The reamer is used to finish machine a previously formed hole to an exact diameter with a smooth finish. It should not be used to significantly enlarge a hole (max. 5% – depending on material and hardness).
Decatur Diamond has a complete line of precision cutting tools specifically designed for machining graphite. The tool geometries are optimized for such applications as electrodes, molds, and hydrogen fuel cells. These designs provide excellent cutting performance while not sacrificing tool life. Fewer changeovers and more time in the cut promote long runs and application automation for improved cost savings.
CVD coated diamond tools are a perfect match for machining the graphite moldforms for EDM. The abrasive nature of EDM graphite grades severely limit the life of carbide tools, and PCD diamond tools are not available in the configurations required for detailed moldmaking.
Tools with diamond on the surface wear longer and have a lower coefficient of friction. These characteristics provide substantial benefit to machining operations.
Because diamond tools last 10 to 50 times longer than carbide tools, they:
When cutting graphite, most tool wear is caused by the abrasive nature of the graphite structure rather than by the material temperature or cutting speed. Unlike metal cutting, there is no heat generated when machining graphite, so tool speed is typically not seen as a wear factor. This distinction warrants the need for an abrasion resistant tool surface such as CVD diamond.
Because small feeds and depths of cut do not lead to increasing the amount of material chipping, tool wear will advance rapidly with light feed, but stabilize as feed is increased. Therefore, in addition to increasing the volume of material removed, increasing feed can extend tool life.
The depth of cut should not exceed one-half of an insert’s leg length or one-third of an endmill’s diameter. These parameters will minimize breakage at the exit of a cut.
Tool life is determined by the quality of the cutting edge and the thickness of the diamond layer at the cutting edge. A tool will go through a break in period that refines the cutting edge, resulting in an improved surface finish. This will be followed by a prolonged period of consistent performance and a gradual wearing of the diamond layer. End-of-life occurs when the diamond wears through, revealing the carbide substrate or when the diamond surface becomes chipped or fractured.
Tool configuration: use square endmills with a small radius whenever possible. Diamond tools are more brittle than carbide tools and sharp corners may break upon entry into a cut at high feed rates. A radius of 0.010” to 0.015” will greatly strengthen the tool, providing extra durability.
For roughing at high feed rates 2-flute endmills should be used to minimize the possibility of tool breakage from flute packing. For general purpose and finish cutting use 4 flutes. Improved surface finish and longer life usually result from multiple flutes in finishing operations.
Chipping: to avoid chipping, several techniques can be employed. Milling a short distance at the exit side of the part before starting the cut is very effective in avoiding breakout, just as chamfering the end of a cylinder is for turning. Lowering feed rates will lessen chipping upon exit, but directly affects productivity. Tool rotation can be used to lessen exit edge chipping for flat surfaces by using climb milling rotation rather than conventional milling rotation.
Feed rate: it is important to keep the tool engaged in the cut. If the feed rates drop too low (<.0001 to .0005” or <.00025 to .013mm) the tool tends to burnish the part, rather than cut. This can cause rapid tool wear.
When calculating the correct RPM for chip load at a given traverse speed it is important to consider if the machine is ever reaching the optimum traverse speed. It can take 1⁄2” or more to reach a high traverse speed. If the tool path has a lot of small adjustments, reduce RPM’s as the tool is never reaching the full traverse speed.
Machining Parameters: starting conditions vary considerably; 2000 SFM and 0.004” per flute per revolution is a conservative start point for 1⁄4” and larger endmills.
Dust removal: particular care should be used to clear the machining dust from holes during drilling. Proper removal will allow using higher spindle speed as well as reducing drill wear.
Machining Parameters: the table below shows starting machining parameters for drilling graphite. As are all applications, these conditions will vary according to the grade of the graphite being machined and the set-up and dust removal practices.
Machining Parameters: the table below shows starting machining parameters for Dapra & Millstar style ball nose, flat bottom, and back draft profiling cutters.
Turning and milling with inserted cutters
Tool configuration: perishable inserts with 1/64” to 1/32” nose radii are most effectively used for turning and milling graphite. A positive rake insert with a finish ground flank is preferred.
Surface finish: finish can be improved be selecting the appropriate tool geometry and feed rates. Larger nose radii will improve finish, but with increased tool pressure. A smaller nose radius will relieve pressure, but feed must be reduced to achieve comparable surface finish. DOC will not affect surface finish unless it causes excess tool pressure resulting in vibration, or if it is too light (under 0.005”) to remove an adequate amount of material.
Breakout: breakout at the end of a pass is always a concern. This can be avoided by having a chamfer cut on the end of the part to ease exit of the tool or provide stock which can be later cut off. Avoid square-nosed cut-off tools to prevent breaking prior to completion of the cut. A 20- degree angle is recommended.
Workpiece configuration: when machining long rods and cylinders, higher speeds and depths of cut can be employed with higher strength graphite materials.
Depth of cut: DOC should always be maximized when possible without incurring distortion of the part. When distortion is present, feed and DOC must be adjusted. Lower feed rates will allow holding deeper cuts. Feed rates of 0.005” per revolution for roughing and between 0.001” to 0.003”: for finishing might be necessary. Deeper cuts always generate higher pressures and larger fracturing particles, thereby producing rougher surface finishes.
Machining Parameters: the table below shows starting machining parameters for general purpose and finish turning.
Workpiece configuration: when milling large surfaces or volumes, higher speeds and depths of cut can be employed. Use higher strength graphite materials when there are thin walls involved.
Depth of cut: DOC should always be maximized when possible, to reduce multiple passes. Lower feed rates will allow holding deeper cuts. Feed rates of 0.004”/tooth/revolution for roughing and between 0.0005” to 0.002”/tooth/revolution for finishing might be necessary.
Multiple cutters: for multiple-pocket milling cutters it is recommended that axial alignment be used to align all inserts within +/-0.0002” for best results. This will improve surface finish and reduce insert wear, as all the inserts will be cutting equally.
Machining Parameters: the table below shows starting machining parameters for general purpose and finish turning.
There is sometimes confusion over the difference between Knurl Cutting and Knurl Forming and what is the best application to use for each method. Here's a quick synopsis of the differences and ideal application solutions.
Cutting Type Knurling tools create a knurling pattern by Material Removal.
For a Cutting Knurl, the knurl wheel’s axis is rotated to provide a leading edge, where the sharp edge will cut the knurl pattern into the work piece. Additionally, with a Cutting Knurl, less pressure is required for the operation and higher speeds and feeds can be used (use the same cutting data of High Speed or Cobalt turning tools). When Knurl Cutting, use full faced knurl wheels with a sharp edge, to penetrate into the work piece and cut the knurl pattern.
Forming Type Knurling tools create a knurling pattern by Material Displacement.
In Forming Knurl, the knurl wheels axis is set parallel to the work piece axis, and forced against the work piece, displacing the material to form the knurl pattern. A large amount of pressure is required to displace the material that forms the knurl pattern. When Knurl Forming, use beveled edge wheels to protect the edge from chipping which will create a smooth surface finish.
Paul Horn GmbH is responding to the requirements of users with their product line expansion to the tool range for slot milling and slot cutting, .
Horn now offers the cutter body of the M310 milling system with an internal coolant supply. This increases the service life of the indexable inserts and therefore reduces tool costs. The internal coolant supply also allows a higher level of precision when slot milling as no heat is transferred from the cutting zone into the component.
What’s more, the flushing action of the coolant, combined with the geometry of the cutting edges, prevents chip jamming in deep grooves.
Horn offers two types of milling and slotting cutter. The screw-in milling cutter is available in diameters from 50 mm (1.969") to 63 mm (2.480") with widths from 3 mm (0.118") to 5 mm (0.197").
As an arbour milling cutter, the main bodies are available with diameters from 63 mm (2.480") to 160 mm (6.300"). The widths are also between 3 mm (0.118") and 5 mm (0.197"). The three-edged S310 carbide inserts are bolted on the left and right of the main body and therefore ensure a good distribution of the cutting forces.
In addition to further geometries for processing different materials, Horn is introducing inserts with a geometry for milling aluminium alloys.
As well as expanding the M310 system, Horn is rounding off the range of the M101 and M383 milling systems.
For the M101 tool, S101 inserts are available from stock with a width of 2.5 mm (0.098").
What’s more, new inserts with an 8-degree lead angle are available especially for slot cutting. For the 383 system, HORN is expanding the range of bodies with diameters of 125 mm (4.921") and 160 mm (6.300").
Orders accepted beginning July 15, 2021. First shipments from inventory July 26th 2021
F&L Technical Sales is excited to announce the launch of a brand new workholding product line for CNC Milling machines! Check out the press release below! We'll be adding more technical information after the product launch and after we return from our training in July! This is exciting stuff!!
Mate Precision Technologies, a global leader in metal forming and metalworking solutions, announced today that it is launching a new line of 52/96 workholding technology for CNC machining operations.
A New Era for Workholding
Leveraging nearly six decades of machining Mate’s workholding line offers an impressive selection of options:
The Mate 52/96 workholding system includes QuickSpecs™, Mate’s unique product identification system. QuickSpecs allows real-time access to critical user data, CAD models and potential integration into business systems. Additionally, the product supports common robotic interfaces and palletizing systems to support factory automation.
This new line is designed and manufactured with Mate’s renowned performance standards for best-in-class accuracy and repeatability. The workholding system is backed by the company’s sophisticated technical support, unsurpassed product quality, responsive customer service, and 100-percent satisfaction guarantee. Learn more online: mate.com/products/workholding.
The workholding announcement comes shortly after Mate changed its corporate name to Mate Precision Technologies to reflect the company's broader commitment to metalworking and using its expertise to drive innovations to shape the future of factory productivity. In describing the name change Sundquist commented, “It truly supports our mission statement, which focuses on improving our customers’ factory productivity, and we are now better positioned to extend our skills and technologies to other markets like the metal cutting and machining industry.”
US Manufacturing Technology Orders increased 45.4% from February 2021 and increased 66% over March 2020 in New England
U.S. Manufacturing Technology Orders totaled $437.9 million, an increase of 16.1% over February 2021 and an increase of 41.6% over March 2020, according to the latest U.S. Manufacturing Technology Orders report published by AMT...
by Kristin Bartschi May 10, 2021
Read the Full Press Release report below
Why is total cost per hole reamed far lower with carbide tipped reamers despite its higher initial cost?
Carbide runs at higher Higher feeds & speeds due to heat resistant cutting edges and this reduces your machine cycle time per part. Carbide also provides consistent quality: It maintains hole size and surface finish far longer than steel. That is a direct result of longer tool life which reduces down time for tool changes. At the end of the run, your shop is more profitable using carbide tipper reamers from Hannibal Carbide.
The 2021 Techniks Catalog is available for download now!! It features the MegaFORCE Retention Knobs that we talked about in our February Article as well as the new Triton Hydraulic Holders.
The only thing standing between a job well done and catastrophic failure is the retention knob. MegaFORCE Retention Knobs are designed to deliver superior performance and enhanced safety for the critical connection between your machine spindle and the tool holder. Retention Knobs are subjected to extreme pulling forces of up to 5,000 ft. lbs. Over time, this stress exploits weaknesses in the retention knob and can lead to breakage.
MegaFORCE Retention Knobs have been designed and manufactured to increase the strength and durability of this critical connection.
The longer overall length engages threads deeper in the tool holder, reducing taper swelling and maximizing taper/spindle contact for the most rigid connection. MegaFORCE also features a redesigned, blended radii for improved overall strength, making MegaFORCE the strongest high-torque retention knob in the market.
The Triton Hydraulic Holders by Techniks feature a new hydraulic design to provides excellent vibration damping properties, so tools run longer and quieter and produce superior surface finishes. Triton provides 3.5X clamping force of standard hydraulic chucks.
Triton hydarulic chucks are charged with hydraulic fluid in a vacuum chamber to eliminate air and gas from the system. Coupled with a redesigned oil sealing system, Triton chucks are built to provide maximum holding power for years!
You can page view or download the new catalog below!
The acquisition of North American Tool Corporation extends custom product capability into the threading space, a new offering for GWS that adds a powerful dimension to the already robust product and service portfolio.
TAVARES, Fla., Feb. 4, 2020 /PRNewswire/ -- GWS Tool Group is pleased to announce it has acquired North American Tool Corporation (NATC).
"NATC is an exciting add for us," said Rick McIntyre, GWS' CEO. "Their customer service model is one of the best in the business, and their focus in taps and threadmills fits in like a perfect puzzle piece to our dynamic and holistic offering. We are very excited to be continually expanding our value proposition for our customers with highly additive acquisitions like this," McIntyre continued
"North American Tool is very excited to be joining GWS Tool Group, a company that embodies the attributes that have long made us successful," said Curt Lansbery, NATC President & CEO. "A customer-centric approach to business rooted in a commitment to quality and quick delivery marry perfectly with our model here at North American Tool. We have no doubt that this move to join GWS will be positive for our associates and will ensure the continued growth of the legacy that we have worked to develop."
The team at NATC will continue to operate from the Illinois facility as a manufacturing arm of GWS Tool Group, and the company expresses intent toward continued investment in the facility, machinery and equipment, and human resources. Customers of NATC are said to expect continuity of the NATC offering and customer service disposition under cover of the GWS ownership.
About GWS Tool Group
GWS Tool Group is a U.S.-based, vertically integrated manufacturer of highly engineered custom, standard, and modified standard cutting tools, primarily servicing the aerospace and defense, power generation, automotive and medical sectors. GWS Tool Group has acquired multiple businesses in the course of its growth, which now serve as the respective manufacturing divisions of the Company.
Retention Knobs are the critical connection between your machine tool and the tool holder and they are the only thing holding a steep taper tool holder in the machine’s spindle.
Techniks has recently introduced their MegaFORCE retention knobs that have some rather unique features when compared to standard pull studs. Before delving into the features of the MegaFORCE pull studs, let's review some things that you may not know, or think about, on a daily basis.
However, if you're running multiple shifts, 24-7, making lots of tool changes, making very heavy cuts with long reach or heavy cutting tools, and/or have ball lock style grippers instead of collet type grippers used on the retention knob, you will probably need to replace your studs at least every six months.
Given the spindle speeds that we are running at to remain competitive, retention knobs are not an item that you want to take a chance on breaking. I can tell you firsthand that 5 pound toolholder with a drill in it flying out of the spindle at 23,000 RPM is not something you want to experience.
Metal Fatigue: Why they fail
Pull studs encounter catastrophic failure as a result of metal fatigue. The metal fatigue can be caused by a number of reasons including poor choice of base material, engineering design, machining process, poor heat treatment, and, sometimes, they have just met or exceeded their service life. We're going to dig into each of these reasons below but first let's look at some threading fundamentals.
That is why the length of engagement of the thread on a pull stud is generally limited to approximately one to one & a half nominal diameter. After that, there is no appreciable increase in strength. Once the applied load has exceeded the first thread's capacity, it will fail and subsequently cause the remaining threads to fail in succession.
Retention Knob design
Repetitive cycles of loading and unloading subject the retention knob to stress that can cause fatigue and cracking at weak areas of the pull stud.
The most common failure point for a retention knob is at the top of the first thread and the underside of the pull stud where the grippers or ball bearings of the drawbar engage and draw the toolholder into the spindle.
Remember, bigger Radii are stronger than sharp corners. More on that soon.
Not all retention knobs are made from the same material, however, material alone does not make for a superior retention knob. Careful attention to design and manufacturing methods must be followed to avoid introducing potential areas of failure.
MegaFORCE retention knobs are made from 8620H. AISI 8620 is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to develop a case-hardened part. This case-hardening will result in good wear characteristics. 8620 has high hardenability, no tempering brittleness, good weldability, little tendency to form a cold crack, good maintainability, and cold strain plasticity.
There are some companies making retention knobs from 9310. The main difference is the lower carbon content in the 9310. 9310 has a tad more Chromium, while 8620 has a tad more nickel. Ultimate Tensile Strength (UTS) is the force at which a material will break. The UTS of 8620H is 650 Mpa (megapascals: a measure of force). The UTS of 9310H is 820 Mpa. So, 9310H does have a UTS that is 26% greater than 8620H.
That said, Techniks chose 8620 as their material of choice because of the higher nickel content. Nickel tends to work harden more readily and age harden over time which brings the core hardness higher as the pull stud gets older. The work hardening property of 8620 makes it ideally suited for cold forming of threads on the MegaFORCE retention knobs.
It should be noted that some companies are using H13. H13 shares 93% of their average alloy composition in common with 9310.
Rolled Threads vs. Cut Threads
A cut thread, image 1, has a higher coefficient of friction due the the cutting process, while a roll formed thread, image 2, has a lower coefficient of friction which means that it engages deeper into the toolholder bore when subjected to the same torque. You will notice that Cutting threads tears at the material and creates small fractures that become points of weakness that can lead to failure. Rolled threads have burnished roots and crests that are smooth and absent of the fractures common in cut threads.
Rolled threads produce a radiused root and crest of the thread and exhibit between a 40% and 300% increase in tensile strength over a cut thread. The Techniks MegaFORCE retention knobs feature rolled threads that improve the strength of the knob by 40%.
megaFORCE GeomEtric design
There are some claims that a longer projection engages threads deeper in the tool holder preventing taper swelling. While a deeper thread engagement can help prevent taper swelling, applying proper torque to the retention knob is an effective way to reduce taper swelling.
An over-tightened retention knob may still cause taper swelling regardless of how deep it engages the threads of the tool holder. Additionally, the longer undercut section above the threads presents a weak point in the retention knob.
Magnetic Particle Tested
Each MegaFORCE retention knob is magnetic particle tested to ensure material integrity and physical soundness. MegaFORCE retention knobs are tested at 2.5X the pulling forces of the drawbar.
Retention Knob Best Practices
In order to maximize the life of your retention knob and prevent catastrophic failure here are some technical tips to keep your shop productive and safe.
indication marks on Pull Studs
There have been some who claim that drawbar gripper fingers and/or ball marks that appear on retention knob head after several tool changes is normal.
It is NOT. THAT IS FALSE.
According to Haas CNC, ball or gripper marks on the edge of the pull stud indicate that the drawbar does not open completely. If you see these indication marks you should check your drawbar and replace these pull studs immediately.
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GWS Tool Group
High Speed Whirling
Taps: Roll Form