Monday, August 30, 2010
Q&A with Jeff Kiszonas: Converging sinker and wire technologies

Q - Is it possible to have a RAM-type EDM attachment on a WEDM? Would such a thing ever work?

A - Makino offers a fine hole sinker (EDGE2-FH) with a wire EDM electrode dressing attachment, but nothing more. The dressing attachment is a rudimentary wire drive system used, for example, to make a graphite rod into a triangle for making diffuser holes in blades and vanes for turbine engines.  It runs off of the sinker generator.  Wire and sinker EDM generators are different (electronics, waveform generation and shapes, etc.). Wire EDM typically uses much higher frequencies than sinker EDM. This is relative to duty cycle, based on the 'ON TIME' and 'OFF TIME' values, as well as voltages and amperage.  Also, wire EDM typically uses de-ionized water as the dielectric, and sinker EDM uses oil. There's also a huge difference in the design of the Ram for sinker EDM and the upper/lower heads for wire EDM. I suppose a hybrid machine could be designed that would incorporate two generators - a ram for sinker, upper/lower heads containing flushing and wire guide components, and a selectable water/oil dielectric system - but I think you can see where this is going……….$$$$$$$$$$.

-Jake-

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 Wednesday, August 18, 2010
Q&A with Jeff Kiszonas: Choosing Ram or WEDM for producing samples

Q - We’re looking to perhaps buy an EDM but we would use it for a variety of things. One of the main things we’d use it for is excising samples from billets of material, as well as forgings/castings. Most of the samples would be for things like tensile testing, fatigue testing, etc. In many cases, the layout of these specimens is somewhat complex, in which many pieces are taken from a billet in a variety of directions. In that case, as far as I know, a wire EDM would be best. But in other ways, sinker EDM would suit our needs as well.  So my question is this: can a sinker EDM reasonably be used to take out specimens like that? Or would it need to wear away all of the surrounding material before you would get a specimen out?

A - From what you describe, I would have to direct you to Wire EDM machines. Sinker EDMs are used more for machining details and cavities. Using a sinker to cut out samples and coupons would result in large amounts of material removal around the area in question. Sinkers are also inherently somewhat slow. Wire EDMs (WEDM) would be the way to go here. Using WEDM, you would be able to remove a sample or coupon from a large piece of material fairly quickly, and with good results. WEDM would be useful as long as the cut can go through the entire thickness of the part.

-Jeff-

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 Wednesday, June 23, 2010
Carbide Machining Without the Worry of Binder Depletion

EDM is a popular means of machining tungsten carbide materials, because the hardness of the material is not a concern for the EDM process.  Both Wire and Sinker EDMs can used to machine fine details and near mirror finishes in tungsten carbide materials.  The major drawback to the use of WEDM to machine tungsten carbide has always been the electrolytic action between the carbide material and the dielectric (de-ionized) water used in WEDM machines.  This electrolytic action can actually break down the binder in the carbide, usually cobalt, and produce what looks like rust on the surface of the material.  Under magnification, this break down is apparent as voids in the surface of the material (see photo 1a & 1b).  These voids weaken the structure of the material, and will result in shortened tool life, especially for impact tooling such as punches, and dies used in stamping, forging, or cold heading. 

WEDM using oil as the dielectric has been a slow process, historically, and there have been few of these kinds of machines produced.  Makino now offers a machine designed to operate with oil dielectric, and to cut carbide and PCD materials with extreme accuracy and surface finishes.  The UPV3 and UPV5 WEDM machines are the next evolution of the award winning U-Series WEDMs from Makino.  Although designed for machining carbides and PCD materials, the UPV machines also perform well in tool steels.  Leaving only sporadic measurable recast, and no measurable HAZ, these machines can achieve measurable surface finish results of 0.08ymRz or better! (see photo 2).  For more information about these ultra-precise, oil dielectric WEDMs, watch the new Makino webinar on "Faster Cutting of Carbide and Hardened Materials."


Photo 1a – Carbide machined in oil; no cobalt depletion.



Photo 1b – Carbide machined in de-ionized water shows signs of cobalt depletion.



Photo 2 – Reflections of parts in surface of carbide block taken directly from UPV.


Cycle Time Reduction | High Speed Burning | Surface Finish
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 Monday, April 19, 2010
What is a small hole, and what machines make them?

I have seen a lot of questions on some industry forums lately about small holes, and the kind of machines needed to produce them.  Here are some things to think about if you find yourself in a position to produce these holes, or to consider a piece of equipment capable of producing them.

The hole specifications will usually define the hole drill machine requirements.  If you need to blast a simple WEDM start hole through some hardened tool steel, any cheap, fast “hole popper” will suffice.  These machines can be manual, ZNC, or full CNC, and range in price, accordingly, from around $15,000 to $35,000.  Even if they have ZNC/CNC controls for positioning and drilling, the generators are relatively crude, they have little if any regard for accuracy of any kind and surface finish is not a concern.  These are used almost exclusively for drilling WEDM start holes as fast as possible, using regular water as a dielectric. 

The next level of EDM hole drills, that are commonly referred to as “fast hole drills” are more sophisticated, touting more advanced generators, tilting drill heads, ability to integrate A/B tables, breakthrough technology, and use deionized water as a dielectric.  This breakthrough technology allows the machine to drill holes through one wall of a part without violating an internal wall or structure, such as in blades and vanes for turbine engines.  Accuracy requirements for these applications will usually be tighter than those of the simple WEDM start holes.  Where hole poppers are meant to be nothing more than support equipment for WEDMs, the more advanced fast hole drills are usually used as the main process center for drilling more accurately sized and shaped holes in a production application.  These machines will typically range in price from just under $100,000 to upwards of $300,000, depending on size, options, and configuration. 

The third level of EDM hole drilling machines are known as fine hole drills.  These machines have advanced generators, highly adaptive spark gap control, full CNC operation, and a variety of burn condition settings to cover a wide range of applications.  EDM fine hole drills will also use oil as the dielectric, which allows finer spark gap monitoring and control, and superior finishes.  These machines may be capable of achieving L:D ratios of up to 100:1, with typical hole sizes of 0.003” – 0.020”.  The big difference with these machines is that the holes they produce will be very accurate in shape, location of entry to exit, cylindricity, size, and position.  EDM fine hole machines are used for manufacturing parts for medical, aerospace, and electronics applications, as well as drilling WEDM start holes where size of hole is limited, and location is critical, such as some small stamping dies.  These machines may also be able to perform as standard sinkers, being able to burn cavities for molds, or details on small parts, punches, or mold inserts.  You can expect to pay between $180,000 and $500,000 for one of these machines, depending on size and options.  Options can include automatic part/tool changers, A/B tables, electrode dressing devices, and robotic automation components.

For more information on EDM hole drilling, check out some of the other entries in this blog on the topic, or visit Makino.com and look for information about the EDGE2 Fine Hole EDM.

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 Wednesday, March 03, 2010
Calculate Your Wire Consumption Costs Today


Wire consumption is one of the most critical components to impact the profitability of a wire EDM. It’s my belief that every WEDM owner should know the cost of their machine’s wire consumption, so I developed a wire consumption calculator that determines their spending for them (www.makino.com/wirecalc). Try out the calculator for yourself here - simply select your specific wire diameter in use, followed by your wire speeds, machining times, and the price you’re paying for a pound of wire. If this is your first time looking into wire consumption costs I think you’ll be surprised by the results. Makino has addressed wire consumption in the design of their new DUO series WEDMs, significantly reducing the wire unspooling rates without any loss in speed or accuracy. Our DUO customers have been reporting consumption savings as high as 60 percent! If you have any questions about the significance of wire consumption and what it means to your overall business, feel free to e-mail me at jeff.kiszonas@makino.com.

Consumables
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 Thursday, December 10, 2009
More Information on Fine Hole EDM Drilling Results

Since small hole drilling is becoming more popular for production applications in aerospace, medical, electronics, and other sectors that require very small, extremely accurate holes with good surface finish, Makino is seeing a growing demand for machines that can produce these holes consistently and repeatably. Here are some test results that were produced by the Makino EDM Applications Department in Auburn Hills, MI. 

The Applications Department performed this test to prove the repeatable accuracy of the EDGE2 Fine Hole machine. A series of 15 holes, 0.010" (0.254mm) diameter, was made on the machine using 0.008" (0.203mm) diameter copper pipe to predrill each hole, then a solid copper rod was used for finishing. The holes were measured for entrance and exit size, and also shape accuracy on an OGP Quest Vision System. 

There are several factors that determine the accuracy and speed at which the 0.010" (0.254mm) diameter holes can be produced. When the 0.008" (0.203mm) diameter copper tube is at full length, the machining time is longer and a greater taper is produced from entrance to exit for the solid finishing rod to remove. This is indicated by the values shown for holes 1 through 9. As the roughing pipe electrode becomes shorter, the machining speed and break-through at the bottom of the holes are much faster. The roughing process produced a slight taper of 2 ~ 4 tenths (5-11 micron) which was removed during the finishing process. It was critical to perform these tests in a climate controlled room, and to use only the highest quality copper tubes available to reach these results and times. To maintain the better results shown in holes 10 through 15, the electrodes should be purchased in a maximum of 6.0” lengths. All 15 holes where roughed and finished in approximately 60 minutes for an average of 4 minutes to include dressing between holes.

       Hole #       Entrance        Exit               Difference
        1               0.010032”       0.010432”       0.000400”
        2               0.010090”       0.010242”       0.000152”
        3               0.009993”       0.010127”       0.000134”
        4               0.010033”       0.010131”       0.000098”
        5               0.010048”       0.010145”       0.000097”
        6               0.010040”       0.010320”       0.000280”
        7               0.010065”       0.010569”       0.000504”
        8               0.010025”       0.010348”       0.000323”
        9               0.009994”       0.010336”       0.000342”
        10              0.009962”       0.010039”       0.000077”
        11              0.009966”       0.009984”       0.000018”
        12              0.009956”       0.010038”       0.000082”
        13              0.010052”       0.010064”       0.000012”
        14              0.010056”       0.010066”       0.000010”
        15              0.009996”       0.010004”       0.000008”

Cpk Results of Entrances
Based on specific pre-defined requirements for these holes, Cpk is 1.82. 
This Cpk is considered exceptional based on the following scale:
        0 to less than 1.0 is unacceptable - sometimes called "not capable"
        Greater than 1 to 1.33 is fair
        Greater than 1.33 to 1.66 is acceptable
        Greater than 1.66 is exceptional
These Cpk values and ratings are per QualityAdvisor.com

Hole Shape and Location

The holes shown above were photographed at 166x magnification on the OGP Quest Vision System.  Pitch between center of holes was programmed at 0.0250” (0.635mm)

      


The two photos shown above were taken at 403 magnification.  Back light shown at left, surface and back light shown at right.

For more information on these test results or the Makino Edge2 Fine Hole EDM machine, send an email to either jeff.kiszonas@makino.com or bill.paul@makino.com.

Accuracy
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 Monday, November 16, 2009
Edge2 Fine Hole EDM - Making the Impossible a Reality

I have written here in the past about EDM fine hole drilling, but I have some update info that is very interesting.  Makino recently did some testing for a customer who needed a 0.007-0.008" (0.177mm - 0.203mm) diameter hole drilled through 0.75" (19.05mm) of CPM material.  That's a Length-to-Diameter ratio (L:D) of 125:1.  Some will say "That's impossible, it can't be done.".  However, Makino Application Engineers were able to produce this very thing on the Edge2 Fine Hole machine.  Using a 0.006" (0.15mm) diameter copper pipe and a tooling set-up that allows 90 degree incremental part indexing, they were able to produce a 0.0075" (0.1905mm) diameter hole through 0.75" (19.05mm) of CPM-M4.  Here's a picture of the block of material with a piece of 0.004" (0.101mm) wire running through it, and magnified view of the hole itself.  The hole, drilled from both sides to meet in the middle, took 30 minutes.  When the part was cut open with WEDM to inspect the middle of the part where the 2 holes met, there was no visible line or mismatch at the meeting point.

Accuracy | Surface Finish
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 Thursday, August 06, 2009
How wire unspooling rates can affect profits

I was recently made aware of a new video clip on the internet comparing wire consumption of 2 WEDMs.  I have provided a link to this clip so you can check it out.  The video shows 2 WEDM machines during the cut.  The camera focuses on the wire spools as they unspool wire during the rough cut of the same part detail.  The difference in unspooling rates is pretty staggering.  According to the video, both machines performed about as well regarding cycle times, accuracy and finish, but one of the machines uses 55% less wire than other.  This can represent a huge amount of money over time.  For a shop that has a machine that uses this much more wire, and spends say $10,000 a year for wire, the lower wire consumption means that this shop could reduce their wire expense by about $5500 per year, at today's wire price of about $5/lb for brass wire.  Commodity prices are rising again, and that means the raw materials needed to make wire (copper and zinc) are at a higher price as well.  This will tend to drive the price of wire even higher than today's price of about $5/lb.  Who remembers the days of brass wire costing $7-8/lb?  Well, if the price of wire goes up, the cost savings will be even more.  The other way to look at it is if the price of wire goes up, and you use a machine that consumes more wire, you have to either raise the price of the parts you make for your customers, or you will realize lower profits.



Some will say that most WEDMs can be run at far lower wire speeds, which is true.  However, if these machines are set to lower wire feed rates, they will also see longer cycle times.  As wire feed rates are reduced, cutting speeds must also be reduced to avoid things like excessive wire breaks, inaccuracies, and poor surface finishes.

Makino has been working with their customers for several years, educating them on the added value provided by Makino WEDMs, that do indeed use far less wire to do the same job as other machines.  In today's extremely competitive business environment, who can afford not to consider a machine that has proven itself to save several thousand dollars each year in wire cost?  Especially if that machine can achieve results equal to or better than competitors that consume 30%-55% more wire.

I will be presenting a webinar on September 10 that will address this issue in detail.  In the meantime, you can contact me to receive a free wire consumption calculator that will allow you to input wire feeds, cutting speeds, and cost of wire per pound to see just how much wire is used, and how much you spend in wire, for any given job.

Consumables | High Speed Burning
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