Rotary Milling Cutter - Operating Instructions
I. Purpose
The wiper insert is used in conjunction with the wiper cartridge (CART-2) to produce superior surface finishes while maintaining the high speeds and feed rates characteristic of the Rotary Milling cutter. The wiper insert is designed to follow the rotating inserts, and clean or "wipe" off surface asperities left by the rotating inserts.
Fig. 1 - The wiper insert, set above the round inserts removes the surface asperities and eliminates the influence of height variation (face Runout).
The wiper system can be used for all materials presently machined with rotating inserts for semifinish, finish and superfinish milling operations for depths of cut not smaller than 0.010" (0.250mm) and not larger than 0.090" (2.3mm) (See explanations under Section V. Application Notes)
The cartridge CART-2 is designed to securely hold the wiper insert: A conventional square negative precision ground insert 1/2" I.C. x 1/8" thick - SNC 422 (12.7 mm I.C. x 3.2 mm thick.)
The CART-2 cartridge replaces one of the standard Rotary Milling Cutter cartridges (CART-1) in the cutter body of the Rotary Milling Cutter. It is clamped in the cutter body with the same front and rear clamps as the standard cartridge.
II. Cartridge Installation Procedure
1. Front and rear clamps hold the CART-1 cartridge in the cutter body. With the TWS-2 Torque Wrench, loosen the differential screws holding these clamps 1/4 turn.
2. Clamp the wiper insert into the CART-2 cartridge following the wiper insert indexing procedure (section III).
3. Insert the CART-2 cartridge, with the wiper insert securely clamped in its seat, into the cutter body. Tighten the rear clamp first, while at the same time pressing on the dovetail end of the cartridge. Tighten the front clamp last.
4. Check the height of the wiper edge with an indicator gauge or optical comparator. The cutting edge of the wiper insert should automatically position itself higher than the highest "tip" of the round insert by 0.001 - 0.003" (0.025 - 0.075mm). This is the optimum operating condition. If this position is not obtained, switch CART-1 and CART-2 cartridges in the Rotary Milling Cutter body until this relative position is achieved.
5. If the Rotary Milling Cutter is an older model that has cartridge height adjusting screws instead of solid set stops, it is recommended that the wiper CART-2 cartridge be placed in the pocket with the highest round inserts.
III. Wiper Insert Indexing Procedure
1. Loosen the wedge (2) by turning the differential screw (3) counterclockwise with the TWS-2 Torque Wrench. If the wiper was used in machining, remove the wiper, clean it and locate a new sharp edge. The wiper has 4 edges on each side of the insert permitting a total of 8 indexes.
 |
1. Body of wiper cartridge
2. Wedge WIR-1
3. Differential screw DS-1
4. Wiper Insert |
| Fig. 2 - Wiper Cartridge CART-2 |
2. Clean the CART-2 cartridge wiper pocket.
3. Insert wiper insert back in the pocket (between wedge and cartridge body.) Push it close to the cutter body radially and tighten the differential screw. Do not over tighten. Check that the wiper insert is on a flat plane with its entire support edge seated securely in the pocket. This step is most important!
With correct radial positioning of the wiper in the cartridge, the radius corner will be behind the tip of the round insert by 0.120" (3.0mm) assuring an optimum position for "wiping". This wiper position reduces the effective cutting diameter of the Rotary Milling cutter by approximately .250" (6.4mm)
If a larger "wiped" diameter is required, the wiper insert can be pushed closer to the effective cutting diameter, however, a minimum of 0.040" (1.00 mm) must be maintained between the effective cutting diameter and the corner of the wiper insert. By making this adjustment the effective "wiped" diameter will be smaller than the nominal effective cutting diameter by .080" (2.0 mm).
If exceptionally good surface finishes are required, it is recommended that the indexing be performed by taking the cutter off the machine, in order to inspect the wiper edge position and its parallelism with greater accuracy.
If the indexing of the wiper insert is performed on the machine, experience has shown that caution should be used when loosening the wedge to be sure the wiper does not fall out.
Fig. 3 - Effective Cutting Diameter and Effective Wiping Diameter for a Rotary Milling Cutter.
IV. Types of Wiper Inserts
Wiper inserts currently available from Rotary Technologies Corporation for the Rotary Milling Cutter are:
| WR-25 |
Tungsten Carbide wiper substrate equivalent to C2 carbide grade (K20). Recommended for non-ferrous metals/materials. |
| WR-55 |
Tungsten Carbide wiper substrate equivalent to C5 carbide grade (P20). Recommended for a wide variety of carbon and alloy steels. |
| WR-105 |
Silicon Nitride recommended for cast iron (providing milling speeds and feeds are adequate) and for carbon and alloy steels. |
| WR-110 |
Cubic Boron Nitride (CBN) for cast iron, nodular iron, nickel alloys, etc.
|
V. Application Notes
If the Rotary Milling Cutter with MU1000 silicon nitride round inserts is used to machine various non-ferrous metals and alloys (aluminum, magnesium, etc.) at very high cutting speeds, a C2 (P20) grade substrate (WR-25) or equivalent is recommended in order to prevent premature wear of the wiper edge.
The Rotary Milling Cutter with wiper inserts have been used to 'rough' up to 0.180" (4.6mm) depth of cut, then finish in a second pass at 0.040 - 0.070" (1.0 - 1.8 mm) depth of cut (cast and nodular iron applications).
VI. Operating Tips
Rotary Milling cutters are manufactured to have total indicator repeatability of 0.002" (0.05 mm). With appropriate feeds and speeds, consistent surface finishes of 80 - 125 micro inch - 2.0 - 3.2 micrometer Ra can be obtained without the CART-2 wiper cartridge and wiper insert system.
In order to assure repeatability, some users number the pockets on the cutter body. With this method each cartridge can be returned to the identical pocket from which it was removed for indexing.
VII. Depth of Cut
The Rotary Milling Cutter is most efficient at depths of cut less than .150" (3.8mm). Deeper cuts are possible at the sacrifice of insert life. Depths to .300" (7.6mm) in cast iron and .400" (10.0mm) in aluminum are possible if machine horsepower is available. The faster feeds and speeds at which the Rotary Milling cutters are operated will not only offset the depth of cut limitations, but also decrease floor-to-floor machining time. In addition, machining at shallower depths is easier on the machine spindle, table screws, and job fixturing.
VIII. Rigidity
As with conventional double negative geometry cutters, the Rotary Milling cutter requires strong fixturing, part rigidity (avoid thin walled parts), and minimum spindle extension to perform to its full capability. Compromising in any of these areas can have an adverse effect on overall performance.
IX. Coolant
When using silicon nitride inserts, coolant is generally not required. When using carbide inserts, flood coolant is required. As a general rule, a light spray mist should be used when cutting aluminum regardless of the insert used.
X. Maintenance
Under ordinary circumstances, the Rotary Milling cutter requires very little maintenance to keep it in top working condition. The cartridges should be lubricated with high temperature lubricant at the time the inserts are indexed or after 10 hours of actual cutting time. Apply lubricant (HTL-1) through the vent hole in the dove tail end. Rotary Technologies part number CLS-1 includes the lubricant and a convenient applicator designed for this purpose. Note: Over lubrication provides no additional benefit. One complete stroke of the applicator is sufficient. Rotary Technologies Corporation high temperature lubricant (HTL-1) is required. Any other lubricant used will reduce cartridge life.
|
