DRILLING INSERTS SUPPLIERS,LATHE MACHINE CUTTING TOOLS,CARBIDE INSERTS

DRILLING INSERTS SUPPLIERS,LATHE MACHINE CUTTING TOOLS,CARBIDE INSERTS,We offer round, square, radius, and diamond shaped carbide inserts and cutters.

Basic Math For Ballnose Tools

The ballnose end mill is a special sort of tool. Its ability to mill up and down the contours of complex surfaces makes it invaluable to mold shops and other makers of 3D forms. And yet, the tool is lacking in a capability one might take for granted in other cutters: the ability to machine a flat surface.

Because the ballnose tool cuts along a ball instead of a straight profile, it has distinctive Carbide Turning Inserts characteristics. Its “effective diameter” varies according to the depth of cut. Also, adjacent passes with the tool leave behind scallops on the surface that vary in height according to the stepover distance.

Users can control both of these characteristics by choosing the right parameters for the cut. The nominal diameter of the tool, for example, is the wrong value to use when calculating the correct rpm value to achieve a particular value of surface feet per minute (sfm). The diameter at which the tool cuts is determined instead by how much of the ball is engaged. To calculate this effective diameter, DEFF, use the tool diameter D and the axial depth of cut DOC in the following formula:

Then use this diameter in the rpm calculation. That is:

The important conclusion is this: When using a ballnose tool, the only way to maintain a constant sfm is to change the rpm as the axial Shoulder Milling Inserts depth of cut changes.

The other depth of cut—radial depth, or stepover distance—affects the machined surface. The larger the stepover, the larger the height of the scallops between passes will be. To hold this height below a certain limit, find the right stepover distance using the formula below. Here h is the height of these peaks—in inches, assuming the diameter is in inches—and D is the full diameter of the ball:


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Retooling Saves Time And Space

Fermer Precision (Ilion, New York) machines a variety of precision parts from aluminum, cast iron, powdered metal, carbon steel and low-carbon steel for automobiles, firearms, medical products and train brake systems. The company relies on a Mori Seiki SV-500 and two OKK KVC 600 vertical machining centers for drilling, reaming and chamfering operations. Typical drilling requirements for the machines are to drill nine holes in six workpieces mounted in a single fixture.

A retooling process started when Rick Bunce, engineering manager, decided that tool life on the drilling operation was unacceptable. The powdered-metal core drills were supposed to last 200 parts per drill, but they were only averaging 120. Mr. Bunce was also concerned about operator safety when it came time to replace dulled drills. Operators were at risk of burning their hands when removing the tooling from the shrink-fit toolholders.

"The shrink-fit toolholders are very difficult to use at times," explains Mr. Bunce. "Any time you use tools with steel shanks as opposed to solid carbide, the coefficient of expansion of the toolholder and the tool's steel shank are too close to the same. Because of this, as the toolholder is heated, to release the tool, the shank grows at almost the same rate. In most cases, you need to use a mallet and a drive punch to remove the tool.

"After replacement of the drill, the toolholder still could not be used for another 1.5 hours. It took that long to cool down enough for handling and then retooling," explains Mr. Bunce. "It was during the reheating and cooling of the shrink-fit toolholder that the operators ran the risk of injury."

The long retooling times required Fermer to keep on hand three times the number of toolholders actually needed for drilling. "We had to stock more tooling to keep the vertical milling machine running. While some of the toolholders were being used in the machine, others were cooling following a tool change. Still others were idle near the machining centers waiting to be reinstalled," continues Mr. Bunce.

Mr. Bunce contacted his DoAll representative to discuss alternative tools. DoAll and Sandvik Coromant (Fair Lawn, New Jersey) teamed up to come up with a solution for longer tool life. Fermer's solution proved to be a high precision, hydromechanical clamping toolholder and a dual-grade drill with high toughness and good wear resistance—Sandvik's Delta C GC1020 drill and the Sandvik CoroGrip toolholder.

Although Fermer Precision initially set out to improve throughput on its precision vertical and horizontal machining centers, the company got a whole lot more. It reduced tooling inventory and setup time from hours to seconds and eliminated its existing drills and shrink-fit toolholders. The key to the new drill's performance is the sintering of two substrate materials together at the drill tip. The grade at the tool center provides toughness and withstands tension and pressure on the drill point. The grade at the tool periphery provides wear resistance at high surface speed. This combination results in high speeds and feeds without sacrificing edge security.

While the drill was being tested, the Sandvik sales representative, Paul Ashmore, and the DoAll sales representative, Bill Golder, also suggested that Mr. Bunce try out the CoroGrip high precision chuck for high speed machining. Its design offers twice the clamping force of shrink-fit chucks and three times that of ordinary hydraulic chucks.

After two weeks of use on actual production parts, Mr. Bunce quickly wrote out a purchase order for the composite drill and the high precision chuck.

Right away, the tooling combination demonstrated dramatically longer tool life. The average number of parts each drill handled increased from 120 to 300. Depending on the application, Fermer gained an increase from 50 to 200 percent on tool life. "Sandvik's combination of the TwinGrade drill and the hydromechanical chuck is the greatest," says Mr. Bunce. "If I had to give up this tooling now, I would rather go back to using set holes than the shrink-fit toolholders we were using for drilling and SNMG Insert reaming."

The low-runout design of the CoroGrip was another big-ticket feature for Mr. Bunce. "The nearly non-existent runout we have with this toolholder is just great. The drills and reamers for our applications have to be right on the money, and the CoroGrip is incredibly close," he adds. Runout on the CoroGrip is 0.002 mm.

Feeds and speeds on the machines remain unchanged with the new drill and toolholder. A typical operation is drilling several 0.4313-inch diameter holes, 1 ¾ inch deep at 250 sfm in low-carbon steel workpieces. Programming on the machining center indexes the Delta C drill into place to perform all hole drilling, then indexes a reamer to ream out the holes.

A pleasant improvement for Fermer technicians was the safe, easy and quick tooling setup with the CoroGrip chucks. The toolholders Surface Milling Inserts are fitted with a tool and ready for insertion into the machines in just 15 seconds," says Mr. Bunce. "That is 360 times faster than the setup time required for the shrink-fit toolholders."

As a result of faster setup, Fermer no longer needs to inventory more toolholders than necessary to support its drilling operations. "We still have multiple toolholders. This is so we can simply pop in a toolholder when a tool becomes dull and keep the machine up and running. This strategy has added hundreds of hours a year to our useable machine time," says Mr. Bunce.

Gone are the gloves and mallet necessary to change drills. Also, a simple tool pot (in Fermer's presetter) is all that is needed to hold the toolholder during tool insertion. During tool setup there are no forces exerted on the clamp or the tool pot, since only shop air is applied to move internal toolholder components.

The design of the CoroGrip toolholder optimizes balance and torque transmission. The absence of a set screw means the tool has good balance for minimal, if any, vibration during operation. "This toolholding system allows us to get the best performance from Sandvik's solid carbide drilling tools. The combination has increased overall productivity and the quality of our products," concludes Mr. Bunce.


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Strict Tooling Policy Ensures Engraving Shop’s Quality

Some would say that True Mark Engraving Co. of Cleveland, Ohio, goes a bit overboard with its tooling rituals, but according to owner and President Dave Timura, the shop’s meticulous methodology maintains process consistency and ensures no other engraving shop can compete with its quality. To ensure the working life of its cutters, True Mark relies on tooling from Rego-Fix (Indianapolis, Indiana), along with in-house cutting tool grinding and replacing machine tool spindles when they run out as little as 0.0001 inch.

True Mark machines Carbide Inserts and engraves dies for a wide variety of industries and applications, including valves, high-end fittings and bolt heads. It also produces hot stampers for marking plastic parts such as oven dials, inserted-type dies that mark date codes on products and dies for forging companies. Most of the engraving work involves dies that mark final products. These dies are typically made from tool steels such as D2 and M2, and many of them are tiny and intricate. In fact, some letters/characters are so small it is impossible to read them with the naked eye. Representative of its high-end work is one of the smallest die blanks True Mark produces. This die’s machined letters are no taller than 0.004 inch from top to bottom, while the largest characters on other projects can measure up to 1-inch tall. The engraving process also requires Cermet Inserts the use of tiny, single-flute, custom-made cutters that must work at zero runout when taking 0.001-inch depths of cut. The shop has several recurring projects, and turnaround times for jobs vary anywhere from two hours to a couple of weeks. Typical lot sizes range from one to six parts, but the shop can take on 300-piece jobs as well.

Mr. Timura says that when he took the helm at True Mark in 1999, business was basically stagnant in terms of new work, profit and any kind of equipment investments, so his first order of business was to improve the shop’s quality and shorten job turnaround times. Now, the company follows very specific procedures when it comes to toolholder usage.

It begins by assigning every one of its toolholders to a specific CNC milling machine. Each machine’s designated group of holders is stored in racks marked with numbers corresponding to that particular machine. Also, the shop’s individual collets each run in a designated holder. Collets do not move from one holder to another, nor do toolholders move from machine to machine. The holders are stored in the same positions, and they are loaded into spindles with brand names facing toward the front of the machine. Additionally, only certain machines run certain-size-diameter toolholders. For example, a machine will never run a 0.25-inch-diameter holder one day then a 0.5-inch-diameter holder the next. Plus, every holder must run through an ultrasonic cleaning system any time it is detached from the spindle or has a cutter removed from it. Machine tool spindle interfaces are thoroughly cleaned as well.

“I admit it. I’m funny about my tooling,” Mr. Timura says. “But in addition to my specific holder procedures, I use only Rego-Fix tooling in my CNC machines and have ever since we transitioned from manual pantograph-type engraving machines to our first of several CNC mills. Once we saw the benefits and how easy the system works, we were hooked.”

True Mark uses Rego-Fix ER collets and the powRgrip (PG) system, which includes holders and tool loading/clamping units. Unlike other clamping systems that use heat or hydraulics to expand the holder, the PG system is designed to use the mechanical properties of the toolholder material to generate high gripping force with runout smaller than 0.0001 inch. Each surface interface, from the toolholder to collet and collet to cutter, is key to a PG holder’s vibration damping and high-transferable-torque capabilities, even after 20,000 cutter exchange cycles.

True Mark’s machining processes typically require smaller-sized cutters, so the company primarily runs PG 10 holders for cutter diameters between 0.0787 and 0.2362 inch. The shop’s largest collets are 0.250 inch in diameter, and machine spindle interfaces vary from HSK 63F to ISO 20 and 30 tapers. The shop has two manual PG clamping units, and programmer/machinist Cassie Timura, Mr. Timura’s daughter-in-law, does most of the tool cleaning and tooling setups. However, any of the shop’s four employees can operate the Rego-Fix system when necessary.

Rego-Fix products make up approximately 95 percent of True Mark’s tooling, with the remaining 5 percent consisting of other types of tooling for the shop’s manual machines. Each CNC machine is assigned 15 to 20 Rego-Fix holders—either ER collets or PG holders or both.

“I’ve looked at heat-shrink, and, in my opinion, it takes way too long to load and unload cutters,” Mr. Timura says. “Plus, we need as much working life out of our holders as possible, and heat-shrink only lasts so long. We’ve had most of our Rego-Fix tooling for more than seven years and have yet to replace any of the holders or collets due to wear. Even our very first Rego-Fix holder is still in use. There is a bit more cost involved with the tooling, but it’s a non-issue considering the performance, quality and longevity Rego-Fix brings to the table.”

Mr. Timura checks the shop’s CNC machine spindles dutifully, so he knows how each and every one of them is performing. He says it is typical for him to load a cutter in a factory-prebalanced Rego-Fix holder and get zero runout when checking with a 0.0001-inch-increment indicator. “It’s totally amazing,” he says. “And, if there is runout, I can confidently rule out the Rego-Fix tooling as the cause and go right to checking the spindle itself.”

The engraving process uses the very tip of the cutters, and any surface imperfection or off-center split in a cutter’s geometry worsens at the tip. Therefore, any flaw in the toolholder or the machine tool’s spindle will significantly shorten the cutters’ working lives and ruin an entire engraving job. That’s why True Mark grinds its own solid-carbide, single-edge cutters for engraving die blanks. According to Mr. Timura, the shop sees better performance with the cutters it makes itself. While they may look like a simple 45-degree cutter with a split, the finish and size of the tool points are different than those of off-the-shelf cutters. The shop makes its cutters from 12-foot barstock, which a local grinding shop cuts it to individual tool lengths, and roughs in the general shapes and splits of each tool. True Mark finishes the split and grinds the critical angle of the tool’s cutting edge. For the final step, the company manually polishes each tool to remove any grind lines or waviness, and ensure splits are precisely centered.

Depending on workpiece material and character size, cutter life can range from several hours to mere minutes, with total machining times also varying, the company says. To determine cutter life, the shop examines each finished part under a microscope. This visual information, along with past experience, establishes a reference point for how long cutters will last when processing particular materials and character sizes. With some parts, however, cutter wear is highly visible without a microscope.

The tools at True Mark typically operate at speeds of 25,000 or 30,000 rpm, with some running as fast as 40,000 rpm. Roughing and finishing cutter geometries differ from one another, and most jobs can be completed using a total of four or five cutters.

Some may call the steps it takes extreme, but by grinding its own cutters, following a specific tooling methodology and using Rego-Fix toolholders, True Mark is able to ensure continuous machining precision.


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