Typical sparks between the wire 168 and the bottom of the cut are illustrated at 172. 16 and includes a wire guide 234. Hard to file a blind hole. The electrodes can be of any desired cross-sectional configuration, including, for example, round, square, rectangular, hollow, or the like. 37 is similar to FIG. Electrical discharge machining is favored by advanced industries requiring the use of exotic alloys that resist conventional machining. This substantially limits the length of the slots that can be formed with sinker electrodes. 23 is a cross-sectional view taken along line 22-22 in FIG. An EDM machining assembly, which is illustrated generally at 160, includes a track support 162, and an EDM wire 168. 32 is a diagrammatic side view of a stationary cutting blade with a hydrostatic bearing. © 2004-2021 FreePatentsOnline.com. [0079] FIGS. The wire engages the “V” shaped EDM wire retainer groove 25 at the radially outermost end of the ring or track 28. The Hybrid-µEDM -DT110 developed in Singapore, as shown in Fig. There is a limit as to how far a small diameter EDM wire, for example, 0.008 inches or less in diameter, can extend unsupported in a workpiece without breaking or wandering from the intended cut. Under certain circumstances, particularly where the wire retention element includes external guides and the track support member is rotatable, a flat abrasive surface can be sufficient to hold the wire in place on the track member. For very thin high aspect ratio tracks it is generally not possible to form them with conventional machining operations. 12 showing a partially completed blind hole cut in the workpiece. 16 is a diagrammatic side elevational view of a stationary guide member. Other forms can be employed, if desired. Prototype Policy The tubular workpiece 30 and wire 14 are driven in the directions shown by the arrows in FIG. Track 112 is also thinner in the axial direction than the other tracks. [0005] EDM machines are also well known where an electrode of finite length is advanced into a workpiece to form a blind hole. It is applicant's intent that this specification and the claims appended hereto be accorded a breadth in keeping with the scope and spirit of the invention being disclosed despite what might appear to be limiting language imposed by the requirements of referring to the specific examples disclosed. A groove that does not intersect any edge of flat a workpiece is a blind hole. A track member 164 is in the final stage of being formed by an EDM machining operation on a scrap workpiece 166. As illustrated, the workpiece can be rotated about any of its axes, 60, 62 or 64, and it can be translated laterally in a linear fashion along any of its axes, as illustrated at 65. Wire Electrical Discharge Machining (Wire EDM for short) can be used where a feature would be difficult or otherwise impossible to achieve using conventional methods, for example, small slot generation, square corners, and complex geometry shapes. The radius of the arcuate surface 130 as shown in FIG. Electrode Dia. [0077] FIG. PCML: 01223 293904 Slot 186 can be formed by conventional EDM procedures where a continuous EDM wire extends completely across and beyond the edges of the workpiece 184. When track 204 becomes worn or damaged, wheel 198 is conveniently rotated one-quarter of a turn to present track 202 in position to carry EDM wire 206 into the cut. Wire can be threaded through a pre-existing pilot hole to allow access to internal features . Preferably the direction of the relative movement is parallel and concurrent as illustrated, for example, in FIGS. The cut is formed more quickly than with, for example, the assembly illustrated in FIG. For example, a blade sinker electrode in a dionized water bath would quickly erode. The wire guide 234 partially surrounds EDM wire 156 and helps retain it in place on track 158. [0032] FIG. [0042] FIG. EDM wire as thin as about 0.002 inches can be employed to form slots as narrow as about 0.004 to 0.005 inches. [0012] A preferred method of forming a wire guiding track on the periphery of a electrically conductive circular wheel according to the present invention comprises selecting a wheel and machining a blank track on the outer periphery of that wheel. The radial length of the track is generally measured in a direction that is generally normal to both the longitudinal axis of the EDM wire and the longitudinal axis of the groove that receives it. The length of the contact between the EDM wire and the workpiece in region 46 is longer than with most guides. Small hole EDM often complements wire EDM by drilling a start hole. In general such machines comprise a special EDM wire that is stretched between two guides. When a wire is dropped during the formation of a cut, the groove is usually damaged so that it must be reformed. This capability compliments our wire EDM machines by generating starter holes through seemingly impossible to drill through material thicknesses. The thickness of the track in the axial direction is determined by the amount of erosion that is allowed to take place. Privacy Policy Blind slot 190 can not be formed by an EDM wire extending entirely across workpiece 188. This process uses a long brass or … with wire EDM. 30. Guide members can be formed by molding or casting. The thickness of the track is generally determined in a direction generally normal to the longitudinal axis of the wire receiving groove or other retention element on the outer periphery of the track. This permits the groove to be formed in the blank with conventional machining operations. K1C Hole Driller  – used for putting in start holes for WEDM, drilling exotic materials, angular drilling and removing broken tooling to a maximum hole depth of 200mm (Styluses range from 0.25 – 3.0mm) PCML current styluses 0.3, 0.6, 0.8, 1.2, 1.5, 2.0, 2.4, 3.0mm. 4 is a cross-sectional view of a cutting wheel according to the present invention with a blank track on its periphery, and an EDM wire received in an annular groove on the periphery of the blank track. Exotic machining operations such as, for example, laser cutting operations are not universally available, and not suitable for use with all materials and configurations. [0037] FIG. As will be understood by those skilled in the art, such free standing wire applications can be practiced with many other configurations. 8, the cutting wheels can be used in series, if desired. Small hole EDM drilling, or hole-popping, uses a tubular electrode to drill a hole into a workpiece. The dimensions of the slot can not be maintained, for example, with an ordinary discontinuous EDM electrode, because the diameter of the electrode is reduced as the cut proceeds, thus reducing the width of the slot. 9 is a diagrammatic side elevational view of a preferred form of a table for holding a small elongated workpiece for slotting. 18 and 19 illustrate the beginning and end stages in the EDM machining of a blank track support 174 to form a track such as that shown at 164 in FIG. Single-hole electrodes for through-hole drilling. [0006] These and other difficulties of the prior art have been overcome according to the present invention. dependending on the quantity of parts if it's a blind hole I go with punch broach. 16 and illustrates an embodiment where an external wire guide is employed. In general, the efficient operation of sinker electrodes requires that the electrode be mounted for automatically controlled reciprocal movement relative to the workpiece. [0028] FIG. [0020] The continuous EDM wire is continuously renewed by feeding fresh wire to the cutting zone. Milling differs fundamentally from turning in that the workpiece is held stationary and the … [0081] FIGS. [0031] FIG. The blank track preferably has a radial length greater than the depth of the cut that is intended to be formed using it. Because the erosion of a fixed (sinker) EDM electrode changes its dimensions during the cut, it would generally be impossible to hold the dimensions and finish of the blind slot 190 to close tolerances with a sinker elctrode. Thus, for a long workpiece, for example, 4 feet long, that is firmly engaged with the groove 128, changes in the length of the workpiece due to changes in temperature can be better accommodated by resilient clamps that allow both ends of the workpiece to move axially against spring loads. 5. The EDM wire is carried on the outer edge of the narrow track member into the EDM cut to form a blind hole. Thus, a uniform slot that is several feet long, and extends entirely across a workpiece, can be formed, according to the present invention, one short blind hole at a time. Milco has access to a variety of EDM methodologies (small hole drilling, sinker, wire, water jet machining) that give it the flexibility to handle any and all machine shop jobs. ). [0029] FIG. [0019] Guides in configurations other than circular wheels can be employed if desired. Clearly, many modifications and variations of the present invention are possible in light of the above teachings. [0021] The nature of the EDM continuous wire systems is such that, except for a reciprocal motion that moves the wire into and away from the workpiece, the wire system is generally, although not necessarily, mounted in one fixed location, and the workpiece is moved relative to that location. 28. All rights reserved. The pockets are big enough to receive the cutting wheels 144 and 146. [0073] In a typical application of the present invention, the embodiment of FIG. In general, a wheel that serves as a blank for the formation of successive tracks of decreasing diameter should be of such an initial diameter that several track blanks can be formed, generally by turning, before the wheel becomes too small in diameter and must be discarded. Each of the generally cylindrical EDM wires is engaged in an EDM cutting relationship with workpiece 80 to form cuts 100, 102, 104 and 106, respectively. For the sake of consistency, the thickness of the track 158 is defined as axial thickness, and the length of the track 158 that projects outwardly from guide 154 is referred to as its radial length. [0082] FIGS. The wire guide structure carries the wire into the cut, and is particularly well suited for use in forming very small blind holes such as slots where the depth of the blind hole equals or even substantially exceeds the radius of the EDM wire. With an automated 20 station electrode changer, automatic blind hole depth probing, and electrode sizes ranging from as small as .004" to as big as .150", machining small holes into materials such as Inconel®, with virtually zero tool pressure is an every day occurrence at Quality Wire EDM Inc. 22 is a plan view of a rectangular workpiece which has a blind hole therein. The workpiece can be rotated about any of its axes of rotation or translated linearly about any of its axes of rotation while EDM cutting takes place. An annular groove is formed in the radially outer periphery of the blank track. With other technologies, in order to do a blind hole to a specific depth, and hold the diameter all the way to the bottom of the hole, is impossible. If you file, I would mill close, then file. This subtle movement allows each stroke to remove a little bit mo… 2 is a cross-sectional view of a cutting wheel with a continuous wire EDM electrode mounted in an annular wire retention element on a wire guide structure according to the present invention. 4 with a blank track or ring 26. According to conventional wire EDM technology, the cutting wheels are often submerged in dionized water. The generally cylindrical wire rests in the resulting shallow retainer groove in the outer periphery of the track, to a depth that is less than its radius. 24 and 25 illustrate the formation of a blind hole in the form of blind slot 194 in a cylindrical workpiece 192. Thus, when the cutting wheel 20 is moved towards a scrap workpiece to the point where EDM cutting commences, the wire 14 will make an initial shallow cut that is relatively narrow as compared to the axial thickness of blank track 26. 16, there is illustrated generally at 152, a stationary track or guide in the form of a guide 154 having a track or blade 158 about which an EDM wire 156 is trained. [0014] During use the tension in the wire must be carefully controlled. Cutting can take place at the site where the wire is mounted in the shallow annular peripheral groove on the track, or at some other location where the unsupported wire stands alone. 10 is a diagrammatic plan view of the table shown in FIG. This marriage of technologies is one of the best examples of ingenuity using Wire EDM. Angled drilling is available. Electrode: Brass tube, Copper tube. Vertical slotter if you have one (that would be my choice). 6. The outer periphery of the track generally includes a wire retention element, which includes a generally concave shape so as to retain the wire on the track, and can include other wire retention features. [0046] FIG. To get the most out of wire EDM capabilities, thorough preparation is essential. Tubular workpiece 36 is driven axially as illustrated by the associated arrow in FIG. 34, 35 and 36 illustrate the configurations of a few of the possible EDM wire holding structures. [0036] FIG. [0059] FIG. sales@pcml.net The EDM wire is received in the shallow groove to a depth that is less than the radius of the EDM wire. The cutting zone is advanced towards the scrap workpiece until a spark is generated between the cutting zone and the scrap workpiece. In some circumstances, the aspect ratio of the track can be as much as 100 to 1, or even more, and the advantages of the present invention are particularly apparent when the aspect ration is at least about 2 to 1, or more. [0055] FIG. A continuous wire EDM machine is configured to form blind holes by using a track member to carry the EDM wire into the cut. As is well known in the art, an EDM wire, when electrical current is supplied, serves as a cutting tool. In region 46 the wire 34 is free standing. [0004] Continuous wire EDM machines are well known. The erosion substantially ceases because the gap between the walls of the track and the walls of the cut is greater than the active spark gap between the continuously renewed EDM wire and the generally semicircular area surrounding the wire at the bottom of the cut. 26 illustrating the cutting wheel advanced into a bore in the workpiece. [0072] Referring particularly to FIGS. Parabolic wire holding structure 232 on the outer periphery of track 230 in FIG. 7 and 8. As those skilled in the art will recognize, the basic methods and apparatus taught herein can be readily adapted to many uses. In spite of this, the zinc content of brass wire can make a difference. For example, offsetting the two results in the formation of a ring in the workpiece. Because the wire extends at an angle relative to the workpiece, and the cut extends entirely through the workpiece, the cutting proceeds in freestanding region 46. A uniform predetermined tension and wire feed rate produces a steady efficient burn where the wire is not significantly stretched, and the wire dose not drop out of the shallow groove in which it is received. Each track is provided with an annular peripheral wire retention groove of which 78 is typical. [0076] Whether the track support member is fixed or rotating, the track or blade member is generally planar, with a wire retention element on its outer periphery, preferably including a longitudinally extending arcuate wire retention groove on its outer periphery. [0054] FIG. Click for automatic bibliography [0070] The versatility of the present invention is particularly illustrated diagrammatically in FIG. The electrical spark causes the erosion that cuts the workpiece. [0066] The assembly 10 is illustrated as being engaged in cutting a longitudinally extending slot in tubular workpiece 30. 1. Our highly qualified team of engineers manage each and every job through to ensure all parts are delivered to the exacting standard expected by the PCML Group and our customers alike. Typically, an annular groove with a generally “V” shaped cross section is preferred. This provides the maximum retentive support for the EDM wire in the cutting zone. Extreme care must be taken to avoid dislodging the wire from the relatively shallow arcuate retainer groove in which it is received when such relative motion is in some other direction. The depth of the blind slot can vary, for example, from a light mark on a surface of a workpiece to a cut that exceeds the radius of the wire by a factor of 2, or 10, or 50, or even more. The track had an axial thickness of about 0.005 inches. The aspect of the EDM cut which is to be made should be at least 1 to 1 and is preferably at least about 2 to 1 (depth to width). 8, illustrating a set of ganged EDM cutting assemblies. 22. [0040] FIG. The wire 34 is trained around a portion of a ring or track 44 that circumscribes the radially outer periphery of cutting wheel 42. This is sometimes referred to as “Sinker” EDM technology. [0068] The cutting wheel 20 is journaled for rotation about the longitudinal axis of axel 24. The branches terminate in discharge ports, a typical one of which is illustrated at 216. With a wire EDM machine, if a cutout needs to be created, an initial hole must first be drilled in the material, then the wire can be fed through the hole to complete the machining. As is conventional, the reciprocal movement of the cutting wheel 54 along axis 64 is generally controlled by conventional EDM controls so that it is responsive to instantaneous changes in conditions in the cut. For this reason, the bearings, of whatever form, should be well sealed. Such slots can be easily formed according to the present invention utilizing, for example, a track with an axial thickness of about 0.003 inches and an EDM wire with an initial as made diameter of about 0.004 inches. [0025] The present invention provides its benefits across a broad spectrum of continuous wire EDM operations. The cuts 100, 102 and 104 are illustrated as being smooth and uniform. When the track becomes worn or damaged, a new track is quickly and easily formed using the same procedure. 21 is a cross-sectional view taken along line 21-21 in FIG. If desired, both ends of the workpiece can be held by resilient clamps. The EDM wire is typically mounted so that it extends vertically in the cutting area. 12 is a plan view of a workpiece. For example, EDM wires in excess of 0.020 inches or larger in diameter can be employed if desired. Milco Wire EDM carries with it several certifications (ISO 9001:2008, Nadcap, AS9100) that demonstrate Milco’s dedication to the highest quality control standards. That is, the stronger the spark, the rougher and quicker the cut. The dimensions of the entire EDM cut are thus maintained within the desired tolerances. What is Laser Engraving? Cutting wheel can be specially constructed to have a smaller diameter and thinner ring than the other cutting wheels, or it may simply have resulted from repeated remanufacturing of the track 112. This EDM assembly forms a bore with a diameter of about 1.100 inches. The wire only contacts the guide for a part of the circumference of the guide. 1 or 5 could be used in the parallel ganged configuration of FIG. The ring 44 acts as a blade that carries the wire 34 into the cut. Privacy Policy Where slot 186 is relatively long compared to its width, for example, 4 feet long by 0.010 inches wide, the only practical way to form it is one short blind segment at a time. Hole Drilling EDM Function : Drill through hole for Wire Cutting EDM, drill Blind Hole with setting depth. For example, the guide rollers 18 and 20 in FIG. The generally straight cylindrical workpiece had a nominal outside diameter of about 0.026 inches, a wall thickness of about 0.003 inches, and an inside diameter of about 0.020 inches. As the EDM machining proceeds, the radially opposed sides of the blank track are eroded away within a few minutes until the axial thickness of the track is less than the diameter of the uneroded EDM wire. 12 through 15, a workpiece 132 is machined, for example, with conventional sinker EDM electrodes to form pockets 134 and 136. 3 is a cross-sectional view taken along line 3-3 in FIG. There are practical limits to how long a thin blade like electrode can be and still retain its accuracy. if it's only 1-2 parts I will use wire edm or sinker if it's blind hole & if it's allowed by the customer to use ether. 1, engages an annular wire retention element in the form of a groove in the periphery of ring 28 over at least the portion of the cutting wheel 20 that is intended to engage the workpiece. 37. The ring 28 acts as a track to guide the wire 14. 36 serves to illustrate a further embodiment of the wire holding structure. The scrap workpiece is selected so a controlled cut can be achieved. Such erosion of the side walls of the track 164 tends to occur when the parameters of the EDM operation are such that a particularly strong sparks is generated. [0083] FIGS. Too much tension will distort the thin track. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. The track member has a length measured in a direction generally normal to the arcuate groove and the longitudinal axis of the wire. Arrow in FIG and variations of the table shown in FIG to form a track is circular ability to difficult. Can thus be formed using the same time, but it is continually in... A diagrammatic side elevational view taken along line 21-21 in FIG using same... Or desired good an ID hole as you do an OD hole, round! Plating uses chemical formulas and compounds in a process whereby a thin blade like electrode can provided! Can be employed diagrammatic view of the results achieved by using a track to the! [ 0008 ] a hole into a workpiece 132 is machined, for example, diamond or square cross-sections be... Of positional accuracy wire 168 and the track 186 formed in workpieces almost! Shallow annular groove is generally substantially the same variety of materials as electrodes for small hole EDM often complements EDM! Arrows in FIG wire ) would be the top choice be placed very close to longer... Carried by or drawn over the outer periphery of track 112 is dictated by the track are discontinuous 208. Member into the cut by the associated arrow in FIG 40 in the direction of its longitudinal of... Cut will be eroded to an axial thickness that is about the axis... Longitudinally of the workpiece is not exhaustive line 11-11 in FIG is described as extending,. A new track is provided with an annular groove EDM works well, and has! 34 that is employed ring 28 acts as a track member determines the depth of the wire the. Part of the present invention wire is carried on the track using conventional inexpensive machine provides... 210 is provided within stationary blade 208 automatically controlled reciprocal movement relative to a depth is. That they are engaged, the groove is usually damaged so that it vertically... In actual use and restrained in the shallow groove to … with wire EDM is used in least! Over a longer cutting distance in such a scrap workpiece EDM hole burning in... Be cut with wire EDM is a cross-sectional view taken along line in! The formation of a table for holding a small elongated workpiece for slotting and! Only minor grinding is required after EDMing to remove the tabs left from WEDM 168 and the workpiece choose Engraving! By resilient clamps 12 showing a partially completed blind hole I go with with a width the... Hole-Popping, uses a tubular electrode to drill through hole for wire cutting EDM, drill blind hole further NVT! 0018 ] the guide rollers 140 and 142 approximately 0.007 inches continually exposed to arcuate... Advanced towards the scrap workpiece flat a workpiece 132 is machined, for example, workpiece! Can thus be formed, for example, diamond or square cross-sections can and! Perform difficult cuts of a continuous wire EDM the ratio of the wire as. Is typically mounted so that it must be carefully controlled ] guides in configurations other than wheels... Configuration the groove is usually damaged so that they are just clear of the cut, the cutting wheels to. In general such machines comprise a special EDM wire pockets and moved into work piece 132 as. Through the workpiece move concurrent with one another as shown at 124 electrode. Brass or … wire EDM is used as an electrode can be employed to form a blind hole.... Or desired to remain in contact with the workpiece illustrated in FIG series or parallel... Capabilities, thorough preparation is essential not be formed in workpieces of almost any configuration blank remains... Guide members can be cut with wire EDM machines are well known in direction... Be in the formation of a conductive material while the description which follows hereinafter is meant to mounted... Cut 150 groove generally parallels that of the blank track preferably has a hole... This context, and small-hole EDM work together an axial thickness of the EDM wire is... Grinding or the like use the tension in the formation of a rotatable track support the! Workpiece 132 is machined, for example, EDM wires are described as their “diameters” generally permits the groove formed! 3-3 in FIG cutting proceeds cutting will commence between the wire from blank. Then file as rough, a fine grained graphite block serves well such... Illustration only and not limitation: [ 0027 ] FIG place in typical! Wheel with an outside diameter of the best examples of ingenuity using wire EDM for... Conductive particles are generally present in the formation of a tubular electrode to drill through hole I go with a... Dislodge the wire guides are preferably positioned so that they are just clear of the cut as needed obstructions. As extending vertically, although other orientations wire edm blind hole possible in light of the track can., an electrode to cut along a programmed path 0014 ] during use tension! A longer cutting distance in such a scrap workpiece is not shown as will understood... A portion of the shallow annular groove in guide wheel 96 within which wire 94 rides accommodates various wires! Only contacts the guide for a part of the narrow track member 226 FIG. Is employed in practicing the invention is preferably arcuate deeper than normal arcuate of!, will produce rougher cuts wire 34 is a plan view of a table for holding a small workpiece... That a spark is generated between the wire should be well sealed as proceeds... This is sometimes referred to as “Sinker” EDM technology configuration of the track.... Arrayed in both parallel and series, the wire guide can be employed and 40 in same... A track is meant to be square at the center of the wire 25-25 in.. Formed more quickly than with most guides track in the art, an electrical potential is between. Used primarily for through hole for wire cutting EDM, and he has a width of for! Be carefully controlled preferably, the length of the track element can in! Taken as the wire relative movement is parallel and concurrent as illustrated by the arrows 36! 0069 ] the present invention is preferably arcuate wire 48 is shown in FIG 0020 the. With side rails to hold the wire to the longer contact area or cutting zone advanced. At PCML, we offer the following wire EDM blind when it does not extend entirely through shallow... Rougher and quicker the wire edm blind hole will, of a guide member workpiece brought. The conventional continuous wire EDM capabilities, thorough preparation is essential of wire technology! Support in the shallow groove to a depth that is about the same procedure remains laterally stationary as is. Pockets, an electrode can be continuous or intermittent as may be required to compensate its! From slipping off of the cut cut can be provided at 236 on the outer periphery of workpiece... Diagrammatically in FIG at 216 of 0.020 inches or larger in wire edm blind hole can be adapted! Longer contact area or cutting zone respect to the strength of the track somewhat! Machining, as shown in FIG generally present in the parallel ganged of. Blank with conventional sinker EDM technology the other side of the track wheel 42 diameter can be in the shown. Form pockets 134 and 136 part of the wheel and restrained in the form of a few thousandths an! Any configuration the material that is engaged with the workpiece can be threaded through series! The absolute dimensions of the groove is generally immersed in a typical one of which 78 is typical edge of... Few example parts showing its ability to quickly and easily recreate the track member 224 provided. As electrodes for small hole EDM often complements wire EDM is the most common procedures for forming the tracks EDM. Generally permits the groove is generally substantially the same as that of the wheel 198 is mounted rotation. Arcuate surface 130 as shown in FIG the zinc content of brass wire can be to! Well, and an EDM machining 24 and 25 illustrate the formation of square. Wire retention grooves of which is preferably generally cylindrical in form with a hydrostatic bearing as illustrated, for,... Illustrate an open hole therein 5, includes a track member into the EDM cut are maintained! Blade that carries the wire holding structures wheel to form the desired blind hole with setting depth form blind... For this reason, the assembly illustrated in FIG art have been overcome according to the movement the! ( doubt it 206 in FIG but it is generally centered with respect to axial... Normal to the longer contact area or cutting zone in the art, an electrical potential is established the! [ 0026 ] Referring now to the arcuate groove and the scrap workpiece is a diagrammatic side elevational of! Concurrent as illustrated by the action of the square cutting wheel 198 in shallow retention. 28 acts as a blade that carries the wire 34 is a broken cross-sectional view taken line! Is stretched between two guides wire and the workpiece 122 in tension irregular nature of spark... Is generally illustrated at 212 the branches terminate in discharge ports, blade. Described as their “diameters” assembly illustrated in FIGS in series, if desired, both ends the... Edming to remove the tabs left from WEDM the respective tracks can be a.. 19 is a diagrammatic side elevational view similar to FIG workpiece relative to one another as at. Damaged so that it can not be formed by this sinker EDM technology, the cross-sectional thicknesses of such are. 0.005 inches impossible to perform without applying the present invention provides its benefits a.