it possible for shops that have never done so before to achieve successful “lights out” machining processes. If the shop can run unattended after hours, capturing machine capacity that is not even being used today, then arguably the costs of both labor and machinery for this work drop to zero. After all, no operators are present, and the machinery has been paid for by the daytime machining. That is why unattended machining can be one of the most profitable ways for a high-performance tool to can transform the machining process.
Next: Rule #5 - Consider the Cutting Tool from the Very Beginning
The Carbide Inserts Blog: https://rcmxinsert.bloggersdelight.dk
Carbide Drilling Inserts Substrates, coatings, geometries and other aspects of cutting tools keep on getting better. How much time do you spend on evaluating new tools?
In this article, a Boeing plant describes how finding an alternative to its “standard” roughing tool led to a seven-fold improvement in roughing metal removal rate.
In another article, a die shop describes how just keeping current with the improvements in new tools allows the shop to steadily do more work with high speed milling as an alternative to EDM.
There is a trade-off, of course. You need your capacity for today’s jobs—and many of those jobs require the tools you already know well. However, if you don’t evaluate new tools now, then tomorrow’s jobs won’t benefit from what you discover.
What is your shop’s BTA deep hole drilling inserts philosophy on experimenting with new cutting tools? How often do you do this? What kind of process improvements have you made by discovering the latest and best tool for your process?
The Carbide Inserts Blog: https://markpayne.exblog.jp/
Brenner Tool is a job shop. It's a big job shop.
The 400-employee contract manufacturer in Croydon, Pennsylvania, has areas devoted to mold making, die making, production machining of small parts and production machining of large turbine parts on vertical lathes. It also has an aerospace division that includes machining as well as Carbide Drilling Inserts finishing processes such as anodizing. Each of these disciplines within the company could qualify as a significant enterprise on its own. But because they have been combined in one company—and because the company has been successful at encouraging employees from separate divisions to pool their experience—Brenner Tool benefits from synergies that help the company in all of its pursuits. Employees from various disciplines all teach one another what they know well.
The area devoted to production batch machining—part of the company's mold division—illustrates how all of the different disciplines benefit. One example relates to through-coolant drills. When the production machining area had a need to begin using this type of drill extensively, it drew on expertise in the die machining division to use the tooling more effectively. Another example relates to vacuum workholding. The production area knew little about this technology, but the aerospace division knew a great deal. The aerospace group even provided one of its large-capacity vacuum pumps to take the place of an off-the-shelf pump that proved too small for the application the production area had in mind.
But a far more significant example of sharing expertise between disciplines relates to the employees themselves. Brenner Tool uses toolmakers—employees who developed their skills and knowledge in mold machining—to run batch production jobs.
The approach is precisely opposite that of a great many contract manufacturers. Many successful shops today have changed their processes on the shop floor to make them more rigidly defined, so shopfloor employees with less skill and experience can work effectively. Brenner Tool, by contrast, uses highly skilled production machining personnel in combination with a more open process. Toolmakers in this area are encouraged to take their own initiative to find more productive ways to machine each part.
For example, in his search for ways to machine a complex miniature gearbox more efficiently, mold division manager Mike Magas placed a sample of the part on every production employee's desk.
"A dollar a minute" is a phrase he uses repeatedly when he seeks the toolmakers' input in this way. The refrain is a reminder that even tiny efficiency improvements have value. The seconds add up . . . and the shop stands to earn at least a dollar more for every 60 seconds it can shave off of the entire production run for a particular batch of parts.
Mr. Magas says there are multiple reasons why a toolmaker can be particularly effective at finding more efficient ways to machine a production job. Any batch part is probably going to be part of an assembly, he notes. A skilled toolmaker is adept at the sort of "tolerance management" necessary to achieve the part's required fit without spending the tolerance window too early in the machining process, and without spending time machining non-critical features to an accuracy greater than their function requires.
Another reason the toolmaker can perform effectively in this role has to do with managing setups. The toolmaker is used to looking at complex parts with an eye toward how to machine them with the fewest setups possible.
Toolmaker Dave Toppin jokes, "It's really just a matter of being lazy."
Three recent production jobs show the kind of processing strategies the toolmakers use to run batches more efficiently:
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The search for commonality is an element of all of these processes. Separate units are machined in a single cycle, and family variations are machined on a common platform. A toolmaker is used to running parts in quantities of one. And as the first example illustrates particularly well, sometimes the most efficient way to machine a production batch is to transform that batch into a single piece.
However, the toolmaker is also no stranger to repetition. "I've worked on 80-cavity molds," Mr. Toppin says. "A job like that is a lot like batch production."
In other words, mold machining and production machining are not all that dissimilar.
Using high-skill employees on production jobs that are sometimes low in complexity does come at a cost, says Mr. Magas. He says Brenner Tool sees a return on that investment in several ways.
One benefit is the more efficient machining that results from having a larger number of experienced metalworking employees available to think about each job. In shops where the process engineering knowledge is located entirely in the engineering or programming department, jobs are often run inefficiently simply because there is a lack of time and lack of people available to imagine how to run them better. By contrast, the toolmakers at Brenner Tool often can't help but to conceive more efficient ways to run the jobs that come their way.
Another benefit is the more efficient use of these toolmakers. The cyclical nature of Brenner Tool's mold business means the amount of mold machining work the shop has in-house at any given time can vary considerably.
But perhaps the most important return on investing more knowledge and creativity into how each job is machined is the stronger relationships with customers that result. "We want to look shoulder milling cutters at each customer as a client who will continue to be a source of work in the future," Mr. Magas says.
The die components shown in Figure 3 illustrate this principle in action. Studying the entire family of parts let Brenner Tool engineer a single machining platform that works across all of the variations. In the future, the customer for this part may create more variations still. If so, there will be little question which shop is best prepared to take on the additional work.
The Carbide Inserts Blog: https://ccmg.bloggersdelight.dk
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'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 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 Carbide Milling Inserts 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 Carbide Drilling Inserts 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.
The Carbide Inserts Blog: https://cncinserts.blog.ss-blog.jp/
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