Monday, July 11, 2011
Q&A with Jeff Kiszonas: Swapping deionized with reverse osmosis

Q - Can Reverse Osmosis water be used in place of Deionized?

A – This would not be feasible. Reverse Osmosis (RO) removes particulates to a sub-micron level, but really does not control pH or conductivity levels.  The machine could be filled or “topped off” with RO water, but it would still need to go through the de-ionizing resin system for pH and conductivity control.  RO systems are also somewhat slow in filtering. The best practice is to fill or top off the water levels in the machine with whatever clean water supply is at hand, and use the resin system for operational control.

-Jeff-

   |  Comments [0]  | 
 Wednesday, April 20, 2011
Lowest Price vs Lowest Cost of Ownership

When looking at new machines today, whether milling, turning, EDM, or any other piece of capital equipment, there are a number of factors that people will consider before making a final purchase decision. These range from the manufacturer and their product models, to operational costs, financing and more. In many cases, the decision may come down to a question of price. “Who can provide me the cheapest machine that meets my requirements?” Some shops will buy strictly on price, thinking that the lowest priced machine will save them the most money. In many cases, however, the lowest priced option may cost more in consumables, maintenance, and support fees. 

Many of today’s machines are built with consideration of power consumption, and how the machine can conserve power when they are out of the cut. This is usually accomplished with software that allows the machine to shut down certain power consuming circuits when they are not required or in use. For example, the Makino EDAF series sinker EDMs can be programmed to shut down several circuits and functions, such as dielectric pumps, certain cooling fans, etc, after a job is completed. This can result in as much as a 69% reduction in power usage when the machine is in an idle state. By doing this when using unattended burning, the machine can finish a job at 3 a.m. and go into Power Save mode until someone comes into the shop the next day to restart the machine’s systems for normal operations. Without something like Power Save mode, the machine will continue to feed pump motors and cooling fans in the generator that are not really required after the burn is complete. Not only does this save energy that would otherwise be used for no reason, it lowers the overall cost of operation, and allows shop owners and machine operators to rest assured that they need not make a special trip into the shop in the wee hours of the morning to turn things off. With today’s push for more green technologies, these machines meet the challenge to decrease power usage, and thereby cost less to operate. 

Another thing to consider with WEDMs is the rate at which they consume wire. Plain brass wires today cost about $6/pound. Most machines sold in North America spin off wire at a rate of about 1-1.5 pounds per hour, with factory settings. Makino customers have reported that their DUO machines save them up to 60% in wire cost, compared to other machines they have used. This is because Makino WEDMs consume wire at a rate of about 0.5-0.7 pounds per hour with factory settings. This can result in $10,000 - $15,000 per machine, per shift in wire cost savings compared to other WEDMs on the market today. 

Even wire selection can have a big impact on operational costs. One Makino customer was hesitant to switch from brass to coated wire because of the 2.5 times price difference from brass to coated. This particular customer was cutting parts that had a cycle time of about 57 hours using brass wire. With simple math equations, the customer was educated to understand that by changing to coated wire, they would incur an additional $150 per part in wire cost, but they could shave the cycle time to about 45 hours per part (coated wires typically cut about 20% faster than brass wires). This was a “no brainer” to the customer, as the trade off of wire cost ($150) for cycle time (12 hours x shop rate) made them more competitive, more efficient, and allowed them to delay the purchase of another machine to add capacity. 

Contact Makino today to see how we are meeting the requirements of ever increasing performance, while using less of our planet’s finite resources. You can also get more details here:

Wire Consumption Rates Impact EDM Profitability
Faster Burning, Lower Wire Consumption with 0.012-inch Wire
EDM Wire Consumption Calculator

As always, you can also contact me, Jeff Kiszonas, EDM Product Manager at Makino, for further discussion or comment.

Consumables | High Speed Burning
   |  Comments [0]  | 
 Monday, January 31, 2011
EDM Additive Technologies – HQSF

Additive technologies for EDM have been around since the late 1980’s. These technologies traditionally utilized silicon or chrome based additive particles in the EDM fluids to produce extremely fine surface finishes. By getting a better surface straight off the machine, secondary operations like hand polishing can be greatly reduced or eliminated. Makino’s version of this technology is called HQSF (High Quality Surface Finish). For detailed information about HQSF, click here to view my latest webinar.

During this webinar I discuss the limitations of traditional EDM processes in trying to achieve very fine finishes, and how additive technologies have aided in these applications. I also explain the differences between additive materials, discuss several HQSF applications and review some case study data that compares standard EDM to HQSF.

Also, please look out for the latest edition of EDM Today featuring Lens Tool & Mould on the cover. Based in Windsor, ON, Lens Tool has become the “go-to-guys” for all types of difficult tooling, including a variety of speaker grill molds. Thanks to their knowledge, expertise and HQSF technology, this customer has gained a reputation throughout North American as a top shop for this kind of work.

Surface Finish
   |  Comments [0]  | 
 Friday, October 01, 2010
Q&A with Jeff Kiszonas: The forces produced during EDMing

Q - What kind of force(s) are put out during the process of EDM? What is required to hold the specimens? I would presume a magnetic table, but then you’re severely limiting what you can cut to ferrous materials only, and my understanding with EDM is that any conductive material can be cut.  So is there a complex clamping system involved?  A standard T-table, with bolts/nuts/clamps, etc?  Or is the force not significant enough to move the specimen? I understand that there is no direct contact between the wire and the specimen, but I would imagine there’s still significant pushing power involved.

A - Even though I have heard many EDM old timers say that there are no forces in play during EDM, they are wrong.  When I was a sinker EDM instructor for another EDM builder, I tested this. I placed a block of steel on a magnetic chuck, but did not activate the magnet. I then used a 1” round graphite electrode to do a side burn across the block, about 0.25” deep. In essence burning a 1” channel across the top of the block. As the burn progressed, I watched the block slowly move in the direction of the burn. This indicated to me that there were electromagnetic forces in play that had enough energy to move the work piece if it was not held down. It also seems that this effect is different from one machine make to another, as each manufacturer designs and builds their spark generator to different specs.

One thing I discovered in using magnetic chucks was that the closer the actual burn area was to the chuck (and the magnetic flux field), the more it affected the spark activity, resulting in a shallow burn. The flux field can actually change the spark activity in the gap, and in the cases I saw, seemed to shorten the sparks, resulting in a shallow cavity. So my extrapolation was that the stronger the magnet, coupled with a deeper burn (closer to the flux field), resulted in inaccurate burn depths. After all, any electrical activity will produce some kind of electromagnetic field. When you add another electromagnetic or mechanical magnetic field to the equation, it will affect the field produced by the first electrical source. During WEDM processing, the electromagnetic field around the traveling wire can actually cause the wire to push away from the work piece, resulting in a bowing of the cut area.  The thicker the material, the more pronounced the bow.

As for work holding, I have seen the use of mechanical magnets, electromechanical magnets, mechanical chucking systems (Erowa, System3R, Hirschman), vacuum chucks (especially good for thin work, like typical test coupons), T-slot clamps, toe clamps, V-blocks with clamps, fixtures, etc.  The size and shape of the work piece can help determine the best kind of work holding to use for a particular cut.

-Jeff-

   |  Comments [0]  | 
 Wednesday, September 22, 2010
New Makino UPV Series WEDMs target carbide and PCD materials

Makino is introducing a new WEDM designed for tungsten carbide and PCD applications.  These include high speed, precision stamping tooling and inserts, and PCD cutting tools and inserts.  The UPV3 and UPV5 machines use oil for dielectric instead of water.  This carries more than one advantage.  Besides developing smaller spark gaps for achieving near mirror finishes, the oil dielectric also prevents corrosion of steel parts and electrolytic cobalt depletion of carbides during long periods of submersion.  This new technology cuts about 2-1/2 times faster during roughing than prior oil based machines.  The first of these new machines was introduced at Allegheny Machine Tool in East McKeesport, PA.  The pictures below were taken of parts cut on the machine there.  The part is carbide, 1 inch thick.  0.008” diameter brass wire was used to machine a series of teeth along the face of the carbide block.  The photos comparing the parts cut with water to the parts cut with oil clearly show damage to the cutting edges when using water, and virtually no damage when using oil.

          


For more detailed information of the problems associated with WEDMing carbides and PCDs, and how the UPV machines respond to these problems, see my webinar titled "Faster Cutting of Carbide and Hardened Materials."
Surface Finish
   |  Comments [0]  | 
 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……….$$$$$$$$$$.

-Jeff-

   |  Comments [0]  | 
 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-

   |  Comments [0]  | 
 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
   |  Comments [0]  |