Calculate and design thread whirling blade parameters for Dental Implant 07

)

There are 6 blades in a swivel (Bl=6). Using the workpiece rotation speed 50 RPM (Nw=50), the numbers of chip for one pitch length can be calculated by the formula (2-15).

)

2. Effected of tilt angle and blade parameters on the thread profile (Figure 2-13) Using the thread profile forms blade profile.

a = 0.65 mm

Dw = 12 mm (Diameter of whirling ring)

The helix angles of thread can be calculated by the following formula (2-7)

There are many helix angles of thread with each diameter from Di to Do. Using C1 to C2, the helix angles are obtained as follows.

o

*When the tilt angle A=C1 the thread profile parameters can be calculated follow below formulas

4.4o

A=

B is the angle created by the centre line of workpiece’s cross section with the intersection of Whirling ring and external diameter. B is shown in figure 2-10.

f represents the expansion width when the tilt angle is 0º. The value of f and B is given by formulas (2-8) and (2-9).

683

c is the distance of the outer edge of the workpiece to the threaded top (formula 2-10).

d is the width of the threaded section.

e is the depth of the threaded section (formula 2-12).

The values of c and d by the following formula available,

g is moving distance of the nose blade when tilt angle varies from 0º to C2.

A mm

t

*When the tilt angle A=C2 the thread profile parameters can be calculated follow below formulas 2-10, 2-14, 2-12.

Table 2-2 shows different ways and will be able to explain the difference in diameter and threaded to be 4.4º, 5.8º tilt angle of the swivel.

Table 2-2 thread parameters vs tilt angles.

A (^o)

Comparison of d values and the width of the blade indicate that, the differences value are less than 2% or 0.008mm, while the difference value between e and the depth of the blade is less than 1%. This difference in engineering can be ignored. The blade engineer drawing

all dimentions in three corners are symmetric.

Relief angle 7

Z Scale 40:1

Figure 2-15 external thread whirling process in 3D model.

CHAPTER 3

OPERATIONAL STEPS AND CNC PROGRAMMING FOR MACHINING DENTAL IMPLANT 07

3.1 Operational steps

There are two ways to machine a dental implant using main spindle during cutting time and using main spindle and sub spindle simultaneously by using a Swiss-type lathe, SR-20RII.

The advantages and disadvantages of each method combined with the accuracy and productivity of the product are evaluated in order to make a best choice.

3.1.1 Machining dental implant using main spindle only

Figure 3-1 presents the method to machine dental implant using main spindle during cutting cycle.

Figure 3-1 machining dental implant using main spindle only.

In this case, the product is completed in one chuck. Therefore the product gets more concentric and coaxial. The clamping forces are located out of cutting area except cut off step.

The sub spindle chucks on to thread profile whith a force that can make workpiece stable is

3.1.2 Machining dental implant using main spindle and sub spindle simultaneously The second way to machine dental implant uses the main and sub spindles simultaneously as shown in Figure 3-2 and 3-3.

Figure 3-2 main spindle steps.

Figure 3-3 sub spindle steps.

Using this method, it will not achieve the best concentric and coaxial result, because the product is completed in two chucks. While using sub spindle, as shown in Figure 3-3, the clamping force is applied on the threaded area. Chuck marks will be found if clamping inproperly.

The processing does take advantage of extra sub spindle for processing in simultaneous with the main spindle. When the main spindle begins cutting a new product, the sub spindle

3.2 CNC program for machining dental implant

CNC programs shown below are for main (HEAD1) and sub spindle (HEAD2). Both programs are running independently. To ensure simultaneity, WAIT command(M200-M999) are added if nessary.

%

O0056 (HEAD1program)

#531=5.0 G99M3S500 M11

G4U0.2

G0Z10.0T0M25 M200

M20 M10 G4U0.2

T100 M27

G99G0X6.0Z-1.0M3S1000 T0

M1

G99M3S2000

T400 (Facing and Turning) G0X6.0Z0.0T4

G4U0.03 G1X-0.5F0.015 G4U0.05 G1X0.0F0.1 G4U0.03

G2X2.5Z0.6R1.60F0.015 G4U0.03

G1X3.3Z3.1F0.015 G4U0.03

G1Z6.5F0.015

G4U0.03 G1W0.5F0.02 G0X7.0 G0Z-1.0 T0

G101M5 (Grooving) M8

T3100 M36S4000 G50W-11.0

G0Y0.0X4.8C0.0T22 G0Z-2.6 G4U0.05

G1Z4.0 H237.6 F0.15 G4U0.05

G0 Y6.0

G0Z-2.6

G0Y0.0X4.8C120.0 G4U0.02

G1 Z4.0H237.6 F0.15 G4U0.05

G0 Y6.0 G0Z-2.6

G0Y0.0X4.8C240.0 G4U0.02

G1 Z4.0 H237.6 F0.15 G4U0.05

G0 Y6.0

M9

G101M5 M8

T3411 (External Thread Whirling) M36S6000

G50U0.912V18.298W-6.0 G0X0.0Y5.5Z-4.0C0.0 G0Z-1.0Y2.5

G1W11.4H5130F0.7 G0Y6.0

G0Z-5.0

G50U-0.912V-18.298W6.0 M36S1500

G4U0.1 M38 M9 T0

G101M5 (Deburr Grooves) M8

T3100 M36S4000 G50W-11.0

G0Y0.0X4.8C0.0T22 G0Z-2.6

G4U0.05

G1Z4.0 H237.6 F0.45 G4U0.05

G0 Y6.0

G4U0.05 G0 Y6.0 G0Z-2.6

G0Y0.0X4.8C240.0 G4U0.02

G1 Z4.0 H237.6 F0.45 G4U0.05

G0 Y6.0 G50W11.0 G0Z-1.0 T0 M38 M9

G99M3S2000 T400 (Turning) G0X6.0Z7.9T4 G4U0.03

G1X3.3Z8.9F0.015 G1Z10.9F0.015 G4U0.04

G1X3.5Z13.90F0.015 G4U0.03

G1W2.0F0.015 G4U0.04 G1X4.7F0.04 G4U0.03

G1X5.0W0.5F0.03 G4U0.03

G1W0.5F0.02

G99M3S200 T300 (Threading) G50W0.0

G0X7.0Z10.57 G4U0.01 G0X6.3

G66P6002W4.0R0.2095F0.33 X6.25

X6.20 X6.15 X6.12 X6.07 X6.04 G67 G50W0.0 G0X7.0 G0Z-1.0 T0

G99M3S2000 T400 (Deburring) G0X6.0Z0.0T4 G4U0.03 G1X-0.5F0.015 G4U0.05 G1X0.0F0.1 G4U0.03

G2X2.5Z0.6R1.60F0.015 G4U0.03

G1X3.3Z3.1F0.015

G4U0.02 G1W2.0F0.015 G4U0.03 G1X4.7F0.03 G4U0.03

G1X5.0W0.5F0.03 G4U0.03

G1W0.5F0.02 G0X7.0 G0Z-1.0 T0

G99M3S1700 T100 (cutoff) G50W-12.0 M300

G0X6.0Z14.0T1 G4U0.03

M82 M40

G1X4.0F0.01 G4U0.04 G1X4.2F0.1 G4U0.02 G1X3.0F0.01 G4U0.02 G1X3.8F0.1 G4U0.04 G1W-0.17F0.1 G4U0.04

G1X2.2F0.1 G4U0.02 G1X1.0F0.01 G4U0.04 G1X1.2F0.1 G4U0.02 G1X-1.0F0.007 G4U0.05 M41 M83 G50W12.0 G0W-10.0

M400

T1100 (drill 2.0) M500

M600 T100 G0W10.0 G0X6.0T1 G1X-1.0F0.2 M80

/G0X6.0W-0.5 /G0W2.0 /M98P7000 M81

M99 N0 M5 M11

%

O0156 (HEAD2 program) G99M5

G28W0.0T0 T2000 M200 M20 M75

/T2300 (drill 1.6) /G50W-45.65 /G0Z-0.5T26

/G83Z6.6R3.0Q700P200F0.02 /G80

/G50W45.65 /G0Z0.0 /T0

/T2200 (borring tool) /M3S4000

/G50U1.842W-42.678 /G0X3.1397Z-0.5T23 /G4U0.03

/G1U-0.8938W3.2150F0.01 /G4U0.03

/M1

/G1W0.5F0.01 /G4U0.04

/G1W0.3U-0.6F0.01 /G4U0.04

/T2400 (punching) /G50W-26.0 /G99M3S200 /G0Z-1.0 T24 () /G4U0.02 /G1Z2.20F0.05 /G4U0.02 /G50W26.0 /G0Z0.0 /T0

/T2200 (deburr borring tool) /M3S4000

/G50U1.842W-42.678 /G0X3.1397Z-0.5T23 /G4U0.03

/G1U-0.8938W3.2150F0.01 /G4U0.03

/M1

/G1W0.5F0.01 /G4U0.04

/G1W0.3U-0.6F0.01 /G4U0.04

/G0Z-1.0

/G50U-1.842W42.678 /G0Z0.0

/T0 /M5

/M1 /G4U0.05 /G0X2.17 /G0Z2.0 /G4U0.05 /M29S30

/G84Z5.7 F0.4 (H) /G80

/G4U0.05

/G50W33.0U-1.2 /M58

/G0Z0.0 /G4U0.05 /T0

/T2300 (deburr 1.6) /G50W-45.65 /G0Z-0.5T26 ()

/G83Z6.6R3.0Q700P200F0.02 /G80

/G50W45.65 /G0Z0.0 /T0

/M5 /T2900 /G0Z36.5 /M11 /M14 G4U2.0

/M84

G98G1 Z168.0 F2000 M14

G99M3S3000 (drill 2.00) G50W-18.5

G83Z3.25Q1000P100F0.02 G80

G50W18.5 T0

G28W0.0 M600 M5 M99

%

CHAPTER 4

USING PARTMAKER SWISSCAM TO PROGRAM NC MACHINES FOR MACHINING DENTAL IMPLANT 07

4.1 PartMaker SwissCAM introduction

The invention of NC (Numerically Controlled) machines has revolutionized the metal cutting industry. Computer controlled machine tools are faster and have a higher degree of accuracy and repeatability. NC machines can be programmed manually, which means typing machine "language" motion and other instructions into a computer text file. Such a file, called a part program, is then loaded into the NC machine memory for execution. Since the earliest days of computer technology a significant effort has gone into automation of the programming process by utilizing CAM (Computer Aided Manufacturing) Software. CAM systems accept user input in an interactive manner and generate a part program file automatically. CAM Systems provide assistance in tool path calculations and verification.

The overall productivity improvement resulting from a use of a particular CAM System depends on how long it takes to learn the software, how easy it is to use it and how much information a user has to enter during each programming session.

PartMaker relieves the tedious process of reentering the same tooling and process information over and over again in every program. It captures information about how to machine individual part features, namely, holes and profiles, and makes it available for future use. Using PartMaker the parts can be programmed faster, with higher precision. A tools database allows keeping track of current tool inventory. Geometric characteristics saved with each tool are used for the automatic determination of cutting conditions. The software performs automatic hole depth calculations by maintaining through hole clearance and blind hole relief distances for each tool. A cycles database allows creating and store cycles, sequences of repetitive operations such as center drilling, drilling, tapping, boring, reaming, chamfering and circular hole milling. A materials database allows storing materials data that is used in the automatic calculation of feedrates and spindle speeds. The software comes with

PartMaker allows visually synchronize processes being performed on separate spindles or by different tool posts [6]. This eases the process of optimizing cycle time to assure CNC Swiss-type lathe is being used most productively. PartMaker comes with an integrated simulation module that graphically simulates the entire cutting process utilizing solid modeling techniques. This allows catching errors before expending machining time.

4.2 PartMaker SwissCAM programming Dental Implant 07

4.2.1 Import 3D model and machining functions setup

PartMaker allows the user to create the geometry in CAD condition directly or import the model created from other design softwares. The ways to importing 3D solid model and selecting titanium alloy are shown in Figure 4-1 and 4-2.

Figure 4-1 import dental implant solid 3D model.

Stock boundary is set to Ø5 mm. The operation will be performed on main spindle of the machine. The stock boundary parameters need to be set for each cutting window face plane. (Shown in Figure 4-3)

Figure 4-3 define stock boundary.

The method to setup default machine is shown in figure 4-4. The chosen machine model is Star-20RII.

4.2.2 Determining window faces are associated with each face of a part

PartMaker’s Patented Visual Programming approach greatly simplifies programming parts involving both turning and milling operations in a single set-up, where such operations are being performed on multiple spindles. With this approach machining functions such as turning, plane milling and cylinder milling are carried out in separate 2D planes, allowing breaks down a part into its most basic elements when developing a part program. Program machining operations in different faces (planes) and specify up to twenty-four different faces per part. A separate face window is associated with each face of a part.

Dental implant is broken down into 3 elements plans (3 window faces) shown in Figure 4-5, which are turning process, milling helix groove process on main spindle and turning process on sub spindle .

Figure 4-5 define faces window.

4.2.3 Operational steps and tool paths

Complete machining of Dental Implant 07 requires 3 window faces. Each window face involves some operational steps with the detail of cutting conditions such as selecting tools, tool parameters, tool location, depth of cut, tool paths definition, cutting point, …etc.

Figures 4-6 and 4-7 show the operational steps and the tool paths of each window face

Figure 4-6 operational steps on main spindle.

4.2.4 Generating process table and synchronization

The process tables, detailing all of the machining processes for a part are shown in Figure 4-8. When PartMaker generates a process table, all cutting conditions such as feed rate and spindle speed (rpm) are calculated automatically based on the tools and material information previously entered. A time duration for each operation is shown, along with total machining time for both the main and sub spindles. These time calculations give a sense of how closely “balanced” machining is for a part, i.e. how much cycle time is expended on both main and sub spindles in addition to the total time to cut the part. Time calculations in PartMaker include both “in-cut” time as well as tool change time.

Figure 4-8 process table and synchronizing steps.

4.2.5 Simulating process

Having completed generating the process table and synchronizing operational steps, a simulation process is followed. The simulations are shown in turn by Figure 9, 10 and 4-11. Dental implant can be cut just how it would on machine tool. Simulation will show synchronization between the main and sub spindles. Figure 4-12 shows the product after process.

Figure 4-9 simulation on main spindle (turning).

Figure 4-11 simulation on sub spindle.

Figure 4-12 completion of simulation.

4.2.6 Generating NC program

Figure 4-13 NC program after CAM process viewing.

CHAPTER 5

CONCLUSIONS AND SUGGESTIONS

5.1 Conclusions

This thesis presents the machining technology for making dental implant that includes thread whirling process, CNC program, and CAM.

For thread whirling process, this study indicates that while the tilt angle is within ± 0.5º of the set value, variation of thread profile is negligible. In the case of small tilt angles, the thread cross-section can be used as the blade profile. Thread whirling can be used to machine multiple-thread by single-tip tool in multiple-lapse or multiple-tip tool in one lapse.

There are two ways of writing CNC programming for cutting dental implant. They are (1)using main spindle only during cutting time, or (2)using both main spindle and sub spindle simultaneously. This research recommands the second way aiming to reach optimal cutting time. The processing time was reduced significantly.

Currently there are many CAM softwares in the market such as MASTERCAM, PARTMAKER, CAMWORKS,…etc. PARTMAKER integrates the best with Swiss-type lathe and was chosen for the research. It is easy to program and simulate. The NC codes generated afterward were accepted by Star SR-20RII.

5.2 Suggestions

In thread whirling the workpiece is placed either inside or outside the whirling ring. This thesis only presents the fist process. The second is shown in Figure 5-1 below. Further research can try it for comparison to determine the better choice.

Workpiece Whirling Ring

REFERENCES

[1].http://www.tuannguyendds.com/index.php?option=com_content&view=article&id=47btrn g-rng-nhan-to-dental-implant&catid=36:tin-tuc-nha-khoa&Itemid=58

TM North Valley Dental Care Dr. Tuan Hoang Nguyen, D.D.S., & ASSOCIATES

[2].Operation Manual Guider Book (SR-20J CNC Automatic Lathe FANUC 18i−TB) STAR MICRONICS CO.,LTD.

[3]. CNC programming handbook: a comprehensive guide to practical CNC programming Peter smid.

[4]. http://www.genswiss.com/whirldata.htm

[5]. Titanium Design and Fabrication Handbook for Industrial Applications http://www.timet.com/fab-p14.htm

[6]. PartMaker SwissCAM User Manual Guide www.delcam.com

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