Exit Drill Burr and Drill Tool Life

Tool Research and Application Department Exit Drill Burr and Drill Tool Life Research Report Facility: AAM, Colfor, Minerva OH Line: Turbine Shaft 1 and Turbine Shaft 2 Tool: Prepared by: Carbide twist drills 5.8, 5.7, 5.4 and 5.0 mm Dr. Viktor P. Astakhov, Tool Research and Application Manager January, 2007 1

Executive Page SUMMARY Tool life of the carbide twist drills and exit burr formed in drilling of cross holes in turbine shaft (Fig.1) were analyzed by a team of AAM Colfor and PSMI specialists. The problems short description and supporting evidences as well as some basic background are presented in the report body and in Appendixes. Carbide twist drills manufactured by Guhring, Mitsubishi and Kennametal companies were compared in terms of tool life and the parameters of the exit burr. Figure 1. Turbine shaft with five cross holes. CONCLUSIONS 1. Mitsubishi drills showed the least amount of tool wear and thus the longest tool life. The change frequency for these drill can be safely set at 1000 parts. Although these drills produce the largest burr, this said burr is thin-walled and can easily be separated from the exit edge of the drilled hole (Crown burr as shown in Fig. 3) as its connection with this edge is not continuous. Such burr is the best in terms of deburring by the subsequent deburring operation used on the machine. 2. Kennametal drills (Guhring drills re-sharpened and re-coated by Kennametal for the test) showed good tool life comparable with Mitsubishi drills. Comparison of the chip structure produced by these drills showed that the chip is more deformed compare to Mitsubishi drills. Therefore, the cutting and the thrust forces are high for these drills. Although these drills produce small exit burr, this burr is found to be a part of the pushed-out work material (uniform burr as shown in Fig 3) that can make the subsequent deburring operation difficult as the deburring tool used at Colfor is of relatively low rigidity. 2

3. Guhring drills showed low tool life (approx. 300 pieces) and high burr as the pushed-out work material. As the coating on all three said drills was the same (TiAlN), and the carbide tool material for Guhring and Kennametal drills was the same, the only reason for the said inferior performance is drill geometry. Our analysis of the geometry of these drills showed two major problems: (a) excessively honed cutting edges; (b) insufficient relief (flank) angle at the periphery cutting edges. The excessively honed cutting edges combined with relatively shallow cutting feed per revolution caused great cutting forces. The mentioned insufficient relief angles caused premature wear of the drill periphery corners. Both symptoms contribute significantly to the formation of the excessive exit burr. 4. The deburring tool used at Colfor was found to not have sufficient rigidity for the application. Although it performs its intended action reasonable well, its performance can greatly be improved. 5. Buckling instability was found to be the case in drilling with 5.4mm dia. drills. This instability causes the distortion of the drilled holes and the formation of the entrance bell mouth of an irregular shape. RECOMMENDATIONS 1. The Mitsubishi drills and modified Kennametal carbide twist drill can be used fo r cross holes drilling at Colfor with tool life 1000-1200 shafts. 2. The inspection fixture used at Colfor for assessment of the drilling exit bur should be re-designed as improper judgment about the actual burr side can be made due to the coolant concentrated around the cross-hole edge that may create the impression of excessive burr. 3. Regardless of a particular manufacturer, 5.4 mm dia. drill should be redesigned. It shank diameter should be increased to the maximum allowed by the hole location. 4. A more rigid deburring tool can be used. For example, the deburring tool produced by E-Z Burr Tool Company, Inc. 41180 Joy Road Plymouth, MI 48170-4634Phone (734) 459-5310 Fax (734) 459-2427. 5. Phoenix drills by Big Kaiser company should also be tested for the application. Special flute and tip geometry of these drills assures low cutting forces and optimum chip breakage. Ultra-fine-grain solid carbide delivers increased wear resistance plus a high degree of toughness. Normally, no deburring is required for these drills in machining steel-like materials. A quote for the said drill and short description are attached to this reports as PDF file. 3

Introduction A Burr is defined as a rough projection left on a workpiece after drilling or cutting. Burr formation in drilling is one of the serious problems in precision engineering and mass production. Since the deburring process is fully automated, the productivity of advanced manufacturing systems is often reduced. Therefore, understanding the drilling burr formation and its dominant parameters is essential for controlling the burr size. Figure 2. Exit Burr Formation Figure 2 describes the formation of an exit burr in drilling. As the drill approaches the exit, the workpiece deflects and then plastically deforms due to the thrust force created by the drill (frame 2). Once this deformation is initiated, it increases as the drill (frame 3) cuts more of the workpiece material. When the drill exits the workpiece, the remaining material deflects creating an exit burr (frame 4). Two burr types are normally distinguished as described in Figure 3. When there is no subsequent deburring operation used, the uniform burr type (Type I) is preferable as it is smaller. When there is subsequent deburring, the crown bur type (Type II burr) is preferred as it is much easier for deburring. Figure 3. Two basic types of burr observed in drilling. 4

Figure 4 shows the difference in the burr formation mechanism between the uniform burr and the crown burr. As the drill approaches the exit surface, the material under the chisel edge begins to deform. The distance from the exit surface to the point where the deformation starts depends on the thrust force of the drill. As the drill advances, the plastic deformation zone expands from the center to the edge of the drill. At the final steps, the remaining material is bent and pushed out to form a uniform burr with a drill cap (A). A larger thrust force induces plastic deformation earlier in the process, making the thicker material layer ahead of the drill undergo plastic deformation, inducing a larger maximum stress on the exit surface. As a result, initial rupture will occur at the center. The remaining material is then bent and pushed out without being cut to form a relatively large burr (B). Burrs are categorized as optimized uniform burr (Type I) whose height is under 5% of the drill diameter, uniform burr(type II) whose height from 5% to 15% of the drill diameter and crown burr(type III) height of over 15%. Although Type I and Type II have the same mechanism of formation, Type I has smaller height that is preferable in most cases when no subsequent deburring is used. Figure 4. Burr formation mechanism (A): Uniform burr (B): Crown burr The formation of burr is governed by the parameters of drill geometry as well as the cutting feed. As such, the lower the thrust (axial) force, the lower the burr. 5

Drills: Tool Life and Burr Comparison Fanuc Robodrill machines were used. The drilling regimes used for the test drills are shown in the Table 1. Analysis of these regimes showed that the feed rate is excessive that cause the instability of drilling (explained further). Table 1 Drilling regimes used Drill diameter, mm 5.00 5.40 5.7 5.8 Rotational speed, rpm 9315 8625 8130 8013 Cutting speed, m/min 146.3 146.3 145.6 146 Feed, mm/rev 0.13 0.10 0.13 0.13 Feed rate, mm/min 1211 862.5 1057 1042 The same drill holders (collet chucks) as shown in Fig.5 were used for all tested drills. The runout of test drills did not exceed 20 micrometers as controlled using a Zoller presetter as shown in Fig.6. Figure 5. Collet chuck used Figure 6. Drill runout control on a Zoller presetter. MULTAN B-400 coolant supplied at pressure of 450 psi was used. The coolant concentration was kept within the limits shown in Fig. 7. Before the test, the coolant ph was controlled using a ph tape. As seen in Fig. 7, the ph was 8-10 as recommended for such a coolant. 6

Coolant type and maintenance Coolant concentration chart Coolant Ph control before testing Figure 7. Coolant particularities. The cross hole-machining cycle includes deburring for each drilled hole. However, to reveal the type of burr produced by Mitsubishi and Kennametal tools, a special test was carried out using a manual cycle without deburring. After being drilled, the shafts (Fig 8a) were axially sectioned (Fig. 8b) and the exit burr type was examined. (a) (b) Figure 8. Test specimens. 7

Mitsubishi drill A drawing and particularities of Mitsubishi drill design and geometry are shown in Fig. 9. Main view Flutes profile Chamfer Figure 9. Drawing and particularities of Mitsubishi drill. Split chisel edge 8

The analysis of the geometry and design features (Figure 9) of Mitsubishi drills showed that the drills have two important features that result in great tool life and the formation of Type II easy-toremove burr. First, these drills have the split chisel edge (US Patent 5,716,172 issued to Mitsubishi) that significantly (by approx. 40%) reduce the axial (thrust) drilling force. Second, the chafers having 45 o angle (Figure 9) are applied to the drill corners that reduce the push out of the work material at the exit of the hole being drilled. The appearance of the chip (Figure 10 shows the chip produced by drill 5.8mm dia.) reveals its least deformation and preferable condition of the contact surface. The result of the measuring of the chip compression ratio as the most relevant characteristic of the energy spent in cutting (Astakhov, V. P., Shvets, S. (2004). "The assessment of plastic deformation in metal cutting." Journal of Materials Processing Technology 146: 193-202) confirmed the results of visual observation. Figure 10. The chip formed by a Mitsubishi 5.8 mm dia. drill. Chamfer drills with 60 and 40 chamfer angle at the corner of the cutting edge are designed for Type II burr formation (Figure 11). Figure 11. Features of chamfered drills. The burr height from conventional drills is larger than from a chamfer drill. The chamfer drill with 60 chamfer angle produces a larger burr than a drill with 40 chamfer angle. The burr is formed when bending deformation occurs as the chamfer edge starts cutting. Considering the same normal stress on the chamfer edge, it can be predicted intuitively that the stiffness of the remaining part (shown as a hatched area in Figure 11) is larger in the drill with 40 chamfer angle than in the drill with 60 chamfer angle. The remaining part is cut if this part is stiff enough not to be bent into burrs. This is the key concept for burr minimization in drilling. 9

Figure 12 shows the burr formed at the exit of a 5.7 mm dia hole. The Type II burr can clearly be observed. The same can be said for the next hole of 5.4 mm dia shown in Figure 13. However, an issue is found in the analysis of this hole. Figure 12. Burr formation for 5.7mm hole. Figure 13. Exit burr for 5.4 mm dia. hole. The said issue is buckling instability of 5.4 mm drills because the length of these drills is greater and diameter is smaller than those of other drills. The former is due to the location of 5.4 mm dia. hole (as seen in Fig.1). Figure 14 presents the results of the said buckling instability. As seen, an enormous asymmetrical bell mouth forms at the entrance of these holes. Therefore, the drilled holes are not straight. The exit, however, shows a preferable burr that almost separated from the edge of the drilled holes and thus can easily be removed with the deburring tools used at Colfor. To resolve the issue, the following is proposed. The simplest solution is to reduce the feed rate at the entrance of the hole being drilled. However, this will increase the cycle time which is not desirable. Another feasible solution is to re-design the drill to increase 10

its shank diameter to the maximum allowed by the flange of the turbine shaft (Fig.1). It should be pointed out, however, that the buckling instability does not affect tool life of 5.4 mm dia. drills. If the defects of drilled holes shown in Fig. 14 are acceptable, the shank design and feed rate can be left as they are now. Asymmetrical bell mouth Curved hole Exit burr Curved hole Figure 14. Holes drilled by 5.4 mm dia. drill. Asymmetrical bell mouth It was found that the exit burr for hole drilled with 5.8 mm dia. drills is insignificant even before deburring as it seen in Fig. 15. 11

Figure 15. Exit burr for a hole drilled with 5.8 mm dia. drill. The pinch of the feed mark equal to the feed per revolution (0.13mm) serves as a geed scale. Analysis of wear development was conducted separately for major drill components as the main cutting edges (lips), corners, chisel edges, and margins. The drills were observed after 300 and then 600 drilled holes. The observation showed that the amount of wear observed on drills 5.4, 5.8 and 5.0 mm was insignificant on all mentioned components. No difference was found in the amount of wear of 5.4 mm dia. and 5.0 mm dia. drill compared to the 5.8 mm dia. drills although the latter produces two holes per a shaft. Therefore, it was concluded that tool life for the said drill diameters can be safely set at 1000 cycles. This is 2-3 folds higher than that achieved with Guhring drill used currently at Colfor. A special issue was found with 5.7 mm dia. drills. Although the amount of drilling done by these drills are the least compared to other drills used, the analysis these drills after 600 drilled holes shows the presence of excessive wear. With the wear found, these drills are not suitable for the further use. Further inquiry clarified the said issue. Among the mentioned set of drills by Mitsubishi, only 5.7 mm dia. drills were not originally made to the drawing shown in Fig.9. Rather, they were modified from standard on-shelf Mitsubishi drills by applying the chafers and a new layer of coating. Clearly, the said modification cannot be considered as a success as the lips are not symmetrical, the relief angles along the chafers are not sufficient, and recoating done without striping of the previous layer of the coating caused the coating failure. Therefore, we would not recommend the use of any modified drill in the future. The lesson is learned to avoid the similar failures in the future. 12

Kennametal drills The design features of Kennametal drills are shown in Fig. 16. These were made by resharpening of 5.8 and 5.7 mm dia. Guhring drills. The re-sharpening was done by Better Edge Company The president of this company Mr. Bill Shafer was at Colfor on the first day of testing (Jan. 03, 2007). Main view Flutes profile Split chisel Negative rake Figure 16. Design features of Kennametal drills. The analysis of the geometry and design of Kennametal point grind (Figure 16) showed two important features. The first is the S-type chisel according to US Patent 6,739,809 (Kennametal, Bill Shafer) that reduces the axial (thrust) force and thus reduces burr formation. The second important feature is negative rake faces ground at the periphery regions of the major cutting edges (lips). The perception was that the work material is relatively hard (AISI 1040 at HB >200) so negative rake face at the drill periphery should fracture the remaining work material which normally would deform into a burr on drill exit. The price to pay is a higher cutting force during drilling and formation of Type I burr, which has smaller height but its structure consists of a heavily deformed (strain-hardened) work material. The appearance of the chip (Figure 17 shows the chip produced by drill 5.8mm dia.) reveals its heavier deformation compare to Mitsubishi drills. The results of the measurement of the chip compression ratio as the most relevant characteristic of the energy spent in cutting (Astakhov, V. P., Shvets, S. (2004). "The assessment of plastic deformation in metal cutting." Journal of Materials Processing Technology 146: 193-202) confirmed the results of visual observation, i.e. approx. 20-25% higher plastic deformation and thus energy spent in drilling. 13

Figure 17. The chip formed by a Kennametal 5.8 mm dia. drill. The results of observations of the exit burrs for holes drilled by 5.7 and 5.8mm dia drills conform to the above-made analysis. Some results for 5.7 and 5.8 mm dia. drill are shown in Fig. 18. Exit burr Figure 18. Exit burr for holes drilled with 5.7 and 5.8 mm dia. Kennametal drills. The analysis of the structure of the exit burr produced by Kennametal drill shows that this burr is not easy to remove as that in the case of Mitsubishi drill. Moreover, the heavilydeformed structure of this burr prevents its complete removal by the deburring tool used at Colfor. On the other hand, the remaining part of the burr after deburring is relatively low so it is found acceptable although greater wear of deburring tool should be anticipated in the long run. As cutting forces are higher with Kennametal drills, 20-25% lower tool life should be anticipated. However, if the pre-set tool life is 1000 cycles, the difference in tool life between Mitsubishi and Kennametal drill will not be noticed. 14

Guhring drills Guhring drills were not considered as an alternative due to low tool life and the formation of an excessive exit burr. Nevertheless, the major causes of poor performance of these drills were analyzed. Figure 19 illustrates the findings. Rapid corner wear Insufficient relief angle Damage of the chisel on grinding the hill Insufficient secondary relief angle - interference Improper location of the coolant hole Excessive wear of the chisel edge Improper shape of the cutting edge Chipping of the cutting edge due to insufficient flank angle Figure 19. Common causes for poor performance of Guhring drills 15

High cutting forces and great plastic deformation in drilling with Guhring drills were verified by the analysis of the chip formed (shown in Fig. 20). The appearance of the chip (Figure 20 shows the chip produced by drill 5.8mm dia.) reveals its much heavier deformation compared to Kennametal and Mitsubishi drills.. The results of the measurement of the chip compression ratio as the most relevant characteristic of the energy spent in cutting (Astakhov, V. P., Shvets, S. (2004). "The assessment of plastic deformation in metal cutting." Journal of Materials Processing Technology 146: 193-202) confirmed the results of visual observation, i.e. approx. 40-50% higher plastic deformation (compared to the Mitsubishi drills) and thus energy spent in drilling. Figure 20. The chip formed by a Guhring 5.8 mm dia. drill. The discussed poor performance cannot be attributed to the difference in the grade of the carbide tool material as the Kennametal drills used in the test made of the same carbide. The same can be said about chip flute profiles and special location and diameter of the coolant holes. As the only difference between Kennametal and Guhring drills was the point grind and the quality of this grind. Detailed analysis and observations showed that the point grind used for Guhring drills is inferior to the Mitsubishi and Kennametal. The quality of the grind is poor in terms of the surface finish of the ground surfaces and damage of the cutting edge while grinding the secondary surfaces. 16

. Few miscellaneous suggestions Few suggestions can be maid in order to improve the quality of drilled shafts and reduce tooling cost per part: A cross hole-machining cycle includes deburring for each drilled hole. The design of the deburring tool is shown n Fig.21. The tool is characterized by relatively low rigidity as the force that can be applied on deburring depends on springability of the slotted shank. The said tool can be effective in removing of Type II burr while it much less effective due to inferior tool material and tool design when Type I burr is the case. Figure 21. Deburring tool used at Colfor. A more rigid deburring tool can be used for example produces by E-Z Burr Tool Company, Inc. 41180 Joy Road Plymouth, MI 48170-4634Phone (734) 459-5310 17

Implement the Phoenix drill by Big Kazer. The Phoenix is a special heavy-duty solid carbide drill developed to cut hard materials. Normally, the implementation of these drills results in higher productivity and longer tool life compared to its conventional solid carbide counterpart. Special flute and tip geometry assures low cutting forces and optimum chip breakage. Ultra-fine-grain solid carbide delivers increased wear resistance plus a high degree of toughness. Balzers coating assures high wear resistance and optimum chip evacuation. Normally, no deburring is required for these drills in machining steel-like materials. A quote for the said drill and short description are attached to this reports as PDF files. The fixture used today at Colfor (Fig 21) does not allow objective determination of the actual burr size. Everything is left to the discretion of the operator who should be able to look though the drilled hole assessing the burr. It was noticed that some remaining water soluble coolant concentrated around the edges of the cross holes might create visual impression of an excessive burr while the actual burr size is normal. Therefore, it is suggested that the fixture should be redesigned to provide more objective burr measurements. Shaft rests on two V- blocks Holes to look though for burr assessment The source of light Figure 21. Inspection fixture. 18

Appendixes 19

Twist drills basic features (From Viktor P. Astakhov, Cutting Tool Geometry, PSMi Manual, 2006/2007) The twist drill bit was invented by Steven A. Morse who received U.S. Patent 38119 for his invention Improvements of Drill-Bits in 1863. The original method of manufacture was to cut two grooves in opposite sides of a round bar, then to twist the bar to produce the helical flutes. This gave the tool its name. Nowadays, a flute is usually made by rotating the bar while moving it past a grinding wheel which axis inclined by the helix angle to the axis of the bar and which profile corresponds to the flute profile in the normal section. A twist drill is defined as an end cutting tool having one or more cutting teeth with cutting lips formed by the corresponding number of helical chip-removal flutes. A common twist drill is shown in Fig. A1. It consists of the body, neck (optional) and shank. The working part has at least two helical flutes called the chip removal flutes. The lead of helix of the flute depends on many factors including the properties of the work material so it varies from 10 to 15 degrees; standard angles are about 22-30 degrees; and up to 45 degrees for high-helix twist drills. The flute profile and its location with respect to the drill longitudinal axis determine many facets of twist dill performance because: Flute profile determines the geometry of the drill rake face: the shape of the cutting edge (lip); the rake angle and its variation along this edge; the cutting edge inclination angle and its variation along this edge; the rake angle of the side cutting edge defined as the line of intersection of the drill margin and the flute over the length that slightly exceeds the feed per revolution. As a result, a great number of various flute profiles have been developed and many of them are available as applied to twist drills produced by various drill manufacturers. Flute profile parameters determine the diameters of the web (the core thickness), i.e. directly affect buckling stability of the dill. Flute profile together with the flute helix angle determine the torsional stability of the drill. Flute profile determines the reliability of chip removal, i.e. chip breakage into pieces (sections) suitable for transportation and easiness of such transportation. Therefore, the flute profile one of the major design features of a twist drill. 20

TAPER SHANK LEAD OF HELIX TANG DRIVE MARGIN FLUTES OD HELIX ANGLE STRAIGHT SHANK DRILL AXIS HEEL MARGIN FLUTE LENGTH BODY NECK SHANK LENGHT OVERALL LENGHT POINT (WORKING PART) SHANK DIAMETER CLEARANCE DIAMETER LAND FLANK POINT ANGLE BODY DIA. CLEARANCE HEEL DIAMETER CHISEL EDGE ANGLE CUTTING EDGES (LIPS) CHISEL EDGE RAKE FACE WEB DIAMETER or CORE THICKNESS PERIPHERY CORNER Figure A1 Illustration of terms applying to twist drills. The chip removal flutes intersect the flanks and the lines of intersection form the major cutting edges often called the lips. The drill manufacturer often contrived that the flute profile, flank shape and the point angle chosen produce a straight cutting edge as shown in Fig. A1 although a number of recent twist drill designs feature curved shape of these edges. The major cutting edge of a twist drill does not pass through the center of rotation as seen in Fig. A1 so the inclination angle of the cutting edge to the drill radius varies as the radius changes. The internal ends of the lips (called sometimes chisel edge corners) are connected by the chisel edge as shown in Fig. A1. Some important terms related to the twist drill design and geometry are defined as follows: Axis - the imaginary straight line which forms the longitudinal center line of the drill. Back Taper A slight decrease in diameter from front to back in the body of the drill. Body The portion of the drill extended from the shank or neck to the periphery corners of the cutting lips. Body Diameter Clearance That portion of the land that has been cut away to prevent its rubbing against the walls of the hole being drilled. Chip Packing The failure of chips to pass through the flute during the cutting action. Chisel Edge The edge at the end of the web that connects the cutting lips. Chisel Edge Angle The angle included between the chisel edge and the cutting lip, as viewed from the end of the drill. Clearance The space provided to eliminate undesirable contact (nterference) between the drill and the workpiece. 21

Cutter Sweep The section formed by the tool used to generate the flute in leaving the flute. Cutting Tooth A part of the body bounded by the rake and flank surfaces and by the land. Double Margin Drill A drill whose body diameter cleara nce is produced to leave two margins on each land and is normally made with margins on the leading edge and on the heel of the land. Drill Diameter The diameter over the margins of the drill measured at the periphery corners. Flutes Helical or straight grooves cut or formed in the body of the drill to provide cutting lips, to permit removal of chips, and to allow cutting fluid to reach the cutting lips. Flute Length The length from the periphery corner of the lips to the extreme back end of the flutes. It includes the sweep of the tool used to generate the flutes and, therefore, does not indicate the usable length of flutes. Galling An adhering deposit of nascent work material on the margin adjacent to the periphery corned of the cutting edge. Hill The trailing edge of the land. Helix Angle The angle made by the leading edge of the land with the plane containing the axis of the drill. Land The peripheral portion of the cutting tooth and drill body between adjacent flutes. Land Clearance See preferred term Body Diameter Clearance. Land Width The distance between the leading edge and the heel of the land measured at right angle to the leading edge. Lead The axial advance of a helix for one complete turn or the distance between two consecutive points at which the helix is tangent to a line parallel to the drill axis. Lip (Major Cutting Edge) A cutting edge that extends from the drill periphery corner to the vicinity of the drill center. The cutting edges of a two flute drill extending from the chisel edge to the periphery. Lip Relief The relief made to form flank surface. Therefore are can be several consecutive relives as the prime relief, secondary relief etc made to clear the loip as well as to prevent interference between the flank surface and the bottom of the hole being drilled. Lip Relief Angle Obsolete term as by Lip Flank Angle. Normally defines as the axial relief angle at the periphery corner of the lip. Although this angle is often shown in twist drill drawings, it does not make much sense as the lip flank angle normally varies over the lip. Margin The cylindrical portion of the land which is not cut away to provide clearance. Neck the section of reduced diameter between the body and the shank of a drill. Overall Length The length from the extreme end of the shank to the outer corners of the cutting lips. It does not include the conical shank end often used on a straight shank drills and taper shank drills. Periphery The outside circumference of a drill. Periphery Corner The point of intersection of the lip and the margin. In a two-flute drill, the drill diameter is measured as the radial distance between two periphery corners. 22

Peripheral Rake Angle The angle between the leading edge of the land and an axial plane at the drill point. Relative Lip Height The difference in indicator reading between the cutting lips. Lips Runout is another commonly used term. Relief The result of the removal of tool material behind or adjacent to the cutting lip and leading edge of the land to provide clearance and prevent interference (commonly called rubbing or heel drag) between the cutting tooth and the bottom of the hole being. Shank The part of the drill by which it is held and driven. Web the central portion of the body that joints the lands. The extreme and of the web forms the chisel edge on a two-flute drill. Web Thickness The thickness of the web at the point, unless another specific location is indicated. Measured as the web diameter as shown in Fig. A1. Web-Modification Modification of the web from its ordinary thickness, shape and/or location to reduce drilling thrust, enhance chip splitting and change chip flow direction. The simplest modification is web thinning. 23

Sphinx Phoenix Drill The Phoenix is a special heavy-duty solid carbide drill developed to cut extra-hard materials. You can be up to 100 times more productive with this drill than with its conventional solid carbide counterpart. Moreover, you can increase your feeds and speeds many times over. All of this is made possible by utilizing a completely new geometry, internal coolant and the most modern of coating techniques. Applications: Steel Stainless steel Cast iron materials Non-ferrous metals Product advantages: Maximum productivity due to ultra-high speeds and feeds. Special flute and tip geometry assures low cutting forces and optimum chip break. Solid carbide cutting material (ultra-fine-grain solid carbide) delivers increased wear resistance plus a high degree of toughness. Balzers coating assures high wear resistance and optimum chip evacuation. Special dimensions available upon request. Performance examples: Tool: Art. 50940 Ø1.30mm Piece being cut: Corrugated sheet Material: High Carbon Steel Drilling depth: 7.0mm (0.276 ) Coolant: Yes Parameters: v c 265 SFM f 0.005 /Rev. No deburring! Tool: Art. 50940 Ø3.50mm Piece being cut: Perforated plate Material: 316 LSS Drilling depth: 12.0mm (0.472 ) Coolant: Yes Parameters: v c 365 SFM f 0.006 /Rev. No deburring!

Sphinx Phoenix Drill Art. 50 940 d 1 - h6 d 2 - h6 l 1 l 2 l 3 40.50940.0100 1.0 3.0 38 6 8 40.50940.0110 1.1 3.0 38 6.6 8.6 40.50940.0120 1.2 3.0 38 7.2 9.2 40.50940.0130 1.3 3.0 38 7.8 9.8 40.50940.0140 1.4 3.0 38 8.4 10.4 40.50940.0150 1.5 3.0 38 9 11 40.50940.0160 1.6 3.0 38 9.6 12.6 40.50940.0170 1.7 3.0 38 10.2 13.2 40.50940.0180 1.8 3.0 38 10.8 13.8 40.50940.0190 1.9 3.0 38 11.4 14.4 40.50940.0200 2.0 3.0 50 12 15 40.50940.0210 2.1 3.0 50 12.6 15.6 40.50940.0220 2.2 3.0 50 13.2 16.2 40.50940.0230 2.3 3.0 50 13.8 16.8 40.50940.0240 2.4 3.0 50 14.4 17.4 With Internal Coolant 40.50940.0250 2.5 3.0 50 15 18 40.50940.0260 2.6 3.0 50 15.6 18.6 40.50940.0270 2.7 3.0 50 16.2 19.2 40.50940.0280 2.8 3.0 50 16.8 19.8 40.50940.0290 2.9 3.0 50 17.4 20.4 40.50940.0300 3.0 3.0 50 18 22 40.50940.0310 3.1 6.0 66 18.6 22.6 40.50940.0320 3.2 6.0 66 19.2 23.2 40.50940.0330 3.3 6.0 66 19.8 23.8 40.50940.0340 3.4 6.0 66 20.4 24.4 40.50940.0350 3.5 6.0 66 21 25 40.50940.0360 3.6 6.0 66 21.6 25.6 40.50940.0370 3.7 6.0 66 22.2 26.2 40.50940.0380 3.8 6.0 66 22.8 26.8 40.50940.0390 3.9 6.0 66 23.4 27.4 40.50940.0400 4.0 6.0 66 24 28 641 Fargo Avenue Elk Grove Village, IL 60007 Tel: 847-228-7660 Fax: 847-228-0881 www.bigkaiser.com 01/06 COPYRIGHT 2006 BIG KAISER PRECISION TOOLING, INC. ALL RIGHTS RESERVED

TO: PSMi 641 Fargo Avenue Elk Grove Village, IL 60007 ATTN: Viktor Astakhov phone: 847.228.7660 fax: 847.228.0881 FROM: Chris Prystawsky BIG Kaiser Ref: 07-11765 DATE: January 11, 2007 Page 1 of 1 Subject: American Axle Dear Viktor, Per your request, I am pleased to offer the following quotation. 1. Phoenix Drills Qty. Part Number Description Price Each Total Price 1 40.50940.0500 Phoenix Drill Ø5mm x 6xd $71.20 $71.20 1 40.50940.0540 5.40mm Phoenix Drill x 6xd $71.20 $71.20 1 40.50940.0570 5.70mm Phoenix Drill x 6xd $71.20 $71.20 1 40.50940.0580 5.80mm Phoenix Drill x 6xd $71.20 $71.20 *The only drill shank that needs modification is the Ø5.4mm which interferes with the flange of the shaft. All drills have Ø6.0mm shanks. All prices quoted are list. Quote is valid for 30 days. Delivery: Stock, BIG Kaiser Precision Tooling. F.O.B.: BIG Kaiser Precision Tooling, Elk Grove Village If you have any questions, please do not hesitate to contact me. Best Regards, Chris Prystawsky Application Engineer Asst. Product Manager Tooling Systems (BIG) cprystawsky@bigkaiser.com cc: Randy Richardson